1、 Recommendation ITU-R F.1764-1(05/2011)Methodology to evaluate interferencefrom user links in fixed service systems using high altitude platform stationsto fixed wireless systems in the bands above 3 GHzF SeriesFixed serviceii Rec. ITU-R F.1764-1 Foreword The role of the Radiocommunication Sector is
2、 to ensure the rational, equitable, efficient and economical 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 funct
3、ions of the Radiocommunication Sector are performed by 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 refer
4、enced in Annex 1 of Resolution ITU-R 1. Forms to be used 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 I
5、TU-R patent information database can also be found. Series 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 se
6、rvice (television) F Fixed service M Mobile, radiodetermination, 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 a
7、nd fixed service systems SM Spectrum management SNG Satellite 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,
8、2011 ITU 2011 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R F.1764-1 1 RECOMMENDATION ITU-R F.1764-1 Methodology to evaluate interference from user links in fixed service systems using high altitude platform
9、 stations to fixed wireless systems*in the bands above 3 GHz (2006-2011) Scope This Recommendation provides a methodology for interference evaluation that could be used for sharing studies between user links in fixed service (FS) systems using high altitude platform stations (HAPS) and conventional
10、fixed wireless systems in the frequency bands above 3 GHz. Interference situations from HAPS airships and ground stations to the fixed wireless stations are analysed. In this Recommendation, HAPS gateway links are not considered. The ITU Radiocommunication Assembly, considering a) that new technolog
11、y utilizing high altitude platform stations (HAPS) in the stratosphere has been developed to provide high-capacity services; b) that some administrations intend to operate the systems using HAPS in the bands allocated exclusively by the Table of Frequency Allocations or by footnotes for terrestrial
12、radiocommunication such as the fixed services; c) that information on architectures, including user and gateway links, of systems using high altitude platform stations in the band 5 850-7 075 MHz can be found in Recommendation ITU-R F.1891; d) that HAPS user links may operate in the bands 47.2-47.5
13、GHz and 47.9-48.2 GHz; e) that in some countries HAPS user links may operate in the band 27.9-28.2 GHz and 31.0-31.3 GHz on a non-harmful interference, non-protection basis, recommends 1 that the methodology described in Annex 1 may be used to evaluate interference from user links in fixed service s
14、ystems using high altitude platform stations to fixed wireless systems in the bands above 3 GHz. *The term “fixed wireless system” used in this Recommendation means point-to-point fixed wireless systems. Therefore, the term “fixed wireless station” is also used. 2 Rec. ITU-R F.1764-1 Annex 1 Methodo
15、logy for interference evaluation from user links in fixed service systems using high altitude platform stations to fixed wireless systems in the bands above 3 GHz 1 Introduction This Annex provides a methodology for interference evaluation to be used for sharing studies between user links in fixed s
16、ervice systems using HAPS and fixed wireless systems in the frequency bands above 3 GHz. Interference situations from HAPS airships and ground stations to fixed wireless stations are considered. It also provides an example of interference evaluation at 6 GHz1. This frequency is assumed only to show
17、an example of the interference evaluation. 2 Calculation methodology of interference from fixed service systems using HAPS to fixed wireless systems 2.1 Interference from HAPS airships to fixed wireless stations Figure 1 shows the interference situation from HAPS airships to fixed wireless stations.
18、 FIGURE 1 Interference environment from HAPS airships to fixed wireless stations HAPS airshipFixed wireless station1It is recognized that the frequency 6 GHz is not in a band allocated exclusively for terrestrial radiocommunication. It was chosen for this analysis to facilitate the development of th
19、e methodology because of the prevalence of available technical data for the terrestrial system. Rec. ITU-R F.1764-1 3 Currently most FS systems employ digital modulation. In the case of digital point-to-point (P-P) and point-to-multipoint (P-MP) FS systems, it is appropriate to evaluate interference
20、 in terms of fractional degradation of performance values of routes, FDProute, as defined in Recommendation ITU-R F.1107, assuming that the interference level is time-invariant. For digital P-P fixed service systems with n hops operating at frequencies where multipath fading generally predominates a
21、nd acknowledging that, in general, the performance objectives for multi-hop P-P FS systems are specified on a route basis as follows: % )(100 1TnkkrouteNnIFDP=(1) where: NT: receiver thermal noise Ik: aggregate interference falling into the k-th receiver from visible HAPS airships. NOTE 1 This model
22、 reflects a multi-hop fixed wireless station system for baseline interference studies, reflecting the period when microwave systems provided long-haul high-capacity traffic. However, with the development of metropolitan, national and international fibre optic networks, such systems are rapidly being
23、 replaced with back-haul systems carrying a diverse variety of traffic and connecting to the fibre network. Hence, most modern deployments contain mainly short links. Therefore, any analysis based upon 50-hop end-to-end degradation of performance caused by interference may no longer be applicable. I
24、nstead, each hop would need to be protected individually. The aggregate interference received at a digital fixed wireless station can be determined by summing the contributions from all visible HAPS airships. Each contribution can be determined as follows: ID=frLGF +4log10)()(2(2) where: F(): pfd of
25、 HAPS airship according to the angle of arrival above the horizontal plane, (dB(W/(m2 MHz) G(): antenna gain of fixed wireless station to the direction of HAPS airship, (dBi) : wavelength of the carrier (m) Lfr:feeder loss of fixed wireless station (dB). 2.2 Interference from HAPS ground stations to
26、 a fixed wireless station Figure 2 shows the interference situation from HAPS ground stations to a fixed wireless station. The interference power from a HAPS ground station to a fixed wireless station is obtained by equation (3): IGfrHRbRHfhHGLGpLGLP +=)()()( (3) where: PHG: transmission power densi
27、ty from HAPS ground station (dB(W/MHz) Lfh: feeder loss of the HAPS ground station (dB) 4 Rec. ITU-R F.1764-1 G(HR): transmitting antenna gain of HAPS ground station at the angle, RH between the direction of main beam of HAPS ground station and the direction of the interfered fixed wireless station
28、(dBi) Lb(p): basic transmission loss not exceeded for time percentage, p(%) given in Recommendation ITU-R P.452 G(RH): receiving antenna gain of fixed wireless station at the angle HR between the direction of main beam of fixed wireless station and the direction of the interfering HAPS ground statio
29、n (dBi) Lfr: feeder loss of the fixed wireless station (dB). FIGURE 2 Interference environment from HAPS ground stations to a fixed wireless station HAPS airshipHAPSService areaNadirDesired signalInterferenceHRrRHThe interference power at a fixed wireless station from multiple inputs of HAPS ground
30、stations can be obtained using equation (4) taking into account the mechanism shown in Fig. 3. In equation (4), it is assumed that the atmosphere absorption can be ignored on the line-of-sight propagation path below 10 GHz. And the propagation model used is based on Recommendation ITU-R P.452 with t
31、he percentage of time, p being 50%: IG-T = PHG Lfh 92.5 20 log f 1010log1010)(10)(222RHHRGGijijjiyx+ Lfr (4) Rec. ITU-R F.1764-1 5 where: f : frequency (GHz) =+=+=)odd(2)12()even(jdirjidrxij: x position of HAPS ground station yij= jd sin 60: y position of HAPS ground station r: distance between fixe
32、d wireless station and nadir of HAPS airship d: distance between HAPS ground stations i, j: cell location on x axis and y axis, respectively. FIGURE 3 Mechanism for calculating interference from HAPS ground stations to a fixed wireless station HAPS ground stations(, )xyij ijFixed wirelessstationTo a
33、irshipj = 1j = 0(, 0)rii = 2 = 1iii = 0 = 1 = 2HRrRHyd(0, 0)xOnce the interference level at a fixed wireless station has been assessed, the I/N ratio can be assessed as follows: I/N = IG-T dB )log(10 NFBTk + (5) where: k: Boltzmanns constant = 1.38 1023(J/K) T: temperature (K) B: bandwidth (Hz) NF:
34、noise figure of fixed wireless station (dB). 6 Rec. ITU-R F.1764-1 3 Example of interference evaluation from HAPS systems to fixed wireless systems 3.1 Interference from HAPS airships to fixed wireless stations Figure 4 shows the assumed distribution model of HAPS airships and fixed wireless station
35、s for interference evaluation. FIGURE 4 Distribution model of fixed wireless stations and HAPS airships HAPS airshipsFWS route 1route 2FWSroute 3FWSroute 4FWSroute 5FWS route 6FWSroute 7FWS100 kmLongitude (degrees)Latitude(degrees)12 9 6 3 0 3 6 9 1212963036912HAPS airships at a fixed point of an al
36、titude of 20 km can cover a service area of 110 km in diameter on the ground (elevation angle: 20), so that the location of HAPS airship nadir can be distributed uniformly with 100 km interval considering the overlap between service areas, as shown in Fig. 4. It is assumed that HAPS airships are uni
37、formly distributed in an area of 1 000 1 000 km2. Interfered routes of a fixed wireless system composed of 50 hops are assumed to be distributed aligning the centres of the routes with the centre of airship distribution. Table 1 shows the system parameters of a fixed wireless system and HAPS airship
38、 used in the calculation. The frequency of 6 GHz is chosen just to show an example of interference evaluation. For the interference evaluation in this Annex, all coordinates take into account the curvature of the Earth. Rec. ITU-R F.1764-1 7 TABLE 1 Common parameters of a fixed wireless system and H
39、APS airship Parameters ValuesFrequency 6 GHz Fixed wireless system Number of hops per route 50 Distance between hops 50 km Number of routes 600 HAPS airship Number of airships 126 Altitude 20 km Table 2 shows the system parameters of a digital fixed wireless system and HAPS airship used in the calcu
40、lation. The system parameters of a fixed wireless system for frequency sharing are also based on Recommendation ITU-R F.758. For bands where the fading is controlled by multipath, Recommendation ITU-R F.758 states that, in principle, the interference level relative to receiver thermal noise should n
41、ot exceed 10 dB (or 6 dB). In the case of digital FS systems, these values correspond to an FDP of 10% (or 25%), respectively. However, since this usage would be superimposed on already existing links which have been coordinated with other systems, the allowance of 10% may already be used up. In ord
42、er not to increase this interference, it may be required to limit interference to below 1 to 2%. Nevertheless, for illustrating the methodology, assuming the required protection level is 10%, the estimated interference distributions from HAPS airships to digital fixed wireless stations are shown in
43、Figs 5 and 6, with the variables of pfdlowand pfdhigh. TABLE 2 System parameters of a digital fixed wireless system and HAPS airship Parameters Specifications Fixed wireless system Antenna radiation pattern Recommendation ITU-R F.1245 Maximum antenna gain 45 dBi Feeder loss 5.5 dB Receiver noise fig
44、ure 4 dB Elevation angle between fixed wireless station Gaussian distribution HAPS airship pfdlow146 _ 140 (dB(W/(m2 MHz) pfdhigh127 _ 118 (dB(W/(m2 MHz) 8 Rec. ITU-R F.1764-1 In Fig. 5, when the pfd level of HAPS airship is assumed to be 140/118 (dB(W/(m2 MHz), the FDP of fixed wireless stations wo
45、uld be less than 10% in about 58% of the routes. As pfdlowdecreases, experienced interference also decreases. For example, when pfdlowis decreased by 6 dB, i.e. pfdlowis 146 (dB(W/(m2 MHz), the FDP of fixed wireless stations in 100% of the routes would be less than the assumed interference criterion
46、 of 10%. FIGURE 5 FDP distribution with pfdlowfrom HAPS airships 1.00.90.80.70.60.50.40.30.20.10.0pfd pfdlow/ = 170/142 dB(W/(m 169/142 dB(W/(m 168/142 dB(W/(m 167/142 dB(W/(m )166/142 dB(W/(m )165/142 dB(W/(m )164/142 dB(W/(m )high22222224 kHz)4 kHz)4 kHz)4 kHz)4 kHz)4 kHz)4 kHz)FDP, (%)FInterferen
47、ce distribution()iF0 5 25 30 3510 15 20Figure 6 shows the interference distribution with the changes of pfdhigh, when pfdlowis 145 (dB(W/(m2 MHz). Even though pfdhighis decreased by 6 dB from 121 (dB(W/(m2 MHz), the maximal difference of the interference distribution less than 10% is only about 5%.
48、3.2 Interference from HAPS ground stations to a fixed wireless station Table 3 shows the system parameters of a fixed wireless system and a HAPS system used in the calculation. Rec. ITU-R F.1764-1 9 FIGURE 6 FDP distribution with pfdhighfrom HAPS airships 1.00.90.80.70.60.50.40.30.20.10.0pfd pfdlow/
49、 = 145/127 dB(W/(m )145/126 dB(W/(m )145/125 dB(W/(m )145/124 dB(W/(m )145/123 dB(W/(m )145/122 dB(W/(m )145/121 dB(W/(m )high2222222MHz )MHz )MHz )MHz )MHz )MHz )MHz )FDP, (%)FInterferencedistribution()iF05 2010 15TABLE 3 System parameters of a fixed wireless system and a HAPS system Parameters ValuesFrequency 6 GHz Fixed wireless system Antenna radiation pattern Recommendation ITU-R F.12
