1、 Rec. ITU-R F.1613 1 RECOMMENDATION ITU-R F.1613*,* Operational and deployment requirements for fixed wireless access systems in the fixed service in Region 3 to ensure the protection of systems in the Earth exploration-satellite service (active) and the space research service (active) in the band 5
2、 250-5 350 MHz (Questions ITU-R 113/9 and 218/7) (2003) The ITU Radiocommunication Assembly, considering a) that the frequency band 5 250-5 350 MHz is allocated to the Earth exploration-satellite service (EESS) (active) and space research service (SRS) (active) for spaceborne active sensors and to t
3、he radiolocation service on a primary basis; b) that the allocations in the frequency band 5 250-5 350 MHz will be reviewed by WRC-03 under agenda item 1.5 with a view to allocating this band to the fixed service in Region 3 on a primary basis; c) that some administrations in Region 3 have proposed
4、using the band 5 250-5 350 MHz for licence-based fixed wireless access (FWA) systems in the fixed service; d) that these FWA systems operating outdoors may cause unacceptable interference to the EESS/SRS (active) in the above band; e) that there is a need to specify operational and deployment requir
5、ements for FWA systems in Region 3 in order to protect spaceborne active sensor systems, *This Recommendation was developed jointly by Radiocommunication Study Groups 7 and 9, and any future revision will also be undertaken jointly. *This Recommendation should be brought to the attention of Radiocom
6、munication Study Groups 7 and 8. 2 Rec. ITU-R F.1613 noting a) that the interference from EESS/SRS (active) systems into FWA systems with the characteristics described in Annex 1 is considered to be acceptable, recognizing a) that it is difficult for FWA and other types of wireless access systems (i
7、ncluding radio local area networks (RLANs) to operate simultaneously on a co-coverage, co-frequency basis, recommends 1 that the aggregate interference from FWA systems (sum of the directional e.i.r.p. towards the satellite) should be smaller than 7.6 dB(W/20 MHz) at the Earths surface within the fo
8、otprint of the active sensor of the EESS/SRS satellite (see Notes 1, 2 and 3); 2 that the methodology described in Annex 1 should be used to assess the aggregate interference level from FWA systems; 3 that, based on the FWA system characteristics presented in Table 4 for Region 3, a maximum density
9、of 23 FWA base stations per 220 km2should be allowed within a satellite active sensor footprint. Variation of the maximum e.i.r.p., antenna pattern and frequency planning would imply a variation in the maximum allowed density of FWA base stations; 4 that the maximum e.i.r.p. of each FWA station shou
10、ld be no more than 3 dB(W/20 MHz) (see Notes 4 and 5); 5 that administrations should control these systems to ensure that the deployment requirements for FWA systems specified in the above recommends are satisfied. NOTE 1 This aggregate interference level is derived from the interference threshold o
11、f 132.35 dB(W/20 MHz) at the satellite receiver specified for the SAR4 in Table 5. NOTE 2 The footprint of the active sensor of the EESS/SRS the satellite referred to here has an area of about 220 km2. NOTE 3 The aggregate interference from FWA systems toward the spaceborne active sensor satellite d
12、epends on such parameters as transmit power of the FWA systems, the antenna directivity and the number of the FWA base stations using the same RF channel within the satellite active sensor footprint. NOTE 4 If the main beam direction is above 10 in elevation, a 6 dB lower e.i.r.p. limit should apply
13、, i.e. a maximum e.i.r.p. of 3 dB(W/20 MHz). NOTE 5 The direction of FWA station antennas should be controlled in order to avoid accidental direct illumination to the satellite due to misalignment of antenna direction, for example, a remote station not pointing towards the base station. NOTE 6 Addit
14、ional guidance should be developed in order to facilitate the application of this Recommendation. This matter requires further study. Rec. ITU-R F.1613 3 Annex 1 Frequency sharing between FWA systems and spaceborne active sensor systems in the EESS (active) and the SRS (active) in the band 5 250-5 3
15、50 MHz 1 Introduction The frequency band 5 250-5 350 MHz is considered to be suitable for FWA systems in the fixed service to provide high-speed Internet or other multimedia service applications. Since the frequency band is allocated in the ITU Radio Regulations to the EESS (active) and the SRS (act
16、ive) on a worldwide basis, sharing feasibilities between FWA systems and systems in the EESS/SRS (active) needs to be determined. In this frequency band various types of spaceborne synthetic aperture radar (SAR), spaceborne radar altimeter and spaceborne scatterometer systems in the EESS/SRS (active
17、) are operating. This Annex deals with sharing consideration between FWA systems and these spaceborne active sensors, using typical system parameters that are currently available or being considered in the developmental stage. 2 Technical characteristics of spaceborne active sensors Technical charac
18、teristics of spaceborne active sensors in the 5 250-5 350 MHz are given in Tables 1 to 3. TABLE 1 5.3 GHz typical spaceborne SAR characteristics Value Parameter SAR2 SAR3 SAR4 Orbital altitude (km) 600 (circular) 400 (circular) Orbital inclination (degrees) 57 RF centre frequency (MHz) 5 405 5 305 5
19、 300 Peak radiated power (W) 4 800 1 700 Polarization Horizontal and vertical (HH, HV, VH, VV) Pulse modulation Linear FM chirp Pulse bandwidth (MHz) 310 40 Pulse duration (s) 31 33 4 Rec. ITU-R F.1613 TABLE 1 (end) Value Parameter SAR2 SAR3 SAR4 Pulse repetition rate (pps) 4 492 1 395 Duty cycle (%
20、) 13.9 5.9 Range compression ratio 9 610 10 230 1 320 Antenna type (m) Planar phased array 1.8 3.8 Planar phased array 0.7 12.0 Antenna peak gain (dBi) 42.9 42.7/38 (full focus/beamspoiling) Antenna median side-lobe gain (dBi) 5 Antenna orientation (degrees) 20-38 from nadir 20-55 from nadir Antenna
21、 beamwidth 1.7 (El), 0.78 (Az) 4.9/18 (El), 0.25 (Az) Antenna polarization Linear horizontal/vertical Receiver noise figure (dB) 4.62 Receiver front end 1 dB compression point referred to receiver input 62 dBW input Receiver input maximum power handling (dBW) +7 Operating time 30% of the orbit Minim
22、um time for imaging (s) 15 Service area Land masses and coastal areas Image swath width (km) 20 16/320 Footprint (km2) 159.03 76.5 76.5-220 Receiver bandwidth (MHz) 356.5 46.00 Interference threshold (dB) I/N = 6 Rec. ITU-R F.1613 5 TABLE 2 5.3 GHz typical spaceborne altimeter characteristics TABLE
23、3 5.3 GHz typical spaceborne scatterometer characteristics Jason mission characteristics Lifetime 5 years Altitude (km) 1 347 15 Inclination (degrees) 66 Poseidon 2 altimeter characteristics Signal type Pulsed chirp linear frequency modulation C band PRF (Hz) 300 Pulse duration (s) 105.6 Carrier fre
24、quency (GHz) 5.3 Bandwidth (MHz) 320 Emission RF peak power (W) 17 Emission RF mean power (W) 0.54 Antenna gain (dBi) 32.2 3 dB aperture (degrees) 3.4 Side-lobe level/Maximum (dB) 20 Back-side-lobe level/Maximum (dB) 40 Beam footprint at 3 dB (km) 77 Interference threshold (dBW) 118 Parameter Value
25、System name Scatterometer 1 Scatterometer 2 Orbital altitude (km) 780 800 Inclination (degrees) 81.5 Centre frequency (GHz) 5.3 5.255 Pulse width 70 s (mid) 130 s (fore/aft) 8 ms (mid) 10.1 ms (fore/aft) Modulation Interrupted CW Linear FM (chirp) Transmitter bandwidth (kHz) 15 500 PRF (Hz) 115 (mid
26、) 98 (fore/aft) 29.4 Antenna type Slotted waveguide 6 Rec. ITU-R F.1613 TABLE 3 (end) 3 Technical features of FWA systems Technical parameters of FWA systems should be decided to meet both the high-speed Internet service requirements and the sharing criteria with other services. When FWA systems are
27、 to operate in the band 5 250-5 350 MHz, the following points have to be considered: FWA systems are composed of a base station and many remote stations within the service coverage, in other words a cell. It is assumed that all the remote stations communicate to the base station only during the assi
28、gned time slot (in case of time division multiple access (TDMA) or accessible timings (in case of carrier sense multiple access (CSMA). This means that within a cell only one station is transmitting at any instant in time. Therefore, the deployment density (per km2) of FWA base stations will affect
29、the interference to a spaceborne active sensor satellite station. The antenna directivity for high elevation angle is important. If the antenna at the FWA stations has enough upward discrimination, the interference power will be sufficiently suppressed. Active ratio of a group of FWA transmitters in
30、 a cell may become 100% in the worst case. Licence-based measures will be required to control the deployment density of FWA systems. Parameter Value Antenna gain (dBi) 31 (mid) 32.5 (fore/aft) 28.5 (mid) 29.5 (fore/aft) Antenna main beam orientation (degrees) Incidence angles: 18-47 (mid) 24-57 (for
31、e/aft) Incidence angles: 25.0-54.5 (mid) 33.7-65.3 (fore/aft) Antenna beamwidth (3 dB) elevation (degrees) Azimuth beamwidth (degrees) 24 (mid) 1.3 26 (fore/aft) 0.8 23.6 (mid) 1.1 23.9 (fore/aft) 0.8 Instrument elevation angle (degrees) 29.3 37.6 Antenna polarization Vertical Transmitter peak power
32、 4.8 kW 120 W Receiver noise figure (dB) 3 Service area Oceanic and coastal areas, land masses Interference threshold (dB(W/Hz) 207 Rec. ITU-R F.1613 7 Considering the aforementioned features, examples of technical parameters for FWA systems are assumed as shown in Table 4 for the purpose of prelimi
33、nary studies in this Annex. The characteristics chosen in this analysis are those which would result in the worst-case interference to a narrow-band SAR receiver. For this type of FWA system, if the antenna boresight is pointed approximately along the horizon for a point-to-multipoint connection, th
34、e angle from the boresight becomes the elevation angle. At nadir angles of 20 to 55, FWA station elevation angles directed towards a spaceborne SAR range from 69 to 30. TABLE 4 Technical characteristics of FWA system at 5.3 GHz 1613-010 1020304050607080902015105051015FIGURE 1Base station antenna pat
35、ternGain(dBi)Elevation angle (degrees)Base station Remote station Frequency band (MHz) 5 250-5 350 Operational mode Point-to-multipoint Cell radius (km) 1-2 Maximum transmit e.i.r.p./power (W) 2/0.2 2/0.063 Antenna gain/ characteristics 10 dBi/ Rec. ITU-R F.1336 Omnidirectional pattern (k = 0) (Fig.
36、 1) 15 dBi/ Rec. ITU-R F.1336 Low-cost, low-gain antenna (Fig. 2) Bandwidth (MHz) 20 Receiver noise figure (dB) 8 Interference threshold I/N = 6 dB or 128.8 dB(W/20 MHz) Polarization Vertical or horizontal Active ratio (%) 90 10 8 Rec. ITU-R F.1613 1613-020 20 40 60 80 100 120 140 160 18010505101520
37、FIGURE 2Remote station antenna patternGain(dBi)Off-axis angle (degrees)4 Frequency sharing between spaceborne active sensors and FWA systems 4.1 Sharing between SAR and FWA 4.1.1 Interference from FWA into SAR Table 5 presents a calculation result of interference from an FWA system with parameters i
38、n Table 4 to SAR4 in Table 1. Although SAR2, SAR3 and SAR4 provide the equivalent interference threshold per MHz, the analysis hereafter refers to SAR4 with the most stringent requirement in absolute value. In calculating the interference, the side-lobe effect of the FWA antenna and the scattering e
39、ffect at the surface/building are considered. With regard to the side-lobe interference from remote stations, the average e.i.r.p. towards the satellite from all remote stations surrounding the base station is calculated (see Appendix 1 to Annex 1). Note that the frequency reuse factor of 4 is assum
40、ed in Table 5. The surface scattered contribution or eventual scattering from nearby buildings will be possible sources of interference. This is dependent on the area where these systems are deployed and on which altitude they will be placed (top or side of buildings), etc. It can be envisaged that
41、FWA systems are present in high-density urban areas where by definition scattering from a wide range of objects will occur, so besides surface scattering these other cases will have to be taken into account. One could especially envisage modern office buildings, which are constructed out of metal wh
42、ere the possibility of a high reflectivity into the direction of the sensor cannot be excluded. As the worst-case approach, a scattering coefficient is taken as 18 dB. This assumption may need to be reviewed. The above analysis is based on the hypothesis of having only FWA transmitters not using sec
43、tor antennas. The presence of sector antennas would deteriorate the sharing scenario related to scattering. The result indicates that 23 FWA cells can be operated in the SAR4 footprint within an area of 220 km2while the interference to the SAR satellite receiver is smaller than the acceptable level.
44、 If the parameters of FWA systems are different from those listed in Table 4, including the case where sector antennas are employed at the base stations, the number of cells allowed within the satellite footprint would be different. Table 5 should be recalculated with the actual parameters. Rec. ITU
45、-R F.1613 9 TABLE 5 Interference from an FWA system to SAR4 20 from nadir 55 from nadir Parameter Value dB Value dB Transmitted peak power (W) 0.2 7.00 0.2 7.00 Transmit antenna gain (dBi) 14.20 8.80 Active ratio 90% 0.46 90% 0.46 From base station e.i.r.p. (dBW) 21.66 16.26 Transmitted peak power (
46、W) 0.063 12.00 0.063 12.00 Average transmit antenna gain (dBi) 4.96 2.34 Active ratio 10% 10.00 10% 10.00 From remote station e.i.r.p. (dBW) 26.96 24.34 Interfering e.i.r.p. due to FWA antenna side lobe Total e.i.r.p. due to side lobe (dBW) 20.54 15.63 Transmitted peak power (W) 0.2 7.00 0.2 7.00 Ac
47、tive ratio 90% 0.46 90% 0.46 From base station Transmitted power (dBW) 7.46 7.46 Transmitted peak power (W) 0.063 12.00 0.063 12.00 Active ratio 10% 10.00 10% 10.00 From remote stations Transmitted power (dBW) 22.00 22.00 Total transmitted power (dBW) 7.31 7.31 Scattering coefficient (dB) 18.00 18.0
48、0 Interfering power due to scattering at the surface Total scattered e.i.r.p. (dBW) 25.31 25.31 Total interfering e.i.r.p. from a cell (dBW) 19.29 15.19 Receive antenna gain (dBi) 42.70 42.70 Polarization loss (dB) 3.00 3.00 Free space loss (dB) (427 km) 159.55 (749 km) 164.43 Interference power rec
49、eived at SAR Power received (dBW) 139.14 139.92 Noise figure (dB) 4.62 4.62 kT 4.0 1021203.98 4.0 1021203.98 Receiver bandwidth (MHz) 20.0 73.01 20.0 73.01 Noise power (dBW) 126.35 126.35 SAR receiver sensitivity SAR interference threshold (I/N = 6 dB) (dBW) 132.35 132.35 Margin (dB) 6.79 7.57 Maximum number of FWA cells using the same RF channel within the SAR footprint 4.78 5.71 Allowable number of FWA cells Maximum number of FWA cells assuming frequency reuse factor of 4
