hash
stringlengths 32
32
| doc_id
stringlengths 7
13
| section
stringlengths 3
121
| content
stringlengths 0
3.58M
|
|---|---|---|---|
f7d157762f0f1ce82de62a5fe14e2af8
|
101 640
|
1.2 References
|
The following documents contain provisions which, through reference in this text, constitute provisions of the present document. • References are either specific (identified by date of publication and/or edition number or version number) or non-specific. • For a specific reference, subsequent revisions do not apply. • For a non-specific reference, the latest version applies. • For this Release 1997 document, references to GSM documents are for Release 1997 versions (version 6.x.y). [1] Council Directive 89/336/EEC of 3 May 1989 on the approximation of the laws of the Member States relating to electromagnetic compatibility. [2] EN 50082-1 (1992): "Electromagnetic compatibility - Generic immunity standard. Part 1: Residential, commercial and light industry". [3] IEC 801-3, (1984): "Immunity to radiated, radio frequency, electromagnetic fields". [4] GSM 01.04 (ETR 350): "Digital cellular telecommunications system (Phase 2+); Abbreviations and acronyms". [5] DTI/RA: "A summarized report on measurement techniques used to investigate potential interference from new digital systems". [6] INIRC (1988): "Guidelines on limits of exposure to radiofrequency electromagnetic fields in the frequency range 100 kHz to 300 GHz". [7] NRPB (1989): "Guidance as to restrictions on exposures to time varying electromagnetic fields and the 1988 recommendations of the International Non-Ionizing Radiation Committee". [8] IEEE C95.1 (1991): "IEEE standard for safety levels with respect to human exposure to radio frequency electromagnetic fields, 4 kHz to 300 GHz". [9] Draft DIN VDE 0848 Part 2 (1991): "Safety in electromagnetic fields; protection of persons in the frequency range from 30 kHz to 300 GHz". [10] CENELEC European prestandard ENV50166-2 (January 1995): "Human exposure to electromagnetic fields ,High Frequency (10 kHz to 300 GHz)".
|
f7d157762f0f1ce82de62a5fe14e2af8
|
101 640
|
2 Information available
|
A number of European organizations have conducted extensive investigations into GSM EMC. These investigations looked at the potential of a GSM transmission to interfere with a wide range of electrical apparatus. Having conducted both objective and subjective investigations, it was discovered that personal audio equipment (e.g. Walkmans) and hearing aids were most susceptible and most likely to be in close proximity to GSM apparatus. ETSI ETSI TR 101 640 V6.0.1 (2001-11) 6 (GSM 05.90 version 6.0.1 Release 1997) Of these two types of apparatus, hearing aids were considered the greatest potential problem and thus a considerable amount of modelling work was conducted in order to assess the likely incidence of interference in various scenarios. Interference with pace-makers was considered of utmost seriousness and consequently tests were made to investigate the possibility of interfering with certain types.
|
f7d157762f0f1ce82de62a5fe14e2af8
|
101 640
|
3 Cause of potential EMC interference
|
The source of GSM interference is the 100 % amplitude modulated RF envelope introduced by burst transmission necessary for Time Division multiple Access (TDMA). Audio apparatus having some non-linear component able to demodulate this Amplitude Modulation (AM) envelope will be subject to interference in the audio pass-band since the frame and burst rates for GSM are 220 Hz and 1,7 kHz. Another source of interference is the DTX (Discontinuous Transmission) mode of operation in GSM. In the DTX mode there are two signal components with much lower frequencies than the normal GSM transmission: a component with a frequency of 2,1 Hz corresponding to the transmission of the 8 timeslots of the SID (Signal Descriptor) message block, and another with a frequency of 8,3 Hz corresponding to the repetition rate of SACCH.
|
f7d157762f0f1ce82de62a5fe14e2af8
|
101 640
|
4 Laboratory results
| |
f7d157762f0f1ce82de62a5fe14e2af8
|
101 640
|
4.1 Hearing aids
|
Objective laboratory results from the United Kingdom, Department of Trade and Industry, Radiocommunications Agency (DTI/RA) [5] showed that a typical "behind the ear" hearing aid in normal (amplifying) mode was susceptible to peak GSM field intensities of: - between 10 V/m and 17 V/m in order to produce the same audio power as speech, 0,5 m in front of the hearing aid; and - between 5 V/m and 8,5 V/m to produce "audible, slightly annoying" interference. It was noted that the group of hearing aids tested showed a 4 dB spread in susceptibility in the normal mode and a 13 dB spread in susceptibility in the inductive loop mode. Subjective investigation conducted at BTRL with the hearing aid worn by the user showed that "audible, slightly annoying" interference was perceived when subject to a peak field intensity varying between 10 V/m and 4 V/m depending upon the orientation of the head. This was modelled by a peak field intensity of 10 V/m for a 270° arc and 4 V/m for the 90° arc not shielded by the head inferring an 8 dB attenuation provided by the head. This directional susceptibility corresponds to an average of 6,6 V/m and thus agrees with the DTI/RA objective results. These results were subsequently used for modelling activities to assess the consequences of this susceptibility in various scenarios. It should be noted that the susceptibility without head attenuation used in the model (4 V/m) is somewhat worse than the DTI measurements (5 V/m - 8,5 V/m) and thus the modelling results will be very much worst case. It was found that metallising the hearing aid case reduced the susceptibility with no head attenuation from 4 V/m to 12 V/m (10 dB). Laboratory measurements have been carried out also in Australia by Telecom Research Laboratories and National Acoustic Laboratories (annex F). In these measurements the field strength level causing useful "annoyance" threshold level of 10 dB above the noise floor of the hearing aids was measured and then compared to measured field strength of 2 W and 8 W GSM MS to determine the distances where the threshold levels can be expected. Both behind-the-ear and in-the-ear type hearing aids were measured, the former ones both with microphone input and telecoil input. The results are shown below. ETSI ETSI TR 101 640 V6.0.1 (2001-11) 7 (GSM 05.90 version 6.0.1 Release 1997) Table 1: Field strength and safety distances for noticeable interference Hearing aid type Field strength for noticeable interference Distance for noticeable interference 2 W MS 8 W MS Behind the ear, microphone input 0,7 - 3,1 V/m 2,0 - 10 m 3,5 - 20 m Behind the ear, telecoil input 0,4 - 4,9 V/m 1,5 - 20 m 2,5 - 40 m In the ear 4,9 - 32,3 V/m 0,2 - 0,6 m 0,4 - 1.5 m NOTE: The distances in table 1 can not be compared directly with those in table 2 because table 1 distances are approximate real-life distances whereas table 2 is based on theory. In Denmark a study initiated by the Danish ministry of communications has been carried out recently. The results of the study are in a report "Interference to hearing aids caused by GSM mobile telephones". Following are the main conclusions of the report: - so far there have not been many actual examples of interference but it must be foreseen that in 3 - 4 years there will be frequent reports of interference to hearing aids occasioned by GSM mobiles; - it is anticipated that existing hearing aids will be replaced by new models with generally greater immunity to GSM signals; in any event, in 5 - 7 years the risk of interference should have diminished significantly; - solutions to decrease the amount of interference based on GSM system will either have a highly limited effect (transmitter power regulation) or will be financially unfeasible (cell size optimization); - solutions based on design changes to hearing aids will generally be possible and must offer immunity against signal strengths of up to 10 V/m; some hearing aids used today already satisfy requirements and future models will be able to be so constructed as to meet them too; designing a new hearing aid with the requisite level of immunity would increase prices approx. DKK 100 per unit, which is a 4 - 7 % increase to a current price of a hearing aid.
|
f7d157762f0f1ce82de62a5fe14e2af8
|
101 640
|
4.2 Cardiac pace-makers
|
Work was carried out by CSELT Italy to investigate the effects of GSM type burst structure on cardiac pace-makers (annex D). Unipolar and bipolar types from one manufacturer were tested. The results show that, although it was possible to interfere with pace-maker operation in free space, it was not possible, with the equipment power used, to interfere with operation when the pace-maker, leads and electrodes were placed in a phantom simulating realistic use in the human body. The equivalent maximum field strength used for this test would not normally be exceeded at further than 0,5 m away from any allowed GSM transmitter except the maximum power base station. For information the field strength required to defeat the pace-maker in free space was in excess of 40 V/m for the most sensitive class of pace-maker. As there does not appear to be a problem with defeating of pace-maker operation by a normal GSM signal, the remainder of the work done by GSM, and thus the remainder of the present document, is restricted to scenarios for audible interference with hearing aids.
|
f7d157762f0f1ce82de62a5fe14e2af8
|
101 640
|
4.3 Domestic equipment
|
Tests carried out by various laboratories and collected together by the Radio Technology Laboratory (RTL) of the Radiocommunications Agency (annex E) show that for a limited number of devices under test the cassette decks, television receivers and portable radios/cassette players etc. are the most susceptible domestic equipment with the mean field intensities causing "visible/audible, but not annoying" interference being 2,9 V/m, 4,0 V/m and 5.6 V/m, respectively. For example for 8 W MS the field strength of 4 V/m will be found at distances less than 5 m (worst case assuming 100 % efficiency and free space path loss) as can be seen in table 1. This means that in practice, due to building attenuation etc., interference will not occur unless the transmitter and the victim equipment are in the same room. This is likely to occur if the GSM terminal is transportable (8 W output power for instance). ETSI ETSI TR 101 640 V6.0.1 (2001-11) 8 (GSM 05.90 version 6.0.1 Release 1997) Studies on the GSM interference to the fixed network telephone equipment have been carried out in France, Norway, U.K. and Italy (annex G). All the studies highlight the fact that due to the lack of an international immunity standard to the fixed network telephone equipment the interference problem varies from country to country depending on the national immunity standards. The study carried out in France summarizes that no telephone analogue equipment or audio terminal can comply with a 10 V/m GSM type field strength, and half of the telephone sets tested did comply with the 3 V/m immunity level, both results derived with a selected performance criteria of -50 dBmop/600 Ω in transmit direction and 50 dBA on receive direction. Regarding the maximum distances for potential interference the study gives the distances of 10 metres for 8 W GSM terminal and 5 metres for 2 W GSM terminal. The U.K. study tests the fixed network telephones and PBX equipment at 3 V/m and 10 V/m field strengths and concludes that in the U.K. the vast majority of telephones and telephone equipment is not susceptible at even 10 V/m. Hence, due to the immunity standard for fixed telephones the interference from GSM terminals is not considered as a major problem in U.K. In the Norwegian study it is summarized that with a 40 dB S/N ratio as a quality limit and with 10 W GSM transmitter 10 m away from a telephone, half of the telephones tested pass the test. Also, the study highlights the very large difference in the immunities of the fixed telephones, the immunities calculated in field strength being from 12,3 V/m to 0,6 V/m, with the same quality limit of 40 dB S/N ratio. The Italian study uses the same pass criteria as the French one and concludes that out of the tested fixed telephones, only an RF-shielded model and another with a very compact structure resulted complying with immunity requirements up to 6 V/m GSM field strength (that is 0,8 W GSM emission at 1 m distance), while some models did not even comply with 3 V/m (i.e. 0,8 W GSM emission at 2 m distance).
|
f7d157762f0f1ce82de62a5fe14e2af8
|
101 640
|
5 Modelling results
|
A wide range of scenarios were modelled (annexes A and B) to include the possible interference to hearing aid users from base stations, mobiles and handportables. Not surprisingly, by far the highest incidence of interference was caused in crowded urban environments where hearing aids and handportable transceivers are likely to be in closest proximity. It was found that a hearing aid user would experience 3 s of interference every 8 minutes whilst walking on a London street and would be subject to a 2,4 % probability of interference whilst travelling on a commuter train for a GSM system occupying 2 x 25 MHz. Further results showed that with 1 % of the train passengers using GSM transmitters (0,1 % previously) and an average susceptibility of 4 V/m, the probability of interference was 5 %. These modelling results were based on a small sample of hearing aids with immunities in the region of 3 V/m. More recent measurements have shown that some hearing aids, in particular the in-the-ear aids, have immunities up to 30 V/m (see annex F). This would reduce these probabilities by a factor of 100. It should be noted that the modelling work is based on free space path loses. The effect of, for example, people in a crowded train has not been measured, but in general it is expected that the presence of people or objects between the MS and the hearing aid will be to reduce the interference in most cases. It should be noted that all the scenarios examined assumed the hearing aid was active all the time. Clearly, there will be instances where the user will switch off the aid when not required to communicate. A further modelling exercise indicated that it was unlikely that a hearing aid user will be able to use GSM handportable terminals due to the interference effects.
|
f7d157762f0f1ce82de62a5fe14e2af8
|
101 640
|
6 Solutions
|
The generic immunity standard, EN 50082-1, produced by CENELEC, calls for immunity to RF electromagnetic fields of 3 V/m. This work has shown that current hearing aids have immunities close to this proposed level and that a handportable GSM transmitter is likely to present a field strength greater than this at regular intervals in a crowded environment and thus cause interference to the hearing aid user (annex C). The actual field strength from a dipole, as calculated from IEC 801-3, is shown in table 2 (the values are independent of frequency). ETSI ETSI TR 101 640 V6.0.1 (2001-11) 9 (GSM 05.90 version 6.0.1 Release 1997) Table 2: Close proximity field strengths Peak transmit GSM MS power Peak field strength (V/m) power (Watts) class 1m 2m 5m 0,8 5 6,3 3,1 1,3 2 4 9,9 5,0 2,0 5 3 15,7 7,8 3,1 8 2 19,8 9,9 4,0 DCS 1 800 MS power class 0,25 2 3,5 1,8 0,7 1 1 7,0 3,5 1,4 A solution to this potential problem could be achieved by a combination of increased hearing aid immunity and constraints placed on the GSM system in urban environments. Due to the likely peak field strengths that will be experienced from GSM transmitters in crowded urban areas, it is proposed that the immunity of future body worn apparatus, such as hearing aids, should be increased to 10 V/m since this has been found to significantly reduce the probability of GSM interference (this 10 V/m figure is derived from considerations of frequencies around 900 MHz and may not be applicable to frequencies significantly higher or lower than 900 MHz). Further to this, a number of simple constraints for urban GSM system design should be adhered to: - dynamic power control to be implemented at the MS such that only the minimum required transmit power is used at all times (BS interference was shown not to be a problem); - urban cell sizes limited to reduce required transmit powers; - discontinuous transmission (DTX) to be implemented where possible; - GSM base site and mobile pay phone (e.g. on train) transmit antennas should not be located in close proximity to electrical apparatus likely to be susceptible to this type of interference. It is assumed that DTX will provide a reduced interference potential although this has not been verified.
|
f7d157762f0f1ce82de62a5fe14e2af8
|
101 640
|
7 Non-ionizing radiation
|
Guideline levels for exposure to non-ionizing RF radiation have been published by many organizations including Non- Ionizing Radio Committee (INIRC), the UK National Radiological Protection Board (NRPB), the Institute of Electrical and Electronics Engineers (IEEE), German Electrotechnical Commission of DIN and VDE (DKE) and CENELEC. reference to these standards are given in reference [6] to [10].
|
f7d157762f0f1ce82de62a5fe14e2af8
|
101 640
|
8 Conclusion
|
Extensive research has highlighted a potential compatibility problem between GSM transmitters and body worn audio apparatus; in particular hearing aids. However, this research has been based on a limited sample of hearing aid types of fairly old design. An increased immunity for future body worn apparatus, enforced through the Community's EMC Directive (89/336/EEC), combined with some urban cellular design constraints aimed at ensuring the minimum transmit power is employed should ensure incidences of interference from GSM apparatus is kept to a minimum. The studies made have shown that the immunity level of currently available hearing aids may not protect hearing aids very well from the interference of GSM phones. Also, it has been shown that increasing the immunity to 10 V/m, as found possible by simple hearing aid modification, will reduce the probability of interference considerably. More recent research has shown some modern hearing aids to have 10 times the immunity of the older designs (in V/m). This would reduce the interference probabilities by a factor of 100. Concerning the domestic equipments it can be concluded that GSM transportable 8 W mobile stations are likely to cause problems to domestic equipment being used in a domestic environment. ETSI ETSI TR 101 640 V6.0.1 (2001-11) 10 (GSM 05.90 version 6.0.1 Release 1997) Further, it is recommended that the user's data (like user's manual) of the mobile should include a warning of the possible interference effects of the GSM mobile to the other electronic equipments.
|
f7d157762f0f1ce82de62a5fe14e2af8
|
101 640
|
9 Other EMC reports
|
CEPT-SE report "Summary document on the interference to radio and non-radio devices from TDMA-type transmissions". The report from CEPT covers much of the work included in the GSM report and considers EMC susceptibility of a far greater range of products. The findings of the two reports are similar. CEPT-SE report "Draft report from the ERC within CEPT on the impact from ISM emissions on mobile radio services operating in the 900 MHz band". The present document studies the potential for interference on GSM and other terminal equipment operating in the 900 MHz band caused by ISM equipment (Industrial, Scientific and Medical). It shows that spurious emissions from ISM equipment can degrade mobile radio service coverage at considerable distances. ETS 300 342-1 to 3 "Radio Equipment and Systems (RES); ElectroMagnetic Compatibility (EMC) for European digital cellular telecommunications system (GSM 900 MHz and DCS 1 800 MHz)". This standard defines performance requirements for radio communication equipment to meet the Community directive 89/336/EEC. It contains requirements for GSM terminal equipment but does not address the potential of interference with other electronic equipment such as hearing aids and cardiac pace-makers. Page 13 Annex A: A GSM interference model “ A GSM interference model. 22nd February 1990 Jon Short Cellular Radio Systems BT Laboratories 0473643954 ,’ Summarvo This document attempts to forecast the likely extent of intcrfercncc to hearing aid users fiwn GSM transmitters. The assessment is made through modclling of the GSM cellular system in various scenarios as the system matures fkom 1991 onwads. The potential intcrfczence in the individual scenarios is combined to asses the actual interference perceived by through modclling of ‘days in the life of hearing aid users. The critical inputs to the model are the hearing aid immunities as determined during extensive laboratory testing. The report concludes that a hearing aid user will experience regular daily intcrfemncc from GSM transmissions and this has been previously shown to be due to the TDMA name of the system. .“ .. (GSM 05.90 version 6.0.1 Release 1997) 11 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 14 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Qmmt!i 1) 2) 3) 4) ,,, 5) 6) 7) 8) Introduction Aasumptiona Cell Characterization 3.1) RF Link Budget 3.2) MinimumMS transmit POW= 3.3) Affetid area 3.4) Spectmm allocation 3.5) OveraUpmbabfity Scenarios 4.1) Vehicle mountedMS 4.1.1) Vehiclesand pedestrians 4.1.2) Trains 4.2) Bases 42.1) Low sites 4.2.2) High sites 4JL3) BuildingCWWW 4.3) Portableand transportableMS 4.3.1) Railway Station 4.3.2) 05ee 4.3.3) street 4.3.4) !lkain ‘ A day in the life of’ Eoexiarios 5.1) Daily commuterfi=omoutaidaLondon 5.2) Person workingand dwellingin Umdon 5.3) Retired person 5.4) Motommlytrafficjam . Ihamaaion 6.1) GSM Customerswith HearingAida. 6.1.1) Hand - Portables u~ 6.1.3) Mobiles 6.2) %hxtiona 6.3) ... Other interferences 6.4) Possiblevariables Conclusions References (GSM 05.90 version 6.0.1 Release 1997) ETSI 12 ETSI TR 101 640 V6.0.1 (2001-11) Page 15 ETR 357 (GSM 05.90 version 5.0.0): January 1997 u Introduction. Having completed extensive hearing aid immunity testing U. 5, 81 with simulatad GSM transmission, it was necessary to assess the likely impact of the laboratoryresults on hearing aid users. The key results taken km these laboratoryinvestigationswere that the hearing aids testedgave rise to ‘pemeptible’interkrance when subjectto a field strengthof 4V/m in some directions. A typical urbsn cell is eharactarizedusing an RF link budget and a number of necessaryassumptions.The salient assumptionsused in this paper are Iiatadin section 2 with local assumptionscontainedin individualscenarios. Having characterizedthe call, individualscenario’swithin the cell wherehearing aid usersmaycomein contactwith GSMtransmitterswerechosen.A conclusionis drawn horn the individualscenario’swhich highlightsthoselikelyto have the highestincidence of interference. Having arrived at a model covering separate scenmio’s, it was necessary to combinethese to build a ‘day in the life of a hearing aid user. Four typical ‘days’ were chosen -d illustratethe incidence of interferencewith respect to the hearingaid user. Subsequent discussion covers GSM subscribe who use hearing aids, possible solutionsand other interferences to hearingaids. It willbe notedthat this documenthasbeencompiledfiwn R@. 10,11and12with modificationsagreedat the coordinationmeetingsof 4/12189and 15/1/90heldat the DTL ~ i) ii) iii) iv) v) vi) vii) viii) ix) Aazmnmtione. A centralLondonbase site has a 2krnradiusand a base stationin power class4 (40W). All cells am operating at 50%capacity. Vehicle mounted transceivers have power control to sustain at least 102 uplink BER. Transportable arein power class2 (8W)andportablesin powerclass4 (2W)with antennashatig OdBigain. Subscriberswill be evenly distributedbetweenvehiclemountedtransceiver and portables/tranaportables. People are evenly distributedin the cell. Vehicle mountedtransceiversare locatedon threeconcentricrings withinthe ceII and are distributedin the ratio of their distancetlom the BS. The ri&ber of hearing aids in the UK is 1.5 miIIion(DEWSestimate 1 to 2 million)i.e 2.5% of the UK population. The mean duration of a call is 2 minutes. ETSI (GSM 05.90 version 6.0.1 Release 1997) 13 ETSI TR 101 640 V6.0.1 (2001-11) Page 16 ETR 357 (GSM 05.90 version 5.0.0): January 1997 & (W characterization S.1) RF link budget. This budgetis based on GSM Recommendation03.30. Rx RF input sensitivity= NF (dB) + Et/No (dB) + W - kT @BS for 102 BER (dBm) Where thermalnoiee, kT = -174 dBm/Hz@ 290K W (bitrate)= 10log 270.833kbit/s NF (noise figure)= 8dB E&o = 8dB Therefore,Rx RF input sensitivity@ BS = -104dBm. Ieotropicpower= RXsensitivity+ Interferencemargin+ Cable 10SS- btenna Gain Where interferencemargin= MB cable lees = 4dB antennagain = 12dBi , Therefore,Isotropicpower = -109dBm !’ Allowingfor Iognormel(5dB) and Rayleighfading(lOdB) marginsgives Minimumsignal level for 102BER = -94dBm. 32) Minimum MS tranarnit powers The requiredpowerto be radiatedfkoma mobilestationto maintaina 102uplink BER maybe fbundafter characterizationof the propagationpath lees. A typicalcentralLondoncell is 2kKnin radiusand has a BS located2m above the roof of a tall building.This buildingwillbe locatedin a denseurban environmentand of similarheight ta its surroundings(@m). Assuminga receive antennaheight of 2m and a fkequencyof 900MHz,the path loss maybe found from equation3.25 in Ref17 ~ti = 69.55+26.1610gf - 13.8210g& - A(hJ + (44.9-6.5510ghJlog ~~ (dB) where f- ikequencyin MHz (900) & - transmitantennaheight(62M) &-diatmca&om BSinkm and km equation3.27 in Ref7 A(k)”: 3.2(log(ll.75 hJ~ -4.97 (dB) L - receive antennaheight(2m) These equationsthus simplifi to L@= 121 + 3310g~ti (m) ETSI 14 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 17 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Such a callmaythusbe characterizedby a lkm interceptof 121dBand a pathloss of slops Y=3.3.Hence the minimum tran@t power needed - the MS to maintaina 104BER will be 121.94= 27dBm @ lkm (500mW’) .27+3310gl.5= 32.8dBm@ l.lkn (1.9W) 27+3310g2= 36.9dBm@ 2km (4.9W) all powersquoted being ERP at MS. Equationfor interferingdistance, &, S. 3?2 and S = G P, where S = power density E 4%~~ G = antennagain E = field strength Therefore, ~~ = G 302P, However, since path loss calculation leads to ERP‘:&m the mobile station then the antennagain term, G, is redundant.i.e G = 1. It was founcl during interference tests lJtE&5],that a realistic hearing aid susceptibilitywas 4 V/m for a 90 degreearc and 10V/m fbrthe remaining270 degreesas shown in Fig.lo -. Fig.1 Let interference radius at 4 V/m be & and at 10 V/m d10then %2= 30 P, = 1.875Pi and 16 . ETSI (GSM 05.90 version 6.0.1 Release 1997) 15 ETSI TR 101 640 V6.0.1 (2001-11) Page 18 ETR 357 (GSM 05.90 version 5.0.0): January 1997 di~ = 30 P, = 0.3Pi as shownin Fig.1 100 and & = 3z4d,7 = 0.71 Pt as shownin Fig.1 Therefore, &= Al+& = 2.18 Pi Eq. 1 3.4) spectrum allocation The GSMsystemwill probablyoperatewith3 basesitesper clusterandtherefore, even if sectorizationis employe&the entirespectrumallocationwill be used repeatedly by groups of these base sites. It has been assumedthat each base site ( BS ) covers a cimllar ma of radius 2kln. The GSM systemwill begin in 1991with an initial duplex spectrumallocationof 5MHz per operatorabove the current TACSbands.This allows252001sHz carriers and thus 25/3=8 tiers per BS and 8 x 8 time slots = 64 physid bek per BS w operator. Assuming that there will be no more than 8 of these time slots unavailablefor trafliq then 56 physical channelsremaingivinga maximumof 112 subscribers. Asthe GSMsystemmatures,thecurrentTACSallocationwillbe graduallyhanded over untilGSMoccupiestheentire25MHzcellularallocation.Eachoperatorwilltherefore have 12.5MHzor62200kHz carriersandthus620=21 carriersperbasesite.Thisnumber of carriers allows 21x8=168 physical channels and thus 160 available for traffic per operatorand 320in total. %5) Overall probability. It was found that a good approximationto even distributionof MS’s could be attained by assuming the transmitters were located on three concentric rings and distributedin the ratio of their distancefmm the BS. Two rings provedto be inaccurate with four givinglittle changein the result obtainedwith three. Using a 10MHzallocationand fidl cell capacitygives the followingresult: l12x~= 25 MS @ lkm 4.5 l12x~=37Ms@l.5km 4.5 112x 2 =50 MS@2km 43 .. ETSI 16 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 19 ETR 357 (GSM 05.90 version 5.0.0): January 1997 The aflbctedarea around each transmitterfivm equation 1 is: 2.18 x 0.5 = l.lmz 2.18 X 1.9= 4.1m2 2.18 x 4.9 = 10.7m2 Giving a total a.fEectedarea from MS’s of 25x1.1 + 37x4.1 + 5ox1O.7= 714.2m*. Assumingthe BS is power class 4 (40W) then, fiwm equation 1 them will be a ibrther affectedarea of 87.2mzamnmdthe BS giving a total of 801.4m2. Since the ama of the 2km cell is YC(2000Y= 1.26x107mZthen the percentage @ected area is ~o,” o.oo649b Substitutingfigures for a fully loaded 25MHz systemyields a total affectedama of 2123.4m2or 0.017%. As yet, however, we have no informationconcerning the fiwquencyand duration of this interference. ~ 4s) u giving scenarios 1, Vehicle mounted MS. Vehicles and pedestrians. A mobile on the edge of the 2km cell has been shown to be transmitting4.9W rise to an ailkctedarea of 10.7m2and hence a meaninterferenceradiusof 1.8m. Assumingtheseparationbetweenpedestriansonthepavementandvehicleson the road is 4m, the hearing aid user will not experience interferenceh the transmitter. Evenif theaidis orientatedwithmaximumsusceptibilitytowardsthe road,thecarwould still have to be closer than 3m to causeinterkence. It is uniihely thut inteqkmce will be pemeived ~m vehide8 on the road whilst walking on the pavement. . 4.1.2 Trains. If it is assumed that there is a IOdB attenuation into a carriage fkom a rod mountedantenna,thena GSM pay phone on the train in power class 1 (20W) will have an affkctedradius in the train equivalentto that from a 2W transmitter. Aeeumingthetrawdttar klocatadinthe centreof thetrain,it is foundthat 1.2M or 1.2% of the train will be afEectedfkom equation 1. Assuming people are evenly distributedon the train then the probabilityof perceivingintetierence is 0.012. It should be noted that investigationhas shown that pemonal tape players are equallyas susceptibleto AM transmissionand there is likely to be a high densityof such equipmenton commutertrains. The probability of interference fim a pay phone on a train is 0.012. ETSI (GSM 05.90 version 6.0.1 Release 1997) 17 ETSI TR 101 640 V6.0.1 (2001-11) Page 20 ETR 357 (GSM 05.90 version 5.0.0): January” 1997 402) Bases. 4.2.1) Low sites. If it is assumedthat the BS is ~wer class 4 (40W),then the afkcted areawill be 942m2&am equation 1. Assuming people are evenly distributedwithinthe cell, then the probabilityof a hearing aid user experiencinginterferencewill be 942 = 7.5X l& 1.26x107 since the area of a 2km radius cell is 12.6km2. The probability of intetienmce j%oma base site whilst walking on the pavement is negligible. This is fiwther reduced since BS’S will be sited on top of buildings and not at ground level. 4.2.2/ Hizh Sites. Many (MM BS will be located on top of tall buildingswhich maybe office blocks containing a high densityof people. hbgtieti~io ~ofa~doffi~~~~~x 15x15 mwitha BS antenna mounted 10M above the top floor then radiation at angles greater than 60 degrees from the main lobe will penetratethe buildingassuming the antennahas not been tilted to mo@ coverage. The vertical radiation pattern fkoma typical sectorizedBS antinna shows that radiationat 60 degreesor greatertim the mainlobeiasuppressedby 20dBto SOdBand thus, assuming an attenuationof 10dBlRef.6]into the buildingand a further 5dB from the roof (no windows ) gives a minimumattenuationof 35dB. Assuming the transmitteris in powerclass 1 (320W)55dBm,then the analogous scenario is a 55435= 20dBm (1OOMW)transmissioninto &es space. This equat8sto an interference radius of 0.26m at 60 degrees born the main lobe and O.&m (65dB attenuation)vertically downwardsfrom equation1. It is themfom unlikeiy thut hearing aid users in an ome block directly underneath a (2SM BS will experience any interfmnce even if they w at the top of the building and the BS is in power cltis 1. 4.2.3) Building coveraze. A typkal attenuationinto a building is 10dB [Ref.6] and thus the interference radius fmm a class 4 BS (40W) into a building will be equivalent to that &m a 4W . ~* an.cmensite. It fbllowsthat anY buiklbw within a 1.7mradiusfkomthe BS will have su&ie& field strength inside th~ buildi~ to hearing aid users. rise to 403) SLiLD As th,iadistance is not practically malisabls, it is most interfienmce in a@acent buildings. Portables and Tranaportables. Railwav Station. give *e to interferenceto unlikely that a BS will give Portable GSM transmitters may be in power class 4 and will hence have a ETSI 18 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 21 ETR 357 (GSM 05.90 version 5.0.0): January 1997 maximumpower of 2W. This gives ~ to an tiected ama of 4.4m9per transmitter, assumingno antennagain at the portable;fkomequation 1. Taking the area of a platform as IOOmx 10m = 1000rn*and the number of platformsas 10 then the total station area is 10,000m*.If each train has 10 carriages carrying 100 people, and a train arrives at each platform during the rush hour simultaneouslythen NM()x 10 = 10JMOpeople will be in the station at any one time leadingto 1 personper m2. Thepopulationof greaterLondonis roughly7 millionin an areaof 15801Rn2which is assumedto rise to roughIy10million,&un tra.i%cflow analysis,duringworkinghours. Assumingthe stationis locatedin a 2km radiuscall of ama 12.6km2and that the populationof Londonis evenly distributedin the 1580km*within Greater hmdon, then Ioxl@ X 12.6 = 80,000 1580 people will be in the cell. Since there are 10,000peoplein the station during rush hour (1/8thof the total), assumingthe cell is 50% loaded and that 50% of calls will be fkomhand portables then 28x l/8 = 3.5 calls will be activein the stationat any one time duringrush hour with a 10MHZallocation Since each transmitterhas an af%ctedarea of 4.4rn2around it then a total area of 3.5 x 4.4 = 15.4m2( 0.154% ) of the station area will be affbctad.Them is thus a probabilityof 0.00154that a hearing aid user will be in an a6@ed ama assumingclass 4 portabletransceivers. When the system @y occupies25MHz, the number of calls originatingin the stationiiwmhandportablesrisesto 80x l/8 = 10,the afIbctedareato 10x 4.4 = 44m2and thus the probabilityrises to 0.0044. Theprobability of interference~m a handportable tmnsceiver in a milwaystatwn is 0.00154 with a 10MHz allocation and 0.W44 with 25MHz. It has been found that there are 80,000 people in a 2km radius cell thus with a 50% loaded cell and a 10MHz allocation,28 of these ( 1 in 2800 ) will be using a GSM hand portable.A typical office has 1 personin l(hnaand hence with a 10 storeybuilding with 100 people per floor there will be 1000people in 10,000m2. Since 1in 2800peoplewill be usinga GSMtransmitter,0.36peoplein thebuilding will be radiating2W (class 4) givinga total affected area of 1.6m*fkomequation 1. This equates to 0.016% of the office area and hence a probability of interference of 0.00016 assumingeven distributionof workers. With a 25MHzallocation,1 in 1000peoplewill be using a GSM handportableand thus the totalfiected areawill be 4.4m2ikomequation1 and theinterferenceprobability rises taOJIUWL Thepmbabiiity of interjknce jhm hand portable tmnsceivers in an o#Ze bkch k 0.00016 with 10MHz allocated and 0.00044 with 25MHz. - 4.3.3] Street Assumingthe pavementsof central London are 3m in width and are locatedon both sides of the road then, knowing there are 17.5 km of road per km2,we have a pavementarea of 17.5xl@ x 2 x 3 = 100,000m2in Usm2.Assuming there is 1 personper 5m2then there will be 20,000 peopleon the pavementsin lkna2. Assumingthis representsa 50%loadedcell andthe allocationis 10MHzthenthere ETSI (GSM 05.90 version 6.0.1 Release 1997) 19 ETSI TR 101 640 V6.0.1 (2001-11) Page 22 ETR 357 (GSM 05.90 version 5.0.0): January 1997 will be 28 actively transmitting hand portablesdistributedbetween20,000 people ( 1 in 714 ). Since the pavement is 3m in width then there will be 1 person every 1.6m and hence 1 hand portable every 1.6x 714= l143m. Assumingthe transmitteris stationary and the hearing aid user is walkingat 3km/h (0.83m/s),then it will take 23 minutes to walk between transmitters. When the system occupies25MHz,there will be 1 in 250 people with an actively transmittinghand portable and thus one transmitterevery400m. At 3km/hit will take 8 mi!lllt= to -k bCtWW!Xitransmitters. If the transmitters in power class 4 (2W) thentheinterfimnce radiuswillbe 1.2m from equation 1, and thus the subject will have to walk fbr 2.4m whilst experiencing interference.At Win/h this will take 2.9 seoonds. The@re, a hearing aid ueer walhing along a Lm&n street duringpeak time will experience 2.9 seconds of inte~emnce j%omhand portable tmnsceivers every 23 minutes with 10MHz allocated and evay 8 minutes with 25MHz. 4.3.4) Train. Sinceit has bean shown that there are 80,000peoplein a 2km radius cell and assuming50%of the 112 channelcapacitywill be takenup by hand portablesthen 1 in 2800 people will camy portabletransceivers. .1 Assuming the train is carryingworkersto L&don, then roughly 0.36 people will be using a GSM hand portable.If this is a class 4 (2W) transmitterthen the interfering radius will be 1.2m and hence, assumingthe transmitteris not at the end of the train, a 0.36 x 2.4 = 0.9m length of the train ( 0.9% ) will be affected. Assuming an even distributionof peopie, the probabilityof interferenceis 0.009. Witha 25MHzallocation,thepenetration rises to 1transmitterin 1000peopleand thus 2.4% of the train will be afkted and the probabilityrises to 0.024. Again there are likely to be a large number of personaltape playem on such a train which have been found to be equallyas susceptibleto interference. Thepmbability of inte#emnce fim a hand portable transceiver on a train is 0.009 with 10MHz alkmzted and 0.024 with 25MHz. n ‘A Day in the life of scenarim 5.1) Daily commuter from outside I.andom This day in the life of a hearing aid user is made up of the followingscenarios Travel fkomhome ( mral ) to railwaystationand return 2 x 15mins= 30mins Re@xL.tzainjOumay tAhmdon 2xlhr =2hrs Time spent leaving and waiting for train 2x15mins=30inins Tubejourney 2x15mins=30mins Walking to ~d fkomoffice 2x15mins=30mins Time spent in office 8hrs The travel conducted in the rural area and on the tubemaybe ignored since them will be no interference. When traveling on the train, interferencemaybe causedby a pay phone on the train or fkom a hand portable. The probabilityof perceiving interference fkomeither of these ETSI 20 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 23 ETR 357 (GSM 05.90 version 5.0.0): January 1997 sources is P*, = Pm*+ pa+ PP*PH = 0.012+ 0.009 + 1.08x104 = 0.021for IOMHZ Pti = 0.012+ 0.024 + 2.88xl@ = 0.036for 25 MHz Assumingthe average durationof a call is 2minaand since the time spent on the train is 2 hours, then Total interferenceduration= 120x 0.021 = 2.5 mine Numberof calls = 2.5 = 1.26 calls 2 ‘.NmebetweencaIIs= 120 = 95 mine 1.26 SubstitutingP-l = 0.036 gives a correspondingtime between calls for a 25MHzsystem of 56 minutes. U will be notedthat if the probabili~ ofinterfemnm fiwrnthe pay phone and the handportabletransceiverareseparated,thetimebetweenexposuretointerferenceforthe duration of a call is 167 minutes due to the pay phone, 222 minutes due to the hand portablewith 10MHzallocatedand 83 minutesdue to the hand portable with 25MHz. Whilst on the train interference wiU be experienced for 2mhs evtvy 95mins for a 10MHz system and evew 56 minz fbr a 25MHz system. Whilst in tbe railway station,the probabilityof incidence of interference is 0.00154( 10MHz) or 0.0044 ( 25MHz ). Assuming 30 minutes ( 1800s ) are spent in the railway stationand a call lasts for 2mins, then Total interferenceduration= 1800x 0.00154= 2.8seconds Numberof calls = 2.8 = 0.02 calls m Time betweencidls = 30 = 22 hours a Substitutinga probabilityof 0.0044givesa correspondingtimebetweencalls for a 25MHz systemof 7.6 hours. Whilst in a milwa.. - interfikrenceLuillbe experiencedfor 2 reins eve~ 22 hours /br 10MHz and eve~ 7.6hours for 25MHz. It has been s@wn in section 4.3.3 that a 2.9 second burst of inteflenmce wiff be heard eve~ - 23 minutes jbr 10MHz and eve~ 8 minutes for 25MHz. During the 8 hours in the office, the probabilityof interferenceis 0.00016 with 10MHz and 0.00044with 25MHz.Assuming2 minutecall durationthen Total interferenceduration= 8 x60x60x 0.00016= 4.6seconds Number of calls = 4.6 = 0.038 calls ETSI (GSM 05.90 version 6.0.1 Release 1997) 21 ETSI TR 101 640 V6.0.1 (2001-11) Page 24 ETR 357 (GSM 05.90 version 5.0.0): January 1997 120 Time between calls = 8 = 208 hoiws 0~8 Substituting a probability of 0.00044 gives a correspondingtime between calls for a .25MHzSySteMof 75 hours. Whilst in the ofiee, inteqfmmce will be heard for 2 minutes eve~ 208 hours /br a 10 MHz system and evay 75 hours fir a 25MHz system. Ovendl conclusion of *cenaria S.10 The incidence’sof interference will be as follows: 10MHZ. 1 x 2 minutes every day on the train 1 x 2 minutes at the station every 1.5 months 1 x 3 secondburst every day whilst walking on the street 1 x 2 minutes every month in the @ice ? 25MHZ. 2 x 2 minutesevery day on the train 1 x 2 minutesat the station every 2 weeks 4 x 3 secondburst every day whilst walkingcmthe street lx2minutes every 9daysintheoffice M) Person working and dwelling in London. This day in the life of a hearing aid user maybe characterizedbt the followingscenarios . Walk &omhome to tube station 2x15mins=30rnins Tubejourney - No interference Walk *m tube station to office 2x15mins=30mins Total time on street= 60 mine ‘lYmespent in office 8 hours OvemU conclusion of scenario 63. Using the reasoning in 5.1, the incidenceof interferencewiIIbe as foIIows. 10MHZ. — .+ 3 x 3 second burst every day whilst walkingon the street 1 x 2 minutesevery month in the offke 25MHZ. 7 x 3 secondburst every day whilst walkingon the street ETSI 22 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 25 ETR 357 (GSM 05.90 version 5.0.0): January 1997 1 x 2 minutes every 9 days in the office 5.3) Retired peraom Whilst the retiredpersonis dwellingin a rural araa,the incidence of interfbnmcewill be negligible. However,if that person spends a day shopping in London, the day may be characterizedas f~ows. Travel fkomhome ( rural ) to railwaystation and return No Merf&wence Return trainjourney b London 2xlhr =2hrs Time spentleavingand waitingfor train 2x15mins=30mins Tubejourney No interference 3 hours shoppingof which 1 hour is spent in the street 1 hour Overall conckwn of 8cenario 5.3. Using the reasoningin 5.1, the incidenceof interferencewill be as follows. 10MHZ. lx2minutes onthe train Unlikelyincidenceof intdersnce at station ‘” 3 x 3 secondburst whilst walkingon the street 25MHZ. 2x2minutes onthetrain Unlikelyincidenceof interferenceat station 7 x 3 secondburst whilst walkingon the street 5.4) Motorway traffio jam Ithasbeenshown~f.10] thata hearingaiduserdrivinga vehicleon a motomvay, with the aid orientated such that maximum susceptibilityis towards the trafEc, will experienceinterferen~ if the adjacentvehicleis radiatinga (XM transmitpowerof more than 2W. It wasfoundthat theprobabilityof the adjacentvehiclehaving a GSM transceiver was 0.05 andthatif the traflichad a relativespeedof 5 mph interferencewould be heard for 2 secondsevery 4 minutis. 6.1) GSM customers with hearing aids. - 6.1.1) HandPortables. Equation1 states that&= 2.18 P, and hence d2mm= 2.18 P, K The distancebetweenthe ears is less than 0.25m and hence ETSI (GSM 05.90 version 6.0.1 Release 1997) 23 ETSI TR 101 640 V6.0.1 (2001-11) Page 26 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Pt= 0.252 = 90mW 0.7 or, the maximumtransmitpower fmm a hand-portabletransmitterheld to the unaided ear is less than 90MW to prevent interferenceto the hearing aid on the other ear. Ifit is assumedthat minimum susceptibilityis in the directionof the transmlGtter ( i.e throughthe head) than this power may rise to 210mW.Since GSM hand portable’s in power class 5 will be radiating 800MW,a hearing aid user will be unableto use such a transceiverwhen not under power control. mm nmmtables. Transportable transceivers will be in power class 2 end will hence radiate a maximumpowerof8W with an interferenceradiusof 2.4m&omequation 1.‘I%eoperator of such a transceiver will obviously be within this radius and hence interferencewill be perceivedby a he*g ~d -r whi~t a @ iSbetig made. It is Pmsiblethat thesubject could orientate himself with respect to the antenna to eliminate the interfkrencaand make a call possible. 6.1.3) Mobiles. An investigationM.9] has shownthata hearingaideddriverof a vehicleis likely to be ableto use a GSM mobiletransmitterprwided the antennais mountedin thecentre of a continuousmetallicroof. Other antennapositiom or a non-metallicsun-roofmaylead to unacceptablyhigh field strength inside the vehicle. 62) &dUtiOIML It was noted during in&fbrence testing, that the 100% AM introducedby the TDMA structure of GSM was the cause of the interkrence and that continuousGMSK had no effect. The inter&rence &m the base site could therefbrebe eliminatedby till loading at all times i.e all time slots active all the time and constant amplitude transmission.However this dramaticallyincreasesCA fm the fbllowingreasons: i) Continuoustransms“ sion requires unused time slots to be active . ii) Discontinuoustransmission(DTX) at the BS wouldbe impossibleleadingto a two fold degradationin spectral efficiency since one way speechis interspersedwithroughly50% of silence. iii) Adaptivepower control at the BS wouldbe impossiblesince this wouldbe requiredon individual-timeslots leading to amplitudemodulationof the carrier. It should be noted that anythingless than 100%loading WWresult in a similar audiospectrumperceivedby the subjectashavingonly one timeslot active.Thisis tosay that the audio spectrum demodulated&oma one time slot activeBS will be the sameas that from one with one time slot inactive. The base site scenarios presentedin this documentarebased on the resultsof the interferencestudies at BTRL i.e one camier active.However,a GSM basesite will have 8 carriers per cell when occupying 5MHz per operator and utilking a three cell repeat pattarm.Since TDMA fkames on separate carriers will be synchronbed at the BS, the broadband AM demodulation process may give rise to 8 times (9dB) increase in ETSI 24 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 27 ETR 357 (GSM 05.90 version 5.0.0): January 1997 interferencelevel when correspondingtime slots are active. 6=6) Other interferences. Thetwo hearingaid users whotookpartin theoriginalsusceptibilitytesting were given a questionnaireconcerningcurrentlevelsof interibrence. It wasdeterminedthatonesubjectusedhishearingaidonly once or twice a month where the other used his for the mqjori~ of the working day. The times when the aids would defitely be used were in the office, at meetingsand during lecturw. Bothsubjectsveryrarelypemeivedanyinterferenceto theiraidswithone recalling only ever hearing a single burst lasting for several minutes. The second subject recalled hearing bursts lasting a second or so very intkequentlyand identified the source as fluorescent lights. 6.4) Possible variabl~ The scopeof this model is seen to be smalland dominatedby assumptions.There follows a list of variables that may significantlyaffect the conclusions drawn fkomthe model. i) ii) iii) iv) v) vi) vii) viii) ix) The hearing aid user may switch the aid off for periods of the day when verbal communicationis not essential. Hearingaidusersmay identi&the sourceof theinterferenceand learn to position themselvesaway * this source. The scenariosonly apply to GreaterLondon. There tendsto be a naturalexclusionzonearounda personusing a hand portable transceiverwhich will reduce the areain which a hearing aided pedestrian may be and hence reduce the probabilityof interference. Discontinuoustransmissionat the MS will produce breaks in transmission will change the way in which interferenceis perceived. . Not all trainswill have a publicpayphoneand those that do will have the phone locatedbetweencarriagesi.e where thereare no passengers. The hearing aided populationwill be biased towards retired people who do not commuteinto the city. Due to the natureof the calculation,the numberof exposures to interfiince are averagefigures.The standarddeviationawaytim this mean is likely to be large. The ‘l&d portableon a train’figuresmaybe si~cantly reduced if the hearing aid is not locatedin the centreof the trainand if a significantattenuation of the transmittedsignal is createdby the crowdedenvironment. ETSI (GSM 05.90 version 6.0.1 Release 1997) 25 ETSI TR 101 640 V6.0.1 (2001-11) Page 28 ETR 357 (GSM 05.90 version 5.0.0): January 1997 n i) ii) iii) iv) v) vi) vii) viii) ix) x) xi) Concluaions. The scenariospresentedin this documentsuggestthat the maximum incidence of GSMinterfbmncewill be 5om hand portableandtransportabletransmv“em Since this appsuatusis carried by the public into areasof high populationconcentration. There is also a significant probability of interferencefkoma public pay phoneon a commutertrain. It appears that a hearing aid user will be unable to use a GSM portable or transportabletransca‘ver in any power class. Itislikely thatahearing aiduger will beableto usea vehicle mounted transceiverprovided the antenna is mountedin the centre of the mof Sinceit hasbeen found that interferencemaybe perceivedinikaquentlytim other sources, then it is GSM interference perceiveddaily that gives rise to the most concern. Of the four ‘dayin the life of scenarioschosenthe dailycommuterto La&n from a rural areais mostlikely b experienceregularintarkrence with a dailyexposure fm the duration of a call (2mins) whilst on the train and a 9 second daily burst whilst walking on the street even with the initial 10MHzallocation. This rises to two daily exposuresfa a cdl durationandfour 8 semmddailybursts when the allocationreaches 25MHz. The scenario of the London worker dwelling in the aty highlight a smaller eXPOSIUW tointerference.-t operatingwitha 10MHzallocation,three3 second burstswill be experiencedon the streeteve~ dayrisingto sevendailyburstswith systemmaturity. The retired personis fhr more likely to be wearinga hearing aid but less likelyto be in the city. If spending a day shoppingin the sty, the exposureto intdbmnce will be high during that day with a burst for a call duration during the train journey andthwe 3 secondbumtawhilstwalkingbetweenshops.Thisrisesto two exposuresfor a call duration and seven 3 secondbursts with systemmaturity. Whilst in a vehicle in a motomvaytrafficjam moving at 5mph, a hearingaid user will experienceburataof interference lastingz secondsevery 4 minutes. It caaba seen that givan the cument immunityof NHS hearing aids to 900MHz GSM EMI, a person wearing such an aid and requiring to use it during the working / traveling day will experience regular daily interference as the GSM system maturee. If the incidence of interference is deemed unacceptable,a greater hearing aid immunityat 900MHzwill be requiredtoreducetheincidenceof GSMinterference, since there appearsto be no practicalmodificationto the GSM stmcture that will achieve this. ETSI 26 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) al 1) .2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12) 13) Page 29 ETR 357 (GSM 05.90 version 5.0.0): Janua~ 1997 References. CentralStatisticalOfEce- ‘Annualabstractof statistics 1987’ HMSO No. 123 Central Statistical Office - ‘&giOIl&dtrends 1985’ HMso CCIR - ‘VHF and UHF propagationcumes for land mobile services’ CCIR Rec.529Rep.567-3 GSM recommendations 03.30 and 05.05 Short J M - ‘An investigationinto the eft’ectsof RF interferenceon hearing aid users’ W8f89 IEE GroupEll - Propagation ktors andinteflerence modellingfor mobileradio systems’ IEE Colloquium,DigestNo. 1988/123 HolbecheR J - ‘Land mobile radio systems’IEE Telecommsseries 14 Peter Peregrinus 1985 t Tattersall P R - ‘Domestic equipment susceptibility to GSM mobile radio transmission’ X3W89 Short J M - ‘An investigation to determine the penetration of 900MHz RF into vehicles’ 23/lW89 Muaday P J - ‘GSM EMC scenariomodel - MotoxwaytdEc jam’ 9/lf80 ShortJ M - ‘GSM InterferenceScenarios’ 3W11/89 Short JM-’Adayin thelife ofahearingeiduse# 9n/90 Munday P J - Correspondenceof 31/1/90and 12/12/89 . ETSI (GSM 05.90 version 6.0.1 Release 1997) 27 ETSI TR 101 640 V6.0.1 (2001-11) Page 30 ETR 357 (GSM 05.90 version 5.0.0): January 1997 AnnexB: GSM -Hearingaidinterference modelling parameters MODELLINGP~ Intarfarwce levels causing 1 4v/m in mOdd ‘audibleslightly~9’ (5to 8.5V/m measured) interference. Attenuationproduced by wearer’s head: VP to ~ dB GSM Power ~Vdm DistancefzomG5M Transmitter 2W o.8m to lo9m 5R 1.3m to 3oom 8W 1.6mto 3.8m 2oi? 2.4m to 6.Om — Note - Best 8i& T&at side of head of head Metallishg hearingaid casegave about 10dB reduction“inmwceptti~ty ETSI 28 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 31 ETR 357 (GSM 05.90 version 5.0.0): January 1997 1 other 10 other patmengaz pamengers o 0 in o 0 !, m, 12v/m ZW,4V/m area area 0 0 0 Cxowded Train Scenario Crowded !l!raim sC81i?Ui0 Assume : Half GSMEPU88used on a given journey Averagecalllast8Z dn Passengers with 21?GsMEPu 1* --- 3% 10% mobabilitsr of 2 * id-f-- on a given- jouzney 4V/m 5% 14* 40% lZV/m. 0.5% 1.5* 5* ETSI (GSM 05.90 version 6.0.1 Release 1997) 29 ETSI TR 101 640 V6.0.1 (2001-11) Page 32 ETR 357 (GSM 05.90 version 5.0.0): January 1997 1/ /’ i,I \ \ \ 1... . . . . G ,-’ . . . . r ..“ .“ ,“ .J ,.~ . ,, )2 ,.” . ,. . -- -. ..”.- ------- G . . -.”. . . . . . . . . .. ..- . l!loto-ayTxafficJam Soe=io ———— -- MotorwayTrafficJam Scenario . lwsume: 5% of vehicleshave GSM phone 20t of GSM phonesactive at a the Averageoallalast 2 *UteS Traffic Interference 2W18W120W 8W 20W 4V/n 8V/m 12vhn 4v/in4v/in Stationary 2 min interference burstswith Prob+ 2% 58 lot .. Lanespassing Interferencebursts+ O.7uevery 28 38 at IOkm/hr (onaverage) 3min everyeveq 3min 2-5 B ETSI 30 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 33 FTR 357 (GSM 05.90 version 5.0.0): January 1997 Annex C: New digital transmission technologies - the EMC conundrum IJEW DIGITAL TRANSMISSION TECHNOLOGIES - THE EMC CONUNDRUM 1 INTRODUCTION The growth of our ‘cordless’ society has placed a premium on personal mobility. In the telecommunications sector the growth in the use of cordless telephones and cellular radios has been spectacular. To provide for this growth, in an age where frequency spectrum is similarly in demand, has required the development of new technologies. 2 RADIO TECENOLOGXES Recent developments in radio in Europe and worldwide have selected ‘time division multiple access’ (TDMA) technologies for assigning channels to individual radio users. The traditional frequency division multip,le access (FD~)# mainlY analogue, techniques are still used extensively but are slowly being replaced by digital TDMA systems, which offer both improved performance and spectral efficiency, particularly in large ‘public systemsl. 3 WANTED RP EMISSION In a TDMA system the ‘channel’ used by an individual represents one time slot from say 10, allocated to that user normally at a sub-audio rate, for example, 200Hz. The resultant effect is that a burst of RF is transmitted at that sub-audio rate, in the example above the RF burst would last for 5 msec and be repeated every 50 msec. The 5m-= RF burst would contain the transmitted information at a rate 10 times faster than the basic rate to provide a continuous transmission for the user. The RF signal described above is amplitude modulated (AM), in this case at 200Hz, this AM is in addition to the modulation contained within the RF burst itself. Tests to date have shown that many radicrand non-radio (particularly audio products) are susceptible to an RF signal with these characteristics. .. The growth of cordless telephones and personal communications equipment also means that the transmitter will be physically much closer to potentially susceptible equipment. 4 EMC DIRECTIVE AND LEGISL74TIVE PROVISION The Community’s EMC Directive requires that all electrical/electronic equipment neither emit nor radiate unwanted RF signals, and not be susceptible to other (wantedl RF signals, ie legitimate radio transmissions. Legitimate radio transmissions are licensed in the UK by the Radiocommunications Agency of DTI, under the ‘Wireless Telegraphy’ Acts. The licence provision includes the frequency, form of modulation, permitted power level and ETSI (GSM 05.90 version 6.0.1 Release 1997) 31 ETSI TR 101 640 V6.0.1 (2001-11) Page 34 ETR 357 (GSM 05.90 version 5.0.0): January 1997 controls spurious and other parameters by only licensing equipment approved to definitive standards of performance. The EMC Directive will come into force on 1 January 1992; it offers the power to control, from that date, equipment ‘placed on the market’ and will require compliance with essential immunity’ standards. The pan-European digital cellular radio system - GSM - which is also supported by a Community Directive, should become operational at a similar date. The WT Act licence offers the potential to control the power levels of GSM equipment. s 2!EE CONUNDRUM The ‘generic’ immunity standard being set by CENELEC has been currently agreed to be set at ‘3 volts per metre~ The immunity standard necessary to avoid interference from a GSM equipment will need to be in the range ‘IO volts per metre~ to ~20 volts per metrel if the current power levels of GSM equipments are to be maintained. IIIt is, of course, subject to the distance between the &M transmitter and the target device being defined. The obvious incompatibility and potential hazard to ‘safety related’ or ‘pseudo-medical$ applications eg hearing aids, provides the conundrum. 6 DISCUSSION Scant regard, has in the past been paid to the design of equipment with realistic immunity standards - particularly in the domestic market. The EMC Directive provides the legislative framework to correct this deficiency. The ‘generic’ immunity standard of ‘3 volts per metre’ has been pitched at a level that most equipment designs already meet and thus provides little or no real improvement. A more realistic figure would be ‘1O volts per metre~. The adoption of TDMA technology, with its inherent advantages is more intrusive, in EMC terms, than previous FDMA technologies. This is particularly true of ‘audio* equipments such as”~a~ stereos, which have& high prd)ab~~~ at being in close proximity to the new digital radio telephones. It could.-be argued that the AM component of the TDMA transmission is also Iunwantedl and hence covered by the EMC Directive; this view is not shared by the spectrum managers, where it seen as a legitimate and efficient transmission. The spectrum manager has the option of defining the maximum radiated power, to a level compatible with realistic immunity standards. ETSI 32 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 35 ETR 357 (GSM 05.90 version 5.0.0): January 1997 7 CONCLUSION A compromise between ‘immunity’ standards for all radio and non-radio equipments, coupled with a limitation of radiated power from, particularly hand held TDMA transmitters, will be essential to avoid unwanted EMC problems. The attached Annex proposes a scenario for discussion purposes. o J WHEATON 4.5.90 I ‘ EMCCONUN ETSI (GSM 05.90 version 6.0.1 Release 1997) 33 ETSI TR 101 640 V6.0.1 (2001-11) Page 36 ETR 357 (GSM 05.90 version 5.0.0): January 1997 ANNEx EMC CONSIDERATIONS 1 Assumpt ions: the minimal distance between a radio transmitter and a target radio or non-radio equipment shall be 1 metre; safety conscious and pseudo medical have higher immunity standards than standard level. 2 Proposes that: systems shall the ‘generic’ generic immunity standards for all equipment be set at 10 volts per metre minimum: sectorial immunity standards for body worn audio equipments be set at 15 volts per metre minimum; sectorial immunity standards for any ‘safety conscious’ system be set at 25 volts per metre minimum. t 3 Transmitters using AM ox TDM,Atechnologies be limited in radiated power to: hand held devices - 1 watt peak power: vehicle mounted equipment, where the antenna is at a minimum height of 1.5m, located at least 0.75m from the vehicle~s outline - 5 watt peak power. . “ EMCCONUN ETSI 34 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 37 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Annex D: Potential GSM hazards on cardiac pacemakers Source: CSELT (Italy) Potential GSNI Hazards on Cardiac Pacemakers Operation arc pulse generators implanted in subjects suffering from 1 = Pacemaker Cardiac pacemakers hcan disease in order to stimulate artificially the beat of the heart. 1, Demand types sense when the heart beat is abnormal and make necessary corrections. Most pacemakers in use arc of the demand type. A simplified block diagram of a demand type pacemaker is shown in fig. 1. The circuit and the power supply (a solid state battery) arc sealed in a titanium package to reduce the rejection phenomena as weil as to improve the electromagnetic shielding. The circuit is implanted in the abdomen of the patient while the pacing lead carncs the pulses directly to the hcmt. The pacing lead is a catheter introduced through veins and has the double function of exciting the cardiac activity and detecting the spontaneous signals. In fact when the detector reveals the natural heart beat (which is an electric pulse with G peak to peak ampIitudc near to 5 mV) turns off the pulse generator (which give out G peak to peak pulse of approximately 5 V). So acting the pacemaker reduces the power consumption and avoids unnecessary stimulations. There Grc two different kinds of pacing leads: unipolar and bipolar, bipolar leads arc less sensitive to the external interferences but they are ICSS sensitive to the cardiac signal too. Single channel and multichannel dcviccs (i.e. with a stimulation irtrd dwecrim in more than a single hcan point) arc available according to the patient needs. In a large part of the pacemakers the physician can program the parameters of the implanted generator (e.g. amplitude, frequency, sensitivity) using a radio int crface cent rolled by a computer. Moreover the radio interface allows the physician to get the operating parameters of the stimulator using some !clcmctry measurement functions built in into the device. 2 - GSM Interference to Pacemakers Since the pacing lead acts as an antenna. exposure to an electromagnetic field may: a ) Introduce cuments from the leads into the heart causing fibrillation or locai heating: ETSI (GSM 05.90 version 6.0.1 Release 1997) 35 ETSI TR 101 640 V6.0.1 (2001-11) ETR 357 (GSM 05.90 version 5.0.0): January 1997 b ) Induce voltages in the lead that damage the pulse generatoc c ) Induce voltages in the lead that the pacemaker confuses with the intrinsic heart signal and turn off the pulse generator. - Additionally implantable pulse generators incorporate reed switches which are used for controlling the battery charge and may be Gctivated by strong magnetics fields. T& safety of implantablc pacemakers and their protection against EMI (E1ectro Magnetic Interference) is the subject of the CENELEC European Standard 5600]. A draft amendment prepared by the Technical Committee 62 [1] suggests both the maximum ratings of interference and the measurement methods to which pacemakers should comply. Surely clauses a) and b) do not concern the GSM system because the power of a direct radiation excited in the lead which can damage the hcan or the pulse generator is very much higher than the power of the GSM fixed or mobile equipments. Moreover the transmission frequencies of the GSM system arc so high that the by-pass capacitor which protects the pacemaker input filtrates enough the residua) components. For instance it has been verified that AM radio broadcast transmissions using very high power.’ (kilowatts or megawatts) can introduce a strong hazard. instead. clause c) has needed some investigations because an interfering signal with low frequency components approximating the heart beat could cause potential hazards even if their power is relatively low. In caac of GSM signals, while the normal burst transmission has a repetition rate of 216 Hz Gnd risks cannot Grise (consider that a 50 Hz component is already strongly filtered by the post-detector filter of the pacemaker detector input), the particular case of DTX (Discontinuous Transmission) mode had to be carefully investigated. In fact DTX mode has signal components Gt frequencies much lower than in the case of normal C3SM transmissions (see fig. 2): there is a sub-component with G repetition rate of ?.08 Hz, which corresponds to the transmission of the 8 timesiots of the SID (Silence Descriptor) message block frame and another low frequency component rcprescntcd by the SACC14 repetition rate (8.33 Hz). The amplitude Gnd duty cycle (one timcslot out of 26) of this component are much lower than those of the previous one. Since electrical signals with G periodicity below 6-8 Hz inhibit the pulse generator while interfering signals with G penodicity above 6-8 Hz will reven the paccmakcr operation into the so called asynchronous mode at the basic prugrtmmmk me, it Waa” fW&Wtcaad- importance to identify possible danger thresholds, In fact, if the power excited by these signals in an active enough, the pulse generator could bc turned off and the heart failure. 3 - Experimental Tests pacemaker were high person could have a Compatibility tests have been conducted both with unipolar and bipolar pacemakers manufactured by SORIN using the test set-up shown in fig. 3. ETSI 36 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 39 ETR 357 (GSM 05.90 version 5.0.0): January 1997 An arbitrary waveform generator jointly with an RF generator simulated the 900 MHz DTX transmission. The signal was amplified by a power amplifier. Pacemakers were placed in a phantom, an imitali.on of the human body filled with G physiological solution (water and NaCl whose concentration corresponded to a specific conductivity of 0.5 S/m al 20”C room lcmpcraturc) according to the -standard values. The phantom was a Plexiglas cylinder 1.7 m ta[l, with G diameter of 0.3 m. The pacing lead was placed in 8 loop similar to the one really done in the human chest and his distance from the plexiglas wail was not larger than 1 cm. An oscilloscope con-ted to two steeJ plates plunged into the soiution was used to detect the regular operation of the generators. Experiments were conducted in a controlled (anechoic) environment with the aim of measuring the field strength next to the phantom chest by an isotropic detector atvoiding any unwanted component. The measurement results show that no risk of hazards exists aminst Pacemakers from GSM quiprncnt. In fact it has been verified that it is necessary (corresponding to 8 W transmit peak power distance) for inhibiting an unipolar pacemaker air with the pacing lead loaded with a 500 interface. . an electric field of Gt least b V/m of- a GSM equipment at 0.S m when the device is leaved in the ohm resistor simulating the tissue On the other hand, when the device was put into the physiological solution, it was not poasibie to inhibit his regular operation even with electric fields of 200 V/m (corrcaponding to 208 W transmit peak power at 0.5 m distance). For bipolar pacemakers the results are even more reassuring: with the device in the opeu air the electrical field could inhibit the pub generator only if it was above 75 V/m (corresponding to G transmit peak power of 28 W at 0.5 m distance). Obviously no inhibitions have been detected with the Dacemaker plunged - into the solution. “ 4 - Cmchasions DTX transmissions of a GSM equipment produce waveforms which cardiac stimulators but formal experiments carried out with modern bipolar pacemakers manufactured by SORIN have demonstrated hazard exists. References [1] “S8fety of implantable cardiac pacemakers”, Draft CENELEC (1989) could inhibit unipoIar and that no real pr EN 50 061 [2] “immunity to disturbance of cardiac pacemakers in RF fields of powerful radio transmitters”, Institut fur Runfunklcchnik GMBH, Munchcn, 1987. ETSI 37 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 40 ETR 357 (GSM 05.90 version 5.0.0): January 1997 i I I I I I I I I i I ----- --- -4------ ------ -_1 I I I I I I I I “i I I I ; I I I I I I I I 1- 1- ----- ----- _____ _. I I I I I I I I I I I I 3 I I I I I I I I I I ! I I I I I ----- --~ Em .- U & .- I& (GSM 05.90 version 6.0.1 Release 1997) 38 ETSI ETSI TR 101 640 V6.0.1 (2001-11) i!{— .. !i<— Page 41 ETR 357 (GSM 05.90 version 5.0.0): January 1997 j t-,, ==f -*-- B w & .- L& (GSM 05.90 version 6.0.1 Release 1997) 39 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 42 ETR 357 (GSM 05.90 version 5.0.0): January 1997 ii . .. . u) IA (GSM 05.90 version 6.0.1 Release 1997) 40 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 43 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Annex E: Summary document on GSM-TDMA interference PROJKT : 60 Support to R2/MTS2 July 1991 Project Manager Project Technicians -. Approved F Mellish, 1.Eng. MIEIE L williams, I.Eng. FIEIE Head of Research and Development ETSI 41 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 44 ETR 357 (GSM05.90 version 5.0.0): January 1997 “ , Comlmtms G 1. Summary of Requirement. 2. Summary of Findings. 3. Immunity Data. s, 3.1 Sources of Data 3.2 Normalisation of Data. 3.3 linalysisof Data. 4. Observations. 5. Conclusions. .. ETSI 42 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 45 ETR 357 (GSM 05.90 version 5.0.0): January 1997 In the course of a meeting to disouss the potential interference [1] problems associated with the introduction of GSM and other transmission systems eqloying IZIMAtechniques, Mr Williams of the Radio Technology Laboratory was tasked with producing a .. summary document covering all of the work carried out to date. The minutes of that meeting are reproduced in annex 5, it should be noted that the chairman stated that the summary report should aim to concern itself with the direct breakthrough problem only, and ILQ&the TV image problem which may affect the UK only. [z] Interference to TV, radio, audio and information technology equipment, including personal stereo equipment and hearing aids. ., . ETSI (GSM 05.90 version 6.0.1 Release 1997) 43 ETSI TR 101 640 V6.0.1 (2001-11) Page 46 ETR 357 (GSM05.90 version 5.0.0): January 1997 2. Summary of Fidingm . 2.1 Domestic Equipments . Television receivers and portable radios/cassette players etc. proved to be the most susceptible domestic equipments with mean immunities of 4.0 and 5.6V/mreepectively. _nua recg$ ~J these ew~-ts ‘ould ‘nly suf~er er interference from a 20 W GSM mobile at distances of less than about 8 metres (worse case ass@n9 100* effici~cl’ -d free space path loss). ~is means that in practice, due to building attenuation etc., interference will not occur unless the transmitter and victim equipment are very close, and within the same room. 2.2 liearingAids. G Hearing aids also proved fairly’ susceptible, having a me= ilmnunityof 4.1 v/m. Interference to hearing aids (andportable cassette players etc.) outside the domestic environmentis likely to prwe more problematic since the interfering GSM transmission is unlikely to be under the control of the user of the victim eguipment. Work conducted by the RTL and Racal Research Ltd. suggests that the ixnunity of small behind the ear hearing aids canbe improved at reasonable cost (by -t 10 m) by applying conductivePaint to the inside of the hearing aids plastic case. This would reduce the interfering range of a 5 W portable GSM transceiver to about 0.5 metres which is considered acceptable. 2.3 Eighu Frequenoy Systems, DECT, DCS1800 etc. ds ~rw~re su~ to 1900 MlkkhWA This has obvious implications regarding the Introduction of DBCT etc. ETSI 44 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 47 ETR 357 (GSM 05.90 version 5.0.0): January 1997 3. Xnrmunity Data. 3.1 Sources of Data. Reports from the following laboratories were analysed to produce this summaq document; Radio Technology Laboratory Reports KJ109, KJ132, SCJ132a,KJ181 Partl, XJ181 Part2. British Telecom Research Laboratories Report RT4123 Netherlands Pm (hoofddirectieteleconnnunicatie en post) Report Radio Frequency Investigations Report RFI\TR2\2294 3.2 Normalisation of Data. The above laboratories presented their findings in a variety of forms. Introducing this summary report it was necessary to unify the various abstract results and findings, by calculation and extrapolation, to a corrunonform - ,= tv . at w= t was on CCIR grade 3.5 impairment was considered an appropriate limit of acceptabilityfor GSM interferencesince it falls halfway between the impaiment that is considered acceptable, by the CCIR, for continuous interference (CCIR grade 4), and that which is only considered acceptable for a very small percentage of the time (CCIR grade 3). The approximate field intensitiesthat would result in CCIR grade 3 or 4 impairments can be obtained by adding or subtracting 5 dB audio impairment respectively (since a 1 dB change in the field intensity results in approximately a 2 dB change in the audio impairment (square law), multiplying or dividing the grade 3.5 field intensity by 1.33 will produce the approximate grade 3 and 4 field intensities respectively). A description of the impairment associated with each of the standard CCIR impairment grades is given in Annex 1. 3.3 Analysis of the IIata. The original laboratories data and its conversion to field intensity for grade 3.5 impairment is given in Annex 2. The Mean and Standard Deviation of the extrapolated data is given in Annex 3, and Summarised in Annex 4. ETSI 45 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 48 ETR 357 (GSM 05.90 version 5.0.0): January 1997 4 G Obaaz=atiansG 4.1 Earlier work at the RTL has shown that the magnitude of AM or pulse [2] interference is related to the peak envelope power of the transmission. i.e. A victim equipment demonstrating immunity to 3 V/m (carrier)with lkHz, 80% emplitude modulation, is also demonstrating immunity to S.4 V/m peak i.e. a TDMA .immunity of 5•4 Vlln. This is supported by the recent tests conducted on hearing aids by RFI. [2] 1:24< duty ~cl@ <24:1 4.2 The recent tests conducted by RFI shows that the majority of the hearing aids tested (the smaller ones) were more susceptible at 1900 MKz than at 900 MHz (the mean izxzunitywas 7 dB worse). l’hisfinding has obvious inqlications regarding the introduction of DECT etc., and is supported by some (limited) earlier work conducted by the RTIJ (KJ132a). 4.3 Inteationallybhmkforreportwdimmminatedoutdle theAgi?rIcy. ETSI 46 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) 5. Page 49 ETR 357 (GSM 05.90 version 5.0.0): January 1997 cmclus*oa8• 5.1 The extrapolated mean/median peak TDMA field intensities at which various equipments would suffer visible/audible, but not annoying interference (approximatelyCCIR grade 3.5) are listed below. Typo of Xqupanent Hearing Aids Television Receivers Video Cassette Recorders Satellite Television Receivers Tuners/amplifiers Cassette Decks CD Players Portable Radios & Cassette Players etc. Telephones Computers Commters (HOMe/GameS) Piold Intensity (V/=) 4.1 4.0 >13.9 9.5 >8.3 >2.9 >13G 9 5.6 >7.6 >8.5 >13G 5 G&ral Electrical/ElectronicEquipment. >7.8 From the above generalisation it can be seen that the most susceptible equipments are hearing aids, television receive=t cassette decks end portable radios/cassetteplayers etc. ~ ~f these ‘Ould only “Uffer interference from a 20 W mobile at distances of less than about 8 metres (worsecase assuming 100% efficiency and free space path loss). This means that in practice, due to building attenuation etc., interference will not occur unless the transmitter and victim equipment are very close, and within the same room. It can therefore be concluded that GSM interference is unlikely to cause any serious problems to domestic equipment, being used in a domestic environment. Interference to hearing aids and portable cassette players etc. being used outside the domestic environment is more likely. ~rlier work conductedby the RTL and Racal Research Ltd. suggests that the immunity of small behind the ear hearing aids canbe improved at reasonable cost (by about 10 dB) by applying conductivepaint to the inside of the hearing aids plastic case. This would reduce the interfering range of a 5 W portable GSM to about 0.5 metres which is considered acceptable. [41 Although it was requested that this sununaryreport should aim to concern itself with the c!im!?ct_~ poblemonlyr =& not the TV image problem which may affect the UK only, following background information is included for completeness. !- The image (spurious) response of television receivers is potentially quite problematic because, for some of the higher Band V channels, this response falls within the bands allocated to TACS and GSM. However, interference via this mechanism is no worse for GSM (or other ‘IWA systa) t- it is for ~l~e systems e.g. TACS. As no cases of TV image interference from TAC!S have been recorded during several years of operation,major image interference problems from GSM are not anticipated. ETSI (GSM 05.90 version 6.0.1 Release 1997) 47 ETSI TR 101 640 V6.0.1 (2001-11) Page 50 ETR 357 (GSM 05.90 version 5.0.0): January 1997 5.2 The following pertinent information has been extracted from RET’s test report RFI\TR2\2494; 5.2.1 h-iC XZIUJUUityS~. The draft generic immunity standard (prm 50082-1) requires the BUT to be tested at 3 V/m fmm27 MEz to 500 MHz, but since there is no requirement to modulate the field it is unlikely that any hearing aid equipme=t would fail this test. The final version will almost certainly require that two further tests listed in the informative annex to be carried out: Electromagnetic field at a severity level of 3 V/m 80* &itude modulated with 1 kSiztone swept from 80 MHz to 1 GHz. 2. electromagnetic field at a severity level of 3 V/m pulse modulated with a 100 Hz square wave at a frequency of 1.89 GHz. 5.2.2 Field Strength Produced by Porteblo Transcdvers. WfimhumQWwe Wikluhe Qm,ezic a~ RFI have calculated how closely the user of a piece of hearing aid eguipment may approach a portable transceiver before the level of unwanted interference table; symtm C!T2 GSM DX!T becomes unacceptable, Puuer (w) 0.01 2.00 5.00 8.00 20.00 0.25 and produced the following Mlxthum Distance (m) 0.1 M 2.8 4.5 0.5 RFI state that; These figures only provide a rough guide as they make no allowance for the type of modulation employed or for the disturbance of the electromagnetic field caused by the person using the hearing aid. and that; The values calculated above would suggest that users of hearing aid equipment are likeIy to experience ~interferenoe frcxBGSM. mobiles in close any of the above - proxiziityand that they will not be able to use systems themselves. . ETSI 48 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 51 . ETR 357 (GSM 05.90 version 5.0.0): January 1997 Annex F: Interference to hearing aids by the new digital mobile telephone system, Global System for Mobile (GSM) communications standard . Intarforoxxm to Moaring Aids by tho now Digital Mobil. Telephone System, Global systam for Mobil- (GSM Communications Standard ,, Ken H. Joyner Mike Wood ELECTROMAGNETIC COMPATIBILITY SECTION TEI&COM RESEARCH LABORATORIES and Eric Burwood Derek Allison Ross Le Strange ENGINEERING SECTION NATIONAL ACOUSTIC LABORATORIES .. NATIONAL ACOUSTIC LABORATORIES a Divisionof AUSTRALIANHEARINGSERVICES SYDNEY, 30 March, 1993. A AA ETSI (GSM 05.90 version 6.0.1 Release 1997) 49 ETSI TR 101 640 V6.0.1 (2001-11) Page 52 ETR 357 (GSM 05.90 version 5.0.0): January 1997 ABSTRACT :‘ This report gives the details of some measurements on the interference caused to hearing aids by mobile telephones using the new “Global system for Mobilem (GSM) Communications Standard. The widespread use of this system may cause considerable interference to users of hearing aids. It is not known at present if hearing aids can be designed to be completely immune from this interference. This report has been written to alert all hearing aid users and those concerned with the use of hearing aids to the possible disruption to the use of hearing aids that may be caused by the new GSM system. . . . ETSI 50 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) 1 2 3 4 5 6 7 8 9 10 11 Page 53 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Ta.bloof Contants Introduction Acknowledgments Nature of Transmission from GSM Mobile Telephones Interference to Hearing Aids Description of Measurements Interpretation of the Results Interfering Mechanism Remedies Conclusion Recommendation References !,s List of Tables 1 Field Strength for Noticeable Interference to Hearing Aids 2 Threshold Distances for Noticeable Interference to Hearing Aids 3 Measured Field Strengths Near GSM 8 Watt Transportable Mobile Telephone 4 Measured Field Strengths Near GSM 2 Watt Hand-Held Mobile Telephone Li=t of Figures 1 Sample Frequency Spectrum of a Hearing Aid Output with Interference 2 GSM Transmitter - Test Set-Up for Simulating Transmission 3 Hearing Aid Output with an Interfering Signal - Test set-up 4 Sample Acoustic Frequency Response of Hearing Aid 1 1 1 2 2 3 4 4 5 5 5 6 7 8 9 10 11 12 13 .. ETSI (GSM 05.90 version 6.0.1 Release 1997) 51 ETSI TR 101 640 V6.0.1 (2001-11) Page 54 ETR 357 (GSM 05.90 version 5.0.0): January 1997 1 Introduction The new mobile telephone system, using the ‘Global System for Mobile” (GSM) communications standard, is due for introduction in April this year. It uses digital technology and operates at radio frequencies (RF) in the 900 MHZ region. The portable hand held and transportable telephones are capable of interfering with commonly used electronic equipment and can degrade the performance or even prevent the operation of hearing aids. NAL was approached by Telecom Research Laboratories Electromagnetic Compatibility Section about the possibility of checking if the system interferes with hearing aids. Telecom was undertaking an investigation into interference caused by the digital telephones. As a result NAL and Telecom staff undertook a series of measurements designed to establish the nature and extent of interference to hearing aids. The following is a report of these measurements, together with some recommendations. 2 A=knowlodgmeats Dr. Ken Joyner, Head of the Electromagnetic Compatibility Section, Telecom Research Laboratories, first approached NAL through Mr. Eric Burwood and visited NAL on 18th and 19th February, 1993 when it was established that interference may be a problem. Subsequently, measurements were carried out on 4th and 5th March 1993 to quantify the extent of the interference likely to be experienced by hearing aid users. Dr. Joyner and Mike Wood of Telecom Research Laboratories Electromagnetic Compatibility Section set up the equipment to generate the radio frequency field to simulate the telephone emissions and also provided Tables 3 and 4 of field strengths emitted by the GSM mobile telephones. 19essrs. Eric Burwood, Derek Allison and Ross La Strange of National Acoustic Laboratories carried out the hearing aid measurements. . 3 Nature of Transmission from For the GSM system the GSX Mobile Telephones radio spectrum available for mobile-to-base (i.-e.mobile telephone) transmission is between 890 and 915 MHz, and for base-to-mobile it is 935 to 960 MHz. The modulation produces 0.6 MS bursts of RF energy from each telephone transmitter at a pulse rate of 217 Hz. A number of peak power leveIs and equipms-configuzvrtlm are available fox GSM mobile telephones for use within Australia. These include a 2 watt hand held unit and an 8 watt transportable unit. When due account is taken of the pulsed nature of the transmissions, the corresponding average power levels are 0.25 watt and 1 watt respective y. The peak RF field strengths close to the antenna of the mobile telephone can be quite high. At 10 cm from an SW transportable unit a peak RF field of 70-80 V/m has been measured. The GSM system is a pulsed system with a higher peak power than the present analog mobile telephone system. This makes the G!W ETSI 52 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 55 ETR 357 (GSM 05.90 version 5.0.0): January 1997 system much more likely to cause interference into electronic equipment which is apparently not affected by analog RF fields. Obviously the potential for interference depends on the number of GSM mobile telephones in use in the community and this is unlikely to be very high in the next few years. 4 Xnterfarenoe to Xearing Aid* Interference to a hearing aid is considerable, the amount depending on the details of its design. Considerable concern is felt by the European Hearing Instrument Manufacturers Association as the new system is being implemented in all European countries. The Australian Telecommunications Authority, Austel is embarking on an investigation into Nmerging technologies for the delivery of wireless personal communications. The interference from one transmitter is heard in the hearing aid as a constant, distinctive buzzing sound while the telephone is transmitting nearby. Figure 1 shows a typical frequency spectrum of the output of a hearing aid with interference, which occurs across the useable range from 200 to over 5000 Hz. Hearing aids from all manufacturers will be similarly prone to this interference. ., 5 Description of Measurements - Sensitivity of the Hearing Aids to the Interfering RF signal a ~: To measure how the effect of the interference varies with the peak RF field strength, so that useful predictions could be made about the effect on hearing aids in proximity to these telephone transmitters. This was done by:- i Measuring the output of the aids subjected to varying RF field strengths, and ii Subjectively comparing the interfering output with a sound of known intensity. bMWM:” i ii The hearing aids were placed in a known variable RF field generated by the system provided by Telecom shown in Figure 2. The sound output of the hearing aid was measured in a 2 cc coupler with a B&K 2120 FreWencY Analyser set for wide band with a 100 Hz high pass filter ~w= ~t lQW f=w=JcY -ient noise J ‘efer ‘o G The noise floor of each aid was measured with the mic~ophone blocked to ambient noise. The hearing aid output was then measured under a suitable range of field strengths, including that which produced an output 10 dB above-the noise floor. Frecaut-xifi . c : i The measuring microphone and large metallic objects which around the hearing aids. In acoustic 2 cc coupler are alter the field strength order to obtain reasonably ETSI (GSM 05.90 version 6.0.1 Release 1997) 53 ETSI TR 101 640 V6.0.1 (2001-11) Page 56 ETR 357 (GSM 05.90 version 5.0.0): January 1997 accurate field strength at the aid, the 2 cc coupler and microphone were moved away from the vicinity of the aid. A 460 mm length of 2 mm diameter Tygon tubing was necessary tO COUple the iIid6 to the 2CC COUpler. This changed the acoustic frequency response of the aid, an example of which is shown in Figure 4. This change of response does not invalidate the measurements for the purpose of this investigation, since the bandwidth was not reduced significantly. The peak RF field strengths were measured using the apparatus shown in Figure 2. The output of the generator was varied with its attenuator in order to adjust the RF field incident on the hearing aid under test. ii On rotating the aids in the RF field the received interference changed. However, for the purpose of this investigation, it was decided that the orientation which produced the most interference in the majority of aids would be used, since time was insufficient for a more extensive exploration and it is unlikely that significantly more useful information would have been obtained. iii The frequency response of ,each aid was graphed with normal acoustic termination and also with the extra tubing using a NAL 8500 system whose calibration was checked with a B&X calibrator. This shows that the aids were operating correctly. d ~: i The outputs of each aid was recorded with and without interference for subsequent subjective evaluation. ii Recordings were made of the output of some of the hearing aids with test speech passages of known average SPL with and without interference to ascertain what may be deemed a suitable threshold for characterizing the effect of interference. It was confirmed that a useful ‘annoyance” threshold.is the RF field strength that causes an output 10 dB above the noise floor of the hearing aid, i.e. the output without interference and when the microphone was blocked to ambient sound. Increasing levels of interference rapidly increases the level of discomfort~ e.g. when the interference was increased to 20 dB above the noise floor, the effect became unacceptable, even though the accompanying speech was still intelligible. iii It is intended to prepare-a cassette tape recording with samples of a hearing aid output with and without ,.. interference to speech. ETSI 54 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 57 ETR 357 (GSM 05.90 version 5.0.0): January 1997 6 Int@rprct8tioa of tho R@8Ult8 a ~’ Table 1 shows the threshold values obtained with the hearing aids issued by AHS. Interference when the telecoil is used is slightly different to that with the microphone. b ~’ Table 2 gives an approximate indication of the relative distances at which the 20 dB threshold is reached from a 2 watt GSM hand-held mobile telephone, and from an 8 watt GSM Transportable mobile telephone. These are estimated from the hearing aid thresholds in Table 1, and by extrapolating from the peak RF field strength measurements over grass in Tables 3 and 4. AS indicated in Tables 3 and 4, significant variations occur in field strengt~ depnding on the ~ediate enviro~ent~ however the estimated values rank the aids correctly and give a realistic indication of the range where interference will occur. dit&ns under W1’Q~uterf~e Occurs G c G. i The telephones interfere with all the hearing aids tested. A user of one of these hearing aids will not be able to use these telephones, and a hearing aid will often become useless or cause the wearer discomfort close to a telephone when it is being used. This situation is representative of currently available hearing aids. It will be noticed that the 1T312 has the least interference. m explanation is given below. ii Behind-the-Ear hearing aids experience more interference than In-the-Ear aids. iii Hearing aids such as the VHX are likely to be unusable even several metres away from either the hand-held or the transportable telephones. 7 Interfering Meehamism a From the expWimental work we can say that the interference occurs at the most sensitive part of the hearing aid amplifier, where the RF field induces signals in the wires connected to the microphone or the telecoil and detected (rectified) by the transistor input, and possibly W *e output of the microphone which has a simple buffer amplifier. This mechanism applies in high gain audio amplifiers such a those used in public address sptsm?s that are eubject te AU radio and television transmissions. These are normally shielded from this interference and the input shorted by a small capacitor to eliminate the problem. b The higher peak pulses of RF power radiated and the close proximity to the hearing aids where they will normally be used, combine to make this interference more severe than the above cases. c Sometimes a small capacitor is used shunting the amplifier input to prevent RF signals being detected and heard by the wearer. The Calaid Sonata has a small capacitor, but is not ETSI (GSM 05.90 version 6.0.1 Release 1997) 55 ETSI TR 101 640 V6.0.1 (2001-11) Page 58 ETR 357 (GSM 05.90 version 5.0.0): January 1997 close to either the amplifier chip or the microphone. The Serenade, VLK and VMK/MK do not. This explains the lower threshold RF field strengths of the V aids. The new XT312 has much shorter microphone leads than the previous ITE hearing aids Sonata and Serenade, since the microphone is solidly mounted next to the amplifier board. The lower sensitivity to interference is consistent with the above mechanism. i Filtering: The shunt capacitor is a simple filter. It should be placed physically very near the amplifier integrated circuit chip with very short wires. It may also be necessary to place one across the microphone output at the microphone. The capacitors are restricted by their affect on the circuit operation as well as taking up valuable space. By using a small ferrite inductor in series with the microphone leads in conjunction with the shunt capacitor it may be possible to eliminate interference. ,$ ii Shielding: Complete shielding of the whole hearing aid with a conductive sheath will eliminate the interference, but is likely to be impractical. Suitable methods include thin metallic coating on the inside of the case parts, impregnation of the plastic with fine conducting particles and using a Wmetallicn paint. It may reduce the sensitivity of a telecoil if fitted. It is likely to be impossible to completely shield the aid, and connecting leads for audio input and induction pickup coil (telecoil) that are not shielded would present problems. iii Feasibility: It is not known now if these or other remedies will work and to what extent they may work. iv Restricting the use of the new GSM mobile telephones will prevent interference, but would probably make the GSM system useless. b ~: Changes to the large number of existing hearing aids has the following problems: i It may be logistically difficult, if not impractical. ii Feasible. -ications are likeU! to be of minimal effectiveness because of the difficulty in app~ying effective remedial treatments to an existing product. iii .’Modifications to existing aids may be very expensive. c : If effective means to prevent interference are developed, they could be designed into new hearing aids. 9 conclusion a It is likely that hearing aid users will be inconvenienced to some extent very soon after the new telephones are ETSI 56 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 59 ETR 357 (GSM 05.90 version 5.0.0): January-l 997 b c d e 10 a b c 12 a b introduced. Widespread use of the new GSM mobile telephones may make existing hearing aids useless for much of the time. Unless there is a realistic design remedy, new hearing aids will be affected, but possibly to a lesser extent, since partial remedies seem to be possible. Co-operative work to investigate effective design solutions is necessary, to establish if they can be developed. Monitoring the uptake of the GSM service and reports of interference to hearing aid users to gauge the extent of the problem in the short term and in the longer term undertake a co-operative programme to find practical and cost effective solutions. Rocommeadatioa Make this problem known through: i Austel, ii Hearing Aid user Groups, iii Hearing Aid manufacturers, ‘“ iv Relevant government departments, Initiate co-operative work to look for a suitable design solution, Keep the above mentioned bodies informed about the extent of the GSM system and inform GSM mobile telephone users about the interference that may be caused to hearing aid users. Reforona** Buropean Hearing Instrument Manufacturers Association, ‘Implications of GSM for the hearing handicapped”, Bosstraat 135, B1780 Wemmel, Belgium, Tel 32-2-460 2284, Fat. 32-2-460 42449. . AUSTEL, ‘Dispassion Paper: Wireless Personal Communication Semricesm, Mobile Equipment Standards Section, AUSTEL, P.O. Box 7443, St Kilda Road, Melbourne. Victoria, 3004 -. ETSI (GSM 05.90 version 6.0.1 Release 1997) 57 ETSI TR 101 640 V6.0.1 (2001-11) Page 60 ETR 357 (GSM 05.90 version 5.0.0): January 1997 !Mhlo 1 n Field Strangth for Ieotiuoahla Hearing Aids (?rox moa8ur8mon*8of ASS ImtOXfOr@mC@ to Eaaring Aids) Mierophoao 8witahod In T810eoil 8wit8h@d In r Eoariag RFField ?kwdng d8- ~ - d’llm~ Aid (vol&$/ ~ - (volts/ && -) ~ ~) (m RF) -) ~m (noRF) I 9*4 I 69.5 I 10.0 1 9 s 4*9 66.0 10.5 2 Jm12 32.3 78.0 9.5 N?U&- -. ETSI 58 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 61 ETR 357 (GSM 05.90 version 5.0.0): January 1997 TS.blo 2 Threshold Distawos for BIotiuoab18Inttrforenco to Soaring Aids (Calculated from measured aid sensitivity and approximate field strengths near the telephones) m MEms MIC MEIRES +& 50.0I INPW 50.0 i 021 llm2 0.2 0.1 0.11 amllllMmT2.D .. ETSI 59 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 62 ETR 357 (GSM 05.90 version 5.0.0): January 1997 T8blo 3 M@asurod Field 8trongttw Blou 6sM 8 Watt Tr8asportable Mobil. Tol@phoaa, (Source TelecoxnResearch Laboratories personal communication) (m) 0.1 0.2 0.3 0.4 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Fidd = 81.8 53.4 34.9 27.4 21.8 1.2.o Fidd lii?iiE 76.3 51.6 36.9 30.7 23.3 32.0 25.0 3.2.4 10.1 5.7 6’.2 5.9 9.6 4.0 I 7.5 4.1 , 2.8 5.8 .. ETSI 60 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 63 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Tsblc 4 I@asur.d ?i.ld Strmigths M.sr GSlf 2 Watt Hamd-R.ld Xobila Talophona, (Saurce Telecom Research Laboratories personal communication) 0.1 0.2 0.25 0.3 0.4 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 5.0 41.9 38.7 28.7 27.1 24.1 20.8 21.3 3S.0 16.3 13.1 14.7 5.5 7.1 6.2 3.4 6.4 2.4 4.1 3.0 1.7 3.5 1.7 4.3 4.3 1.1 4.0 1.2 2.7 0.8 . . ETSI 61 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 64 ETR 357 (GSM 05.90 version 5.0.0): January 1997 100 90 80 70 60 50 4a 3C 1 68mplo Frquoauy spectrum of G x88riAg Aid output with Iatarfarana. BRNDWIDTH : 1/24 OCT. tWERF@INQ : El@. } 16s ,*, I 20 & I t I 1 I I 12s 250 500 lk 2k 4k 8k Hz . -. ETSI 62 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Figuro 2 Page 65 ETR 357 (GSM 05.90 version 5.0.0): January 1997 GSN Txaa8mittor - Test Sot-Up for 8imulmting Tran8missioa ~ W 19019 PULSE GENEMTOR I 1- %=FCp P!i!El RR POUS? RHFLXFIER 25U1OOOH7 + 223 CORX 30” + Clonl) ROBERTS 900MHz DIPOLE I LENGTH 7.9CIU 1 Zrn I 90014Hz COW TO.. b/WEt3UIEmTOR I TEKTRONIX 2782 sPEcTRl#laNFILYsER 3 ETSI 63 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 66 ETR357(GSM05.90 version 5.0.0): January 1997 Figure 3 Hoariag Aid Output with an Xatorforing Signal - T*8t s-t-up . B&K 4230 CALIBRATOR TUBING HEARING AID 460 MM 2MM DIA MEASURING UNDER TEST A 2 cc COUPLER MICROPHONE & I TAS($AM TAPE RECORDER B&K 2120 MODEL 58-OB L FREQUENCY IJEL_l PHILIPS PM97 SCOPEMEER -i MONITORING AMPLIFIER H LOUDSPEAKER I -. ETSI 64 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) 4 Page 67 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Ssmpl. Acoustic ?raquonoy Rasponse of Haaring Aid, with and w$thout artmdod tubo to 2GC coupler Gaoustio load. 110 100 mlNwIEu ?0 aSPL UITH 4SRN9 x 82.0 m To SwmFmD 55 - 2ccml@LER-ONSE 00 ~;mL& 7n --s .* .6 M(HX ETSI 65 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) ETSI ETSI TR 101 640 V6.0.1 (2001-11) 66 (GSM 05.90 version 6.0.1 Release 1997) Annex G: Studies on interference from GSM terminals to the fixed network telephone equipment This annex includes four studies on the interference from GSM terminals to the fixed network telephone equipment. The studies are made by BTL, France Telecom, CSELT/SIP and Televerkets Forskningsinstitutt. See attached PDF file. ETSISTCSMG2No.S 9tb-12thMarch1993 Brigbttm, UK Same: BTL(USC) Page 69 ETR 357 (GSM 05.90 version 5.0.0): January 1997 T.Doc S2/93 Rev 1 Subject : EMC Considerations forH telephones bttheUK TMtablebdow showsthexesdtsoftestingths imnmnityofvariousfixedtdcphoncsandPBXup@um (both analoguc anddigkd) available intheUK The@dngwasconducted at3V/m and 10V/m using a simulated GSM testsignalasthsintufercncs. “ 10 “ if 3 . . 10 . cm 3 “ G 10 910 Cw 3 . . 10 “ AM 3 “ “ 10 * cm 3 “ 10 955 iv 3 “ 10 “ if 3 . . 10 . m 3 . . 10 R E s u L T 18 lb lb 2 3 & & k J 6 . F F . F . . F F . F F F F . . . . F- . . . . . . . F- ,* F ‘. . . . . F- . i- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Itcanbc ssenthattbsvast majorityoftclep--klqti equipmcnttsstalis notsawzptiblcat evcn10V/3nThisfisIda&uut13will betwssetUSta~of lmfroma Class4mobik. ThcrCfm. skboughit isrecognisedtha{interferem% tim GSMmobilesto fixedtelephonesis anNXUC, duetothe UKimmunitystandardforfixedtelephones,this is notconsidereda majorproblemin theUK. * :“ F Failsd test . Passsdteat . Nottsstcd whenfailllm Uitelia Wss40dBPa. 1 PBXwithvarious tsrminaI equipment 2 PayPhone 3 MIDUDEMUXequipment 4 PBX with various terminal equipment 5 ISDNrquipment 6 Lineterminaleqwpment ETSI 67 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 70 ETR 357 (GSM 05.90 version 5.0.0): January 1997 source: France Teleoom Subject: EIWCoonsiderattons for = Wephonee in France f.lmmduc?ion Mobile GSM PO** terminals have been identified in France as primwy SOU_ of mterferenoe to fbd telepho-, elao&o~ devime and video displays. As these wmat firat,subjecdvamults, bating of W immunityof Vdous M telephones al dose distmme of G pmgmmmable GSA pwtabie equipment was undwtaken. A oommerciisllyGmiletie GSM urdtwas used fortheee teets,withG apadlk test SIM card. mls-m-mm~t ia~mtimm~~daa~,ti frequency (channel),the peak powr and the aequance as well as many other parameters. p Performsnoe orite~ A vefy impoftant point ~ming the immunityd the telephone is the pXfOmUtn= @tefia. For fixed telephones or aoouSM~, themain pelfonnanoe cdte*ktif-tim noise should be fm’tenadto, oaueed by the GSM TDMA pulses (217 Hz Gnd harmonbs) occuring by Gudb mctMoa@n in the IC Gmpillfars,or non linear dmuits of the electroacmmtic4 devices. In sddition, for fixad telaphohes or PABXs, the audio recMcaM“ signal should not be sent in dff’Fef8fW mOde along the tatephone tine. It means that the cxmespondent shoutdnot tieten -to the demodulated signals occunng by the pmsanoe of GSM unit dose to the telephone at the other end. TwQcriteria wedafinedi nFmnsf orthe tek@meemcaming their immunity to the radiated or oonductad interference. R~, ~RF_titi ~~tiatittiphm finetia~kvd higherthan -50 dBm in the Gudii transmission band , on G 600 Ohms ~tde@mne line vuttha differential mode. Second, no nois+higher than 50 dBa weighted, should be listened m the earphone or in the audiimnsducers These pammeters camcterize the performance criteria in the presenoe of RF W-m and provide a generally accepted mpresentadon of the ef!ect of good performance.Of murse, no intem@on of call, neitherbee of stored numbers in memory should ooeur The appendix shw the test deadptbn and detailed resultson these immunitytests. ETSI 68 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 71 ETR 357 (GSM 05.90 version 5.0.0): January 1997 3 R-u?tsGtd ooncluslq tthasto bementioned that no-d ongoing cd,nodiaiingo rmr, m- of stored informationoccxred, buttha dafn@@t8d bvel was u~ptabb. . Even, ifitcouldbe@midemd thetifinthefutur8,88peC#io 82andw’df romthecENELEc ammning telephone oould include euch immunity requirwnente, the GSM interferemoe potentialWay ieto be Wan into aocount beoauee there q millionsoftelaphone equipment that me eusceptlbb to dose dietanoe GSM Gmbaione . We ameidertha! ifa 8 Wpodabk GSM tetmhalk used, he mexhnumdstance ofpotenthl intwbmnce& t@ca#y abouf $0 met- maxhum, andif•2 Watta GSM terminalisused thi3dWenceismduoedtoa~m of5mdu8. in any case, we mcmnwnd Uut for non ar~badmd GSM teminde, the radmed power should not be higherthan 2 Watte paak power. A oonbibutionon thie eubjeot oonoeming G epedllo EMC standard of tetephone and PAM equipm- shouldbe 8entto CENELEC. ltisconeiderad thatintatfamoafm mGSM tarminaletofbcedMephoneeand PA6X isan iseue fhrough the European oommunity, aven lf body worn Gudii and heafth eleotmnic equipment*s major Gnd muohmom important i8eue. ETSI 69 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 72 ETR 357 (GSM 05.90 version 5.0.0): January 1997 AQm!i!k ‘1.Me8swementOfdl 8 hnrnunttv of fixed taIenhotw ado mor@ In otder to evaluate the immunity of eleob’oniotelephones to the emission of GSM terminals, twotypes of experimentsware oarriedout First, a subjective t8$t in 8 aacret8fy -, the ~ is a formal immunity teat in a sem~ aneohoic room. I.1.SubieotNe ~ G h an ordnary secretsIY oflioe, many differentfixedtelephoneswere ins@led . We asked to Va*US people prasant them to call with these Wephone$. An openstorusinga GSMportabk 8W_PSak~-a ~titi-mti. Assoonasthe fhtpheaa of GSM~~-f@d, 8Utheteiephone$ WlWin~fi= were mom or less hightyd~rbad by the presence of the GSM emission by w~rimP@ng a noise on the telephone Gudm bend. Fortie~@ Wowmti~rti tiGSM~, W*wsti-mM(l m tY@osflY)and-* PS@O IJV@mferthef, ths oommun-n was made pos@b@. ,* Typically, at a diatanoe higher of 5 meters, the communidkm with the GSM dd not d~urb the uther telephones. l.nnl munlhr ~ ~e-m GSMtetiti -tibamtia~ F~~a&tiadtin= ofl meters some fixed telephone terminals wem * up with G test fbdwu in order to evaluate the demodulated Gudo noise prwided by wdio n!dbabo.nMti~@toneandonthe telephone line. To avoid Gny coupling with the fiatd strength , the maasumnent equipment vvaa put outside the semi-aneohok room. The field strength w ~. monbrad to make a oormlationbetween~- ~r, the tleld strength and the demwhbted output. 3$.RESUL~ The limits are -50 dBrnopJ600 Ohms of clemodulatad level along the line differential mode (DM),and typically 50 dBA on acoustic Ievd at the earphone ETSI 70 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 73 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Source: CSELT / SIP EMC considerations for fixed telephones in Italy 1 G Introduction some SMG2 documents have been produced up to now on the potential disturbances of GSM transmitters on fixed telephones in UK (SMG2 Tdoc. 52/93), in France (SMG2 Tdoc. 89/93) and in Norway (SMG2 Tdoc. 100/93). This document adds some information to the problem, by discussing the results of some tests pedormed in Italy using a set of fixed telephones interfered by GSM emissions at different power. ~, 2- Measurement proceduro The immunity of fixed telephones to the interference of GSM emissions was measured in two different environments: a Gtiz-TEM cell and a properiy equipped flat roof. 2.7- Generation of the GSM intedenmce Most experiments were carried out using an interfering signal produced by a transportable GSM mobile equipment communicating with a base station at a constant power level (since the power control function of the GSM was not active during the test). A portion of the GSM signal was split by a 20 dB directional coupler and sent to the radiating antenna through an RF power amplifier. The signal power level at the antenna was regulated by a variable attenuator and checked by means of a peak power meter. Other experiments were also performed by emulating the GSM emission through a sine-wave (gmmmtedby mearra of a-fr~ SYWU@S@ modulated by pulses (produced by an arbitrary waveform generator). Two modulating signals were considered: a pulse reproducing the GSM frame (repetition ~ateequal to 216.6 Hz, duty cycle of 1/8, guard time equivalent to that of GSM bursts) and a 200 Hz square wave with a duty cycle of 50940. 2.2- Performance criteria for the immunity tests The following parameters were used in order to evaluate the immunity of the fixed telephone to radiated or conducted interferences. ETSI 71 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 74 ETR 357 (GSM 05.90 version 5.0.0): January 1997 G JWM3 re~a the tinQ .(expressed in dBmop on 600 Q), measured by a psophometer and weighted by CCllT curve. A maximum value of -50 dBmop is consistent with the current trend in CENELEC standards. . . G vel of tht? ae~ (expressed in dB-SPL, weighted with the A curve) listened by an artificial ear coupled with the handset. Even if no limits are currently specified, on the basis of laboratory experience, a level of 60 dB-SPL can be considered clearly audible, while a level of 70 dB-SPL gives trouble to the conversation. 2.3- Test setup Formal tests were carried out in a GHz-TEM cell using the block diagram shown in fig. 1; the devices under test were interfered by a verticaliy- polarised plane-wave produced by a radiating element fed by the GSM test signal. The acoustic disturbance was measured by an audio analyser connected to an artificial ear, while the noise rejected along.,;the line was measured by a psophometer. A preliminary calibration of the electrical field strength was pdormed by using a continuous wave signal, whose equivalence with the level of the GSM stimulus was established by means of a peak power meter. Measurement have been performed for electrical field strength of 3, 6, 10 and 15 V/m. The correspondence between, the electrical field measured in the GHz-TEM cell and the power transmitted by a GSM mobile was verified separately on a propefiy equipped flat roof covered with a metal plating and supplied with panels of absorbing mat#rial, which attenuate the scattering from other directions. It has been verified -I the #ectricat field values measured at one meter distance from the calibrated dipple had a good correspondence with the expected values of the .trarmr@ttad power (-6 V/m for 0.8 W, -10 V/m for 2 W, -16 V/m for 5 W and -20 V/m for 8 W). - The equipped flat roof was also used for informal tests: the devices under test were placed on a ~wooden and plastic support. Some experiments were carried out with the same stimuli as those used in the GHz-TEM cell, transmitted by a calibrated electric dipole mounted on a tripod. Other informal experiments were performed by a man bringing the active GS.M transmitters (hand held and portable) directly near the device under test. Ttw disturbances or’r ttNJ fixed telephones were measured in the same way as in the GHz-TEM cell case. ..- 3- Test results A certain number of telephones commonly used in the Italian public network were tested both using the GHz-TEM cell and the equipped flat roof. As far as the GHz-TEM cell is concerned, figs. 2 and 3 show respectively the noise rejected along the line and the level of the acoustic disturbance vs. the electrical field strength of the GSM interferer. Telephones. labelled as T1, T2, T6, 17 are samples produced by different manufacturers of a ETSI 72 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 75 ETR 357 (GSM 05.90 version 5.0.0): January 1997 very common model in Italy. The wide spread between the cumes (more than 10 d8) can be justified by the different ‘sensitivity of the electronic devicesput on the circuit boards of the telephones, by a slightly different arrangement of the device under test and of its wires and by the unceflainty of the measuring equipment. The shape ofthe telephone labelled as T3 looks like that of the previous ones, but its circuits are shielded by a metallic box, making it suitable for strong electromagnetic inteflerence environments. lts immunity (rejected noise lower than -50 dBmop and acoustic level of the order of 50 dB-SPL) is higher than that of the previous models. An immunity of the same oder of magnitude was also achieved by a rugged and compact model (Iabelled T5) without any pecu~ar shielding. The lowest immunity to the radiation was instead obtained by the modelkbelled T4. which uses”more sophisticated electronics for the automatic answering function. tt is worthwhile noting that the sensitivity to the GSM intefierence was caused in all cases by the electronic circuitv of the fixed telephones: in fact the tests performed on an oid electro=mechanicd analoguetelephone did not detect any kind of disturbance, even with very high intefieflng transmitted power (up to 20 w). The immunity of two selected telephones (Tl and 13) to the GSM interference was alsocompared with the irnmuni’ty to different stimuli (GSM-lik8 emulated signal and sine-wave modulated. by a 200 Hz square-wave). Thd resutts of the comparison are shown in figs. 4 and 5 respectively for the noise rejected along the line and the level of the. acoustic disturbance. Note that the spread between the curves is narrow, even if the true-GSM case resutts slightly worse. For the same selected telephones, figs. 6 and 7 compare the immunity parameters (noise rejected along the line and level of the acoustic disturbance) measured in the GJ=fzoTEMcell with those measured on the roof. The levels of the electric field measured in the GHz-TEM cell have been translated to power values in order to use the same scales for the two environments. The measurements on the roof have Ken performed with the dipole vertically and horizontally polarised and with the telephone kept vertical and horizontal, 1 m far from the dipole. The spread between the curves is wide (more than 10 dB), showing that the position of the interferer is crucial. The closest results between the two environments have been obtained when using the same physical conditions (telephone put in horizontal position and radiating antenna with vefticaf polarisation), while the worst results have been detected when putting the telepkmin ver?icaL posithn and using a radiating. antenna with horizontal polarisation, which, on. the other hand, .is a very unuSual arrangement. ‘ 4 = Conclusions From the performed measurements, it fesutts that the disturbances on the fixed telephones. are due to the impulse shape of the TDMA GSM transmission processed by the electronic circuitry of such telephones. Therefore, only the old electro-mechanical analogue telephones are immune from the GSM interference, while all the other current equipment is susceptible to close distance GSM emissions, showing a strong dependence from the power of such an emission. ETSI 73 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 76 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Simple and reliable measurements done with pulsed sine-waves give immunity results quite similar to the true=GSM case. This measurement technique can therefore be proposed as an effective alternative for the immunity tests of the telephones when only low cost, general purpose instrumentation is available (for instance for telephone manufacturers). Out of the tested fixed telephones, just an RF-shielded model and another with a very compact structure resulted complying with immunity requirements up to 6 V/m GSM field strength (that is 0.8 W GSM emission at 1 m distance), while some models did not even comply with 3 V/m (i.e. 0.8 W GSM emission at 2 m distance). The recent decisions made in SMG#7 to leave just the two lowest classes for GSM hand-held units (0.8 W and 2 W) and to assign the remaining two classes (5 W and 8 W) to the Vehiclelpoftable mobiles are then also suppofled by the above considerations. l“. : .!$ 1: I ,’ ,L .’1 .* i !, ,, I ETSI 74 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 77 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Fig. 1 Fig. 2 GW x— // /-; .......................... 1,...................... f ::’11 n, .,. “t--i-” Representation .ofthe experimental setup for the measurements Cell o “lo “20 “so dBm~ -40 “so “60 G70 .,!: . . . ,; ,, ,.4 ‘. , in the GHz-TEM ................. .......................................... ..... ........ ........ . .. ........ ,: ...... ............. ( . . . . . .. . .. . .. . . . .. . .. . . ---n-- ....... ~~................... ......................... .................................................. .......... ................................. a 3 6 9 12 1s VI m --- Rejected noise along the tine for the measured telephones in the GHz-TEM the GSM cell with ETSI 75 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 78 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Fg. 3 Fig. 4 100 90 80 c16-SPL 70 60 so 40 0 3 6 9 12 1s V/m ,’ Level 01 with the - - the acoustic disturbance for the measured telephones in the GHz+TEM cell GSM signal. 1 0 “1o -20 “so amp 40 40 40 ??0 :, .’ T1~ ................................................................................................................ ......... ........................................................................................... ................................................................ “.>’.:...-.-. ...~a(allm$ ................. .................................................................. ............................. ........ ...! ,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. ....... . ....... . ... .. .. ... .... .... ... .. .. ... ... . .. .. ......... ... ........... .. .... .. .... ... . . .. .................. .. ... .. .... ... .... ..... ... ........ , 0 3 6 9 12 1s V/m Rejected noise along the line for two s&mples of telephones in the Gtiz-TEM cell with the GSM signal (straight line), the GSM pulse simulation and the 200 Hz square wave pulse modulation (dotted lines). ETSI 76 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 79 ETR 357 (GSM 0!5.90version 5.0.0): January 1997 Fig. 5 Fig. 6 100 90 80 d64PL ?0 60 so 40 . ..... . . ... ... .............................................. ................. .. ......... ....,, . ...... ...... ..................... ........ ............................... ....... ........................ .... ,.,. . ,-,.. n~) ~ ............................................... ..... 0 s 6 9 12 1s VI m Level of the acoustic disturbance for for two samples of telephones in the Gt=tz-TEM cell with the GSM signal (straight line), the GSM pulse Simulation and the 200 Hz square wave pulse modulation (dotted lines). .m . -------- --- .........................- * ---::--.--- ..-z~---% ... ......... e.,.. !.... .K. ..-”R. . .... .... ... .... .... .. ...... .... ... ... .. .... . ...... ........... ...... ........ . -. --sin-- - .--:Z---. -- -- .... .... ........ ........... . .... . ..... .... .. .. ... .. ....... ..... ... . .. .. . . ... ..... .... ... ...... .... ... .... %=== --, ‘“/ : 1 -------.-.-.-L---- ‘ ~~'.............................................................. ,_~*~..= -==--------------------- ------ “ - .,, .,. ,, ? m. I I o 1 z 3 4 s . w Rejected noise along the line for two samples of telephones in the GHz-TEM cell with the GSM signal (straight line) and in the roof environment for various antenna polarisations and phone positions (dotted lines). ETSI 77 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 80 ETR 357 (GSM 05.90 version 5.0.0): January 1997 100 90 80 d6+PL 70 60 so 40 I . ...... ......... -e.=: =........................................... ................................ . ...... -- ................. .... ..” . ...4 .4 .:.;.:. .........G.........0... u.Oa.*..................................................................... w .......... . .. . . .. ... .... ... ...... . . . . . . ................ .. .. ............ ...................... ......................................... .... ........ 1 m. o ,1 Fig. 7 Level of the acoustic disturbance 2 3 6 s w for two samptes of telephones in the GHz-TEM cell with the GSM signal (straight line) and in the roof environment for antenna polarisations and phone positions (dotted lines). various I ,,.: I ,, .I. l ,. : .’ ETSI 78 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 81 ETR 357 (GSM 05.90 version 5.0.0): January 1997 m TeleverketsForskningsinstitutt Tittel ‘rF-rapport R 4CW2 Intcrkms fiaTDMA-sndmnencidigital mobilkommunikaajon p&PSTN ISBN 82-423-0230=8 ISSN Prosjekt W Forfattem Innsatsmdde M~mu*jon EgilHaugcr Tilgjengdighet Apm Antall tdder 28 D&to 921006 Emneord EMC TDMA Mobbmunikasjon Sammendmg E@ponentarfcmscgTDMA -Tme Division Multiple Access -mndmxeniGSM ogDEC3 systcmenc ogp@& farcn forhdrbar intsrfcrcna iekkmonisk utstyr msdaudio-tttgang. Dct m forctatt intcrferens mtig @ 12godkjente tdsfonappamtcr ogrssul~ viscr enmegststoc -g iimmttnitcten. GSM-systemct vilgisjawrendc intctfctuaa imange av tdefoncne p&flue metersGvstand. Title ktdcmxe from theTDMA structurein digital mobb communicationto PSTN Abstract Therqcm dealswiththeTDMA- Tnc Division MultipleAccess - structurein theGSMand DECT systems and pays attentionto therisk of audibleintctfcrcncein slcctronic devices with rnudiooutput.For 12 type approvedanalogPSTN telephonesets, theinterferencehas been me- Esumdand theresults show a greatvariationin immunity level. I’heGSMsystemwillgiverisetoharmfulintctfctcncein manyof theexamined tckphottc sets fora distance of many metxcs. ETSI 79 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 82 ETR 357 (GSM 05.90 version 5.0.0): January 1997 @ Teledircktoratetsforskningsavdcling 1992 Wtm4&b*tibTumm&t~aWax~*i “Lov om oppbavsmtttil indsvcrk”, “k om rctt til fotografi” ogi“Avta&nMU~ _ ogrctighctshavcrncs aganisasjoncr om kopicringw opphawettsligbkyttet vcrki unden&@svkksomhct”. ,’ . ETSI 80 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 83 ETR 357 (GSM 05.90 version 5.0.0): January 1997 1 Introduction TDh& Tmc Division Multiple Access, is becoming widely used in modem digital radio, particularly formobilecommunication. Inthisway thecarrier canbcsharedbyanurnbcr ofusers. inGSM, thenew digital mobilecommunkation developed byETSI,a 900MHz carrier isdivkkdinto8 slots for8 different mobileusers. Eachtimcslot is0.5428ms with arepetition frequency of217Hz.Intheremaining OFF condition whenthe7 otherusers arconair,the900MHz carrier istobcbelow70dB rcfcrrcd totheON condition. ‘ From an intcrbencc point ofview,thisisanamplitude modulation whichhasthepossibili- tytocrcatc a lotofintcrfcrencc inotherelccaunic &viccs.Analogmobilecommunication suchasNMT andTACS hasaccmstant RF envelope withnamowbandfrequency xnodula- tionandotherelectronic devices am notsensitive tothe=RF signals Serious interferenceis mainlydue to rapidchangesin the envelope of the high frquency interfererand therefore all kinds of amplitude modulation of a potential interferer will in- cmasc the risk for i,ncompatibilkybetween systems using radio communicatkm andother IT-quipment. ETSI 81 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 84 ETR 357 (GSM 05.90 version 5.0.0): January 1997 contents 1 2 3 4 4.1 4.1.1 4.1.2 4.13 5 6 Introduction .““—-” ”””””*.”””-”..””””””*....”.. ... ..““.*..””...*..“..“..-.””-=.”-.. TDIW&Danoduiatcd kpency spcctmm ““”.. ””...O.”...-..” . . ..........”=00.......00.0 Measurementeet-up,method of ~ .. . . . . . . . . . . . ..... ............... ..... .. Measurementsresults for GSM-TDMA~ .-”-””.. --”-”-- ....-..””------- CkxwquencesforPSTNw mthreediffcmntinterferenceuwimnmcnts.. ... . ....... office """"-"Q-"..*"-""-"-"""..--"-""..""..-"-""--....""-""*. .*... ... . . . . .... village ...”-” ”””-..”-”..-”-.---”...-- ”-..”..00..””.....0..”.........00....... . ......-......9..”” .. Best steticmsurroundings .**”””*.-*-. . ... . .. ... . . ... ... ..... . ........... ......... ........ Mumrementsresultsfor DE~-TDMA structm .....”.. ””””...- ....- ......==” -..-... conclusion ".."* -*no-"""-""-"""""""..-"" """"-""..--..* -........"--" .......- Anne%l”15 ,! , . . ETSI 82 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 85 ETR 357 (GSM 05.90 version 5.0.0): January 1997 2 TDMA, Demodulated fkequency spect~m TheRF spectrum fromonemobilemaybe likefig1below.Thish theRF burstfroma GSM mobileinthe900MHz frequency band. A— ~ — ~ T -t to to-o.577 ma Td.615 ma Figur2.1: T13MA StiCtUre forGSM The amplitude of the ficquency spectrum is now given by (2.1) The relative spectmm is shown in annex 1. As can be seen, there is a component foreach 217Hz and the spectrum has zeroes given by T/totimesthepulse repetition frequency. In the same way wc can calculate the TDMA spectrum for the DECI’ system. Here the RF pulse duration is 0.4167 ms with a pulse repetition fkquency of 100 HZ This relative frequ- ency spectrum is given in annex 2. This TDMA structure @es a component fm each 1~ Hz with zeroes for each T/to ( - 24) times 100Hz. ThespechumfromthisTDMA structure ghwsmostofthedemodulated energyintheau- diofrequency band. Thercfom there is a great risk that suchTDMA signals give audible in- terference in electronic devices intended foraudiooutputsuchas hearhg aids and ordiiary PSTN telephone set. Xnthisreport we willgiveresults frommeasurements on~ approved analogPSTN sets. ETSI 83 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 86 ETR 357 (GSM 05.90 version 5.0.0): January 1997 3 Measurement set-up, method of measurement For the time being there is no existing requirement for immunity of analog telephone sets. Therefore there is nostandardized measurement act-up md methodof measurements. In the frequency band we am talkingaboug 1 G& and above, the generation oftheRF- field andbow thefield iscoupledtothevictim’s electronic circuit isofgreatest importance totheintctfenmce resul~Oursuggestionis thatthe measurement should be as “real life” as possible and therefore much effort is given to assm a reproducoableand maiistic immu- nity test W~ch gives as exact as possible the intexforcncelevel the user can, in the worst case, be exposed to. Amex 3gives the ove!viewof the instrument set-up ina semi-anechoic chamber. tiring themeasurement we reslbed theveryimportance ofpositioning thetelephone setandthe transmit antennaThetelephone setwasplacedcma turntable for rotation 0-360 dgr and the antenna wasrotated inthehorizontal andvertical position intheheight from0.95to 2.20m The highest interference level occuncd at an exact position of both the telephone and the antema indicating that the RIVield was coupled to the PCB of the telephone and not indu- ced via telephone line or handset oable. In an ordinary desk telephone where the FCB is ho- rizontal the intetfercncc level was muchhigherfor horizontalpolarizedfield thanfor verti- cal, althoughthe telephone line and the handset cable were vertical as shown on the set-up. Now the antenna in a mobiie system is fomeen to be vertical, but when using a handheld mobileseLthe angle to the verticalis about 65 degrees and in practice ~e angle can be in the whole range fi’omOto 90 degrees. Forcarmountedantennag theangleshouldbenear- lyO degrees tothevertical, but even here the antenna maybe more horizmtsl because of the convenient capacitive coupled window antenna When using acme piece telephone S04 the angle can of course be the same for the fixed and the mobile telephone. ‘l’hemeastmments are taken at a distance of 3 m from the intetiercr antenna to the tele- phone. In this frequency band the far field distance is less than 0.25 ~ so y6u can easily calculate theinterference level foranydistance ofinterest. The interference level was messumd both at receive and transmit side of the fixed telepho- ne. On the receive side, the interference waswe@ed withA-fiker and on transmitside the psophometer fflter wasuse& Due to the high electric ficla andproblem of fdtcring to the anechoic chamber, we had to usc a passive acoustic coupler with tight coupling. This tight coupling had of course snmc influence of the f~uency response of the handse~ but when using the A-falterthe influen- ce was tninitnizd A typical frequency msponsc is given in annex 4 ftx tdephone set no 8. ETSI 84 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 87 ETR 357 (GSM 05.90 version 5.0.0): January 1997 4 Measurements resuh for GSM-TDMA structure TIM immunity mcasurcmcnts have been taken for 12 scpexatctelephcmesets,8 ordinary desk telephonesand 4 one piece, hsndhelz telephme sets.They are all type approvedfor use in the fixed telephone network in Norway. When measuring interference noise at the receive side of the telephone. we used 1000HZ with -10 dBm ffom the fixed side as reference. me noise was then weighted with A-filter and the S/N ratio was calculated The noise measurement at the transmit side was absolute value, weighted with psophometric fitcr. The results are shown in annex 5 for receive and 6 for transrnk As can be seen them is a quadratic function from RF-power to noise power. When increasing the RF-power by 3 dB, the noiseincreasesby 6 dB. ‘Iltehigh transmit noi- se level fortelephone no 4 with low interferencepower is due to high intend noise. Be- low 8wattsGSM powertheinternal noise is dominantin this telephone. If we use 0.8 W RF-power on 3 m distance, the S/N for the reccivcr for the most immune telephone set is about 60 dB and down to 7.7dB for the most sensitive one. This extmrne difference is hard to explain, but this is the consequence of the lack of requirements for field immunity. On the ~smit side the same function can be seen, but there arc differen- ces in intcrfercncc noise tim reccivc to transmit side. If we mfcr to the same RF-power the most immune telephone has a noise level of -71 dBmp and the most sensitive one a noi- selevel of-21.8 dBmp. From the measurednoise valuesforthereceive sidem annex5we can calculate the graph where the S/N ratio is given as a functicmof distance from the interferer. Annex )4 and 15 give the signalhoise with 0.8 W handheld and 10 W car-mounted GSM-telephone.NOW we can divide the telephone sets into three groups Set no 1, 2, 8 and 12 am the most sensi- tive, 5 and 7 arc in the middle group, whiie the most immune ate sets no 3,4,6, 9, 10and 11. If we accept 40 dB S/N as a minimum quality level and the interferer is a 10W GSM tele- phone 10 m away from the fixed telephone, 6 of the 12 telephone sets must be rejected. They all have too high interference noise and for telephone set no 2 the car must be more than 70 m away to satisfy the fixed telephone user. However, we cannot draw the conchJ- sion that eve~ user of telephone no 2 is disturbed by the GSM telephone 70 m away, this is a worst case situation, but this exemise gives us an idea of the problem and indicates that sooner a later this poblem will ark In thesemeasurements we have always used RF-power as reference, but when talking im- munity, field st’sengthis the most Commofdyused.critmi& If we look at the instrument set- up in annex 3 where we have a halfwave dipole 0.95-22 m above perfect reflecting ground and an RF-power of 0.8 W 900 MHz we come up with 3.9 V/m for horizontal pola- rized field and 3.7 V/m for vertical field. This calculation is based on far field quation and with maximizingtheheight of the transmitter antcnrm If we have a quality standatrl of 40 ciBSiN un ihe receive tide, from the graph of annex 5 wc can calculate the immunity for each of the 12 telephonesets The besttelcphcmehas an immunityof 123 V/m and the most sensitive can only withstand 0.6 V/n ‘I%is26 dB vsri- ation in immunity brings dramatic consequences in quality perfmmances. As mentioned earlier, lhc TDMA fkequencyspccaum has most of its energy in the audio frequency band. In annex 7 to 10 there are examples of frequency plot on the rcceivc side for telephone no 2,3,5 and 8. For reference the 1000Hz / -10 dBm tone is also plotted on ETSI 85 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 88 ETR 357 (GSM 05.90 version 5.0.0): January 1997 thesamediagram, By comparing thismessud spectrum withthatofthecalculated oncin chapter 2,agreatconformity h found.Inthelowestfrequency band you have lower interfe- rence wduesduetothe ter. 4.1 Consequences ments clectrichwousticfrequency resp(mse of the telephone and the A-fil- for PSTN user in three different interference environ- Theinterference frommobiletransmitters usingI’!DMAisinfluenced byapat numberof factomWe havetheRF-power, thedistance fromtheinterferer totheVictims, antenna posi- tion, additional attenuation m wallsandthepossibi)ky ofshadowing efiects ofthehuman bodyorotherobstacles. Theuserenvironment isthcmfcae divi&dintothreedifferent inter- ference case~office, village andbase-station surroundings. 4.1.1 Ofiiee In a typical office environment there is a fmcd telc~one in each room and when the mobi- le user is walking m the corridor outside, the ixttcrfmnce distance is m the range ofthree meters. ‘l’he RF-powerfromtheGSM mobilemaybe ashighas20 W anddownto10 mW. Theplot5 and6 cantherefore beusedwithout anychanges. lheantenna efficiency fm thehandheld station isintherangeofO to-3dB referred todipole, sothatwhenrefer- ringtopowerdelivered todipole youmusttakethislossintoconsideration. 4.1.2Village A village w smalltownk,especially inNorway,characterised bysingle-family houses madebywoodsituated neartheroad.Inthissituation theinterference environment forthe fuedtelephone userisquitedifferent fromtheoffice situation. TheRF-powerfromticcar mountedmobdetelephone can,according toGSM specf~cation, beupto20W, butwhen talking to mobileoperators 10W b morerealistic. ‘Iheintelfemnce distance from the road to the freed telephone may be in the range of 5-10 m The dry wooden walls give no addh tional attenuation. If we look at a situation where a 10W mobile is nmning 6 m away from the fixed tele- X=, ~WA-k=~=-U~wk- &lephmeno2. As~wh quality of 40 dB S/N is obtained when the car is 73 m away. In the Nowegian m.quirement for f~ed telephone, the internal noise to the freed lines should be below -65 dBmp. In or- der to meet this requirement the interference distance is mom than 80 m. This exerciseis of come extremein the sense that you havetheworstcaseofinterference andde fried teitqtk~e IJsti has the most seitsitive telephone, but if you look at the great number of freed telephones and the number of GSM mobileswhich is expected in the futu- re, the worst case will also arise. As mentionedearlier, there is a great d~crence in the capability to withstand this ‘fi)MA interference. Themeanvalueforall12telephone setsis36.8dB S/Nandstandard devin- tion19.9dB whentheinterference distance is3 m andtheRF power0.8w. Forthetrans- mitter themeanpsophometric noiseis-46.2dBmp with standard deviation of 15.0 dB. ETSI 86 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 89 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Using this figure fm calculating the necessaryinterference distancewe come up with 12.8 m for 40 dB S/’Non the receive side and 31.4 m for -65 dBmp on the transmit side. ‘Iheconclusionfor fixed telephoneusers in villageareas is that thcmis a strongpossibility for unacceptableTDMAinterferencefrom car mounted(3SMtelephones. 4.13 Base StdOSl surroundings The TDMA stsuctureoftheRF signal k afunction ofthetraffic loadinthebasestation, butyoucanhavethesameRF bum inthisdirection asfromthemobile. TheRF powerk upto40W foreachcarriersnd theantenna gainmsybelOdB.Ifthkkthecasewhen calculating thenccesaaxy interfkrencc distance youcomeupWith198 m in orderto meet the noise mquimmentson the transmitside usingthe meanvaluefm the 12tclepbe sets. In this situationusing the highestpowerand high gain antennathe numberof nearbyfixed telephoneswill probablybe low. A more realistic situaticmwill be using 10 W RF power and 6 dB gain antmtm l%c interference distance is now 62 m for -65 dBmp on the trsns- rnitside snd2Smfor40dB S/N onthe receive side. ?hc base station is on the air all the time and the f~ed telephone user will be exposedto this TDMA interference whenever the subscriber hi calling. Fortheoperator thereisalsothepossibility thatthefwedtelephone atthebasestation ser- vicecenter will be disturbd The operatcxofTDMA atmcture mobde systems must be aware of the relatively strong pos- sibility ofunwanteddistudmnces forthefuedsubscriber inthebasestations ne@bour- hood. ETSI 87 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 90 ETR 357 (GSM 05.90 version 5.0.0): January 1997 5 Measurements results for DECT-’I’3)~ structure The ‘I’DMAstructure for DE(X is somewhat diffcmnt than shown in chapter 2. ‘Ihe pulse repetition fiequcncy is 100 Hz giving the fiqucncy spoctmm in annex 2. The RF power is dcfmcd to be maximum 2S0 mW EIRP and the interference level for tele- phone no 2,5 and 8 is shown in annex 11 to 13. Comparing this interference to a GSM te- lephone with 0.8 W the noise is 30-40 dB lower fm DECI’ tclcphonc than for GSM. This lower interference is caused by a lot of factcxs The reduction of RF-power lower the noise by 10 dB, the doubling of the fiequcncy gives 6 dB lower interference voltage cau- sing 12 dB lower noise, and with this high= frequency the distributed capacitance on the PCB acts as a low pass filter reducing the induced interference voltage. Thepotential TDMA intcrkmnce fromDE(3 into fwed telephone acts is then seen to be much lower than for GSM due to the higher fiquency and the lower radiated power. This is not to say that TDMA in 2 GHz band is of no problem from an interfcrcncc point of view. ETSI 88 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 91 ETR 357 (GSM 05.90 version 5.0.0): January 1997 6 Conclusion As the mcsaummcnts have show there is a high interference potential from a TDMA struc- ture mobile communication system particular with the high powcr transmittm as in the GSM syszcm.TIMlack of immunity rquimmcnta in the VHHUHF band for amplitude me dulatcd field is a scrious matter which has to be dealt with within the relevant standardi- zing idtUtiollS, hke =1 and CENELK, Some considerations has been given to this sub- ject in fcx instance ETSL In a meeting in Paris 10-14 November 1990 in ‘TCRES a“psper WSS pxescntd by UK DTI - RfidiOCOItUINUdCILtiOn A@ItCy “THE EMC CONUNDRUM- ‘1’DMATECHNOLOGY”.A lot of measurements results fi’ombearing aids exposed by TDMA interference arc presented and the conclusions are %hat the proposed generic immu- nity standard of 3 V/m does not offer adequate protection from radio transmitters”. But for the fixed telephones already in use there is little help in better standards for the fu- ture. The mobile system operators must be responsible and take proper action to assure the f~cd subscriber a conversation * ftom TDMA interference also in the future. This is not an easy match, but the cost must be on the intcrfcrw and not the victim ETSI 89 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 92 ETR 357 (GSM 05.90 version 5.0.0): January 1997 I (GSM 05.90 version 6.0.1 Release 1997) 90 ETSI ETSI TR 101 640 V6.0.1 (2001-11) %1 ) t ) . - —— Page 93 ETR 357 (GSM 05.90 vekion 5.0.0): January 1997 17-! I =d=d I , ,.- ------- q 1 0 Annex 2 . . . (GSM 05.90 version 6.0.1 Release 1997) 91 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 94 ETR 357 (GSM 05.90 version 5.0.0): January 1997 ------ [ E m 0 .---- ----- I E m- 0 ------ - P------ --- > > > > > > > > > > > > > (GSM 05.90 version 6.0.1 Release 1997) 92 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 95 ETR 357 (GSM 05.90 version 5.0.0): January-1997 Annex 4 T . . N G o 0 Gz m n 4-Jm k“ ,, 42! . . . . . . G ., . 0 4... mlm m G I I 1 4 L -~= m= Ubto” manl Otx I I (GSM 05.90 version 6.0.1 Release 1997) 93 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 96 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Annex 5 zt- U) L 4 i% — 0 N 0 o Q o N o . 0 (GSM 05.90 version 6.0.1 Release 1997) 94 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 97 ETR 357 (GSM 05.90 version 5.0.0): January 1997 z Annex 6 o w 2 . 0 No0 (GSM 05.90 version 6.0.1 Release 1997) 95 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 98 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Annex 7 . -@ -*s 111—+=i=i= r.. o G 0 0 - I (GSM 05.90 version 6.0.1 Release 1997) 96 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 99 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Annex 8 . 1 I I Ge & & o 0. 0 m - . . . . .* G G G . . uw m L r3 L L >0= . . . (GSM 05.90 version 6.0.1 Release 1997) 97 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 100 ETR 357 (GSM 05.90 version 5.0.0): January 1997 . Annex 9 I 1 1 I I ‘1 I — I I -H= . . IEEE12 . .19 ”}” . I I I ZU n . Ln G G . . . .* G I I I I I 4 I I I — , ti’ - In 1 I 1 1 I I — . I >. (GSM 05.90 version 6.0.1 Release 1997) 98 ETSI ETSI TR 101 640 V6.0.1 (2001-11) 4) Res.Elw 24.6 HZ[3dR] Vid.B~ 30 Hz Date 12.Jun. ’92 The 10:24:09 llF.Att 10 dfl Ref .Lvl CF.Stp 500.000 Hz -10.00 dBm Unit [dEl] o -lO.O -20*o -30.0 -40.0 -50.0 -60.0 -70.0 -80.0 -90.0 -100.0 uin -1 0aio 0 itart Span ‘ Center Weep stop > g ~ oHz 5 kHz 2.5 kHz 26 s 5 kHz S 58 x ma A o i5i5 qd Telephone set nr 8 (GSM 05.90 version 6.0.1 Release 1997) 99 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 102 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Annex 11 — — I T . . . .* — .* . . . I — 1 , L . !_ L (GSM 05.90 version 6.0.1 Release 1997) 100 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 103 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Annex 12 N & o00 sz m I - , 1 I 4 .* } . . 1 - I T . 1 lH’ - m m a . . al la k=t=E I I . E (GSM 05.90 version 6.0.1 Release 1997) 101 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Page 104 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Annex 13 s G - N . E ‘Nu= a E . . . . . — o G o 1 . . . . G . . . . . . I (GSM 05.90 version 6.0.1 Release 1997) 102 ETSI ETSI TR 101 640 V6.0.1 (2001-11) Annex 14 GSM-power 0,8 w (Handheld) dB S/N 70 60 50 40 30 20 10 I . I 11 J 0.75! 3 6 10 12 20 24 I 30 m 1:5 EH.O2WO1O2 ETSI 103 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) Page 106 ETR 357 (GSM 05.90 version 5.0.0): January 1997 Annex 15 GSM-power 10 w (Car-mounted) 70 60 50 40 30 20 10 0 10 20 30 40 50 60 70 so go 100 m S4.920S01-1 ETSI 104 (GSM 05.90 version 6.0.1 Release 1997) ETSI TR 101 640 V6.0.1 (2001-11) ETSI ETSI TR 101 640 V6.0.1 (2001-11) 105 (GSM 05.90 version 6.0.1 Release 1997) History Document history V6.0.1 November 2001 Publication
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
1 Scope
|
The present document is a descriptive recommendation to be helpful in cell planning.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
1.1 References
|
The following documents contain provisions which, through reference in this text, constitute provisions of the present document. • References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific. • For a specific reference, subsequent revisions do not apply. • For a non-specific reference, the latest version applies. • A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same number. • For this Release 1998 document, references to GSM documents are for Release 1998 versions (version 7.x.y). [1] GSM 01.04: "Digital cellular telecommunications system (Phase 2+); Abbreviations and acronyms". [2] GSM 05.02: "Digital cellular telecommunications system (Phase 2+); Multiplexing and multiple access on the radio path". [3] GSM 05.05: "Digital cellular telecommunications system (Phase 2+); Radio transmission and reception". [4] GSM 05.08: "Digital cellular telecommunications system (Phase 2+); Radio subsystem link control". [5] CCIR Recommendation 370-5: "VHF and UHF propagation curves for the frequency range from 30 MHz to 1000 MHz". [6] CCIR Report 567-3: "Methods and statistics for estimating field strength values in the land mobile services using the frequency range 30 MHz to 1 GHz". [7] CCIR Report 842: "Spectrum-conserving terrestrial frequency assignments for given frequency-distance seperations". [8] CCIR Report 740: "General aspects of cellular systems".
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
1.2 Abbreviations
|
Abbreviations used in the present document are given clause 6 (Glossary) and in GSM 01.04 [1].
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
2 Traffic distributions
| |
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
2.1 Uniform
|
A uniform traffic distribution can be considered to start with in large cells as an average over the cell area, especially in the country side. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 7 (GSM 03.30 version 7.1.0 Release 1998)
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
2.2 Non-uniform
|
A non-uniform traffic distribution is the usual case, especially for urban areas. The traffic peak is usually in the city centre with local peaks in the suburban centres and motorway junctions. A bell-shaped area traffic distribution is a good traffic density macro model for cities like London and Stockholm. The exponential decay constant is on average 15 km and 7,5 km respectively. However, the exponent varies in different directions depending on how the city is built up. Increasing handheld traffic will sharpen the peak. Line coverage along communication routes as motorways and streets is a good micro model for car mobile traffic. For a maturing system an efficient way to increase capacity and quality is to build cells especially for covering these line concentrations with the old area covering cells working as umbrella cells. Point coverage of shopping centres and traffic terminals is a good micro model for personal handheld traffic. For a maturing system an efficient way to increase capacity and quality is to build cells on these points as a complement to the old umbrella cells and the new line covering cells for car mobile traffic.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
3 Cell coverage
| |
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
3.1 Location probability
|
Location probability is a quality criterion for cell coverage. Due to shadowing and fading a cell edge is defined by adding margins so that the minimum service quality is fulfilled with a certain probability. For car mobile traffic a usual measure is 90 % area coverage per cell, taking into account the minimum signal-to-noise ratio Ec/No under multipath fading conditions. For lognormal shadowing an area coverage can be translated into a location probability on cell edge (Jakes, 1974). For the normal case of urban propagation with a standard deviation of 7 dB and a distance exponential of 3.5, 90 % area coverage corresponds to about 75 % location probability at the cell edge. Furthermore, the lognormal shadow margin in this case will be 5 dB, as described in CEPT Recommendation T/R 25-03 and CCIR Report 740.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
3.2 Ec/No threshold
|
The mobile radio channel is characterized by wideband multipath propagation effects such as delay spread and Doppler shift as defined in GSM 05.05 annex C. The reference signal-to-noise ratio in the modulating bit rate bandwidth (271 kHz) is Ec/No = 8 dB including 2 dB implementation margin for the GSM system at the minimum service quality without interference. The Ec/No quality threshold is different for various logical channels and propagation conditions as described in GSM 05.05.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
3.3 RF-budgets
|
The RF-link between a Base Transceiver Station (BTS) and a Mobile Station (MS) including handheld is best described by an RF-budget as in annex A which consists of 4 such budgets; A.1 for GSM 900 MS class 4; A.2 for GSM 900 MS class 2, A.3 for DCS 1800 MS classes 1 and 2, and A.4 for GSM 900 class 4 in small cells. The antenna gain for the hand portable unit can be set to 0 dBi due to loss in the human body as described in CCIR Report 567. An explicit body loss factor is incorporated in annex A.3 At 900 MHz, the indoor loss is the field strength decrease when moving into a house on the bottom floor on 1.5 m height from the street. The indoor loss near windows ( < 1 m) is typically 12 dB. However, the building loss has been measured by the Finnish PTT to vary between 37 dB and -8 dB with an average of 18 dB taken over all floors and buildings (Kajamaa, 1985). See also CCIR Report 567. At 1800 MHz, the indoor loss for large concrete buildings was reported in COST 231 TD(90)117 and values in the range 12 - 17 dB were measured. Since these buildings are typical of urban areas a value of 15 dB is assumed in annex A.3. In rural areas the buildings tend to be smaller and a 10 dB indoor loss is assumed. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 8 (GSM 03.30 version 7.1.0 Release 1998) The isotropic power is defined as the RMS value at the terminal of an antenna with 0 dBi gain. A quarter-wave monopole mounted on a suitable earth-plane (car roof) without losses has antenna gain 2 dBi. An isotropic power of -113 dBm corresponds to a field strength of 23.5 dBuV/m for 925 MHz and 29.3 dBuV/m at 1795 MHz, see CEPT Recommendation T/R 25-03 and GSM 05.05 section 5 for formulas. GSM900 BTS can be connected to the same feeders and antennas as analog 900 MHz BTS by diplexers with less than 0.5 dB loss.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
3.4 Cell ranges
| |
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
3.4.1 Large cells
|
In large cells the base station antenna is installed above the maximum height of the surrounding roof tops; the path loss is determined mainly by diffraction and scattering at roof tops in the vicinity of the mobile i.e. the main rays propagate above the roof tops; the cell radius is minimally 1 km and normally exceeds 3 km. Hata's model and its extension up to 2000 MHz (COST 231-Hata model) can be used to calculate the path loss in such cells (see COST 231 TD (90) 119 Rev 2 and annex B). The field strength on 1.5 m reference height outdoor for MS including handheld is a value which inserted in the curves of CCIR Report 567-3 Figure 2 (Okumura) together with the BTS antenna height and effective radiated power (ERP) yields the range and re-use distance for urban areas (section 5.2). The cell range can also be calculated by putting the maximum allowed path loss between isotropic antennas into the Figures 1 to 3 of annex C. The same path loss can be found in the RF-budgets in annex A. The figures 1 and 2 (GSM 900) in annex C are based on Hata's propagation model which fits Okumura's experimental curves up to 1500 MHz and figure 3 (DCS 1800) is based on COST 231-Hata model according to COST 231 TD (90) 119 Rev 2. The example RF-budget shown in annex A.1 for a GSM900 MS handheld output power 2 W yields about double the range outdoors compared with indoors. This means that if the cells are dimensioned for handhelds with indoor loss 10 dB, the outdoor coverage for MS will be interference limited, see section 4.2. Still more extreme coverage can be found over open flat land of 12 km as compared with 3 km in urban areas outdoor to the same cell site. For GSM 900 the Max EIRP of 50 W matches MS class 2 of max peak output power 8 W, see annex A.2. An example RF budget for DCS 1800 is shown in annex A.3. Range predictions are given for 1 W and 250 mW DCS 1800 MS with BTS powers which balance the up- and down- links. The propagation assumptions used in annex A1, A2, A3 are shown in the tables below : For GSM 900: Rural Rural Urban (Open Area) (Quasi-open) Base station 100 100 50 height (m) Mobile height (m) 1.5 1.5 1.5 Hata's loss 90.7+31.8log(d) 95.7+31.8log(d) 123.3+33.7log(d) formula (d in km) Indoor Loss (dB) 10 10 15 ETSI ETSI TR 101 362 V7.1.0 (2000-04) 9 (GSM 03.30 version 7.1.0 Release 1998) For DCS 1800: Rural Rural Urban (*) (Open Area) (Quasi-Open) Base station 60 60 50 height (m) Mobile height (m) 1.5 1.5 1.5 COST 231 100.1+33.3log(d) 105.1+33.3log(d) 133.2+33.8log (d) Hata's loss formula (d in km) Indoor Loss (dB) 10 10 15 (*) medium sized city and suburban centres (see COST 231 TD (90) 119 Rev2). For metropolitan centres add 3 dB to the path loss. NOTE 1: The rural (Open Area) model is useful for desert areas and the rural (Quasi-Open) for countryside. NOTE 2: The correction factors for Quasi-open and Open areas are applicable in the frequency range 100-2000 MHz (Okumura,1968).
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
3.4.2 Small cells
|
For small cell coverage the antenna is sited above the median but below the maximum height of the surrounding roof tops and so therefore the path loss is determined by the same mechanisms as stated in section 3.4.1. However large and small cells differ in terms of maximum range and for small cells the maximum range is typically less than 1-3 km. In the case of small cells with a radius of less than 1 km the Hata model cannot be used. The COST 231-Walfish-Ikegami model (see annex B) gives the best approximation to the path loss experienced when small cells with a radius of less than 5 km are implemented in urban environments. It can therefore be used to estimate the BTS ERP required in order to provide a particular cell radius (typically in the range 200 m - 3 km). The cell radius can be calculated by putting the maximum allowed path loss between the isotropic antennas into figure 4 of annex C. The following parameters have been used to derive figure 4: Width of the road, w = 20 m Height of building roof tops, Hroof = 15 m Height of base station antenna, Hb = 17 m Height of mobile station antenna, Hm = 1.5 m Road orientation to direct radio path, Phi = 90° Building separation, b = 40 m For GSM 900 the corresponding propagation loss is given by : Loss (dB) = 132.8 + 38log(d/km) For DCS 1800 the corresponding propagation loss is given by : Loss (dB) = 142,9 + 38log(d/km) for medium sized cities and suburban centres Loss (dB) = 145,3 + 38log(d/km) for metropolitan centres An example of RF budget for a GSM 900 Class 4 MS in a small cell is shown in annex A.4. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 10 (GSM 03.30 version 7.1.0 Release 1998)
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
3.4.3 Microcells
|
COST 231 defines a microcell as being a cell in which the base station antenna is mounted generally below roof top level. Wave propagation is determined by diffraction and scattering around buildings i.e. the main rays propagate in street canyons. COST 231 proposes the following experimental model for microcell propagation when a free line of sight exists in a street canyon : Path loss in dB (GSM 900) = 101,7 + 26log(d/km) d > 20 m Path loss in dB (DCS 1800) = 107,7 + 26log(d/km) d > 20 m The propagation loss in microcells increases sharply as the receiver moves out of line of sight, for example, around a street corner. This can be taken into account by adding 20 dB to the propagation loss per corner, up to two or three corners (the propagation being more of a guided type in this case). Beyond, the complete COST231-Walfish-Ikegami model as presented in annex B should be used. Microcells have a radius in the region of 200 to 300 metres and therefore exhibit different usage patterns from large and small cells. They can be supported by generally smaller and cheaper BTS's. Since there will be many different microcell environments, a number of microcell BTS classes are defined in GSM 05.05. This allows the most appropriate microcell BTS to be chosen based upon the Minimum Coupling Loss expected between MS and the microcell BTS. The MCL dictates the close proximity working in a microcell environment and depends on the relative BTS/MS antenna heights, gains and the positioning of the BTS antenna. In order to aid cell planning, the micro-BTS class for a particular installation should be chosen by matching the measured or predicted MCL at the chosen site with the following table. The microcell specifications have been based on a frequency spacing of 6 MHz between the microcell channels and the channels used by any other cell in the vicinity. However, for smaller frequency spacings (down to 1.8 MHz) a larger MCL must be maintained in order to guarantee successful close proximity operation. This is due to an increase in wideband noise and a decrease in the MS blocking requirement from mobiles closer to the carrier. Micro-BTS class Recommended MCL (GSM 900) Recommended MCL (DCS 1800) Normal Small freq. spacing Normal Small freq. spacing M1 60 64 60 68 M2 55 59 55 63 M3 50 54 50 58 Operators should note that when using the smaller frequency spacing and hence larger MCL the blocking and wideband noise performance of the micro-BTS will be better than necessary. Operators should exercise caution in choosing the microcell BTS class and transmit power. If they depart from the recommended parameters in 05.05 they risk compromising the performance of the networks operating in the same frequency band and same geographical area.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
4 Channel re-use
| |
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
4.1 C/Ic threshold
|
The C/Ic threshold is the minimum co-channel carrier-to-interference ratio in the active part of the timeslot at the minimum service quality when interference limited. The reference threshold C/Ic = 9 dB includes 2 dB implementation margin on the simulated residual BER threshold The threshold quality varies with logical channels and propagation conditions, see GSM 05.05.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
4.2 Trade-off between Ec/No and C/Ic
|
For planning large cells the service range can be noise limited as defined by Ec/No plus a degradation margin of 3 dB protected by 3 dB increase of C/Ic, see annex A. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 11 (GSM 03.30 version 7.1.0 Release 1998) For planning small cells it can be more feasible to increase Ec/No by 6 dB corresponding to an increase of C/Ic by 1 dB to cover shadowed areas better. C/(I+N) = 9 dB represents the GSM limit performance. To permit handheld coverage with 10 dB indoor loss, the Ec/No has to be increased by 10 dB outdoors corresponding to a negligible increase of C/Ic outdoors permitting about the same interference limited coverage for MS including handhelds. The range outdoors can also be noise limited like the range indoors as shown in section 3.4 and annex A.1.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
4.3 Adjacent channel suppressions
|
Adjacent channel suppression (ACS) is the gain (Ia/Ic) in C/I when wanted and unwanted GSM RF-signals co-exist on adjacent RF channels whilst maintaining the same quality as in the co-channel case, i.e. ACS = C/Ic - C/Ia. Taking into account frequency errors and fading conditions in the product of spectrum and filter of wanted and unwanted GSM RF-signals, ACS = 18 dB is typical as can be found in GSM 05.05. 1st ACS >= 18 dB, i.e. C/Ia1 <= -9 dB for C/Ic = 9 dB in GSM 05.05, imposes constraints of excluding the 1st adjacent channel in the same cell. However, the 1st adjacent channel can be used in the 1st adjacent cell, as C/Ic <= 12 dB and ACS >= 18 dB gives an acceptable handover- margin of >= 6 dB for signalling back to the old BTS as shown in GSM 05.08. An exception might be adjacent cells using the same site due to uplink interference risks. 2nd ACS >= 50 dB, i.e. C/Ia2 <= -41 dB for C/Ic = 9 dB in GSM 05.05, implies that due to MS power control in the uplink, as well as intra-cell handover, it is possible that the 2nd adjacent channel can be used in the same cell. Switching transients are not interfering due to synchronized transmission and reception of bursts at co-located BTS.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
4.4 Antenna patterns
|
Antenna patterns including surrounding masts, buildings, and terrain measured on ca 1 km distance will always look directional, even if the original antenna was non-directional. In order to achieve a front-to-back ratio F/B of greater than 20 dB from an antenna with an ideal F/B > 25 dB, backscattering from the main lobe must be suppressed by using an antenna height of at least 10 m above forward obstacles in ca 0.5 km. In order to achieve an omni-directional pattern with as few nulls as possible, the ideal non-directional antenna must be isolated from the mast by a suitable reflector. The nulls from mast scattering are usually in different angles for the duplex frequencies and should be avoided because of creating path loss imbalance. The main lobe antenna gains are typically 12-18 dBi for BTS, and 2-5 dBi for MS. Note that a dipole has the gain 0 dBd = 2 dBi.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
4.5 Antenna heights
|
The height gain under Rayleigh fading conditions is approximately 6 dB by doubling the BTS antenna height. The same height gain for MS and handheld from reference height 1.5 m to 10 m is about 9 dB, which is the correction needed for using CCIR Recommendation 370.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
4.6 Path loss balance
|
Path loss balance on uplink and downlink is important for two-way communication near the cell edge. Speech as well as data transmission is dimensioned for equal quality in both directions. Balance is only achieved for a certain power class (section 3.4). Path loss imbalance is taken care of in cell selection in idle mode and in the handover decision algorithms as found in GSM 05.08. However, a cell dimensioned for 8 W MS (GSM 900 class 2) can more or less gain balance for 2 W MS handheld (GSM 900 class 4) by implementing antenna diversity reception on the BTS.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
4.7 Cell dimensioning
|
Cell dimensioning for uniform traffic distribution is optimized by at any time using the same number of channels and the same coverage area per cell. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 12 (GSM 03.30 version 7.1.0 Release 1998) Cell dimensioning for non-uniform traffic distribution is optimized by at any time using the same number of channels but changing the cell coverage area so that the traffic carried per cell is kept constant with the traffic density. Keeping the path loss balance by directional antennas pointing outwards from the traffic peaks the effective radiated power (ERP) per BTS can be increased rapidly out-wards. In order to make the inner cells really small the height gain can be decreased and the antenna gain can be made smaller or even negative in dB by increasing the feeder loss but keeping the antenna front-to-back ratio constant (section 4.4).
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
4.8 Channel allocation
|
Channel allocation is normally made on an FDMA basis. However, in synchronized networks channel allocation can be made on a TDMA basis. Note that a BCCH RF channel must always be fully allocated to one cell. Channel allocation for uniform traffic distribution preferably follows one of the well known re-use clusters depending on C/I-distribution, e.g. a 9-cell cluster (3-cell 3-site repeat pattern) using 9 RF channel groups or cell allocations (CAs), (Stjernvall, 1985). Channel allocation for non-uniform traffic distribution preferably follows a vortex from a BTS concentration on the traffic centre, if a bell-shaped area traffic model holds. In real life the traffic distribution is more complicated with also line and point traffic. In this case the cell areas will be rather different for various BTS locations from city centre. The channel allocation can be optimized by using graph colouring heuristics as described in CCIR Report 842. Base transceiver station identity code (BSIC) allocation is done so that maximum re-use distance per carrier is achieved in order to exclude co-channel ambiguity. Frequency co-ordination between countries is a matter of negotiations between countries as described in CEPT Recommendation T/R 25-04. Co-channel and 200 kHz adjacent channels need to be considered between PLMNs and other services as stated in GSM 05.05. Frequency sharing between GSM countries is regulated in CEPT Recommendation T/R 20-08 concerning frequency planning and frequency co-ordination for the GSM service.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
4.9 Frequency hopping
|
Frequency hopping (FH) can easily be implemented if the re-use is based on RF channel groups (CAs). It is also possible to change allocation by demand as described in GSM 05.02. In synchronized networks the synchronization bursts (SB) on the BCCH will occur at the same time on different BTS. This will increase the time to decode the BSIC of adjacent BTS, see GSM 05.08. The SACCH on the TCH or SDCCH will also occur at the same time on different BTS. This will decrease the advantage of discontinuous transmission (DTX). In order to avoid this an offset in the time base (FN) between BTS may be used. If channel allocation is made on a TDMA basis and frequency hopping is used, the same hop sequence must be used on all BTS. Therefore the same time base and the same hopping sequence number (HSN) shall be used.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
4.10 Cells with extra long propagation delay
|
Cells with anticipated traffic with ranges more than 35 km corresponding to maximum MS timing advance can work properly if the timeslot after the CCCH and the timeslot after the allocated timeslot are not used by the BTS corresponding to a maximum total range of 120 km.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
5 Propagation models
| |
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
5.1 Terrain obstacles
|
Terrain obstacles introduce diffraction loss, which can be estimated from the path profile between transmitter and receiver antennas. The profile can preferably be derived from a digital topographic data bank delivered from the national map survey or from a land resource satellite system, e.g. Spot. The resolution is usually 500*500 m2 down to ETSI ETSI TR 101 362 V7.1.0 (2000-04) 13 (GSM 03.30 version 7.1.0 Release 1998) 50*50 m2 in side and 20 m down to 5 m in height. This resolution is not sufficient to describe the situation in cities for microcells, where streets and buildings must be recognized.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
5.2 Environment factors
|
Environment factors for the nearest 200 m radius from the mobile play an important role in both the 900 MHz and 1800 MHz bands. For the Nordic cellular planning for NMT there is taken into account 10 categories for land, urban and wood. Further studies are done within COST 231. Coarse estimations of cell coverage can be done on pocket computers with programs adding these environment factors to propagation curves of CCIR Recommendation 370-5 figure 9 and CCIR Report 567-3 figure 2 (Okumura, 1968).
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
5.3 Field strength measurements
|
Field strength measurements of the local mean of the lognormal distribution are preferably done by digital averaging over the typical Rayleigh fading. It can be shown that the local average power can be estimated over 20 to 40 wavelengths with at least 36 uncorrelated samples within 1 dB error for 90 % confidence (Lee, 1985).
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
5.4 Cell adjustments
|
Cell adjustments from field strength measurements of coverage and re-use are recommended after coarse predictions have been done. Field strength measurements of rms values can be performed with an uncertainty of 3.5 dB due to sampling and different propagation between Rayleigh fading and line-of-sight. Predictions can reasonably be done with an uncertainty of about 10 dB. Therefore cell adjustments are preferably done from field strength measurements by changing BTS output power, ERP, and antenna pattern in direction and shape.
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
6 Glossary
|
ACS Adjacent Channel Suppression (section 4.3) BCCH Broadcast Control Channel (section 4.8) BTS Base Transceiver Station (section 3.3) BSIC Base Transceiver Station Identity Code (section 4.8) CA Cell Allocation of radio frequency channels (section 4.8) CCCH Common Control Channel (section 4.10) COST European Co-operation in the field of Scientific and Technical Research DTX Discontinuous Transmission (section 4.9) Ec/No Signal-to-Noise ratio in modulating bit rate bandwidth (section3.2) FH Frequency Hopping (section 4.9) FN TDMA Frame Number (section 4.9) F/B Front-to-Back ratio (section 4.4) HSN Hopping Sequence Number (section 4.9) MS Mobile Station (section 3.3) PLMN Public Land Mobile Network Ps Location (site) Probability (section 3.1) ETSI ETSI TR 101 362 V7.1.0 (2000-04) 14 (GSM 03.30 version 7.1.0 Release 1998) SACCH Slow Associated Control Channel (section 4.9) SB Synchronization Burst (section 4.9) SDCCH Stand-alone Dedicated Control Channel (section 4.9) TCH Traffic Channel (section 4.9)
|
f48e0f9fa2d7ccfd80e612b2641fd571
|
101 362
|
7 Bibliography
|
CEPT Recommendation T/R 20-08 Frequency planning and frequency co-ordination for the GSM service; CEPT Recommendation T/R 25-03 Co-ordination of frequencies for the land mobile service in the 80, 160 and 460 MHz bands and the methods to be used for assessing interference; CEPT Recommendation T/R 25-04 Co-ordination in frontier regions of frequencies for the land mobile service in the bands between 862 and 960 MHz; CEPT Liaison office, P.O. Box 1283, CH-3001 Berne. 1 Jakes, W.C., Jr.(Ed.) (1974) Microwave mobile communications. John Wiley, New York, NY, USA. 2 Kajamaa, Timo (1985) 900 MHz propagation measurements in Finland in 1983-85 (PTT Report 27.8.1985.) Proc NRS 86, Nordic Radio Symposium, ISBN 91-7056-072-2. 3 Lee, W.C.Y. (Feb., 1985) Estimate of local average power of a mobile radio signal. IEEE Trans. Vehic. Tech., Vol. VT-34, 1. 4 Okumura, Y. et al (Sep.-Oct., 1968) Field strength and its variability in VHF and UHF land-mobile radio service. Rev. Elec. Comm. Lab., NTT, Vol. 16, 9-10. 5 Stjernvall, J-E (Feb. 1985) Calculation of capacity and co-channel interference in a cellular system. Nordic Seminar on Digital Land Mobile Radio Communication (DMR I), Espoo, Finland. 6 A.M.D. Turkmani, J.D. Parsons and A.F. de Toledo "Radio Propagation into Buildings at 1.8 GHz". COST 231 TD (90) 117 7 COST 231 "Urban transmission loss models for mobile radio in the 900- and 1800- MHz bands (Revision 2)" COST 231 TD (90) 119 Rev 2. 8 Hata, M. (1980) Empirical Formula for Propagation Loss in Land Mobile Radio Services, IEEE Trans. on Vehicular Technology VT-29. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 15 (GSM 03.30 version 7.1.0 Release 1998) Annex A.1: (class 4) Example of RF-budget for GSM MS handheld RF-output peak power 2 W Propagation over land in urban and rural areas Receiving end: BTS MS Eq. TX: MS BTS (dB) Noise figure (multicoupl.input) dB 8 10 A Multipath profile 1) TU50 TU50 (no FH) Ec/No min. fading 1) dB 8 8 B RX RF-input sensitivity dBm -104 -102 C=A+B+W-174 Interference degrad. margin dB 3 3 D RX-antenna cable type 1-5/8" 0 Specific cable loss dB/100m 2 0 Antenna cable length m 120 0 Cable loss + connector dB 4 0 E RX-antenna gain dBi 12 0 F Isotropic power, 50 % Ps dBm -109 -99 G=C+D+E-F Lognormal margin 50 % -> 75 % Ps dB 5 5 H Isotropic power, 75 % Ps dBm -104 -94 I=G+H Field strength, 75 % Ps dBuV/m 33 43 J=I+137 C/Ic min.fading, 50 % Ps 1) dB 9 9 C/Ic prot. at 3 dB degrad. dB 12 12 C/Ic protection, 75 % Ps 2) dB 19 19 Transmitting end: MS BTS Eq. RX: BTS MS (dB) TX RF-output peak power W 2 6 (mean power over burst) dBm 33 38 K Isolator + combiner + filter dB 0 3 L RF peak power, combiner output dBm 33 35 M=K-L TX-antenna cable type 0 1-5/8" Specific cable loss dB/100m 0 2 Antenna cable length m 0 120 ETSI ETSI TR 101 362 V7.1.0 (2000-04) 16 (GSM 03.30 version 7.1.0 Release 1998) Cable loss + connector dB 0 4 N TX-antenna gain dBi 0 12 O Peak EIRP W 2 20 (EIRP = ERP + 2 dB) dBm 33 43 P=M-N+O Isotropic path loss, 50 % Ps 3) dB 139 139 Q=P-G-3 Isotropic path loss, 75 % Ps dB 134 134 R=P-I-3 Range, outdoor, 75 % Ps 4) km 2.0 2.0 Range, indoor, 75 % Ps 4) km 0.7 0.7 1) Ec/No and C/Ic for residual BER = 0.4 %, TCH/FS (class Ib) and multi-path profiles as defined in GSM 05.05 annex 3. Bandwidth W = 54 dBHz. 2) Uncorrelated C and I with 75 % location probability (Ps). lognormal distribution of shadowing with standard deviation 7 dB. Ps = 75 % corresponds to ca 90 % area coverage, see Jakes, pp.126-127. 3) 3 dB of path loss is assumed to be due to the antenna/body loss 4) Max. range based on Hata. Antenna heights for BTS = 50 m and MS = 1.5 m. Indoor loss = 15 dB. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 17 (GSM 03.30 version 7.1.0 Release 1998) Annex A.2: (class 2) Example of RF-budget for GSM MS RF-output peak power 8 W Propagation over land in urban and rural areas Receiving end: BTS MS Eq. TX: MS BTS (dB) Noise figure (multicoupl.input) dB 8 8 A Multipath profile 1) RA250 RA250 (no FH) Ec/No min. fading 1) dB 8 8 B RX RF-input sensitivity dBm -104 -104 C=A+B+W-174 Interference degrad. margin dB 3 3 D RX-antenna cable type 1-5/8" RG-58 Specific cable loss dB/100m 2 50 Antenna cable length m 120 4 Cable loss + connector dB 4 2 E RX-antenna gain dBi 12 2 F Isotropic power, 50 % Ps dBm -109 -101 G=C+D+E-F Lognormal margin 50 % -> 75 % Ps dB 5 5 H Isotropic power, 75 % Ps dBm -104 -96 I=G+H Field strength, 75 % Ps dBuV/m 33 41 J=I+137 C/Ic min.fading, 50 % Ps 1) dB 9 9 C/Ic prot. at 3 dB degrad. dB 12 12 C/Ic protection, 75 % Ps 2) dB 19 19 Transmitting end: MS BTS Eq. RX: BTS MS (dB) TX RF-output peak power W 8 16 (mean power over burst) dBm 39 42 K Isolator + combiner + filter dB 0 3 L RF peak power, combiner output dBm 39 39 M=K-L TX-antenna cable type RG-58 1-5/8" Specific cable loss dB/100m 50 2 Antenna cable length m 4 120 Cable loss + connector dB 2 4 N TX-antenna gain dBi 2 12 O Peak EIRP W 20 50 (EIRP = ERP + 2 dB) dBm 39 47 P=M-N+O Isotropic path loss, 50 % Ps dB 148 148 Q=P-G Isotropic path loss, 75 % Ps dB 143 143 R=P-I Range, outdoor, 75 % Ps 3) km 30.7 30.7 1) Ec/No and C/Ic for residual BER = 0.2 %, TCH/FS (class Ib) and multi-path profiles as defined in GSM 05.05 annex 3. Bandwidth W = 54 dBHz. 2) Uncorrelated C and I with 75 % location probability (Ps). Lognormal distribution of shadowing with standard deviation 7 dB. Ps = 75 % corresponds to ca 90 % area coverage, see Jakes, pp.126-127. 3) Max. range in quasi-open areas based on Hata. Antenna heights for BTS = 100 m and MS = 1.5 m. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 18 (GSM 03.30 version 7.1.0 Release 1998) Annex A.3: (DCS1800 classes 1&2): Example of RF-budget for DCS 1800 MS RF-output peak power 1 W & 250 mW Propagation over land in urban and rural areas Receiving end: BTS MS Eq. TX: MS BTS (dB) Noise figure(multicoupl.input) dB 8 12 A Multipath profile TU50 or RA130 Ec/No min. fading dB 8 8 B RX RF-input sensitivity dBm -104 -100 C=A+B+W-174 Interference degrad. margin dB 3 3 D (W=54.3 dBHz) Cable loss + connector dB 2 0 E RX-antenna gain dBi 18 0 F Diversity gain dB 5 0 F1 Isotropic power, 50 % Ps dBm -122 -97 G=C+D+E-F-F1 Lognormal margin 50 % ->75 % Ps dB 6 6 H Isotropic power, 75 % Ps dBm -116 -91 I=G+H Field Strength 75 % Ps 27 51 J=I+142.4 at 1.8 GHz Transmitting end: MS BTS Eq. RX: BTS MS (dB) TX PA output peak power W - 15.8/3.98 (mean power over burst) dBm - 42/36 K Isolator + combiner + filter dB - 3 L RF Peak power,(ant.connector) dBm 30/24 39/33 M=K-L 1) W 1.0/0.25 7.9/2.0 Cable loss + connector dB 0 2 N TX-antenna gain dBi 0 18 O Peak EIRP W 1.0/0.25 316/79.4 dBm 30/24 55/49 P=M-N+O Isotropic path loss,50 % Ps 2) dB 149/143 149/143 Q=P-G-3 Isotropic path loss, 75 % Ps dB 143/137 143/137 R=P-I-3 Range km - 75 % Ps Urban, out of doors 1.91/1.27 Urban, indoors 0.69/0.46 Rural (Open area), out of doors 19.0/12.6 Rural (Open area), indoors 9.52/6.28 1) The MS peak power is defined as: a) If the radio has an antenna connector, it shall be measured into a 50 Ohm resistive load. b) If the radio has an integral antenna, a reference antenna with 0 dBi gain shall be assumed. 2) 3 dB of the path loss is assumed to be due to antenna/body loss. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 19 (GSM 03.30 version 7.1.0 Release 1998) Annex A.4: Example of RF-budget for GSM 900 Class4 (peak power 2 W) in a small cell Propagation over land in urban and rural areas Receiving end: BTS MS Eq. TX : MS BTS (dB) Noise figure(multicoupl.input) dB 8 10 A Multipath profile TU50 TU50 Ec/No min. fading dB 8 8 B RX RF-input sensitivity dBm -104 -102 C=A+B+W-174 Interference degrad. margin dB 3 3 D (W=54.3 dBHz) Cable loss + connector dB 2 0 E RX-antenna gain dBi 16 0 F Diversity gain dB 3 0 F1 Isotropic power, 50 % Ps dBm -118 -99 G=C+D+E-F-F1 Lognormal margin 50 % ->75 % Ps dB 5 5 H Isotropic power, 75 % Ps dBm -113 -94 I=G+H Field Strength 75 % Ps 24 43 J=I+137 at 900 MHz Transmitting end: MS BTS Eq. RX: BTS MS (dB) TX PA output peak power W - 12.6 (mean power over burst) dBm - 41 K Isolator + combiner + filter dB - 3 L RF Peak power,(ant.connector) dBm 33 38 M=K-L 1) W 2 6.3 Cable loss + connector dB 0 2 N TX-antenna gain dBi 0 16 O Peak EIRP W 2 158 dBm 33 52 P=M-N+O Isotropic path loss,50 % Ps 2) dB 148 148 Q=P-G-3 Isotropic path loss, 75 % Ps dB 143 143 R=P-I-3 Range km - 75 % Ps Urban, out of doors 1.86 Urban, indoors 0.75 1) The MS peak power is defined as: a) If the radio has an antenna connector, it shall be measured into a 50 Ohm resistive load. b) If the radio has an integral antenna, a reference antenna with 0 dBi gain shall be assumed. 2) 3 dB of the path loss is assumed to be due to antenna/body loss. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 20 (GSM 03.30 version 7.1.0 Release 1998) Annex B: Propagation loss formulas for mobile radiocommunications B.1 Hata Model [4], [8] Frequency f: 150 - 1000 MHz Base station height Hb: 30 - 200 m Mobile height Hm: 1 - 10 m Distance d: 1 - 20 km Large and small cells (i.e. base station antenna heights above roof-top levels of buildings adjacent to the base station) B.1.1 Urban Lu (dB) = 69.55 + 26.16*log(f) - 13.82*log(Hb) - a(Hm) + [44.9 - 6.55*log(Hb)]*log(d) a(Hm) correction factor for vehicular station antenna height. For a medium-small city : a (Hm) = [1.1*log(f) - 0.7]*Hm - [1.56*log(f) - 0.8] For a large city : a (Hm) = 8.29*[log(1.54*Hm)]2 - 1.1 for f <= 200 MHz a (Hm) = 3.2*[log(11.75*Hm)]2 - 4.97for f >= 400 MHz B.1.2 Suburban Lsu (dB) = Lu - 2*[log(f/28)]2 - 5.4 B.1.3 Rural (Quasi-open) Lrqo (dB) = Lu - 4.78*[log(f)]2 + 18.33*log(f) - 35.94 B.1.4 Rural (Open Area) Lro (dB) = Lu - 4.78*[log(f)]2 + 18.33*log(f) - 40.94 B.2 COST 231-Hata Model [7] Frequency f: 1500 - 2000 MHz Base station height Hb: 30 - 200 m Mobile height Hm: 1 - 10 m Distance d: 1 - 20 km ETSI ETSI TR 101 362 V7.1.0 (2000-04) 21 (GSM 03.30 version 7.1.0 Release 1998) Large and small cells (i.e. base station antenna heights above roof-top levels of buildings adjacent to the base station). Urban areas (for rural areas the correction factors given in subparagraph 1.3 and 1.4 can be used up to 2000 MHz). Lu (dB) = 46.3 + 33.9*log(f) - 13.82*log(Hb) - a(Hm) + [44.9 - 6.55*log(Hb)]*log(d) + Cm with : a(Hm) = [1.1*log(f) - 0.7]*Hm - [1.56*log(f) - 0.8] Cm = 0 dB for medium sized city and suburban centres with moderate tree density Cm = 3 dB for metropolitan centres B.3 COST 231 Walfish-Ikegami Model [7] Frequency f: 800 - 2000 MHz Base station height Hb: 4 - 50 m Mobile height Hm: 1 - 3 m Distance d: 0.02 - 5 km Height of buildings Hroof (m) Width of road w (m) Building separation b (m) Road orientation with respect to the direct radio path Phi (°) Urban areas B.3.1 Without free line-of-sight between base and mobile (small cells) Lb = Lo + Lrts + Lmsd (or Lb = Lo for Lrts + Lmsd <= 0) with : B.3.1.1 Lo free-space loss Lo = 32.4 + 20*log(d) + 20*log(f) B.3.1.2 Lrts roof-top-to-street diffraction and scatter loss Lrts = -16.9 - 10*log(w) + 10 log(f) + 20*log(Hr - Hm) + Lcri with Lcri = -10 + 0.354*Phi for 0<= Phi < 35° Lcri = 2.5 + 0.075*(Phi-35) for 35<= Phi < 55° Lcri = 4.0 - 0.114*(Phi-55) for 55<= Phi <90° B.3.1.3 Lmsd multiscreen diffraction loss Lmsd = Lbsh + ka + kd*log(d) + kf*log(f) - 9*log(b) with Lbsh = -18*log(1 +Hb - Hroof) for Hb > Hroof = 0 for Hb <= Hroof ETSI ETSI TR 101 362 V7.1.0 (2000-04) 22 (GSM 03.30 version 7.1.0 Release 1998) ka = 54 for Hb > Hroof = 54 - 0.8*(Hb - Hroof) for d >= 0.5 and Hb <=Hroof = 54 - 0.8*(Hb - Hroof)*(d/0.5)for d<0.5 and Hb<=Hroof kd = 18 for Hb > Hroof = 18 - 15*(Hb - Hroof)/Hroof for Hb <= Hroof kf = -4 + 0.7*(f/925 - 1) for medium sized cities and suburban centres with moderate tree density = -4 + 1.5*(f/925 - 1) for metropolitan centres B.3.2 With a free line-of-sight between base and mobile (Street Canyon) Microcells (Base station antennas below roof top level) Lb = 42.6 + 26*log(d) + 20*log(f) for d >= 0.020 km ETSI ETSI TR 101 362 V7.1.0 (2000-04) 23 (GSM 03.30 version 7.1.0 Release 1998) Annex C: Path Loss vs Cell Radius 90 100 110 120 130 140 150 160 170 180 190 200 210 220 1 10 100 Cell radius (km) path loss (dB) Urban Urban Indoor Suburban Rural (quasi open) Rural (open) Figure 1: Path loss vs Cell Radius, BS height = 50 m, MS height = 1.5 m (GSM 900) ETSI ETSI TR 101 362 V7.1.0 (2000-04) 24 (GSM 03.30 version 7.1.0 Release 1998) 90 100 110 120 130 140 150 160 170 180 190 200 210 220 1 10 100 Cell radius (km) Path loss (dB) Urban Urban indoor Suburban Rural (quasi open) Rural (open) Figure 2: Path loss vs Cell Radius, BS height = 100 m, MS height = 1.5 m (GSM 900) ETSI ETSI TR 101 362 V7.1.0 (2000-04) 25 (GSM 03.30 version 7.1.0 Release 1998) 90 100 110 120 130 140 150 160 170 180 190 200 210 220 1 10 100 Cell Radius ( km) Path Loss (dB) Urban Urban indoor Rural indoor (quasi open) Rural (quasi open) Rural (open) Figure 3: Path loss vs Cell Radius, Urban BS height = 50 m, Rural BS height = 60 m, MS height = 1.5 m (DCS 1800) ETSI ETSI TR 101 362 V7.1.0 (2000-04) 26 (GSM 03.30 version 7.1.0 Release 1998) 0.1 0.5 1.0 3.0 100.0 110.0 120.0 130.0 140.0 150.0 160.0 170.0 P a t h l o s s d B GSM 900 DCS 1800 (medium sized cities and suburban centres) DCS 1800 (metropolitan centres) Cell Radius (km) Figure 4: Path loss vs Cell Radius for small cells (see section 3.4.2) ETSI ETSI TR 101 362 V7.1.0 (2000-04) 27 (GSM 03.30 version 7.1.0 Release 1998) Annex D: Planning Guidelines for Repeaters D.1 Introduction Repeaters can be used to enhance network coverage in certain locations. This annex provides guidelines for the design and installation of repeaters as network infrastructure elements. It covers both in building and outdoor applications. The principles within it may also form a basis for the design of repeaters for other applications within the system. D.2 Definition of Terms The situation where two BTSs and two MSs are in the vicinity of a repeater is shown in figure 5 below. BTSA and MSA belong to operator A and BTSB and MSB belong to a different operator, operator B. When planning repeaters, operators should consider the effects of the installation on both co-ordinated and uncoordinated operators. In the following sections, it is assumed that in the uncoordinated scenario, the repeater is planned and installed only for the benefit of operator A. Operator A is therefore, co-ordinated and operator B uncoordinated. In certain situations, operators may agree to share repeaters. Under these conditions, the repeater is planned and installed to provide benefit to all co-ordinated operators. If all operators within the GSM or DCS bands share a repeater, only the co-ordinated scenario exists. BTSA BTSB MAA MSB Repeater Figure 5: Repeater Scenario for two BTSs and two MSs The following abbreviations are used in this annex: G Repeater Gain PBTS BTS Output Power (in dBm) PMS MS Output Power (in dBm) PmaxDL Maximum Repeater Downlink Output Power (in dBm) PmaxUL Maximum Repeater Uplink Output Power (in dBm) NDL Repeater Downlink Noise Output in RX bandwidth (in dBm) NUL Repeater Uplink Noise Output in RX bandwidth (in dBm) SMS MS Reference Sensitivity (in dBm) SBTS BTS Reference Sensitivity (in dBm) C/Ic Carrier to Interference ratio for cochannel interference CL1 BTS to Repeater Coupling Loss (terminal to terminal) CL2 Repeater to MS Coupling Loss (terminal to terminal) CL3 The measured or estimated out of band coupling loss between a close coupled communication system and the repeater (terminal to terminal) M Number of carriers amplified by repeater ETSI ETSI TR 101 362 V7.1.0 (2000-04) 28 (GSM 03.30 version 7.1.0 Release 1998) Gsys The out of band repeater gain plus the gain of the external repeater antenna less the cable loss to that antenna. Gcom_3 The antenna gain of a close coupled communications system. Ms A safety margin for equipment used inside public buildings which should include the height gain of the external repeater antenna plus, if appropriate, the out of band building penetration loss. D.3 Gain Requirements The uplink and downlink gains should be such as to maintain a balanced link. The loss of diversity gain in the uplink direction may need to be considered. The gain of the repeater within its operating band should be as flat as possible to ensure that calls set up on a BCCH at one frequency can be maintained when the TCH is on a different frequency. The gain should be at least 15 dB smaller than the isolation between the antenna directed towards the BTS and the antenna directed towards the MSs, in order to prevent self oscillation. It is recommended to measure the isolation before installation of the repeater. Within the GSM/DCS1800 bands, but outside of the repeater operating range of frequencies, the installation of the repeater should not significantly alter the cellular design of uncoordinated operators. In the uncoordinated scenario, the repeater should not: i) amplify downlink signals from another operator such that MSs of that operator within a reasonable distance of the repeater select a remote cell amplified by the repeater as opposed to the local cell of that operator. ii) amplify uplink signals from other operators' MSs within a reasonable distance of that repeater and transmit them in such a direction as to cause more interference to other BTSs of that operator than other MSs in the area. For equipment used in public buildings where other communications systems could operate in very close vicinity (less than [5]m) of the repeater antennas, special care must be taken such that out of band signals are not re-radiated from within the building to the outside via the repeater system and vice versa. When using repeaters with an antenna mounted on the outside of the building, the effect of any additional height should be considered. If the close coupled communication system is usually constrained within the building, it may be necessary to consider the negation of building penetration loss when planning the installation. It is the operators responsibility to ensure that the out of band gain of the repeater does not cause disruption to other existing and future co-located radio communication equipment. This can be done by careful choice of the repeater antennas and siting or if necessary, the inclusion of in-line filters to attenuate the out of band signals from other systems operating in the close vicinity of the repeater. The following equation can be used to ensure an adequate safety margin in these cases: Gsys < Gcom_3 + CL3 -Ms (D.3.1) Where Gcom_3 is not known, a value of 2 dBi should be used. Where Ms is not known a value of 15 dB should be used. D.4 Spurious/Intermodulation Products When planning repeaters, operators should ensure that during operation, the spurious and intermodulation products generated by the repeater at uncoordinated frequencies are less than the limits specified in GSM 05.05. At co-ordinated frequencies, the intermodulation attenuation of the repeater in the GSM/DCS bands should be greater than the following limits: IM3 attenuationDL >= C/Ic + BTS power control range (D.4.1) IM3 attenuationUL >= PmaxUL - SBTS + C/Ic - CL1 (D.4.2) ETSI ETSI TR 101 362 V7.1.0 (2000-04) 29 (GSM 03.30 version 7.1.0 Release 1998) These limits apply in all cases except for initial random access bursts amplified by a repeater. D.5 Output Power/Automatic Level Control (ALC) The maximum repeater output power per carrier will be limited by the number of carriers to be enhanced and the third order intermodulation performance of the repeater. Operators should ensure that the requirements of section D.4 are met for the planned number of active carriers, the output power per carrier, and the repeater implementation. The number of simultaneously active carriers to be enhanced may be different in the uplink and downlink directions. When designing ALC systems, the following should be considered: i) When the ALC is active because of the close proximity of a particular MS, the gain is reduced for all MSs being served by the repeater, thereby leading to a possible loss of service for some of them. The operating region of the ALC needs to be minimized to reduce the probability of this occurrence. ii) The response of the ALC loop needs careful design. The ALC should not result in a significant distortion of the power/time profile of multiple bursts. iii) The ALC design should handle the TDMA nature of GSM signal so that it shall be effective for SDCCH and TCH transmissions with and without DTX. iv) The ALC may not operate quickly enough to cover the initial random access bursts sent by MSs. The intermodulation product requirement listed in section D.4 need not apply for these transient bursts. v) The ALC must have sufficient dynamic range to ensure that it maintains an undistorted output at the specified maximum power level when a fully powered-up MS is at the CL2min coupling loss. vi) In a non-channelized repeater the ALC will limit the total output power (i.e. peak of the sum of powers in each carrier). In most cases, the maximum ALC limit should be 3 dB above the power per carrier for two carriers whose third order intermodulation products just meet the requirements of section 4. When more than two carriers are simultaneously amplified, a higher limit may be employed provided the operator ensures that worst case intermodulation products meet the requirements of section D.4. D.6 Local oscillator sideband noise attenuation A local oscillator of a heterodyne type repeater with high sideband noise can cause a problem in uncoordinated scenarios. If the receive level from an uncoordinated MS is significantly higher than the receive level from the co-ordinated MS, both signals can be mixed with approximately the same level into the same IF, degrading the performance of the wanted signal. To avoid this, an IF type repeater equipped with a local oscillator should have a sideband noise attenuation at an offset of 600 kHz from the local oscillator frequency given by the equation: Sideband noise attenuation = CL2max - CL2min + C/Ic (D.6.1) D.7 Delay Requirements The ability of the MS to handle step changes in the time of arrival of the wanted signal is specified in GSM 05.05. When planning repeaters for contiguous coverage with other infrastructure elements, it is recommended that the additional delay through the repeater does not exceed the performance of the MS. The additional delay through the repeater should not cause a problem except in extreme multipath propagation conditions. The delay of the repeater will reduce the range of the cell in the area enhanced by the repeater. A delay of 8 microseconds is equivalent to a range reduction of 2.4 km. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 30 (GSM 03.30 version 7.1.0 Release 1998) D.8 Wideband Noise Wideband noise is a problem for uncoordinated scenarios. The noise level at the uncoordinated operators' frequencies needs to be such that an uncoordinated MS or BTS in the vicinity of the repeater is not desensitized as a result. The following equations provide the maximum noise output by the repeater in the receiver bandwidth for the downlink and uplink: NDL <= SMS - C/Ic + CL2Bmin (D.8.1) NUL <= SBTS - C/Ic + CL1Bmin (D.8.2) In co-ordinated scenarios, the maximum noise output by the repeater in the receiver bandwidth for the downlink direction is: NDL <= PmaxDL - BTS power control range - C/Ic (D.8.3) D.9 Outdoor Rural Repeater Example D.9.1 Rural repeater example for GSM 900 Rural repeaters are used to enhance areas of poor coverage due to terrain limitations. The repeater is located where a suitable signal strength can be received from the donor BTS. Typical signal levels received from the BTS at the input port to the repeater are in the range -50 to -70 dBm. This figure includes the height advantage and the gain of the antenna directed towards the BTS. The received signal is amplified and retransmitted towards the area of poor coverage. Figure 6 shows typical signal levels in the uplink and downlink directions. Two limiting cases for the MS to repeater coupling loss are shown. A diversity gain of 3 dB is assumed at the BTS making the effective reference sensitivity level -107 dBm. 100 dB BTS Repeater 70dB +43 dBm -57 dBm +13 dBm -57 dBm 70 dB 116 dB -103 dBm MS MS -76 dBm -107 dBm +24 dBm -7 dBm -31 dBm -77 dBm +39 dBm +39 dBm Figure 6: Uplink and downlink signal levels for a rural repeater The minimum coupling loss between the MS and the repeater is assumed to be 70 dB. D.9.1.1 Intermodulation products/ALC setting In this example an amplifier with a third order intercept (PTOI) of +50 dBm is assumed. The setting of the ALC for the two tone case is governed by the following equation (in dB): PALC = (2 PTOI + IM3)/3 + 3 (D.9.1.1) where IM3 is the limit specified in GSM 05.05. The inclusion of factor of 3 dB is described in section D.5. PALC = 24.3 dBm. Dependent on manufacturer guide-lines, the ALC setting may need to be reduced if many carriers are passing through the repeater. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 31 (GSM 03.30 version 7.1.0 Release 1998) In this example, the ALC is unlikely to be activated on the downlink. It could do so in applications with smaller BTS to repeater coupling loss. On the uplink, the ALC is activated when the MS is transmitting at full power, at the minimum coupling loss. The repeater gain is reduced so that the output power is limited to 24 dBm. This gain reduction may degrade the service given to other MSs served by the repeater until the BTS power control algorithm has reduced the MS output power. D.9.1.2 Wideband noise Wideband noise needs to be considered for both the uplink and the downlink for uncoordinated scenarios. A 70 dB coupling loss is assumed between the repeater and the uncoordinated MS and the repeater and the uncoordinated BTS. Then, using equations D.8.1 and D.8.2, the maximum noise power output is given by: NDL = NUL = -104 - 9 + 70 = -43 dBm The maximum noise figure required to achieve this noise level in both the uplink and down link directions is given by the following equation: F <= N - G - kT - B <= -43 - 70 - (-174) -53 <= 8 dB where F is the noise figure, N is the maximum noise level, G is the gain, kT is equal -174 dBm/Hz and B is the bandwidth conversion factor equal to 53 dB. D.10 Indoor Low Power Repeater Example D.10.1 Indoor repeater example for DCS 1800 Indoor repeaters are used to compensate for the losses associated with building attenuation. The signal level received from the BTS at the input port to the repeater is typically in the range -60 to -80 dBm. This figure includes the height advantage of placing an antenna on the roof of the building and the gain of the antenna directed towards the BTS. Figure 7 shows typical signal levels in the uplink and downlink directions. Two limiting cases for the MS to repeater coupling losses are shown. 110 dB BTS Repeater 45dB +39 dBm -71 dBm -26 dBm -56 dBm 40 dB 72 dB -98 dBm MS MS -91 dBm -107 dBm +19 dBm -3 dBm -10 dBm -42 dBm +30 dBm +30 dBm Figure 7: Uplink and downlink signal levels for indoor repeater The minimum coupling loss between the MS and the repeater is assumed to be 40 dB. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 32 (GSM 03.30 version 7.1.0 Release 1998) D.10.1.1 Intermodulation products/ALC setting Indoor repeaters are likely to be small low cost devices. Consequently, for indoor repeaters, the intermodulation performance is not as good as a rural repeater. In this example, an amplifier with a third order intercept (PTOI) of +40 dBm is assumed. For PTOI equal to 40 dBm and IM3 equal to -30 dBm, then using equation D.9.1.1: PALC = 19.7 dBm. On the uplink, the ALC is activated when the MS is transmitting at full power, at the minimum coupling loss. The repeater gain is reduced so that the output power is limited to 19 dBm. The received signal level at the BTS of -91 dBm is likely to be below the desired level which the MS power control algorithm seeks to maintain. Therefore, the MS is likely to remain powered up and the ALC will remain in operation continuously. Since, there is likely to be only one simultaneous user of this type of repeater, this is normally acceptable. D.10.1.2 Wideband noise Assuming a minimum coupling loss between the repeater and an unco-ordinated BTS of 65 dB, and between the repeater and an uncoordinated MS of 40 dBm, the following maximum noise levels are obtained using equations D.8.1 and D.8.2. NDL = -100 - 9 + 40 = -69 dBm NUL = -104 - 9 + 65 = -48 dBm The uplink noise level is easy to achieve in view of the low gain. The maximum noise figure required to achieve this noise level in down link directions is given by the following equation: F <= N - G - kT - B <= -69 - 40 - (-174) -53 <= 12 dB where F is the noise figure, N is the maximum noise level, G is the gain, kT is equal -174 dBm/Hz and B is the bandwidth conversion factor equal to 53 dB. D.11 Example for a Repeater System using Frequency Shift D.11.1 Example for GSM 900 Repeaters are used to enhance areas of poor coverage due to terrain limitations. The useable gain in an installation with a normal repeater is in generally limited in order to keep the repeater gain with a margin of 15 dB below the coupling of donor antenna and coverage antenna. Repeater systems using frequency shift relax the limitation in the usable gain of a normal repeater, due to different frequencies of the output signal and input signal. The repeater system consist of a master unit close to the BTS and at least one remote unit close to the area to be covered. The master unit amplifies the signals from the BTS and shifts them to other GSM channels called link channels in the allocated band of the operator. In the remote unit the link channels will be transferred to the original channels and amplified. A mobile station in the coverage area of the remote unit will detect the signals having passed the repeater system without any difference to a signal directly received from a BTS but the additional delay. The uplink channel settings of the repeater system follow exactly the settings of the downlink channels for the link path. Thus an uplink signal from a mobile in the coverage area of the repeater system will be received on its expected frequency by the BTS. Through application of sideband inversion technique on the downlink signals the BCCH cannot be decoded by a MS located between the master unit and the remote unit. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 33 (GSM 03.30 version 7.1.0 Release 1998) The master unit of the repeater system is located in the vicinity of a donor BTS with a relatively low coupling path loss of typically 30 dB to 60 dB. The downlink amplification is adjusted to the lowest necessary value in order to reduce the transmitted signal strength on the link channels of the master unit output. As a consequence of the high gain of the remote unit of the repeater sytem the distance to the master unit can be relatively high while the desired output power level is still maintained. The link path loss may vary up to 90 dB depending on the maximum gain of the remote unit. Oscillation of the repeater units is suppressed due to the shift between input and output frequencies and the decoupling betweeen coverage antenna and link antenna can be lower than the actual gain set in the remote unit. Therefore the effort for the installation at the remote unit location does not exceed the normal level. Figure 8 shows typical signal levels in the uplink and downlink directions.Two cases with maximum coupling loss of 135 dB and an assumed minimum coupling loss of 70 dB for the MS to repeater path are shown. BTS Repeater System Master Unit Repeater System Remote Unit MS DL 43 dBm -7 dBm -50 dB -90 dB -70 dB MS -135 dB 28 dBm G = 35 dB -62 dBm 33 dBm G = 95 dB -102 dBm -37 dBm UL -57 dBm -7 dBm -57 dBm G = 50 dB 33 dBm -37 dBm G = 88 dB 33 dBm 33 dBm -102 dBm -14 dBm -104 dBm -54 dBm -104 dBm Coupling Path Link Path Coverage Path Figure 8: Uplink and downlink signal levels for a repeater system using frequency shift D.11.1.1 Intermodulation products/ALC setting and levelling criteria In this example a repeater system with separate amplifier chain for each GSM channel is used. Thus a multiple carrier operation does not have an impact on the ALC settings in order to keep intermodulation products low as described in subchapter D.9.1.1. On the uplink, the ALC will be activated when the MS is transmitting at full power, at the minimum coupling loss of 70 dB. The repeater gain is reduced in this example by the ALC setting which is assumed to an output power of 33 dBm. This gain reduction may degrade the service given to other MSs served by the repeater until the BTS power control algorithm has reduced the MS output power. In addition to the definitions in subchapter D.2 the following term are used: GMU(DL,UL) Gain of master unit of repeater system in the downlink or uplink path GRU(DL,UL) Gain of remote unit of repeater system in the downlink or uplink path GTOT(DL,UL) Gain of the complete repeater system in one path calculated from BTS to remote unit repeater in the downlink or uplink path FTOT(UL) Noise figure of the complete repeater system including link path in the uplink path FMU(UL) Noise figure of the master unit of the repeater system in the uplink path FRU(UL) Noise figure of the remote unit of the repeater system in the uplink path CL2max Maximum Coupling loss between MS and repeater system CL(MU<->RU) Coupling loss between master unit and remote unit PRUmax(DL) Maximum output power of the remote unit in the downlink Mn Margin between repeater system output noise level at the BTS and equivalent input noise level of the BTS. This is a positive value if the repeater noise is lower. NTOT Noise level of repeater system at BTS input. As an example for the leveling of a repeater system using frequency shift see figure 8. Downlink levelling: In the downlink path it is intended to have a certain signal level retransmitted from the remote unit for coverage purposes. Thus the leveling of the repeater system is determined by the formula: ETSI ETSI TR 101 362 V7.1.0 (2000-04) 34 (GSM 03.30 version 7.1.0 Release 1998) GRU(DL) = PRUmax(DL) + CL(MU<->RU) + CL1 - PBTS - GMU(DL) In an installation the values for the coupling losses have to be measured. The remaining variable GMU(DL) has to be adjusted such, that the output power of the downlink signals of the master unit is as low as possible without danger of being interfered at the remote unit location. Uplink levelling: The adjustment of the uplink path gain is determined by the two demands: first the downlink and uplink path have to be balanced. Second, the receiver input shall not be desensitised by the repeater noise. The uplink gain between remote unit input and BTS input is GTOT(UL) = SBTS - PMS + CL2max = GRU(UL) + GMU(UL) - CL(MU<->RU) - CL1, which can be transformed to GRU(UL) = SBTS + CL1 + CL(MU<->RU) + CL2max - PMS - GMU(UL). This gives a relation for the gain setting of the remote unit with respect to the gain setting of the master unit when all coupling losses are determined. A further criteria for the leveling of the uplink is the total noise figure of the repeater system. In order to obtain a value close to the remote unit noise figure, the gain setting of the single repeater unit shall not be much lower than the path loss its output signal has to bridge. A desensitisation of the BTS will be prevented by keeping the uplink gain of the single repeater units close to the value of the path loss to be bridged. The noise at the BTS receiver input can be calculated from the total noise figure of the repeater system: FTOT(lin) = FRU(UL,lin) + ( FMU(UL,lin) - 1 ) / ( GRU(UL,lin) * CL(MU<->RU, lin) ). The variables marked by lin are linear and thus not logarithmic values. The noise at the BTS receiver input at room temperature for a given bandwidth of a GSM channel results in: NTOT = FTOT + GTOT(UL) + kT + B = FTOT + GTOT(UL) + (-174) + 53 This noise level has to be smaller than the equivalent noise at the receiver input: NTOT <= SBTS - C/Ic - Mn = SBTS - 9dB - 3dB A noise margin Mn equal to 3 dB is assumed. With a sensitivity of SBTS = -104 dBm the noise level of NTOT = - 116 dBm should not be exceeded. D.11.1.2 Wideband noise The repeater system using frequency shift is supposed to operate with dedicated channelised amplifiers. Therefore the uncoordinated scenario does not apply. D.11.1.3 Multipath environment Regions with strong multipath signals of direct signals from the BTS and delayed signals from the repeater system of nearly equal level should be avoided. One method to achieve this can be a coupling of the master unit of the repeater system to the BTS sector directed to the counterside of the area to be covered by the repeater system. Furthermore the geographic situation may prevent as well the occurrence of such strong multipath areas, so that as well onmidirectional cells as donor cells can be possible. D.12 Repeaters and Location Services (LCS) D.12.1 Uplink−TOA positioning method Figure 9 illustrates the potential problem which can occur when a MS near the service area of a wireless repeater should be located with the Uplink−TOA positioning method (see GSM 03.71 for details about the Uplink−TOA positioning ETSI ETSI TR 101 362 V7.1.0 (2000-04) 35 (GSM 03.30 version 7.1.0 Release 1998) method). It is assumed that a TOA Location Measurement Unit (LMU) is deployed at each BTS site. The LMUs colocated at BTS 1 and 2 will report TOA measurements τ1 and τ2 , which correspond to the propagation path length between the MS and BTS 1 and 2, respectively. An ambiguity will exist, when the RF path between the MS and BTS 3 can either be a direct path (τ3) or a path via the repeater (τR+τd+τRB), where τd is the delay of the repeater. BTS 3 BTS 1 BTS 2 LMU 1 LMU 3 LMU 2 MS τ1 τ2 τ3 Repeater for BTS 3 τR τd τRB LMU R Figure 9: Repeater Scenario for Uplink-TOA. An ambiguity free location solution can be obtained, if a TOA LMU is deployed at the repeater site. The LMUs which should participate in the position measurement procedure are selected by the Serving Mobile Location Centre (SMLC) (GSM 03.71). If a BTS has an associated repeater, then the SMLC should select the LMU colocated at the BTS site as well as the LMU colocated at its repeater site for TOA measurements. When a RF path exists between the MS and the repeater, the LMU R will report the TOA measurement τR, which corresponds to the propagation path length between the MS and the repeater. If LMU 3 and LMU R are reporting TOA measurements, then the SMLC should neglect the TOA measurement from LMU 3, since this TOA measurement can be based on (τR+τd+τRB) and will therefore result in a wrong location estimate. If the TOA LMU co-located at the repeater will not report a TOA measurement, it is obvious that no RF path between the MS and repeater exists. In that case, the TOA measurement from BTS 3 should be used. Other more intelligent processing can also be performed at the SMLC. To guarantee, that the Uplink−TOA positioning method works properly in radio environments with repeaters, a TOA LMU needs to be co located at the repeater site. If no LMU is co located at the repeater site, the SMLC should avoid selecting LMUs co located at a BTS which has an associated repeater. This requires that enough BTSs (LMUs) without repeaters are available in the vicinity of the MS and may therefore depend on the network. D.12.2 Enhanced Observed Time Difference positioning method Figure 10 illustrates the potential problem which can occur when a MS near the service area of a wireless repeater should be located with the Enhanced Observed Time Difference (E-OTD) positioning method (see GSM 03.71 for details about the E-OTD positioning method). Assuming for simplicity that BTSs transmit at the moment 0, the MS will receive signals from BTSs 1, 2 and 4 at moments τ1 , τ2 , and τ4, which correspond to the delays due to propagation paths between the MS and BTSs 1, 2 and 4, respectively. An ambiguity will exist, when the RF path between the BTS 3 and MS can either be a direct path (τ3) or a path via the repeater (τRB +τd+ τR), where τd is the delay of the repeater. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 36 (GSM 03.30 version 7.1.0 Release 1998) BTS 3 BTS 1 BTS 2 MS τ1 τ2 τ3 Repeater for BTS 3 τR τd τRB BTS 4 τ4 Figure 10: Repeater Scenario for E-OTD. An ambiguity free location solution can be obtained, if the MS measures sufficient number of BTSs so that the measurements concerning the BTS 3 (which can be direct measurements or via the repeater) can be dropped off. In the situation in Fig. 10, there are three other BTSs received by the MS, and the measurements from the BTS 3 can be omitted. Another possibility for ambiquity free location solution is to use other avilable information to judge whether the signal from the repeater or the direct signal from the BTS has been measured. For example the initial location estimate based on CI and TA information can be used to estimate whether the BTS or the repeater is more likely to be received by the MS. There can be also other implementation specific solutions in the SMLC. D.12.3 Radio Interface Timing measurements Figure 11 illustrates the potential problem which can occur when a LMU near the service area of a wireless repeater performs Radio Interface Timing (RIT) measurements (see GSM 03.71 for details about the RIT measurements). ETSI ETSI TR 101 362 V7.1.0 (2000-04) 37 (GSM 03.30 version 7.1.0 Release 1998) BTS 3 BTS 1 BTS 2 LMU τ1 τ2 τ3 Repeater for BTS 3 τR τd τRB Figure 11: Repeater Scenario for RIT measurements. The ambiguity problem applies also to LMUs that measure RIT information for E-OTD and Uplink-TOA methods, as well as for certain assisted GPS variants. In Figure 11 the LMU measures directly signals from BTSs 1 and 2 (BTS serving the LMU). However the RF path between the BTS 3 and LMU can either be a direct path (τ3) or a path via the repeater (τRB +τd+τR). The solution is that the operator selects such LMU sites that can only hear only the BTS or the repeater (e.g. based on network planning information). This can be enhanced by using directional antenna for the LMU, so that the antenna points towards e.g. the repeater, not the BTS, or vice versa. ETSI ETSI TR 101 362 V7.1.0 (2000-04) 38 (GSM 03.30 version 7.1.0 Release 1998) Annex E: Document change history SPEC SMG# CR PHASE VERS NEW_VERS SUBJECT 03.30 s25 A003 R97 5.0.0 Repeater Systems using Frequency Shift 03.30 s26 A003 R97 5.0.0 6.0.0 Repeater systems using Frequency Shift 03.30 s29 R98 6.0.1 7.0.0 Version 7.0.0 for Release '98 03.30 s31 A009 R98 7.0.0 7.1.0 LCS operation with repeaters ETSI ETSI TR 101 362 V7.1.0 (2000-04) 39 (GSM 03.30 version 7.1.0 Release 1998) History Document history V7.0.0 July 1999 Publication V7.1.0 April 2000 Publication
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.