1、 Rec. ITU-R F.1609-1 1 RECOMMENDATION ITU-R F.1609-1 Interference evaluation from fixed service systems using high altitude platform stations to conventional fixed service systems in the bands 27.5-28.35 GHz and 31-31.3 GHz (Question ITU-R 212/9) (2003-2006) Scope This Recommendation describes inter
2、ference evaluation methodologies from the fixed service (FS) using high altitude platform stations (HAPS) to conventional FS systems in the bands 28 GHz (27.5-28.35 GHz) and 31 GHz (31-31.3 GHz). Examples of interference calculations using these methodologies are also provided in Annexes 1 to 3 for
3、both point-to-point and point-to-multipoint fixed wireless access (FWA) stations. The ITU Radiocommunication Assembly, considering a) that new technology utilizing high altitude platform stations (HAPS) in the stratosphere is being developed; b) that since the 47 GHz bands, stated in recognizing a)
4、below, are more susceptible to rain attenuation in those countries listed in Nos. 5.537A and 5.543A of the Radio Regulations (RR), the frequency range 18-32 GHz has been studied in ITU-R for possible identification of additional spectrum; c) that the bands 27.5-28.35 GHz and 31-31.3 GHz are allocate
5、d to the FS on a primary basis, recognizing a) that WRC-97 made provisions for operation of HAPS within the fixed service (FS) in the bands 47.2-47.5 GHz and 47.9-48.2 GHz; b) that RR No. 5.537A states that the allocation to the FS in the band 27.5-28.35 GHz may also be used by HAPS in the listed co
6、untries, and the use by HAPS is limited to operation in the HAPS-to-ground direction and shall not cause harmful interference to, nor claim protection from, conventional types of FS systems or other co-primary services; c) that RR No. 5.543A states that the allocation to the FS in the band 31-31.3 G
7、Hz may also be used by HAPS in the ground-to-HAPS direction in the listed countries, and the use by HAPS shall not cause harmful interference to, nor claim protection from, conventional types of FS systems or other co-primary services, taking into account RR No. 5.545; d) that RR No. 5.543A also sta
8、tes that the use of HAPS in the band 31-31.3 GHz shall not cause harmful interference to the passive services having a primary allocation in the band 31.3-31.8 GHz, taking into account the interference criteria given in Recommendations ITU-R SA.1029 and ITU-R RA.769; 2 Rec. ITU-R F.1609-1 e) that Re
9、solution 145 (WRC-03) urgently requested studies on technical, sharing and regulatory issues in order to determine criteria for the operation of HAPS in the bands 27.5-28.35 GHz and 31-31.3 GHz, recommends 1 that the methodologies contained in Annexes 1 and 2 may be used to evaluate interference fro
10、m a HAPS-based system to a conventional FS system (point-to-multipoint (P-MP) and point-to-point (P-P) (see Note 1 and Note 2); 2 that the methodology contained in Annex 3 may be used to evaluate interference from a HAPS to a conventional FS system in the 27.5-28.35 GHz band; 3 that the methodologie
11、s contained in Annexes 1, 2 and 3 may be used to develop bilateral agreements between administrations. NOTE 1 Recommendation ITU-R F.1569 should be referred to for typical parameters regarding a HAPS-based system. NOTE 2 The interference evaluation from a HAPS-based system to the fixed wireless acce
12、ss (FWA) system is discussed for the worst interference scenario in Annex 1 and Annex 2. Adopting interference mitigation techniques described in Recommendation ITU-R F.1608 may shorten the required separation distance. NOTE 3 In Annexes 1 and 2, the numerical parameter such as transmission output i
13、s fixed. For other parameters, it will not be as difficult to calculate on the basis of the results described there. Furthermore, Recommendation ITU-R F.758 lists some system parameters, some of which include the worst case from the viewpoint of the interference issues. Annex 1 Methodology for inter
14、ference evaluation from systems in the FS using HAPS to FWA systems (P-MP) in the bands 27.5-28.35 GHz and 31-31.3 GHz 1 Introduction This Annex provides a methodology for interference evaluation, technical parameters, and operational techniques to be used for sharing studies between systems in the
15、FS using HAPS and FWA systems operating in P-MP in the bands 27.5-28.35 GHz and 31-31.3 GHz. P-MP systems normally consist of one base station and several subscriber stations. In the FWA system, there is no rule to use these two frequency bands between FWA base station and FWA subscriber station. Th
16、erefore, all interference situations have to be considered. 2 Calculation methodology of interference from HAPS-based system to FWA system (P-MP) 2.1 Interference from HAPS airship to FWA station The interference power from the spot beam of HAPS airship to FWA station, I (dB(W/MHz), is obtained by e
17、quation (1). Rec. ITU-R F.1609-1 3 FWAfRxHFFWARxFAtmHmsFBHBHTxBHTxLGLLGPImnmnmnm_)()( += (1) where: PTx_HmBn: transmission power density of spot beam (Bn) of HAPS (Hm) (dB(W/MHz) GTx_HmBn(HmBn_F): antenna gain of spot beam of HAPS airship toward the direction of FWA station (dBi) LS : free space pas
18、s loss between HAPS airship and FWA station (dB) shown in the following: =00014log20dLSd: distance between HAPS airship and FWA station (km) : wave length (m) LAtmHm_F : atmospheric absorption loss between HAPS airship and FWA station (dB) (for details, refer to Appendix 1 to Annex 1 and Annex 2 whi
19、ch is based on Recommendation ITU-R F.1404, where absorption is denoted by A(h,) GRx_FWA (F_Hm): receive antenna gain of FWA station toward the direction of HAPS airship (dBi) LfRx_FWA : feeder loss of FWA station in the receive side (dB). The ratio of the interference power to the receiver thermal
20、noise, I/N, is obtained by equation. )1010293log(10/610/=NFkINI dB (2) where: k: Boltzmanns constant = 1.38 1023(J/K) NF: noise figure of FWA station (dB). 2.2 Interference from HAPS ground station to FWA station The interference power from HAPS ground station to FWA station, I (dB(W/MHz), is obtain
21、ed by equation (3). FWAfRxHFFWARxObsAtmsFHGSTxGSfTxGSTxLGLLLGLPI_)()( += (3) where: PTx_GS : transmission power density from HAPS ground station (dB(W/MHz) LfTx_GS : feeder loss of HAPS ground station (dB) GTx_GS(H_F): antenna gain of HAPS ground station toward the direction of FWA station (dBi) Ls:
22、 free space pass loss between HAPS ground station and FWA station (dB) LAtm : atmospheric absorption loss between HAPS ground station and FWA station (dB), which is calculated by using Recommendation ITU-R P.676 LObs : shielding loss between HAPS ground station and FWA station (it is not included in
23、 the calculation of required separation distance) (dB) GRx_FWA(F_H): receiving antenna gain of FWA station toward the direction of HAPS ground station (dBi) LfRx_FWA : feeder loss in FWA station (dB). 4 Rec. ITU-R F.1609-1 The ratio I/N is obtained by equation (2). 3 Assumptions for interference eva
24、luation 3.1 HAPS system The parameters of HAPS system are described in Recommendation ITU-R F.1569. 3.2 FWA system with P-MP operation Section 1 in Appendix 2 describes the assumed parameters of the FWA system with P-MP operation to carry out the interference evaluation, which includes base station
25、and subscriber station. As for the FWA base station, the following three cases are considered from the viewpoint of antenna beam pattern and scheme of frequency reuse. Herein, it is assumed that the base stations are geographically installed every 2 km. Case a): Assumed antenna beam pattern is based
26、 on Recommendation ITU-R F.1336 and frequency reuse is seemed to be comparatively realistic (segmented 4 4 frequency bands are used by four base stations and its antenna beam is 90 sector: a group of four stations is repeatedly installed). Case b): Assumed antenna beam pattern is based on Recommenda
27、tion ITU-R F.1336 and all base stations use same frequency assigned for the base station (therefore, omni pattern is assumed in azimuth direction). Case c): Assumed antenna beam pattern is a reasonably realistic one, which many service providers would adopt (not listed in Recommendation), and freque
28、ncy reuse scheme is the same as in Case a). 4 Examples of calculation result in the case of FWA system with P-MP operation This section shows examples of calculated I/N characteristics and required separation distance. Regarding the system parameters of the FWA system with P-MP operation, three Case
29、s a), b) and c) are considered for the base station. It is also supposed that the same type of FWA subscriber station is used for three base stations. 4.1 Interference from HAPS airship to FWA system In examination of the interference from the HAPS airship to the FWA base station, it is supposed tha
30、t 11 21 HAPS airships are deployed in the area of 500 km 1 000 km. The I/N characteristics are evaluated as a function of distance between the FWA station and the nadir point of the HAPS airship locating in the middle of the 1 000 km side. Through the calculation, it is assumed that the main beam of
31、 the FWA base station always directs toward the horizontal direction. On the other hand, it is supposed herein for the sake of the worst-case analysis that the FWA subscriber station directly points the HAPS airship up to 60 in elevation. 4.1.1 Interference from HAPS airship to FWA base station Figu
32、res 1 and 2 show the I/N characteristics of the FWA base station of Cases a) and b) respectively, when it is subject to the interference from 11 21 multiple HAPS airships (refer to Fig. 3). The notation “front” in Fig. 1 means that the base stations point toward the centre of multiple HAPS airships
33、face-to-face in azimuth direction. The “side” and “back” indicate the Rec. ITU-R F.1609-1 5 conditions that the base station sees the airship on its side and at its back, respectively. The indicated I/N shows the worst value among all spot beams of HAPS airships using frequency reuse scheme. From bo
34、th Figures, it is seen that the maximum I/N is about 15 dB. Therefore, under the conditions made here, it is said that the multiple HAPS airships may not give serious interference to the FWA base station. It is noted that front is equal to side and back in Fig. 2, because the antenna pattern is assu
35、med to be omni characteristics in azimuth direction. When the reasonably realistic beam pattern is used for the FWA base station as in Case c), the I/N is slightly reduced as shown in Fig. 4. In Case c), the maximum I/N is about 20 dB. 6 Rec. ITU-R F.1609-1 Rec. ITU-R F.1609-1 7 4.1.2 Interference f
36、rom HAPS airship to FWA subscriber station Concerning the I/N characteristic of the FWA subscriber station, when interfered from a single HAPS airship, the worst I/N becomes a large value of about 30 dB as shown in Fig. 5. It is due to larger antenna gain of the FWA subscriber station than that of t
37、he base station and to the assumption that the FWA subscriber antenna directly points the HAPS airship with limitation of maximum elevation angle of 60. Therefore, the HAPS airship will induce large interference to the subscriber station when the same frequency is used. It is noted in Fig. 5 that th
38、e distance of 200 km corresponds to the transition point for the use of 30 cm diameter antenna to that of 60 cm diameter antenna (refer to Note 1 of Table 2). 8 Rec. ITU-R F.1609-1 4.2 Interference from HAPS ground station to FWA system Regarding the interference from the HAPS ground station to the
39、FWA station, analysis is carried out only for the condition of line of sight. Furthermore, it is assumed that the altitude of the HAPS ground station and that of the FWA station (base station and subscriber station) is the same and that the antenna gain of the FWA base station directing toward the H
40、APS ground station is the same in the three Cases of a), b) and c). The calculation is made for only the case of the single entry, under the condition that the two stations, which are the HAPS ground station with elevation angle of more than 20 and the FWA station pointing horizontal direction, poin
41、t face-to-face in azimuth. The assumed I/N value for this analysis is 15 dB. 4.2.1 Interference from HAPS ground station to FWA base station Figure 6 shows the required separation distance when the HAPS ground station gives interference to FWA base station. Using the assumed I/N of 15 dB and the ass
42、umed minimum elevation angle of 20, the separation distance is about 5 km. Considering that the FWA base station is installed repeatedly with frequency reuse by distance of 2-3 km, coexistence of the FWA base station and the HAPS ground station would be difficult unless any interference mitigation t
43、echniques are introduced. Rec. ITU-R F.1609-1 9 4.2.2 Interference from HAPS ground station to FWA subscriber station Figure 7 shows the required separation distance when the HAPS ground station gives interference to the FWA subscriber station using the assumed I/N of 15 dB. Using the assumed I/N of
44、 15 dB and the elevation angle of 20, the separation distance is about 80 km. Coexistence of the FWA subscriber station and the HAPS ground station is impossible without interference mitigation techniques. 10 Rec. ITU-R F.1609-1 5 Summary This Annex shows a method to evaluate interference from the H
45、APS transmitters into FWA receivers (P-MP) in terms of I/N and evaluates the required separation distance for some assumed deployments of FWA stations and HAPS stations. Annex 2 Methodology for interference evaluation from systems in the FS using HAPS to FWA systems (P-P) in the bands 27.5-28.35 GHz
46、 and 31-31.3 GHz 1 Introduction This Annex provides a methodology for interference evaluation, technical parameters, and operational techniques to be used for sharing studies between systems in the FS using HAPS and FWA systems operating in P-P in the bands 27.5-28.35 GHz and 31-31.3 GHz. A P-P syst
47、em consists of one pair of two radio stations directing face-to-face (in this Annex, this radio station is called FWA station for the sake of simplicity). 2 Calculation methodology of interference from HAPS-based system to FWA system (P-P) Since the calculation methodology of interference between th
48、e HAPS system and FWA system with P-P operation is the same as that described in 2 in Annex 1, therefore the equation for calculation is herein omitted. 3 Assumptions for interference evaluation 3.1 HAPS system The parameters of HAPS system are described in Recommendation ITU-R F.1569. 3.2 FWA syste
49、m with P-P operation Section 2 in Appendix 2 describes the assumed parameters of the FWA system with P-P operation to carry out the interference evaluation. 4 Examples of calculation results in the case of FWA system with P-P operation 4.1 Interference from HAPS airship to FWA system In examination of the interference from the HAPS airship to the FWA station, the I/N characteristics are evaluated as a function of distance between the FWA station and the nadir point of the HAPS airship. Through the calcul
