1、 Recommendation ITU-R M.1652-1(05/2011)Dynamic frequency selectionin wireless access systems includingradio local area networks for the purposeof protecting the radiodeterminationservice in the 5 GHz bandM SeriesMobile, radiodetermination, amateurand related satellite servicesii Rec. ITU-R M.1652-1
2、Foreword The role of the Radiocommunication Sector is 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 Recomme
3、ndations are adopted. The regulatory and policy functions 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 t
4、he Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced 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 C
5、ommon Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-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 televisi
6、on BS Broadcasting service (sound) BT Broadcasting service (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 Frequen
7、cy sharing and coordination between fixed-satellite and 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 i
8、n Resolution ITU-R 1. Electronic Publication Geneva, 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 M.1652-1 1 RECOMMENDATION ITU-R M.1652-1 Dynamic frequency selection*in wireless access system
9、s including radio local area networks for the purpose of protecting the radiodetermination service in the 5 GHz band (Questions ITU-R 212/5) (2003-2011) Scope This Recommendation provides requirements of dynamic frequency selection (DFS) as a mitigation technique to be implemented in wireless access
10、 systems (WAS) including radio local area networks (RLANs) for the purpose of facilitating sharing with the radiodetermination service in the 5 GHz band. Annex 1 specifies the detection, operational and response requirements. Other Annexes address the methodologies and provide information which can
11、be used by administrations when conducting sharing studies between radars and WAS including RLANs. The ITU Radiocommunication Assembly, considering a) that harmonized frequencies in the bands 5 150-5 350 MHz and 5 470-5 725 MHz for the mobile service would facilitate the introduction of wireless acc
12、ess systems (WAS) including radio local area networks (RLANs); b) that there is a need to protect the radars in the radiodetermination service operating in the bands 5 250-5 350 and 5 470-5 725 MHz; c) that in many administrations, the ground-based meteorological radars are extensively deployed and
13、support critical weather services; d) that procedures and methodologies to analyse compatibility between radars and systems in other services are provided in Recommendation ITU-R M.1461; e) that representative technical and operational characteristics of radiolocation, radionavigation and meteorolog
14、ical radars are provided in Recommendation ITU-R M.1638, including maritime radionavigation radars in, inter alia, the band 5 470-5 650 MHz; f) that WAS including RLANs as described in Recommendation ITU-R M.1450 are capable of operating both indoor and outdoor; g) Report ITU-R M.2034 which addresse
15、s the impact of certain detection requirements of the DFS on the performance of WAS, *Dynamic frequency selection is a general term used in this Recommendation to describe mitigation techniques that allow, amongst others, detection and avoidance of co-channel interference with respect to radar syste
16、ms. 2 Rec. ITU-R M.1652-1 recognizing a) that the band 5 250-5 350 MHz is allocated to the radiolocation service on a primary basis; that the band 5 250-5 350 MHz is also allocated to the Earth exploration-satellite service (EESS) (active) on a primary basis; b) that the band 5 470-5 650 MHz is allo
17、cated to the maritime radionavigation service on a primary basis; c) that the band 5 350-5 650 MHz is allocated to the radiolocation service on a secondary basis; d) that ground-based radars used for meteorological purposes are authorized to operate in the band 5 600-5 650 MHz on a basis of equality
18、 with stations in the maritime radionavigation service; e) that the band 5 650-5 725 MHz is allocated to the radiolocation service on a primary basis; f) that administrations may take account of detailed information on actual radar deployment when developing guidance for the use of DFS in WAS in con
19、sultation with potentially affected administrations, noting a) that the high RF power level and the receiver sensitivity of radars in the radiodetermination service in conjunction with the expected high density of WAS including RLANs would, in general, not enable compatible operation of WAS includin
20、g RLANs and radars on a co-channel basis in the absence of mitigation techniques; b) that WAS including RLANs could be deployed in these bands as licence-exempt devices, consequently making control of their deployment density more difficult; c) that there are various standards for RLAN specification
21、s; d) that administrations may consider procedures to confirm the ability of interference avoidance mechanisms to function correctly in the presence of the radar systems deployed in this band, recommends 1 that, in order to facilitate sharing with radars, mitigation techniques as described in Annex
22、1 be implemented by WAS, including RLANs in the bands used by radars at 5 GHz; 2 that the mitigation techniques comply with the detection, operational and response requirements as given in 2 of Annex 1; 3 that the methodologies given in Annexes 4, 5, 6 and 7 can be used by administrations when condu
23、cting sharing studies between radars and WAS including RLANs. NOTE 1 Further information on the results of studies on the requirements stated in recommends 2 is given in Report ITU-R M.2115, which provides information on the procedures in place in various administrations and/or regional groups to te
24、st compliance with DFS requirements. Rec. ITU-R M.1652-1 3 Annex 1 The use of DFS in WAS including RLANs for the purpose of protecting the radiodetermination service in the 5 GHz band 1 Introduction 1.1 DFS In relation to studies on the feasibility of sharing between the mobile service for WAS1and t
25、he radiodetermination service in the frequency bands 5 250-5 350 and 5 470-5 725 MHz, link budget calculations have shown that interference mitigation techniques are required to enable sharing of WAS with other services such as radar systems. This Annex describes the interference mitigation techniqu
26、e(s) DFS2as specified in the 5 GHz RLAN standards, with performance calculations based on typical implementations. WAS and radars operating in the 5 GHz band will interfere when operating at the same frequencies and within range of each other. DFS has then been envisaged to: ensure a spread of the l
27、oading across the available spectrum of the WAS under the field of view of a satellite to reduce the aggregate emission levels at the satellites of the FSS (feeder links) and EESS (active) from WAS; avoid co-channel operation with other systems, notably radar systems. Extension of the use of DFS as
28、described herein allows WAS to avoid interfering with the radiodetermination service. The general principle applied is that WAS should detect interference and identify radar interferers and shall not use those frequencies used by the radar. 1.2 Objective of the use of DFS with respect to radars The
29、objective of using DFS in WAS is to provide adequate protection to radars in the 5 GHz band. This is achieved by avoiding the use of, or vacating, a channel identified as being occupied by radar equipment based on detection of radar signals. For the purpose of this Annex, a discussion of radiodeterm
30、ination systems in the 5 GHz range utilized in determining DFS characteristics can be found in Annex 3. The implementation of radar detection mechanisms and procedures used by WAS are outside the scope of this Annex. The main reasons for this are that: WAS design affects implementation; practical ex
31、perience may lead to innovative and more efficient means than can be formulated today; different manufacturers may make different implementation choices to achieve the lowest cost for a given level of performance; therefore only performance criteria rather than specifications for a particular mechan
32、ism should be given in regulatory documents. 1Throughout this Recommendation the term “WAS” denotes “wireless access systems including RLANs”. 2The DFS feature was specified in the 5 GHz RLAN standards initially in order to mitigate interference among uncoordinated RLAN clusters, and to provide opti
33、mized spectral efficiency for high-capacity, high bit-rate data transmission. 4 Rec. ITU-R M.1652-1 2 DFS performance requirements The DFS performance requirement is stated in terms of response to detection of an interference signal. 5 GHz WAS should meet the following detection and response require
34、ments. Procedures for compliance verification should be incorporated in relevant industry standards for RLANs. 2.1 Detection requirements The DFS mechanism should be able to detect interference signals above a minimum DFS detection threshold of 62 dBm for devices with a maximum e.i.r.p. of 48 dBi) H
35、igh-gain (22 48 dBi) Angular interval (degrees) Gain (dBi) 0 to MMto RRto BBto 180 G 4 104(10G/10) 20.75 G 7 29 25 log () 13 TABLE 9 Equations for high-gain antennas (22 G 48 dBi) Angular interval (degrees) Gain (dBi) 0 to MMto RRto BBto 180 G 4 104(10G/10) 20.75 G 7 53 (G/2) 25 log () 11 G/2 TABLE
36、10 Equations for medium-gain antennas (10 G 22 dBi) Angular interval (degrees) Gain (dBi) 0 to MMto RRto BBto 180 G 4 104(10G/10) 20.75 G 7 53 (G/2) 25 log () 0 16 Rec. ITU-R M.1652-1 Appendix 2 to Annex 6 WAS antenna patterns The WAS antenna pattern in the azimuth orientations is omnidirectional. T
37、he WAS antenna pattern in elevation orientations was determined by examination of WAS antenna patterns. The pattern used is described in Table 11. Note that use of directional WAS antennas, given the same e.i.r.p., may result in less interference to the radiodetermination receiver, but could result
38、in significantly higher interference levels to the WAS receiver if main beam-to-main beam coupling were to occur. TABLE 11 WAS elevation antenna pattern In order for most devices to radiate with 1 W e.i.r.p. an antenna gain of 6 dBi will typically be required. For this pattern the following descript
39、ion is given in accordance with Recommendation ITU-R F.1336: )(),(max)(21= GGG230112)(= GG+= kGG5.13021,maxlog1012)(01.03106.107G=where: G() : antenna gain (dBi) : elevation angle (degrees) k = 0.5 G0= 6 dBi. Elevation angle, (degrees) Gain (dBi) 45 90 4 35 45 30 35 0 15 0 1 30 15 460 30 6 90 60 5Re
40、c. ITU-R M.1652-1 17 Annex 7 Interference assessment results analysis and recommendation on DFS threshold values A summary of the results of simulations using the methodologies detailed in Annexes 5 and 6, for simulating respectively static interference from one WAS device and aggregate interference
41、 from a deployment of WAS into a victim radar receiver, is presented for the relevant 5 GHz radars. Table 12 shows the values derived from the calculations in Annex 5 for the case of interference from a single WAS. TABLE 12 Values derived from the calculations in Annex 5 Table 13 shows a summary of
42、required protection threshold levels resulting from the aggregate interference modelling calculations. TABLE 13 Required protection threshold levels Radar type Simulation scenario DFS threshold for protection (TDFS) (Note 1) Rotating radars A, C, E, F, G, H, I, J Radars P and Q Standard per Annex 6
43、52 dBm and operational considerations utilized by radar systems Radar I Annex 6 but radar antenna height between 500 and 1 000 m 62 dBm Radar S Standard per Annex 6 See Note 2 Radar K Standard per Annex 6 67 dBm Annex 6 but half population density 64 dBm Annex 6 but all devices 50 mW 62 dBm NOTE 1 A
44、ssuming a receive antenna gain normalized to 0 dBi for WAS. NOTE 2 The sharing situation between this radar and WAS is extremely difficult. Initial calculations based on the baseline results show that a required DFS detection threshold of values below the operating noise floor of WAS devices would b
45、e required. Based on discussions, it was found that these systems were limited to military aircraft only. It was agreed to not consider this case when developing a detection threshold requirement. Radar per Annex 5 Link budget analysis per Annex 5 62 dBm for 1 W device 55 dBm for 0.2 W device 52 dBm
46、 for 0.1 W device 18 Rec. ITU-R M.1652-1 Notes on parameters and methodologies used The impact of the parameters and methodology variations can be summarized as follows: a) A reduction in active device density by half results in a 3 dB increase in TDFS. Similarly, doubling the active device density
47、results in a 3 dB decrease in TDFS. b) The transmit power of a single interferer in the link budget calculation has a direct dB for dB impact on the required protection threshold. In the aggregate analysis, the impact depends on the distribution of power levels used in the simulation. c) In most cases the interaction of variables in the aggregate modelling is not intuitive and therefore simple conclusions cannot be drawn from changes in a single variable.
