1、 Rep. ITU-R F.2060 1 REPORT ITU-R F.2060 Fixed service use in the IMT-2000 transport network (Question ITU-R 221/9) (2005) 1 Introduction Recently, as traffic demands for mobile communications represented by IMT-2000 are increasing, fixed service (FS) use in the transport network in the mobile infra
2、structure is becoming an important application. The IMT-2000 transport network supports the connections between the different base stations of the network, as well as the connections of one base station to other stations of the IMT-2000 infrastructure, in order to interconnect the IMT-2000 network t
3、o other telecommunication networks. 2 Scope The aim of this Report is to show how the FS could be used at different hierarchical levels of the transport network of IMT-2000, in order to ensure the connections between base stations, and between base stations and higher-level stations within this tran
4、sport network. This Report provides an example of the use of the FS in the transport network of IMT-2000. FS use is necessary to support the operation of IMT-2000 networks in the transport network. Depending on the evolution of IMT-2000 and the required transmission capacities at different levels of
5、 the transport network, different FS frequency bands could be employed. This Report gives possible structures of IMT-2000 transport networks including the outline of the needs of 3G cellular systems (IMT-2000). The Report also examines the possible use of already allocated FS spectrum. Regardless of
6、 the transmission network capacity, the choice of frequency bands depends on the local situation of the various countries (existing deployment of the frequency bands, number of mobile (IMT-2000) operators, etc.). 3 References The reader will find additional guidance in the references listed below: R
7、ecommendation ITU-R F.746: Radio-frequency arrangements for fixed service systems Recommendation ITU-R F.758: Considerations in the development of criteria for sharing between the terrestrial fixed service and other services Recommendation ITU-R F.1245: Mathematical model of average radiation patter
8、ns for line-of-sight point-to-point radio-relay system antennas for use in certain coordination studies and interference assessment in the frequency range from 1 to about 70 GHz Recommendation ITU-R F.1399: Vocabulary of terms for wireless access Recommendation ITU-R M.1224: Vocabulary of terms for
9、International Mobile Telecommunications-2000 (IMT-2000) 2 Rep. ITU-R F.2060 Recommendation ITU-R M.1390: Methodology for the calculation of IMT-2000 terrestrial spectrum requirements Recommendation ITU-R P.530: Propagation data and prediction methods required for the design of terrestrial line-of-si
10、ght systems Recommendation ITU-R P.676: Attenuation by atmospheric gases Recommendation ITU-R P.837: Characteristics of precipitation for propagation modelling Handbook on Deployment of IMT-2000 systems: http:/www.itu.int/itudoc/qs/imt2000/84207.html ECC Report 003: Fixed service in Europe current u
11、se and future trends post-2002 4 List of acronyms 2G 2nd Generation Mobile System 3G 3rd Generation Mobile System (IMT-2000) AAL ATM adaptation layer (i.e. AAL 0, AAL 2, AAL 5,.) ATM Asynchronous transfer mode ATPC Automatic transmission power control BER Bit error ratio BS Base station BSC Base sta
12、tion controller BTS Base transceiver station CBD Central business district CBR Constant bit rate CCDP Co-channel dual polarized CS Central station (or Central base station) C/I Carrier-to-interference ratio DSL Digital subscriber line FDCA Fast dynamic capacity allocation FL Feeder loss FM Fade marg
13、in FS Fixed dervice FSK Frequency-shift keying IMT-2000 International Mobile Telecommunication System-2000 IP Internet protocol LOS Line-of-sight MM Multimedia MSC Mobile switching centre (2G or 3G) OBQ Offered bit quantity PDH Plesiosynchronous digital hierarchy Rep. ITU-R F.2060 3 P-P Point-to-poi
14、nt P-MP Point-to-multipoint POP Point of presence (of a fibre optical operator) PSK Phase shift keying QAM Quadrature amplitude modulation RF Radio frequency RPE Radiation pattern envelope (of an antenna) SAP Service access point SDH Synchronous digital hierarchy STM Synchronous transfer mode Sub-CS
15、 Sub-central station (or sub-central base station) XPD Cross-polarization discrimination XPIC Crosspolar interference canceller 5 Structure of IMT-2000 transport network 5.1 Example of the hierarchical levels in IMT-2000 transport network The transport network of IMT-2000 consists of different trans
16、port hierarchical levels to support the transmission interfaces of the IMT-2000 network. In principle, the IMT-2000 network hierarchy consists of different hierarchical levels and network nodes. In this Report these nodes are defined as follows, using the terms given in Recommendations ITU-R M.1224
17、and ITU-R F.1399: MSC: mobile switching centres in the IMT-2000 network organizing the overall traffic flow as well as representing the interconnection to the fixed network; SAP: service access point The basic node within the network with switching functions for the subordinate base stations in the
18、IMT-2000; CS: central station (or central base station) A base station where several or more links are converging in P-P or P-MP mode to connect the surrounding base stations; Sub-CS; sub-central station (or sub-central base station) A base station having intermediate function of traffic transport b
19、etween CS and other base stations, and BS: base station, except for those categorized as the above nodes, BS is a node forming an end of the transport network. The general topology of the transport network in IMT-2000 is given in Fig. 1. The hierarchical levels each identifying the connection links
20、used for several hierarchy in the transport network will be considered in the later sections from the viewpoint of use of the fixed service. 4 Rep. ITU-R F.2060 FIGURE 1 Example of hierarchical levels of the IMT-2000 transport networks In the start up phase, most of the connections are likely to be
21、provided by fixed wireless links. As IMT-2000 networks mature other high capacity connections (i.e. fibre optics) may be substituted. Examples of detailed topology of the IMT-2000 transport network hierarchical levels are described in Annex 1. 5.2 Capacity and hop length requirements in the transpor
22、t network A large variety of interconnections in terms of hop length and transport capacity are necessary to operate the IMT-2000 networks. In particular the transport capacity depends on the users needs for mobile telecommunication services for which Recommendation ITU-R M.1390 provides a methodolo
23、gy for their estimation. In Table 1 the expected transport capacities are given for the interconnections between the different layers. Detailed consideration on how to derive such expectations are provided in Annex 2. The evolution of the networks has been considered in that respect, expected capaci
24、ties are given for both short term and long term. Table 2 illustrates a variety of hop lengths in different operational environments (rural and urban) of the cellular network. Information on capacity and hop length leads to the media which would best serve the requirements of the different layers of
25、 the IMT-2000 networks. TABLE 1 Expected link capacities for interconnecting the different hierarchical levels of IMT-2000 networks Hierarchical level(1) Short term Long term Hierarchical level No. 0 4-8 Mbit/s 4-34 Mbit/s Hierarchical level No. 1 8-34 Mbit/s 8 Mbit/s STM-1 Hierarchical level No. 2
26、34 Mbit/s STM-1 n 34 Mbit/s n STM-1 Hierarchical level No. 3 34 Mbit/s 2 STM-1 n STM-1 n STM 16 Hierarchical level No. 4 n STM-1 n STM1 n STM-16 (1) See Fig. 1 for definitions Rep. ITU-R F.2060 5 TABLE 2 Hop lengths for interconnecting the different hierarchical levels of IMT-2000 networks Hierarchi
27、cal level(1) Urban (km) Rural (km) Hierarchical level No. 0 0.5-1.4 5-16 Hierarchical level No. 1 0.5-2.5 5-20 Hierarchical level No. 2 2.0-5.0 5.0-20 Hierarchical level No. 3 5-10 5.0-50 Hierarchical level No. 4 0-20 0-20 (1) See Fig. 1 for definitions 5.3 Transportation media used in the transport
28、 network Not all of these connections within the IMT-2000 network are necessarily radio equipment, depending on: the network layer under consideration; technical facilities of a certain network operator; and economic framework. A certain percentage of the interconnections within the IMT-2000 network
29、s may be operated on cables (e.g. DSL systems) or fibre optics. The different network levels have different requirements concerning telecommunication capacity and availability targets due to their function within the network. These levels will build a five hierarchical levels transport network, whic
30、h may be accommodated by different transport media: hierarchical levels No. 0, No. 1 and No. 2 (connections between BSs, access from BS to Sub-CS and/or CS) operated mainly by P-P and/or P-MP fixed wireless links or cable; hierarchical level No. 3 (interconnection of CS and SAP) operated by P-P fixe
31、d wireless links and fibre optics; hierarchical level No. 4 (interconnection between SAPs, MSCs and possibly point of presence (PoP) to fibre optic networks) operated mainly by fibre optics; and core net (interconnection between MSC) operated mainly by fibre optics. Scenarios where an interconnectio
32、n of a certain hierarchical level within the transport network carries traffic of lower transport network layers are possible as well. 6 FS applications within IMT-2000 transport networks In this section, the fixed service frequency bands and their appropriateness/usability for use in the IMT-2000 a
33、re reviewed. Included in this section are: technically and physically related band characteristics, possible link densities, requirements for systems today and in the future, as well as other factors which influence the appropriateness and usability of certain bands. In addition, a comparison of the
34、 topology and band specifics is provided. 6.1 Characteristics of FS bands In general, all frequency bands available for the fixed service could be used in the IMT-2000 transport networks. In the following sections, technical characteristics of certain fixed service bands 6 Rep. ITU-R F.2060 such as
35、appropriate transmission capacities, channel spacings, modulation levels, available number of channels and typical link lengths are examined. 6.1.1 Information on possible frequency bands for IMT-2000 transport networks It should be noted that in some cases national usage can vary from the general c
36、haracteristics described below. Furthermore, it has to be noted that apart from these technically and physically related characteristics as described in Tables 3 and 4 a number of other factors have to be taken into account that could have a significant impact on the usability of a number of bands.
37、These factors are described in 6.4 where the requirements for wireless links resulting from the IMT-2000 network topology are compared with the band specifics. Since the structure and the density of the IMT-2000 transport network requires a large number of frequencies, especially for short hops in t
38、he range of a few kilometres up to some tens of kilometres, most of the frequency bands of interest, especially for densely populated areas, are located in the frequency range above 11 GHz, although bands below 11 GHz may also be used for certain links in more scarcely populated areas within the IMT
39、-2000 infrastructure network. However, it should be recognized that fixed service bands below 3.4 GHz are required to serve more remote communities, where it is necessary to have long-hop lengths in order to minimize the number of sites. This is an important aspect in providing economical network ac
40、cess in remote areas. TABLE 3 Characteristics of frequency bands above 3.4 GHz for P-P and P-MP systems Band (GHz) Recommendation ITU-R F. Typical link length in temperate climatic areas (km) 3.6 1488 5-15 (P-MP) 4 382 635 20-80 5 746 1099 20-80 Lower 6 383 20-80 Upper 6 384 20-80 7 385 20-80 8 386
41、20-80 10 747 10-50 11 387 10-50 13 497 5-35 14 746 5-35 15 636 5-30 18 595 4-25 Rep. ITU-R F.2060 7 TABLE 3 (end) Band (GHz) Recommendation ITU-R F. Typical link length in temperate climatic areas (km) 23 637 3-20 27 748 2-12 32 1520 1-10 38 749 1-6 52 1496 2 57 1497 2 More information on Table 3 ca
42、n be found in Recommendation ITU-R F.746, which includes channel separation for each of these frequency bands. TABLE 4 Capacity of fixed wireless links according to bandwidth and modulation Capacity (Mbit/s) Bandwidth (MHz) 2 2 8 2 8 34 51 155 2 x 155 3.5 4 states 16 states 7 4 states 16 states 13.7
43、5, 14 4 states 16 states 32 states 27.5, 28, 29.65 4 states 16 states 128 states 128 states (CCDP) 40 64 states 64 states (CCDP) 55, 56 16 states 16 states (CCDP) NOTE 1 CCDP operation with cross-polarization cancellation is used up to 13 GHz and may also be used in the near future in higher bands.
44、This mode of operation allows to double the capacity per channel by transmitting simultaneously on two orthogonal polarizations (H and V) within the same channel. NOTE 2 Modulations are referred by their number of digital states; for instance 4-PSK modulation is a 4 states modulation. 6.1.2 Impact o
45、f rain The aim of this section is to provide some guidance on how climatic conditions could affect the choice of frequency bands for FS in the IMT-2000 transport network. The choice of the most relevant band for mobile networks FS infrastructure depends on several parameters being either regulatory
46、(e.g. bands opened or not for FS, licence of the operator limiting access to certain bands) or technical. As far as the latter is concerned, the impact of rain on these parameters, and thus on the choice of the band, should be considered. It is obvious that this choice will be highly dependent of th
47、e geographic zone where the FS networks are deployed. 8 Rep. ITU-R F.2060 Therefore a comparison of the use of the 18, 23 and 38 GHz bands has been made with respect to their ability to comply with the requirements of capillary FS networks. In particular, studies on the maximum hop lengths for these
48、 frequency bands, according to some geographic rain zones, have been led. For the purpose of these studies, Recommendation ITU-R P.837-1 was used. As a result of these studies, it appears that in rain climatic zones M, N, P and Q, which apply in several areas under tropical or equatorial climatic co
49、nditions, the characteristics of 18 GHz band in terms of maximum hop length are very similar to those of the bands 23 or 38 GHz in the rain climatic zone E, which applies to several other geographical areas with different climatic conditions, for instance in Europe. The distance values provided in Table 3 are no more valid for rain climatic zones M, N, P and Q. The bands 23 GHz and 38 GHz, which in the climatic conditions of Europe are perfectly fitted for use in the transport network of mobile systems, may not present the sam
