1、 Rec. ITU-R SF.1719 1 RECOMMENDATION ITU-R SF.1719 Sharing between point-to-point and point-to-multipoint fixed service and transmitting earth stations of GSO and non-GSO FSS systems in the 27.5-29.5 GHz band (Questions ITU-R 237-2/4 and ITU-R 206-2/9) (2005) Scope This Recommendation examines shari
2、ng as described inthe title. The Annex provides various methodologies of interference analysis to support the recommends that administrations avoid the deployment of FS receiver stations and large numbers of FSS transmitting earth stations with overlapping frequencies within the band 27.5-29.5 GHz i
3、n the same geographical area. The ITU Radiocommunication Assembly, considering a) that the band 27.5-29.5 GHz is allocated to both the fixed service and the FSS (Earth-to-space), as well as the mobile service on a primary basis in the Radio Regulations (RR); b) that the use of the band 28.6-29.1 GHz
4、 by FSS systems is subject to RR No. 5.523A; c) that individual FSS earth stations can be coordinated within the whole band 27.5-29.5 GHz; d) that some FSS systems intend to deploy a small number of large antenna earth stations on a coordinated basis; e) that applications in the high density FSS (HD
5、FSS) employ a large number of small aperture ubiquitously deployed user terminals; f) that conventional methods to coordinate such a large number of ubiquitously deployed FSS earth stations may imply a large burden for administrations; g) that administrations wishing to avoid interference potential
6、between FSS earth stations described in considering f) and stations in the fixed service may employ some form of band segmentation either over their entire territory or on a geographic basis, recognizing a) that notwithstanding band segmentation within an administration, coordination under the RR is
7、 still required with other administrations, recommends 1 that, taking into account the results of studies given in Annex 1, the deployment of fixed service receiver stations and large numbers of FSS transmitting earth stations with overlapping frequencies within the band 27.5-29.5 GHz in the same ge
8、ographical area should be avoided. 2 Rec. ITU-R SF.1719 Annex 1 Sharing between point-to-point (P-P) and point-to-multipoint (P-MP) fixed service and transmitting earth stations of GSO and non-GSO FSS systems in the 27.5-29.5 GHz band 1 Introduction Frequency bands have been allocated and identified
9、 for use by GSO and non-GSO FSS systems in the 28 GHz bands shared on a primary basis with the fixed service. WRC-95 and WRC-97 facilitated the use of the bands 18.8-19.3 GHz and 28.6-29.1 GHz for non-GSO FSS systems within the FSS allocations. The interference from a GSO and non-GSO FSS earth stati
10、on transmitting in the band 27.5-29.5 GHz into a fixed service receiver is addressed in this Annex. Co-frequency operation of multipoint distribution systems (MDSs) (e.g. local multipoint communication/distribution systems (LMCS/LMDS) or P-P systems of the fixed service and earth stations of the FSS
11、 (Earth-to-space) in the same geographical area would be difficult and would severely constrain the development of both types of services. Any fixed service system receivers can suffer long-term and significant short-term interference from FSS uplinks as shown in Fig. 1. The severity of this interfe
12、rence is a function of terminal separation, terrain and man-made obstacles, antenna discrimination, FSS earth station output power, and fixed service systems interference allowance. This Annex contains the description and results of two analyses. One of these is the deterministic approach, the other
13、 is statistical. 2 MDS description A generic description of an MDS system has been developed using parameters consistent with Recommendation ITU-R F.758. The applicability of these parameters in the band 27.5-29.5 GHz has been confirmed by current manufacturers and operators of MDS equipment. The re
14、presentative RF receiver characteristics of Recommendation ITU-R F.758 which were used in the deterministic analyses are shown in Table 1 for five hub stations and four subscriber stations. MDS networks comprise one or more hub stations serving multiple subscriber stations. Subscribers are assigned
15、to one hub station, based on proximity. Hub stations employ an omnidirectional or sectored antenna, while the subscriber stations typically use a much higher-gain dish antenna. Service path links will typically be around 5 km. Depending on modulation and access methods, a hub station can potentially
16、 accommodate a large number of users. Characteristics of fixed service links are also provided by the Recommendation ITU-R F.758 and manufacturers have confirmed their validity in the 27.5-29.5 GHz band. Antenna gains are usually higher for fixed service P-P links than for MDS and can reach 46 dBi.
17、Rec. ITU-R SF.1719 3 TABLE 1 Generic MDS system receiver description Parameter Hub systems Hub receiver HUB 1 HUB 2 HUB 3 HUB 4 HUB 5 Receive gain (dBi) 20 (90 sector) 15 (90 15)15 (90 15)24 (45 3) 24 (45 3) IF bandwidth (MHz) 16.4 1.36 2.50 1.36 2.50 Receiver noise figure (dB) 10 7.5 7.5 7.5 7.5 No
18、ise power (dBW) 121.8 135.1 132.5 135.1 132.5 Long-term interference (dBW) 131.8 144.3 141.6 144.3 141.6 Subscriber systems Subscriber receiver SUB A SUB B SUB C SUB D Receive gain (dBi) 47 36 36 36 IF bandwidth (MHz) 16.4 40 1.36 50 Receiver noise figure (dB) 8 7 7 7 Noise power (dBW) 123.8 121.0 1
19、35.6 120.0 Long-term interference (dBW) 133.8 130.1 144.8 129.1 4 Rec. ITU-R SF.1719 3 FSS uplink descriptions Previous studies of coordination distances and required separation distances between fixed service and FSS earth stations have shown that results are similar whether the FSS earth station i
20、s communicating with a GSO or a non-GSO satellite. These analyses examine both non-GSO FSS earth stations and GSO FSS earth stations. 3.1 Generic non-GSO FSS systems Several different non-GSO FSS systems have been proposed with a variety of uplink characteristics. Table 2 provides an abbreviated sum
21、mary of several non-GSO uplink parameters useful in assessing potential interference into an MDS receiver. The LEOSAT-1 system specifies a clear-sky transmit power of 0.7 dBW in 3.1 MHz. The far-side lobe for a small 0.3 m antenna would be 3.8 dBi. Reduced distances would result if FSS antennas with
22、 improved side-lobe performance were to be used. One USAMEO-1 uplink specifies a clear sky power of approximately 11.3 dBW in 2.8 MHz using a 90 cm antenna. Based on Recommendation ITU-R S.465, the far side-lobe level would be 9.6 dBi. TABLE 2 Examples of non-GSO FSS system uplink parameters System
23、Gain (dBi) Bandwidth (MHz) e.i.r.p. density (dB(W/Hz) USAMEO-4 41.9 1.445 21.4 USAMEO-1 65 cm 44.16 0.562 6.06 USAMEO-1 90 cm 46.98 2.812 6.25 USAMEO-3 32 cm 38.8 2.628 26.90 USAMEO-3 52 cm 44.0 13.142 26.89 USAMEO-2 KSL 55.2 250.0 17.27 LEOSAT-2 DTH 35.6 4.244 33.08 LEOSAT-2 LB 48.4 97.421 31.39 LE
24、OSAT-2 SB 45.9 20.31 33.28 USAKA-L1 FWD 56.0 22.6 21.31 USAKA-L1 RTN 39.8 2.93 26.15 LEOSAT-1 TST 35.2 3.1 30.41 4 Analysis for non-GSO FSS and P-MP fixed service systems Any transmitting FSS earth station can contribute to the short and long-term interference levels of the MDS hub and subscriber st
25、ations. 4.1 Deterministic analysis Separation distances required to avoid harmful interference between an FSS earth station transmitter and a fixed service receiver can be calculated using the simplified link equation procedure described in Appendix 1 to this Annex. The calculations assume line-of-s
26、ight propagation mechanisms in clear sky conditions and an additional transmission loss due to diffraction over a spherical Earth for transhorizon paths. The attenuation due to rain has not been taken into account. Advantages in Rec. ITU-R SF.1719 5 terrain blockages and additional fixed service ter
27、minals antenna discrimination (arising from different elevations) were not included in this analysis because their effects cannot be guaranteed in any scenario. Although such effects can result in improvements in the interference, these would tend to be offset by three other factors that would incre
28、ase the interference in a detailed analysis: the present analysis makes the conservative assumption of the FSS earth station transmit antenna only interferes via the back-lobes whereas real implementations would sometimes have the earth station antenna pointed closer to the fixed service receiver ma
29、in beam but for a short time due to the nature of the FSS system; the present analysis assumes only a single FSS transmit channel is active whereas in reality there might be multiple FSS channels transmitting in the fixed service receiver passband; and there could be multiple earth stations in the s
30、ame location operating co-frequency simultaneously with different FSS satellites of the same network and/or multiple networks. By repeating the separation distance calculation for fixed service receiver azimuth angles from 0 to 360, a two-dimensional contour results, known as a “separation zone”. Th
31、ese separation zones represent regions around a fixed service receiver where operation of FSS earth stations may be precluded in order to assure proper operation of the fixed service receiver. 4.1.1 Potential interference from non-GSO FSS systems For an initial assessment of the interference potenti
32、al from non-GSO FSS earth stations, the far side-lobe (back-lobes) levels are used. This provides the lowest level of unobstructed interference as a function of relative orientation. Although the interference levels may periodically increase depending on the servicing satellite location, interferenc
33、e from the far side-lobe is expected to occur most frequently. Figure 2 presents an example non-GSO FSS earth station separation zone around an MDS subscriber station (SUB A) based on the LEOSAT-1 uplink characteristics. The maximum required separation distance (in the main receive beam) ranges from
34、 35 to 50 km, where the upper value corresponds to both subscriber and earth station antenna heights of 30 m and no terrain and building blockage considered. This clearly represents a worst-case scenario but in situations where building and terrain block the interfering signal, these distances are g
35、reatly reduced; the far-lobe-to-far-lobe separation is 700 m. This zone is based on interference power overlapping 19% of the SUB A receiver bandwidth (= 3.1/16.4 MHz). Separation distances computed for the four different subscriber stations resulted in the main-beam boundary being between 29 and 47
36、 km, with the maximum occurring with SUB A (highest receive gain). The back-lobe separation distances ranged from 0.7 to 2.0 km, with the maximum occurring for SUB C (smallest bandwidth). Table 3 provides a summary of the calculated separation distances for LEOSAT-1 and the various subscriber statio
37、ns. Separation distances computed for the five different hub stations show that the boundary varies with the type of HUB between 15 km (HUB 1) to a distance ranging from 35 to 50 km (HUB 5), where the upper value corresponds to both HUB and earth station antenna heights of 30 m and no terrain and bu
38、ilding blockage considered (highest receive gain, similar bandwidth to interference signal). This upper value of 50 km distance corresponds to the worst-case scenario. Table 4 provides a summary of the calculated separation distances between LEOSAT-1 and the various hub stations. Figure 3 shows an e
39、xample LEOSAT-1 separation zone associated with a hub station (HUB 5). The separation between an FSS terminal far-lobe and the hub station main-lobe is significantly larger than most typical MDS service cells. 6 Rec. ITU-R SF.1719 TABLE 3 LEOSAT-1 user terminal/MDS subscriber station separation dist
40、ances MDS system Main beam separation(1) (km) Back-lobe separation (km) SUB A 34.01-46.39 0.71 SUB B 29.21-41.52 0.87 SUB C 31.67-44.00 2.04 SUB D 28.90-41.20 0.78 (1)Range of separations based on station height combinations of (30 m, 5 m) and (30 m, 30 m). Rec. ITU-R SF.1719 7 TABLE 4 LEOSAT-1 user
41、 terminal/MDS hub station separation distances MDS system Main beam separation(1) (km) HUB 1 14.68 HUB 2 15.11 HUB 3 19.51 HUB 4 27.60-34.42 HUB 5 28.46-40.76 (1)Range of separations based on station height combinations of (30 m, 5 m) and(30 m, 30 m). 8 Rec. ITU-R SF.1719 The example subscriber and
42、hub station separation zones for the USAMEO-1 90 cm earth station are shown in Fig. 4 (SUB A) and Fig. 5 (HUB 5), respectively. Separation distances computed for the four subscriber station characteristics showed the main beam boundary ranges from 31 to 49 km, where the upper value corresponds to SU
43、B A (highest receive gain) main beam distance when both subscriber and earth station antenna heights of 30 m and no terrain and building blockage considered. Again this clearly represents a worst-case scenario but in situations where building and terrain block the interfering signal, these distances
44、 are greatly reduced. The back-lobe separation distances ranged from 1.4 to 4.4 km, with the maximum occurring SUB C (smallest bandwidth).The distances computed for the five hub station characteristics showed the boundary varied between 26 to 43 km, with the maximum occurring with HUB 5 (highest rec
45、eive gain, similar bandwidth to interference signal) and HUB and earth station antenna heights of 30 m and no terrain and building blockage considered. Tables 5 and 6 present a summary of the calculated separation distances between USAMEO-1 and the various subscriber and hub stations, respectively.
46、The anticipated number of earth stations is not known, but as shown, just a single earth station is capable of excluding a significant area from MDS service, even if one ignores the area extending beyond the line-of-sight. Rec. ITU-R SF.1719 9 TABLE 5 USAMEO-1 user terminal/MDS subscriber station se
47、paration distances MDS system Main beam separation(1) (km) Back-lobe separation (km) SUB A 36.00-48.40 1.42 SUB B 31.19-43.52 1.73 SUB C 33.92-46.29 4.41 SUB D 30.87-43.21 1.55 (1)Range of separations based on station height combinations of (30 m and 5 m) and (30 m and 30 m). 10 Rec. ITU-R SF.1719 T
48、ABLE 6 USAMEO-1 user terminal/MDS hub station separation distances MDS system Main beam separation(1) (km) HUB 1 26.05 HUB 2 26.93-28.81 HUB 3 27.78-36.06 HUB 4 29.84-42.16 HUB 5 30.70-43.04 (1)Range of separations based on station height combinations of (30 m, 5 m) and (30 m, 30 m). 4.1.2 Remarks I
49、t should be noted that the distances computed above, are probably not typical of an urban or semi-urban scenarios for which some effect of blocking should be taken into account both for the intra-service (cell to cell) and inter-service sharing. It was recognized that the results presented in 4.1.1 would also apply to GSO FSS earth stations if these operate with characteristics similar to those in Table 2. 4.2 Statistical analysis The results presented below were developed using a tool which implements a statistical methodology base
