ITU-R F 1102-2-2005 Characteristics of fixed wireless systems operating in frequency bands above about 17 GHz (Question ITU-R 107 9)《运行在17GHz以上频段的固定无线系统的特征》.pdf
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1、 Rec. ITU-R F.1102-2 1 RECOMMENDATION ITU-R F.1102-2 Characteristics of fixed wireless systems operating in frequency bands above about 17 GHz (Question ITU-R 107/9) (1994-2002-2005) Scope This Recommendation provides characteristics of fixed wireless systems operating in frequency bands above about
2、 17 GHz. The Annex 1 contains possible applications, hop length consideration, basic functions of transmitters and receivers, and other technical/operational characteristics required for the implementation of fixed wireless systems in this frequency range. The ITU Radiocommunication Assembly, consid
3、ering a) that frequency bands above about 17 GHz are allocated to the fixed and other services; b) that the propagation characteristics above about 17 GHz are predominantly governed by precipitation fading and absorption and only suited to short range radio system applications; c) that differing app
4、lications of various administrations may require different radio-frequency channel arrangements; d) that several services with various transmission signal characteristics and capacities may be in simultaneous use in the same frequency band; e) that the various applications may require differing chan
5、nel bandwidths; f) that new applications and network configurations are being used in high density deploy-ment of fixed wireless systems in bands above about 17 GHz, recommends 1 that system design should take into consideration the effects of precipitation outage which critically determines hop len
6、gth; 2 that the frequency bands above about 17 GHz be used for short range applications which will allow equipment to be compact with smaller antennas; 3 that to allow the use of mixed services, whilst achieving spectral economy, the radio-frequency channel arrangements should be based on homogeneou
7、s patterns in accordance with Recommendation ITU-R F.746; 4 that both digital and wideband analogue modulation techniques are applicable; 5 that Annex 1 be referred to for guidance in system design. 2 Rec. ITU-R F.1102-2 Annex 1 Characteristics of fixed wireless systems operating in frequency bands
8、above about 17 GHz 1 Introduction In the frequency bands above about 17 GHz some allocations are provided for the fixed service on a worldwide basis. At these frequencies, outage is due primarily to precipitation fading lasting in excess of 10 s. Hence parameters of particular importance to the impl
9、ementation of such systems are availability and transmitter-to-receiver path length (hop length) that may be achieved. These parameters are considered in this Annex for systems that are typically used in the local network. 2 Application considerations 2.1 Local access/networks The frequency bands ab
10、ove about 17 GHz are being used mainly for short haul links. Compact and highly reliable radio equipment can support voice, data, video, and broadband data transmission. The main applications are: interconnection of LANs; interconnection between LANs (IEEE 802.3/Ethernet and IEEE 802.5/Token Ring) w
11、ith a transmission capacity of the order of 10 Mbit/s; interconnection between LANs (Ethernet including RLANs IEEE 802.11a/IEEE 802.11b/HiperLAN2/HiSWANa) with a transmission capacity of the order of 100 Mbit/s; video transmission; subscriber links; digital primary group or higher speed data links f
12、rom end office to user buildings; cellular phone applications; interconnection between cellular phone exchanges and base stations; relief applications; transportable radio equipment used for backup links when optical fibre systems or other terrestrial circuits have failed; ring closure or point-to-p
13、oint connection in the synchronous digital hierarchy (SDH) access network; high density access networks in, for example, subscriber-based applications. Rec. ITU-R F.1102-2 3 Table 1 categorizes the above applications. TABLE 1 A categorization of applications 2.2 Cost comparison between fibre and rad
14、io links in the access portion An optical fibre system requires construction work continuously along the cable route. On the other hand, radio systems require such work only at the transmitting and receiving stations. For this reason, the greater the distance between locations, the greater the cost
15、for a fibre system will increase. Costs are compared in the following simple model shown in Fig. 1. Physical link configuration Transmission capacity Content of signal Hop length LAN interconnection User to user building Order of 10 Mbit/s Data Several tens of metres to km Subscriber links From end
16、office to user building Analogue or primary rate digital group or higher PDH capacity Data or video Several km to tens of km Inter-cell telephone applications Between cellular system telephone exchange and radio base station 2 Mbit/s up to STM-1 Voice or data Several km to tens of km Transportable e
17、quipment for relief operations (see Note 1) Backup for optical fibre links Analogue or primary rate digital group or higher PDH capacity or SDH Voice, data or video Several km to tens of km SDH access network ADMs ring closure/interconnection or tributary extension SDH hierarchy Virtual containers (
18、Vc) Several km to tens of km High density subscriber-based access Direct access to subscriber Up to STM-1 Data and voice Fraction of a km up to a few km Vertically-connected wireless link From user building to subscriber Order of 100 Mbit/s Data and video Several tens of m ADM: Add/drop multiplexer
19、PDH: Plesiochronous digital hierarchy STM-1: Synchronous transfer mode 1 NOTE 1 See Recommendation ITU-R F.1105. 4 Rec. ITU-R F.1102-2 1102-01FIGURE 1Assumed modelRadio equipment cost: R1Radio installation cost: R2E/O, O/E cost: F1Optical fibre cost: F2E/O, O/E E/O, O/ENumber ofsubscribers: NDistanc
20、e: DBase station User buildingFibre (overhead) installation cost: F3Cost R for introducing a radio system is given by: R = (R1 + R2) N Cost F for introducing an optical fibre system is given by: F = F1 N + (F2 + F3) N D Figure 2 shows the result of cost comparison. According to Fig. 2, with the same
21、 number of subscribers, any increase in distance decreases the cost of radio with respect to that for a fibre system. Further, with the same distance, radio systems are advantageous when the number of subscribers is small. Moreover, the applicable area for radio expands sharply when the distance bec
22、omes greater. 1102-02FIGURE 2Results of cost comparison between fibre and radioHighRadio equipmentpriceEffective area whereradio is suitableStandardLowEffective areawhere optical fibreis suitableNumberofsubscribersDistance (km)Area where theapplicability ofradio is difficultRec. ITU-R F.1102-2 5 If
23、only cost is taken into consideration, the greater the distance, the more the applicable area of radio will expand. However, it is necessary to take into account the fact that the propagation distance of radio systems using frequency bands above about 17 GHz is limited by rain attenuation. The provi
24、sion of multiple-hop short-range links would therefore tip the balance towards the favour of fibre systems, but generally within the local loop multiple-hop systems are rare. In practice a mixture of fibre and radio would be used depending on which system is the most cost effective and practical for
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