1、 Rec. ITU-R F.1606 1 RECOMMENDATION ITU-R F.1606 Interference criteria to protect fixed wireless systems from time varying aggregate interference produced by non-geostationary satellites operating in other services sharing the 37-40 GHz and 40.5-42.5 GHz bands on a co-primary basis (Question ITU-R 1
2、27/9) (2003) The ITU Radiocommunication Assembly, considering a) that it is desirable to determine the protection criteria of fixed wireless systems (FWS) operating in the 38 GHz (37-40 GHz) and 40 GHz (40.5-42.5 GHz) bands with respect to aggregate interference from systems of other services operat
3、ing co-primary, especially short-term inter-ference; b) that in interference situations involving non-geostationary (non-GSO) space stations, FWS are potentially exposed to high levels of interference for short periods of time which could affect the performance or availability of these systems; c) t
4、hat the FS link design in the 38 and 40 GHz bands is controlled by rain attenuation, which can be modelled using Recommendation ITU-R P.530; d) that in the 38 and 40 GHz bands, some administrations employ automatic transmitter power control (ATPC) on some FS links and that such use will increase the
5、 susceptibility of these links especially with regard to short-term interference; e) that some FS links employing small net fade margins may not be fully protected from interference from non-GSO satellite systems without unduly constraining those services; f) that typical FS links using ATPC will re
6、quire tighter protection criteria than those needed for FS links with large fade margin that do not use ATPC; g) that it is desirable to derive the aggregate FS protection criteria based on the calculation of the allowable degradation of error performance objective (EPO) due to interference, conside
7、ring typical FS links using ATPC features; h) that the determination of the maximum degradation of EPO allowable to interference from other services sharing the same frequency band on a co-primary basis is given in Recommen-dation ITU-R F.1094; 2 Rec. ITU-R F.1606 j) that the allowable degradation i
8、n performance of FWS due to interference from other services sharing the same frequency bands on a primary basis, expressed as a permissible fraction of the total EPO is defined in Recommendation ITU-R F.1565, recognizing a) that the bands 37.5-40 GHz and 40.5-42.5 GHz are shared on a co-primary bas
9、is with the FSS, and that Recommendation ITU-R SF.1484 provides pfd levels that are required to protect the FS in these bands; b) that the application of the criteria in this Recommendation is not intended to lead to a revisitation of the conclusions stated in the Recommendation referenced in recogn
10、izing a) above, recommends 1 that the following interference criteria should be used to protect the FS systems from varying aggregate interference from systems of other services operating in the 37-40 GHz and the 40.5-42.5 GHz bands on a co-primary basis; 1.1 for the long term, the I/N at the input
11、of the FS receiver should not exceed 10 dB for more than 20% of the time (see Note 1); 1.2 for the short term, the I/N at the input of the FS receiver should not exceed +10 dB for more than 0.013% of the time, for systems designed in compliance with ITU-T Recommendation G.828, and 0.05% of the time
12、for other systems (see Note 1); 1.3 for the short term, for some links in certain broadband wireless access (BWA) applications, the I/N at the input of the FS receiver should not exceed +5 dB for more than 0.013% of the time, for systems designed in compliance with ITU-T Recommendation G.828 and 0.0
13、5% of the time for other systems (see Note 1); 2 that the information contained in Annex 1 should be used as guidance for the use of this Recommendation. NOTE 1 These I/N levels are referenced to the total noise at the receiver input including system noise level (k T BF) and 1 dB for intra-service i
14、nterference (see 5 in Annex 1). Annex 1 Derivation of FS aggregate protection criteria in the 37-40 GHz and 40.5-42.5 GHz bands 1 Introduction The methodology presented in this Annex is based on the assumption that fading in the 38 GHz and 40 GHz bands is dominated by rain and that, therefore, even
15、if long-term interference has an effect on the performance of the link, the main way to have an outage of the FS link is to have an interference level higher than the fade margin of the link, whatever the propagation conditions may be. Rec. ITU-R F.1606 3 On this basis, the following apportionment o
16、f the effect of interference on the degradation of the link (and on the EPOs) has been assumed: 20% of FS link degradation due to long-term interference; 80% of FS link degradation due to short-term interference. 2 EPOs The allowable degradation in performance of real FWS due to interference from ot
17、her services sharing the same frequency bands on a primary basis are expressed as a permissible fraction (10%) of the total EPOs and are defined in Recommendation ITU-R F.1565. FS systems are currently used in the 38 GHz band for the access networks or mobile telephone infrastructure networks for bo
18、th point-to-point (P-P) and point-to-multipoint (P-MP) applications. Since the same applications are already foreseen in the 40 GHz band the same reference EPOs have been used for the present studies in both bands based on either the access network section or short-haul inter-exchange network sectio
19、n, which are given as similar in Recommendation ITU-R F.1565. The corresponding EPO values are given in Table 1, and correspond to the following assumptions: Short-haul inter-exchange or access network section (Tables 4a and 4b, or 5a and 5b of Recommendation ITU-R F.1565); Rate VC-3 in Tables 4a an
20、d 5a, and rate from 15 to 55 Mbit/s in Tables 4b and 5b; B = C = 8%. TABLE 1 EPO (fraction of any month) based on the application of Recommendation ITU-R F.1565 Total allowable to interference Long-term interference (20%) Short-term interference (80%) Errored second ratio (ITU-T Rec. G.826) 6 1041.2
21、 1044.8 104Errored second ratio (ITU-T Rec. G.828) 1.6 1043.2 1051.3 104Severely errored second ratio 1.6 1053.2 1061.3 1054 Rec. ITU-R F.1606 3 Short-term criteria 3.1 Methodology As explained in 1, the main way to have an outage of the FS link, considering short-term interference, is to have an in
22、terference level higher than the fade margin of the link, whatever the propagation conditions may be. The definition of short-term criteria is then linked to both values of fade margin (or net fade margin considering ATPC1) and EPO allocated to short-term interference as defined in Table 1, consider
23、ing that the fade margin is allocated to the short-term criteria. 3.2 FS fade margins In the 38 GHz and 40 GHz bands, and since link lengths are likely to be short, an FS fade margin of 14 dB was considered representative of conventional links since it was assumed that a majority of such links have
24、a fade margin (or net fade margin1) higher than this value. It has to be noted that this 14 dB fade margin, when considering systems using ATPC, corresponds to a link with higher margin (e.g. = 14 dB net fade margin +10 dB ATPC range). On the other hand, it was also noted that in certain BWA applica
25、tions, a fade margin of 10 dB is used for some short links and that these links would consequently require a lower I/N value. In support of the consideration of these margins, the Table in Appendix 1 to Annex 1, which is based on Recommendation ITU-R P.530, gives the required rain margin for 99.999%
26、 availability for link lengths up to 1.6 km at five different rain rates for both vertical and horizontal polarization. However, it has to be noted that the 14 dB or the 10 dB rain fade margin in these 37 GHz and 40 GHz bands are justified on calculations using Recommendation ITU-R P.530 which does
27、not provide values of fade margin referenced to an error performance measure, but gives absolute attenuation values (rain fading) for a given percentage of time. In addition, according to Recommendation ITU-R F.1498, for a link designed for a 99.999% availability and in particular BWA systems which
28、are assumed to compete with fibre, the fade margin may refer to the BER 106or severely errored second (SES) level. It was agreed to retain the SES level as the reference level for the fade margin. It was also agreed that the design of the FS link should take into account a 1 dB allowance for interfe
29、rence from the FS, which hence increases the reference noise power to 1 dB above the system noise power. In addition, it was also considered that, due to technical reasons (minimum practicable power, available antenna sizes, fixed transmit power for hub stations, ), the FS links in the 38 GHz and 40
30、 GHz bands, and in particular P-MP systems, may present an extra design margin compared to the rain margin. At the minimum, for P-P links, the value of this extra design margin depends on the level of granularity of the power setting, the possible attenuators as well as the antenna gain that 1For an
31、 FS link using ATPC, the net fade margin = total fade margin ATPC range. Rec. ITU-R F.1606 5 would allow the FS designer to adjust the receiver level as close as possible to the theoretical level. Even though it has not been taken into account in the definition of the reference total margin of the F
32、S link, it was agreed to consider it as an additional confidence factor in the derivation of the protection criteria. As the EPO are referenced to ITU-T Recommendations G.826 and G.828 definitions, it is necessary to extrapolate the fade margin corresponding to errored seconds (ES) and SES levels. O
33、n the basis of agreed assumptions, the fade margins (FMs) for ES and SES are respectively 3 dB lower and 1 dB higher than the FM referenced to the BER 106level, which is 2 dB lower than the FM referenced to the BER 103level. Table 2 summarizes these different values of FMs and, associated with the c
34、orrespondent EPO ratios, allows two short-term criteria for the FS in the bands to be defined. TABLE 2 Due to the shape of the calculated interference distributions which in general shows that when the criterion for ES is met, the one for SES is also met, it was decided for simplification to only re
35、tain the ES based criteria. Assume that MSESis the fade margin that brings the C/N + I to the performance threshold TSESfor SES. In the design of a link for a performance threshold to be met for a specified percentage of time, Recommendation ITU-R P.530 is used to determine the required fade margin
36、as was done in developing the margins in Table 2. To accommodate for the allocation of interference the link is designed for an unfaded signal power, C0, so that NMCTSESSES=0(1) where N is the sum at the receiver of the FS system noise and the allocated increment for interference from within the fix
37、ed service. Denoting N0as the total system noise (k T BF), N = N0+ 1 dB. 14 dB rain margin (dB) 10 dB rain margin (dB) Associated EPO ratio ES (ITU-T Rec. G.826) 10 6 4.8 104ES (ITU-T Rec. G.828) 10 6 1.3 104BER 10613 9 SES 14 10 1.3 105BER 10315 11 6 Rec. ITU-R F.1606 More generally, the total nois
38、e including the interference from other co-primary services may be expressed as: )101(log1010/)/( NItotNN += dB (2) The permissible short-term I/N is the largest value that will not cause ES in the absence of fading. In accordance with Table 1, the C/N + I for ES, TES, is 4 dB higher than that for S
39、ES. Hence, TES= TSES+ 4 = C0 N. Using equations (1) and (2) in this expression and recognizing MSES 4 as the fade margin for ES gives the following expression for the I/N (dB): )110(log1010/=ESMI/N (3) Using the considered fade margins from Table 2 for ES, 10 dB and 6 dB, in equation (3), leads to v
40、alues of I/N of 9.54 dB and 4.74 dB, respectively. These values are presented in Table 3 with the associated EPO from Table 2. The I/N values have been rounded to the next higher whole number of decibels. On this basis, the short-term criteria proposed to be used in the 38 GHz and 40 GHz bands are g
41、iven in Table 3 and have been defined associating the ES EPO (see Table 1) and the corresponding FM value as defined in Table 2. TABLE 3 4 Long-term criteria The long-term criterion specified in Recommendation ITU-R F.758 to be used for the 38 GHz band is I/N = 10 dB, not to be exceeded for more tha
42、n 20% of the time. Since similar FS applications are assumed to be used in the 40 GHz band, the same long-term criteria would apply in this band. 5 Noise level reference For both short-term and long-term criteria as given in 3 and 4, the I/N levels refer to the total FS noise level, which includes t
43、he FS system noise and an agreed 1 dB allowance for intra-service interference. This means that N = 10 log (k T BF) + 1 dB. I/N (dB) Percentage of time not to be exceeded Criterion 1 10 0.05% Criterion 2(1)10 0.013%Criterion 1 for low net fade margin systems 5 0.05%Criterion 2(1)for low net fade mar
44、gin systems 5 0.013% (1)Criterion 2 applies to links designed in compliance with ITU-T Recommendation G.828.Rec. ITU-R F.1606 7 Appendix 1 to Annex 1 Rain fade margins for 99.999% availability Fade margin at 39.3 GHz, horizontal polarization (dB) Fade margin at 39.3 GHz, vertical polarization (dB) R
45、ain rate (mm/h) (zone) Rain rate (mm/h) (zone) Link distance (km) 12 (B) 22 (E) 42 (K) 63 (M) 95 (N) 12 (B) 22 (E) 42 (K) 63 (M) 95(1)(N)0.1 0.8 1.3 2.5 3.6 5.2 0.6 1.1 2.1 3 3.0 0.2 1.5 2.7 4.9 7.1 16.4 1.3 2.3 4.2 6 5.9 0.3 2.2 4 7.3 10.6 15.4 1.9 3.4 6.2 9 8.8 0.4 3 5.3 9.6 14 20.3 2.6 4.5 8.2 11
46、.9 11.6 0.5 3.7 6.5 12 17.4 25.1 3.2 5.6 10.2 14.7 14.3 0.6 4.4 7.8 14.3 20.7 29.8 3.8 6.7 12.2 17.6 17.0 0.7 5.2 9.1 16.6 24 34.3 4.5 7.8 14.2 20.3 19.6 0.8 5.9 10.4 18.9 27.2 38.8 5.1 8.9 16.1 23 22.2 0.9 6.6 11.6 21 30.4 43.2 5.7 10.0 18.0 25.8 24.7 1.0 7.3 12.8 23.3 33.6 47.5 6.3 11.0 19.9 28.5
47、27.1 1.1 8 14.1 25.5 36.7 51.7 6.9 12.1 21.8 31 29.5 1.2 8.7 15.3 27.7 39.8 55.8 7.5 13.1 23.7 33.7 31.9 1.3 9.4 16.5 29.9 42.8 59.8 8.1 14.2 25.5 36.2 34.1 1.4 10.1 17.7 32 45.8 63.8 8.7 15.2 27.3 38.8 36.4 1.5 10.8 18.9 34.1 48.7 67.6 9.3 16.2 29.1 41.3 38.6 1.6 11.4 20.1 36.2 51.6 71.4 9.9 17.3 30.9 43.7 40.8 (1)Fade margins for the case of 95 mm/h rain rate for vertical polarization were calculated under the assumption that the latitude is less than 30 (which impacts the calculation in accordance with Recommendation ITU-R P.530).
