1、 STD*CEPT ERC REPORT 97-ENGL i?OOO 232b414 0017086 OBY ERC REPORT 97 European Radiocommunications Committee (ERC) within the European Conference of Postal and Telecommunications Administrations (CEPT) FIXED WIRELESS ACCESS (FWA) SPECTRUM ENGINEERING this point has now also been recognised within the
2、 ITU-R and new Recommendations on such block-based frequency arrangements are under development. INDEX TABLE 1 INTRODUCTION 1 1.1 ADDITIONAL GUIDANCE 1 1.2 TERMINOLOGY 1 FREQUENCY ASSIGNMENT GUIDANCE 1 2 3 FREQUENCY PLANS . 2 3.1 GENERAL 2 3.2.1 General . 3 3.2.2 implementation . 3 4 DEPLOYMENT . 3
3、3.2 TDD ASSIGNMENTS IN BANDS WITH PAIRED SPECTRUM 3 5 EQUIPMENT DESIGN . 4 GLOSSARY AND ABBREVIATIONS 4 STD-CEPT ERC REPORT 97-ENGL 2000 232b1i14 0017089 893 W ERC REPORT 97 Page 1 FiXED WIRELESS ACCESS (FWA) SPECTRUM ENGINEERING sub-bands should not be too small to preserve spectrum efficiency sinc
4、e any guard bands must be accounted for, and wherever possible Co-sharing 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 issu
5、es. plan for traffic growth, and to remember that in general one needs continuous spectrum, although some systems may assist planning in using non-continuous spectrum. take note that, whereas assigning spectrum to several potential operators across a band facilitates comparison of competitive propos
6、als by these operators, it may be equally acceptable to facilitate competition by use of other bands. STDSCEPT ERC REPORT 97-ENGL 2000 2326414 OOL7090 ERC REPORT 97 Page 2 (2.9) (2.10) (2.1 1) (2.12) (2.13) (2.14) take note that if too many operators are assigned spectrum in a band, this may be coun
7、ter-productive in terms of spectrum efficiency. incorporate suitable guard bands to mitigate interference, taking account of the different mix of technologies used, in order to attain an acceptable compromise between performance degradation and necessary protectiodmitigation measures, including guar
8、d bands. specify for FDD systems, a consistent plan for the forward (CS to TS) and reverse (TS to CS) sub-band frequencies. it may be assumed that generally the forward (down) link should be at the higher frequency, similar to accepted usage in most cellular and satellite systems, but exceptional ca
9、ses may dictate the reverse. Account must be taken of the added complications where mixed up/down directions are used. take account that for TDD systems the designation of forward and reverse link directions is no longer possible, and in this case additional interference scenarios need to be conside
10、red. 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 possible approach can be to make appropriate regionaUnationa1 allocations for each FS type from opposite ends of the sub-bands, with the proportion of total band us
11、age for each type perhaps determined by market or other needs; the more conventional approach is to apportion parts of the band for the two FS types on an a priori basis. note that in some cases the spectrum assigned for P-MP applications could in part be used for in-band infrastructure support for
12、the P-MP systems. Where this is done, due account must be taken of the any regulatory or other rules / requirements set for these virtual P-P sub-links. take care when comparing different technologies and their spectrum usage, taking account that there is as yet no definitive guide to comparing spec
13、trum efficiency in a simple manner; consideration needs to be taken of cluster size, consequences of mixed technologies according to these guidelines, quality and grade of service and other factors. use actualhypical parameters, wherever possible, for the calculation of the compatibility factors, ra
14、ther than just the minimum requirement limits from the corresponding ETSUother standards, and take account of the sensitivity of the results to these parameters. Further studies are underway to consider interference between different FWA systems, and their compatibility with systems in other service
15、s. 3 FREQUENCY PLANS 3.1 General For geographically Co-deployed FWA systems, it is necessary to: (3.1) take note that to date FS frequency plans have generally been prepared for P-P telecommunications systems featuring use of FDD, with symmetric channel / sub-band widths which may not be appropriate
16、 for all FWA systems. take account that services with variable asymmetry are often needed, especially for broader band applications. take account that asymmetry may be achieved by: (3.2) (3.3) using asymmetrical TDD. pairing narrower channels in one direction with wider channels in the other using d
17、ifferent orders of modulation in one direction from that used in the other (3.4) take account that having narrower channels in one direction and wider in the other can accommodate traffic efficiently only where this traffic exhibits a fmed asymmetry matching the ratio of the channehb-band widths. Su
18、ch a fixed sub-bands approach is inherently less efficient 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“ up and down links in widely sepa
19、rated bands, for example an up link within one band together with a narrower down link within a lower band to provide fixed asymmetry for certain MWS applications. take note that some MWS systems, especially those derived in concept from broadcast/distribution type systems, may have a bi-directional
20、 rather than unidirectional “interactivity“ channeusub-band. All the guidance provided elsewhere in this document should also apply to this situation. (3.5) (3.6) as opposed to the type offixed asymmetry needed by, for example, video surveillance type systems with narrowband down-link capacity and w
21、ideband upstream capacity. STD*CEPT ERC REPORT 97-ENGLZ000 5326414 0017091 441 ERC REPORT 97 Page 3 (3.7) 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 rang
22、drobustness of the up- and down-links) 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 up- and down-link directions can provide a manner of achievi
23、ng applications having variable, asymmetrical traffic. take account of the need to promote an equitable burden sharing in respect to guard bands. For example, for the first FWA operator in a band it would be considered prudent and fair to ensure that any guard banas are included within the assigned
24、sub-band. note that in general a -1 dB interference criterion may be considered appropriate for interference calculations between FWA systems and with other services, unless otherwise stated within ITU-R Recommendations (3.8) (3.9) (3.10) 3.2 TDD assignments in bands with paired spectrum 3.2.1 Gener
25、al In the case of TDD systems in bands with a conventional channel arrangements for P-P systems, it is necessary to: (3.1 1) (3.12) (3.13) note that where pari of the lower band is assigned to a TDD system then the corresponding pari of the upper band should also be assigned to TDD systems, and vice
26、 versa. ensure that the TDD assignment fully respects the homogeneous pattern of frequency slots as stipulated for the FDD channel raster. note that for fied asymmetrical applications based on FDD and operated with channel arrangements previously designed to be suitable for symmetrical FDD use (havi
27、ng 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 of the upper sub-band. The “surplus“ unpaired Im-nl channels could be usefully assigned to TDD services (including any necessary guard band allowance) take account
28、 that in (3.13), and notwithstanding the availability of the m+n channels for fixed asymmetric FDD services, 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 Sec. 2 are ob
29、served. (3.14) (3.15) 3.2.2 Implementation In the case of TDD systems in bands with a conventional channel arrangement for P-P systems, it is necessary to: (3.16) (3.17) (3.18) note that there may be particular spectrum engineering issues (such as constraints on transmitter masks and the need for gu
30、ard bands) associated with operating TDD systems in a band already accommodating FDD systems. note that additional parameters may have to be considered in coexistence planning of TDD systems. note that it has been asserted that the issue of verifying TDD compatibility with existing FDD systems is a
31、larger task than checking compatibility of a FDD system with existing FDD system (with the same duplex spacing). 4 DEPLOYMENT For deployment of FWA systems, it is necessary to: (4.1) (4.2) consider the benefits of encouraging co-operation between operators in order to minimise interference and conse
32、quent economic impact, and to seek to use the spectrum efficiently. note that where central stations belonging to different operators in the same geographical area are proposed to be sited relatively close, it may be preferable to co-locate these stations to minimise and better define the nearlfar e
33、ffect. This may be especially appropriate in those cases where the directions of the forward and reverse frequency sub-bands are consistent between operators. note that where considering compatibility with P-P and other P-Mp systems, CS and TS installations should wherever possible minimise P-MP ant
34、enna heights and judiciously use antenna angular discrimination, including nulls in the polar pattern, as an additional mitigation measure and to minimise guard band requirements and assist with co-existence. (4.3) * long term; this noise floor degradation is equivalent to 4 dE3 UN. STDoCEPT ERC REP
35、ORT 97-ENGL 2000 2326434 0037092 388 ERC REPORT 97 Page 4 (4.4) (4.5) (4.6) (4.7) (4.8) (4.9) (4.10) (4.1 1) note that similarly where considering Co-existence between Co-frequency operators across service - area boundaries, CS and TS installations should wherever possible minimise P-MP antenna heig
36、hts and judiciously use antenna angular discrimination, including nulls in the polar pattern, as an additional mitigation measure. Note that polarisation may be used as a system propagation discriminate, although less usefully at lower frequencies. This can be useful to mitigate interference. Note t
37、hat in some case terrain features can usefully be exploited to minimise interference, both intro- and inter- service. Note that where considering compatibility with FSS systems, account should be taken of ITU-R Recommendations where available, including any guidelines covering the FSS and P-MP anten
38、na 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 both the ITU-R Radio Regs. and also the ERC Report on necessary s
39、eparation distances (ref. ERC XX-Y), taking account the aggregation effect of P-NLP systems as appropriate. note that where considering compatibility with radiolocationnavigation systems in adjacent bands or in neighbouring countries, account should be taken of existing relevant ITU-R Recommendation
40、s. For radiolocation I navigation systems that may be in-band, account should be taken of ITU-R Recommendations where available, including any specific methodology needed to ensure compatibility for the particular technology and radar typds. Furthermore ERC Report 05 1 may be found instructive in th
41、is regard. take account of the need to plan and deploy CS and TS antennas which are no less directional than is required for the intended intra-system deployment and which are sited no higher than is necessary to ensure adequate performance margin. implement any necessary synchronisation andlor othe
42、r measures to accommodate mixed technologies are implemented as appropriate. 5 EQUIPMENT DESIGN For FWA systems, it is necessary to: (5.1) (5.2) (5.3) take account of the importance of minimising spurious and out of band emissions through appropriate equipment design. take account of the importance
43、of maximising receive selectivity (and noting that ETSUother standards may be insufficiently detaildstringent in all cases). take account of the desirability, consistent with compliance with the required level of quality and grade of service, of incorporating measures to ensure adequate transmit pow
44、er control, dynamic channeifrequency and/or other adaptive measures to enhance compatibility. GLOSSARY AND ABBREVIATIONS cs DRRS FDD Forward link FS FWA MWS Multipoint P-P P-MP Reverse link RPE TDD TS Central (base) station Digital Radio Relay System Frequency Division Duplex CS to TS path, also termed down-link Fixed service (ITU-R service category) Fixed wireless access Multimedia wireless systems Embraces all P-MP and MP-MP FS systems Point - to - point Point - to - multipoint TS to CS path, also termed up-link Radiation Pattern Envelope Time Division Duplex Terminal (end user) station
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