1、 Rec. ITU-R M.1454 1 RECOMMENDATION ITU-R M.1454*,*e.i.r.p. DENSITY LIMIT AND OPERATIONAL RESTRICTIONS FOR RLANs*OR OTHER WIRELESS ACCESS TRANSMITTERS IN ORDER TO ENSURE THE PROTECTION OF FEEDER LINKS OF NON-GEOSTATIONARY SYSTEMS IN THE MOBILE-SATELLITE SERVICE IN THE FREQUENCY BAND 5 150-5 250 MHz
2、(Questions ITU-R 212/8, ITU-R 142/9 and ITU-R 284/4) (2000) Rec. ITU-R M.1454 The ITU Radiocommunication Assembly, considering a) that the band 5 150-5 250 MHz is allocated worldwide to the fixed-satellite service (FSS) (Earth-to-space) for use by feeder links of non-geostationary (non-GSO) systems
3、in the MSS on a primary basis without restriction in time as per RR No. S5.447A; b) that the band 5 150-5 250 MHz is also allocated on a worldwide primary basis to the aeronautical radio navigation service (ARNS) under RR Article S5; c) that the band 5 150-5 216 MHz is allocated to the FSS (space-to
4、-Earth) under RR No. S5.447B and under the provisions of RR No. S9.11A for the use of non-GSO MSS feeder links on a worldwide basis; d) that the band 5 150-5 216 MHz is also allocated to the feeder links of the radiodetermination-satellite service (RDSS) (space-to-Earth) subject to RR No. S5.446; e)
5、 that the band 5 150-5 250 MHz is also allocated per RR No. S5.447 to the mobile service on a co-primary basis in 26 countries in Regions 1 and 3, and subject to coordination under RR No. S9.21; f) that administrations are considering the introduction of RLANs in the band 5 150-5 250 MHz on a nation
6、al basis on an unlicensed and un-coordinated basis; g) that administrations have and are considering designating bands other than 5 150-5 250 MHz for RLAN applications in the 5 GHz band; h) that the large-scale deployment of RLAN transmitters and other wireless portable transmitters in the band 5 15
7、0-5 250 MHz may cause unacceptable levels of interference and reduction in satellite capacity to non-GSO MSS satellite receivers operating their feeder-uplinks in this band under RR No. S5.447A and that therefore the medium- to long-term sharing may not be feasible; j) that there is a need to protec
8、t different types of satellites, including those being developed, employing various modulation and access schemes (e.g. narrow-band time division multiple access (TDMA) frequency division multiple access (FDMA) and wideband code division multiple access (CDMA)-FDMA); k) that there is a need to prote
9、ct the current and long-term use of the 5 150-5 250 MHz band by the non-GSO MSS feeder links (Earth-to-space) RR No. S5.447A (e.g. non-regenerative and regenerative satellite systems); l) that there is a need to specify an appropriate e.i.r.p. density limit and operational restrictions for RLAN and
10、other wireless access transmitters in this band in order to protect non-GSO MSS feeder links; _ *This Recommendation was jointly prepared by Radiocommunication Study Groups 4, 8 and 9, and further revisions will also be undertaken jointly. *This Recommendation should be brought to the attention of R
11、adiocommunication Study Group 3. *In this Recommendation, RLAN means radio local area network or any other portable or fixed devices offering local network connectivity (wired LAN (WLAN) or others) (see also Recommendations ITU-R F.1244 and ITU-R M.1450). 2 Rec. ITU-R M.1454 m) that RLANs are intend
12、ed for both indoor and outdoor use; n) that the excess path loss provided by the indoor-to-outdoor propagation environment is beneficial to the sharing between non-GSO MSS and RLANs, recommends 1 that administrations should ensure that the mean* e.i.r.p. density limit of RLAN or other wireless acces
13、s transmitter devices operating in the band 5 150-5 250 MHz should be no greater than 10 mW in any 1 MHz (or equivalently 0.04 mW in any 4 kHz) per transmitter (see Notes 1, 2 and 3); 2 that, in addition, administrations should take measures to ensure that RLAN or other wireless access transmitters
14、are operated indoors in the band 5 150-5 250 MHz; 3 that for protection of MSS feeder links, power flux-density (pfd) limit of total RLAN interference observed at the victim satellite receiver, for satellites using full earth coverage antennas, should be no greater than the pfd levels specified in R
15、ecommendation ITU-R S.1427 Methodology and criterion to assess interference from radio local area network (RLAN) transmitters to non-GSO MSS feeder links in the band 5 150-5 250 MHz. A lower pfd level should be used as a trigger for administrations to take actions to protect non-GSO MSS feeder links
16、 from aggregate RLAN interference (see Notes 4 and 5); 4 that administrations should consider implementation of mitigation techniques to further reduce interference into FSS systems from RLANs (see Note 6). NOTE 1 Annex 1 contains a methodology and parameters that have been used in sharing studies.
17、NOTE 2 For a particular type of RLAN standard (i.e. HIPERLAN type 1) the e.i.r.p. density limit in recommends 1 should apply only in payload transmission. Its overall e.i.r.p. should be limited to 200 W per device. The provisional date of validity of this Note is until 1 January 2003. NOTE 3 For RLA
18、N carriers with less than 1 MHz bandwidth, the e.i.r.p. density should not exceed 0.01 W/Hz over the carrier bandwidth. NOTE 4 On a provisional basis, the pfd trigger level should be 3 dB below that in Recommendation ITU-R S.1427, but further study is required. NOTE 5 The criterion of interference f
19、rom RLANs to non-GSO MSS feeder links in this band is given in Recommen-dation ITU-R S.1426 Aggregate power flux-density limits, at the FSS satellite orbit for radio local area network (RLAN) transmitters operating in the 5 150-5 250 MHz band sharing frequencies with the FSS (RR No. S5.447A). NOTE 6
20、 Two possible mitigation techniques are power control and spectral spreading. ANNEX 1 Methodology and parameters used in sharing studies 1 Introduction In order to protect non-GSO MSS feeder links operating in the band 5 150-5 250 MHz from interference due to RLANs, it is necessary to define operati
21、onal conditions for RLAN use in the band. These conditions are derived from a sharing analysis based on the following considerations: the criterion necessary to protect the non-GSO MSS feeder links; the receive characteristics of the non-GSO MSS satellites; _ *The mean power refers here to the e.i.r
22、.p. radiated during the transmission burst at the power control protocol which corresponds to the highest power, if power control is implemented. Rec. ITU-R M.1454 3 the transmit characteristics of the RLANs; the propagation environment; the number of RLAN devices. It is noted that there is a signif
23、icant uncertainty associated with a number of the above considerations. Analysis of the interference environment, as addressed in the following sections, is based on two non-GSO MSS satellite systems intending to use the 5 150-5 250 MHz FSS allocation for their feeder links, namely, LEO-D and LEO-F.
24、 Other non-GSO MSS satellite systems are also intending to use this frequency allocation for their feeder links. 2 Overall methodology The two satellite systems being considered here both provide global satellite receive antenna coverage for their feeder links. Because of this it is necessary to int
25、egrate across the satellite field of view in order to obtain the average effect of variations in satellite antenna gain, free space path loss and building loss. This approach can be represented by Fig. 1. 1454-01RediiiAiHiSatelliteEarthFIGURE 1Geometry for aggregating the interferenceFIGURE 1/M.1454
26、.D01 = 3 CM Assuming a certain density of RLAN devices, i.e. DR, then the total number of RLAN devices seen by a satellite (assum-ing the devices are evenly distributed over the Earths surface) is given by N = DR AT, where ATis the total surface area seen from the satellite at height H from the Eart
27、hs surface (AT= 2 2eR 1 Re/ (Re+ H ). Since the devices are not equidistant to the satellite, the visible Earths surface is divided into concentric surface strips (as in Fig. 1), so that one can assume that all of the RLAN devices within the i-th surface strip are at the same distance, di, to the sa
28、tellite, and are seen with the same nadir angle, iand the same elevation angle, i. The number of RLAN devices within the i-th strip is given by Ni= Ai (NT/ AT) = Ai DR, where Ai= 2 2eR cos(i) cos(i-1), (where i i-1). 4 Rec. ITU-R M.1454 The aggregate RLAN interference power, I, at the non-GSO satell
29、ite receiver is therefore given by summation of the i-th component Iias below: fiRxiiRiiiiBGcfdprieNII =Ge5Ge5)()/4()()W(20where: (i) : attenuation due to any obstacles between the RLAN device and the satellite, and is assumed to be elevation dependent, 0 i 90 GRx(i) : satellite antenna receive gain
30、 which depends on the nadir angle i, i.e. the angle between the sub-satellite point and the RLAN device Bf= BW/BR: ratio between the victim carrier (wanted) bandwidth and the interfering carrier bandwidth (RLAN transmissions) (if BW BR, otherwise Bf= 1), which determines the amount of interfering po
31、wer falling into the victims “filtered” bandwidth f0: carrier frequency c : speed of light. If the total aggregate interference power at the satellite is taken to be the tolerable interference power, and average values (see Note 1) are used for the parameters identified above, the expression can be
32、rearranged to derive a maximum tolerable number of simultaneously active RLAN devices, NR, as follows: NR= The tolerable interference power at a satellite (dBW) minus the average e.i.r.p. of an RLAN (dBW) minus the average building blockage across the satellites field of view (see Note 2) (dB) minus
33、 the average free space path loss across the satellites field of view (see Note 3) (dB) minus the average satellite antenna off-beam gain across the satellites field of view (dBi) minus the bandwidth correction factor (dB) It is the above relationship that forms the basis of the calculation template
34、 described in this Annex. Other factors associated with the parameters identified above are addressed in the following sections. NOTE 1 Using average values for the relevant parameters on an individual basis gives rise to an error of a few tenths of 1 dB. NOTE 2 The attenuating effect of building bl
35、ockage is represented by a negative dB value. NOTE 3 The attenuating effect of free space path loss is represented by a negative dB value. 3 Non-GSO MSS interference criterion Recommendation ITU-R S.1426 specifies that the criterion appropriate to the assessment of interference from RLAN transmitter
36、s to non-GSO MSS feeder links in the band 5 150-5 250 MHz should be 3% Tsatellite. This can be translated into a tolerable interference power level at the satellite receiver due to an aggregation of power received from all transmitting RLAN devices within the field of view of the satellite. 4 Non-GS
37、O MSS receive characteristics The key characteristics of the non-GSO MSS receiver necessary to determine the sharing environment are: Average satellite receive antenna gain across the field of view (and the associated free space path loss (FSPL) also averaged across the satellite field of view) (see
38、 subsections below). Satellite noise temperature: 400 K (LEO-F), 550 K (LEO-D). Feed loss: 0 dB (see Note 1) (LEO-F), 2.9 dB (LEO-D). Polarization discrimination: a value of 1 dB has been assumed to reflect the fact that RLAN interference is not polarized. Receiver bandwidth: 25 kHz (LEO-F), 1.23 MH
39、z (LEO-D). Rec. ITU-R M.1454 5 NOTE 1 This value is consistent with notified data for LEO-F. Due to the data format specified in the RR there is no means to specify a feed loss. It is therefore implicit in the notified value for the satellite receive system noise temperature. 4.1 LEO-F The satellite
40、s orbit at a height of 10 390 km and each satellite has a 44.8 field of view covering an area on the Earths surface of just over 158 million km2(approximately 31% of the Earths surface corresponding to an area that can include both North America and Europe simultaneously). The LEO-F satellite receiv
41、e antenna pattern is shaped to provide a uniform gain of 10 dBi over the whole of its coverage area (i.e. the visible surface of the Earth). The FSPL from a LEO-F spacecraft to its sub-satellite point is 187.2 dB and to the edge of the field of view is 190.6 dB. Integrating across the whole field of
42、 view gives an average value of 188 dB. The average value of the combined satellite antenna gain and FSPL across the field of view can therefore be considered to be 178 dB. 4.2 LEO-D The satellites orbit at a height of 1 414 km and each satellite has a 109.9 field of view covering an area on the Ear
43、ths surface of just over 46 million km2(approximately 9% of the Earths surface corresponding to an area which can include the whole of North America). The LEO-D receive antenna gain at the sub-satellite point is about 2.5 dBi and the gain at the edge of the field of view is about 4.5 dBi, with a max
44、imum gain of about 6 dBi at 45 satellite off-axis angle. The average antenna gain across the satellite field of view is calculated to be 5.2 dBi. The average value of the combined satellite antenna gain and FSPL across the field of view is calculated to be 168.9 dB. Taking into account the average a
45、ntenna gain of 5.2 dBi, the FSPL across the field of view is therefore 174.1 dB. 5 RLAN transmit characteristics The key characteristics of the RLAN transmitters necessary to determine the sharing environment are: device e.i.r.p.; modulated carrier bandwidth relative to the bandwidth of the satellit
46、e receiver; averaged large scale device activity. In general it is expected that the RLANs operating in this band will be high bit rate, and therefore wideband, devices having a modulated bandwidth wider than the bandwidth of the MSS carriers. It is therefore necessary to define the RLAN radio chara
47、cteristics in terms of e.i.r.p. spectral density. 6 Averaged transmit-to-silent ratio The interference into the non-GSO MSS satellite at any instant is due to the number of RLAN devices that are simultaneously transmitting at that instant. The relationship between the number of devices actually in t
48、he field of view of the satellite and the number of those devices transmitting at any instant can be reflected by an activity factor called the transmit-to-silent ratio. This factor is the result of other factors such as the data rate of the RLAN devices, the amount of information being transmitted,
49、 the percentage of time the devices are switched on and in use. This ratio should take into account the access method used by the RLAN devices. 7 Propagation environment The average FSPL across the satellites field of view has been addressed earlier, in association with the average satellite receive antenna gain. The other key factor insofar as the propagation environment is concerned relates to the additional shielding afforded by buildings and
