1、 Recommendation ITU-R M.1472-1(01/2010)Methodology to evaluate the impact of interference from time division multiple access/frequency division multiple access(TDMA/FDMA) mobile-satellite service (MSS) space-to-Earth transmissions on basebandperformance in frequency divisionmultiplexing-frequency mo
2、dulation(FDM-FM) analogue line-of-sight (LoS)fixed service receivers in thefrequency range 1-3 GHzM SeriesMobile, radiodetermination, amateurand related satellite servicesii Rec. ITU-R M.1472-1 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and eco
3、nomical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed b
4、y World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be u
5、sed for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. S
6、eries of ITU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodet
7、ermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management SNG S
8、atellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2010 ITU 2010 All rights reserved. No part of this pu
9、blication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R M.1472-1 1 RECOMMENDATION ITU-R M.1472-1*Methodology to evaluate the impact of interference from time division multiple access/frequency division multiple access (TDMA/FDMA) mobile-satellite service (
10、MSS) space-to-Earth transmissions on baseband performance in frequency division multiplexing-frequency modulation (FDM-FM) analogue line-of-sight (LoS) fixed service receivers in the frequency range 1-3 GHz (Questions ITU-R 201/4 and ITU-R 118/5) (2000-2010) Scope This Recommendation provides a meth
11、odology to assess the impact of interference from TDMA/FDMA mobile-satellite service (MSS) space-to-Earth transmissions on baseband performance in FDM-FM analogue line-of-sight (LoS) fixed service (FS) receivers in the frequency range 1-3 GHz. This methodology may also be used in detailed MSS/FS coo
12、rdination to further refine the results obtained implementing the methodology described in Recommendation ITU-R M.1319. The ITU Radiocommunication Assembly, considering a) that the frequency band 1 518-1 525 MHz is allocated to the mobile-satellite service (MSS) (space-to-Earth) and the fixed servic
13、e (FS) on a co-primary basis in all Regions; b) that the frequency band 1 525-1 559 MHz is also allocated to the MSS (space-to-Earth) on a primary basis in all Regions; c) that the frequency band 1 525-1 530 MHz is also allocated to the fixed service on a primary basis in Regions 1 and 3 and the fre
14、quency band 1 550-1 559 MHz is also allocated to the fixed service on a primary basis in some countries; d) that the frequency bands 2 170-2 200 MHz in all Regions and 2 160-2 170 MHz in Region 2 are allocated to the MSS (space-to-Earth) and the fixed service on a co-primary basis; e) that transmiss
15、ions from mobile satellites could cause interference to line-of-sight (LoS) receivers operating in these bands; f) that such interference involves time-varying phenomena such as interference geometry, propagation conditions, and MSS traffic; g) that computer simulation usually is the only way to acc
16、urately evaluate such interference; h) that the output of such simulations is typically in the form of C/I, C/N and C/(N + I) statistics into the given fixed service systems; *This is a joint Radiocommunication Study Groups 4 and 5 Recommendation, and any revision shall be undertaken jointly. 2 Rec.
17、 ITU-R M.1472-1 j) that the impact and acceptability of such interference in most cases can be assessed in detailed bilateral coordination by studying via computer simulation the radio frequency C/N, C/I and C/(N + I) statistics as described in Recommendation ITU-R M.1319; k) that, in some critical
18、cases, there may be a need during detailed bilateral coordination to evaluate via computer simulation the interference impact on analogue FDM-FM fixed service baseband performance objectives, recommends 1 that the methodology in Annex 1 may be used in detailed bilateral coordination between concerne
19、d parties for detailed assessment of the impact of interference from TDMA/FDMA MSS satellites in the 1-3 GHz MSS allocations on baseband performance in analogue FDM-FM LoS fixed service receivers, in cases where the results obtained by the methodology described in Recommendation ITU-R M.1319 needs f
20、urther refinement (see Notes 1, 2 and 3). NOTE 1 The application of the methodology in this Recommendation will require the development of algorithms or calculation procedures to address the implementation of the considerations described. The use or adaptation of these algorithms or procedures in an
21、y bilateral coordination would be subject to agreement by the concerned parties. NOTE 2 In countries where a large number of fixed service systems are in operation, it may be sufficient to apply the analysis to a representative set of existing fixed service systems, using actual fixed service parame
22、ters, especially taking into account those fixed service systems that are likely to be most sensitive to interference. The most sensitive fixed service systems are usually those oriented close to the worst-case azimuth direction; this direction can be established based on the orbital characteristics
23、 of the MSS system. However, this is a matter that will require agreement between the concerned parties. NOTE 3 In the case of GSO MSS systems the calculations are significantly simplified, since there is no need to simulate the orbital mechanics of the MSS constellation, however the potential of in
24、terference from multiple GSO MSS satellites may need to be considered when evaluating the impact of interference. Annex 1 Methodology to evaluate the impact of interference from TDMA/FDMA MSS systems on baseband performance in FDM-FM analogue LoS fixed service receivers operating in the frequency ra
25、nge 1-3 GHz 1 Introduction Sharing between MSS and fixed service involves time varying phenomena such as interference geometry, propagation conditions, etc. Simulation is usually the only way to accurately evaluate interference between MSS and fixed service systems. The output of such simulations is
26、 typically in the form of radio-frequency C/I, C/N and C/(N + I) statistics presented usually as a cumulative distribution function. Rec. ITU-R M.1472-1 3 Recommendation ITU-R M.1319 provides a methodology whereby inter alia baseband performance objectives for analogue FDM-FM and TV-FM fixed service
27、 systems provided in Recommendation ITU-R F.3931and Recommendation ITU-R F.5552can be translated into equivalent radio-frequency C/(N + I) requirements for an associated percentage of time, with if necessary appropriate scaling to address actual fixed service routes of shorter length than the refere
28、nce circuits. These equivalent radio-frequency performance objectives are plotted on the cumulative distribution plots of C/(N + I) in order to determine if the interference from MSS satellites is acceptable. The method described in Recommendation ITU-R M.1319 although it requires extensive computer
29、 simulation is relatively straightforward to implement in software, since all calculations and comparisons are undertaken in the radio-frequency domain. The methodology of Recommendation ITU-R M.1319 should be used in the detailed coordination phase between administrations, when coordination is form
30、ally required and triggered in application of the Radio Regulation (RR), in order to determine if interference is acceptable or not, when considered in the context of actual fixed service system information and the relevant ITU-R performance and availability objectives. In some cases during the bila
31、teral coordination phase, it may be necessary for the parties concerned to further examine the impact of MSS interference on the performance objectives of analogue fixed service systems. This could be the case where the results of the simulation method described in Recommendation ITU-R M.1319 above
32、are not sufficiently definitive to enable the conclusion of frequency coordination. The objective of this annex is to present methodologies to evaluate the baseband performance impairments more accurately for FDM-FM analogue fixed service carriers taking into account the effects of varying frequency
33、 separations that would exist for multiple narrow-band interfering carriers, recognizing that the interference reduction factor or B-factor and the protection ratio requirements of Recommendation ITU-R SF.766 indicate a strong dependence on frequency separation between the wanted and the interfering
34、 carriers. The methodology presented in this annex necessarily involves more sophisticated simulation tools than those described in Recommendation ITU-R M.1319 and is expected to require considerably more computer resources to execute. 2 Methodology for FDM-FM fixed service systems 2.1 Reference FDM
35、-FM fixed service system for simulation In the detailed coordination phase, it is expected that actual analogue fixed service route parameters will be available in order to assess the impact of MSS interference. It is noted that in the 1-3 GHz range, the intermediate fixed service stations in a fixe
36、d service modem section are usually equipped with IF repeaters. Demodulation to the baseband takes place at the terminal station. Since demodulation to baseband does not take place at the intermediate repeaters, it is only necessary to calculate the baseband interference at the last/terminal repeate
37、r in the modem section or actual fixed service route. 1Recommendation ITU-R F.393 was suppressed in 2007. However some fixed systems may continue to exist for which this Recommendation would be applicable. 2Recommendation ITU-R F.555 was suppressed in 2007. However some fixed systems may continue to
38、 exist for which this Recommendation would be applicable. 4 Rec. ITU-R M.1472-1 According to Recommendation ITU-R F.393, the maximum allowable values of noise power at a point of zero relative level in any telephone channel on a 2 500 km hypothetical reference circuit for FDM radio-relay systems sho
39、uld not exceed the values given below, which have been chosen to take account of adverse propagation conditions: 7 500 pW0p, psophometrically weighted one minute mean power for more than 20% of any month; 47 500 pW0p, psophometrically weighted one minute mean power for more than 0.1% of any month; 1
40、 000 000 pW0, unweighted (with an integration time of 5 ms) for more than 0.01% of any month. 2.2 Estimation of statistics of baseband interference and thermal noise 2.2.1 General description The impact of interference from MSS satellite systems employing narrow-band modulation/access schemes into a
41、n FDM-FM baseband telephone channel can be assessed as follows. Using the simulation methods described in Recommendation ITU-R M.1319, at each time step in the simulation period for each fixed service receiver in an fixed service route one can estimate the C/I and C/N values, where now the C/I level
42、s are computed due to each individual TDMA/FDMA MSS carrier within the receiver bandwidth of the FDM-FM fixed service receiver. The r.f. interference power at the k-th receiver may be obtained as the k-th term of equation (1) in Annex 1 of Recommendation ITU-R M.1143. The received carrier power at t
43、he k-th receiver includes the loss due to multipath fading on the k-th hop of the radio-relay route. Once the value of C/I is known for each narrow-band MSS carrier at each time step, the next step is to convert the C/I value into the baseband noise power. The method of computation of baseband inter
44、ference noise power is based on Recommendation ITU-R SF.766. The interference reduction factor B (dB) is expressed as follows: )()()(2log10022f,fDfbf/fpfBm= (1) ()+=10001010)(d )()(d )()(, PffSFFffPFSFFffPFSffD )()()()(0100010010100ffbPSffPSffPSPffS + (2) () () ()fAfPfP21= (3) ()02010APP = (4) (f f0
45、) = 1mmmmmmwhen f = f0(4a) (f f0) = 0mmmmmmwhen f f0where: f : r.m.s. test tone deviation (without pre-emphasis) of the wanted signal (kHz) f : centre-frequency of channel concerned, within the wanted signal baseband (kHz) Rec. ITU-R M.1472-1 5 fm: upper frequency of the wanted signal baseband (kHz)
46、 p(f/fm) : pre-emphasis factor for centre-frequency of channel concerned, within the wanted carrier baseband b : bandwidth of telephone channel (3.1 kHz) f0: separation between carriers of the wanted and interfering signals (kHz) S(f ) : continuous part of the normalized power spectral density of th
47、e wanted signal with pre-emphasis (Hz1)S0: normalized vestigial carrier power of the wanted signal P(f ) : continuous part of the normalized power spectral density of the interfering signal (Hz1)P0: normalized vestigial carrier power of the interfering signal A(f ) : amplitude-frequency response of
48、the wanted signal receiving filter, the origin of the frequencies being the centre frequency of the interfering signal carrier. The power spectral densities are normalized to unity and are assumed to be one-sided (only positive frequencies). The expression of Npin terms of the ratio C/I is derived f
49、rom expressions (5) and (6). In order to determine Np, it is necessary to determine: the wanted signal spectrum (analogue telephony); the interfering signal spectrum. The weighted interference power (Np) is obtained as unweighted power in 1.75 kHz, which gives: ()ICBpN/5.871.010= (5) where C/I is the carrier to interference ratio (dB). The computation of the interference reduction factor involves the convolution of wanted and interfering power spectra. The power spectra of fixed service radio-relay systems of various channel capacities
