1、 Rec. ITU-R F.1519 1 RECOMMENDATION ITU-R F. 15 19 Guidance on frequency arrangements based on frequency blocks for systems in the fixed service* (Questions ITU-R 2 15/8, ITU-R 125/9, ITU-R 136/9, -R 108/9 and ITU-R 22919) (200 1) The Radiocommunication Assembly, considering a) that frequency band p
2、lans have continued to be developed over many years for point-to- point (P-P) digital radio-relay systems and which exclusively feature conventional channelling arrangements; b) multipoint (MP-MP) systems; that new generations of systems include P-P, point-to-multipoint (P-MP) and multipoint-to- c)
3、deployments; d) administrations; that systems may feature frequency reuse in geographically contiguous, cellular-type that a frequency arrangement based on frequency blocks is already in use by some e) arrangements within the area, rather than by link-by-link frequency assignment basis; that fixed s
4、ervice systems may be deployed on an area basis and utilize flexible frequency f) that systems may feature, inter alia, dynamic frequency control; variable traffic (e.g. temporal, fixed asymmetric, symmetric or adaptive); integral in-band, network infrastructure (backhaul); variable or dynamic modul
5、ation arrangements; g) that there are a number of important factors that need to be considered in developing such sub-banding arrangements, including inter alia the choice of appropriate width for the sub-band(s)/block(s) (see Annex 2), recommends 1 frequency blocks in the fixed service (FS) bands,
6、as shown in Annex 1; that administrations consider possible use of frequency arrangements based on contiguous 2 plans are applied (see Note 1). NOTE 1 -Two examples of such arrangements are provided in Annex 3 of this Recommendation and Recommendation ITU-R F.1488. that the material in Annex 2 may b
7、e considered as guidance where frequency block-based * This Recommendation should be called to the attention of Radiocommunication Study Group 8. 39 2 .II -_ I Rec. ITU-R F.1519 ANNEX 1 Illustration of fixed service spectrum terminology (see also Recommendation ITU-R F.1399) FiGLJRE 1 Frequency arra
8、ngement using sub-bands, frequency blocks and their relationship to channelization P Frequency band Sub-bands A Sub-bands B Frequency blocks Channels Slots . . .- spectrum arrangement Note I - Guardbands can occur at any kequency edge m this diagram 1519-01 ANNEX 2 Guidance material in connection wi
9、th the preparation and use of fmed service frequency arrangements based on sub-bands and contiguous frequency blocks, especially for multipoint systems 1 Introduction The material presented here primarily addresses considerations on P-MP and MP-MP systems as used for fixed wireless access (FWA), but
10、 may be more generally applicable to FS systems. These systems generally feature air-side concentration and contiguous cellular (area) deployment arrangements, and it is necessary to take account of the several important similarities with, and differences between, these systems and both conventional
11、 P-P systems on the one hand and cellular mobile systems on the other hand. 40 Rec. ITU-R F.1519 3 Specific bands are not discussed in detail in this Annex, and the material is qualitative rather than quantitative. However, an existing large scale FWA application example is described in Annex 3. Fre
12、quency arrangements based on contiguous sub-bandsblocks can facilitate: - - simpler administration of frequency allocations and the accommodation of simpler, efficient planning of the spectrum; markethechnology evolution; faster deployment of new services due to reduced administrative burdens; equit
13、able treatment of several operators in a region; the encouragement of innovative technologies in a less prescriptive and more flexible regulatory regime (multiple standards, different air interface protocols, technologies, etc.) than is the case for conventional channelization arrangements. - - - Ma
14、ny of these systems are appropriate for the delivery of Internet Protocol (IP) - or asynchronous transfer mode (ATM) - based communications traffic. 1.1 Guidance on coordination and related issues Guidance material has been identified as an important requirement for effective use of available spectr
15、um, including intra-system, inter-system, inter-service issues. In due course this will contain information on interference calculation methodology, systems parameters, reference model results for model scenarios, and some information on interpretation (including sensitivities, identification of sim
16、plifjmg assumptions and other factors which may need considering). Sections 2 to 5 present useful considerations on spectrum engineering issues, including frequency plans for geographical Co-deployment of FWA systems. 2 Frequency allocation guidance For Co-deployment of FWA systems in the same geogr
17、aphical area, it is necessary to: - take account of regional or other recommendations on preferred frequency bands for FWA systems; allocate sufficient spectrum to enable operators to be competitive; frequency blocks should not be too small to preserve spectrum efficiency since any guardbands must b
18、e included, and wherever possible co-sharingl should be encouraged; - - take note that generally best spectrum efficiency is obtained by use of contiguous rather than non-contiguous arrangements, taking into consideration systems design and necessary frequency separation issues; plan for traffic gro
19、wth, and to remember that in general one needs contiguous spectrum, although some systems may assist planning in using non-contiguous spectrum; - 1 Equitable, efficient apportionment of the band between operators within the same regiodarea, not CO- frequency sharing normally. 41 4 Rec. ITU-R F.1519
20、 take note that, whereas assigning spectrum to several potential operators across a band facilitates comparison of competitive schemes by these operators, it may be equally acceptable to facilitate competition by use of different bands; - take note that if too many operators are assigned spectrum i
21、n a band, this may be counter-productive in terms of spectrum efficiency; - incorporate suitable guardbands to mitigate interference, taking account of the different mix of technologies used, in order to attain an acceptable compromise between performance degradation and necessary protectionmitigati
22、on measures, including guardbands; - specify for frequency division duplex (FDD) systems, a consistent plan for the forward central station (CS) to terminal station (TS) and reverse (TS to CS) sub-band frequencies. It may be assumed that generally the forward (down) link should be at the higher freq
23、uency, similar to accepted usage in most cellular and satellite systems, but exceptional cases may dictate the reverse. Account must be taken of the added complications where mixed up/down directions are used; - take account that for time division duplex (TDD) systems the designation of forward and
24、reverse link directions is no longer possible, and in this case additional interference scenarios need to be considered; - take account that when considering accommodation of P-MP with P-P systems in the same band, e.g. for the 24.5-26.5 GHz band, one attractive approach can be to make appropriate r
25、egionalnational allocations for each FS type from opposite ends of the band, with the proportion of total band usage for each type perhaps determined by market or other needs; - take care when comparing different technologies and their spectrum usage, taking account that there is as yet no definitiv
26、e guide to comparing spectrum efficiency in a simple manner; consideration needs to be taken of cluster size, consequences of mixed technologies according to these guidelines, quality, grade of service and other factors; - use actual/typical parameters, wherever possible, for the calculation of the
27、compatibility factors, rather than just the minimum requirement limits from the corresponding standards, and take account of the sensitivity of the results to these parameters. 3 Frequency plans 3.1 General For Co-deployed systems, it is necessary to: - take note that to date FS ffequency plans have
28、 generally been prepared for P-P telecom- munications systems featuring use of FDD, with symmetric channel block widths which may not be appropriate for all FWA systems; 42 Rec. ITU-R F.1519 5 - take account that services with variable asymmetry are often needed, especially for broader band applicat
29、ions2; - take account that asymmetry may be achieved by: - - - using multi-carrier modulation; - pairing narrower channels in one direction with wider channels in the other; using different orders of modulation in one direction from that used in the other; using asymmetrical TDD within the paired sp
30、ectrum; - take account that having narrower channels in one direction and wider in the other can accommodate traffic efficiently only where this traffic exhibits a fixed asymmetry matching the ratio of the channel/frequency block widths. Such a fixed frequency block approach is inherently less effic
31、ient for variably asymmetric traffic which may exhibit only over time a general bias in the traffic in favour of the channel direction enjoying the wider band; - take note that it is possible in some cases to pair uplinks and downlinks in widely separated bands, for example an uplink within one band
32、 together with a narrower downlink within a lower band to provide faed asymmetry for certain wideband applications; - take note that some multimedia wireless systems, especially those derived in concept from broadcast/distribution type systems, may have a bidirectional rather than unidirectional int
33、eractivity channelhlock. All the guidance provided elsewhere in this Annex should apply to this situation; - take account that different orders of modulation may be used for the two traffic directions to offer a limited degree of asymmetry (and could result in different characteristics in terms of r
34、angeh-obustness of the uplinks and downlinks) and that this may permit some variable asymmetry if the equipment can dynamically adapt the modulation scheme independently in the two directions; - take account that TDD with variable time allocated to uplink and downlink directions can provide a manner
35、 of achieving applications having variable, asymmetrical traffic; - take account of the need to promote an equitable burden sharing in respect to guardbands. For example, for the first FWA operator in a band it would be prudent and fair to ensure that any guardband(s) is (are) included within the as
36、signed frequency block or sub-band; - note that in general an interference margin (criterion) of -1 dE3 (IN-6 dB) might be considered appropriate in interference calculations between FWA systems and, unless stated otherwise in ITU-R Recommendations, with other services. 2 As opposed to the type of f
37、med asymmetry needed by, for example, video surveillance type systems with wideband downlink capacity and narrow upstream capacity. 43 6 Rec. ITU-R F.1519 3.2 TDD assignments in bands with paired spectrum 3.2.1 General In the case of TDD systems in bands with a frequency plan based on standard paire
38、d spectrum, it is necessary to: - ensure that the TDD assignment respects the channel or frequency block plans for the FDD assignmentraster; note that where part of the lower band is assigned to a TDD system then the corresponding part of the upper band should also be assigned to TDD, and vice versa
39、 note that for fixed asymmetrical applications based on FDD and operated with channel arrangements previously designed to be suitable for symmetrical FDD use (having equal channel widths in both upper and lower bands), it is possible for n channels of the lower sub-band to be paired with m channels
40、 of the upper frequency block or sub-band. The surplus unpaired (rn - nl channels could be usefully assigned to TDD services (including any necessary guardband allowance); - take account that in the latter case, and notwithstanding the availability of the rn + n channels for fixed asymmetric FDD ser
41、vices, it is possible that these channels could be assigned to one or more TDD channels; take into account the possibility of using the centre gap for TDD, provided the requirements of Section 2 are observed. - - - 3.2.2 Implementation In the case of TDD systems in bands with a frequency plan based
42、on standard paired spectrum, it is necessary to: - note that there may be particular spectrum engineering issues (such as constraints on transmitter masks and the need for guardbands) associated with operating TDD systems in a band already accommodating FDD systems; take note that polarization may b
43、e used as a system propagation discriminant, although less usefully at lower frequencies. This can be useful to mitigate interference; note that additional parameters may be needed for the coexistence planning of TDD systems; note that it has been asserted that the issue of verifjmg TDD compatibilit
44、y with existing FDD systems is a larger task than checking compatibility of a FDD system with existing FDD system (with the same duplex spacing). But once compatibility in the lower (or upper) blockhub-band has been demonstrated, compatibility in the other blocksub-band can be inferred. - - - 4 Depl
45、oyment For Co-deployment of FWA systems in the same geographical area, it is necessary to: - consider the benefits of encouraging cooperation between operators in order to minimize interference and consequent economic impact, and to seek to use the spectrum efficiently; 44 .- Rec. ITU-R F.1519 7 - n
46、ote that where CSs belonging to different operators are proposed to be sited relatively close, it may be preferable to Co-locate these stations to minimize and better define the near/far effect. This may be especially appropriate in those cases where the directions of the forward and reverse eequenc
47、y blocks are mixed or not designated, e.g. where different duplex technologieslspacings are mixed; - note that where considering compatibility with P-P systems, CS and TS installations should wherever possible minimize P-MP antenna heights and judiciously use antenna angular discrimination, includin
48、g nulls in the polar pattern, as additional mitigation and to minimize guardbands; - note that where considering compatibility with fixed-satellite service systems, account should be taken of ITU-R Recommendations where available, including any guidelines covering the fixed-satellite service and P-M
49、P antenna heights, separation distances, allowable range of elevation view angles, additional diffraction or other mitigation measures; - note that where considering compatibility with the radioastronomy service, it is important to comply with the Radio Regulations, taking account of the aggregation effect of P-MP systems; - note that where considering compatibility with radiodetermination systems in adjacent bands or in neighbouring countries, account should be taken of existing relevant ITU-R Recommendations. For radiodetermination systems that may be in-band, account should be t
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