1、STD.CEPT ERC REPORT 48-ENGL 1995 W 232b414 OOL34L 434 W ERC REPORT 48 European Radiocommunications Committee (ERC) L with this is influenced by whether the higher capacity channels fully occupy the frequency range availability, and if not, where the higher capacity channels lie in the available freq
2、uency range. * a band which is being used by two (or more) operators who are using equipment with different spacing could be divided more efficiently using one arrangement method or the other; this would require the determination of the spectral decoupling between the equipments used by the two oper
3、ators, as explained later in this document. 3.1 Primary considerations in choosing channel arrangement 3.1.1 Alignment ofpaerns In all cases the most important consideration is how the basic pattern aligns with the available frequency range (see Annex 3), which will constrain the number of lower cap
4、acity channels which could be accommodated into the plan. a) If the widest channels align such that there is little or no spare spectrum at either end of the plan, then it will be possible to maximise the number of lower capacity channels by the use of channel subdivision (Annex 3, Case l), whilst t
5、he interleaved pattern would not be able to accommodate as many lower capacity channels. b) If, however, there is a greater amount of spare spectrum at either end, it would be possible to assign an additional low capacity channel at each end of the plan by using the interleaved arrangement, so that
6、the interleaved plan offers more channels than the subdivision plan (Annex 3, Case 2). c) In other case it might be found that the alignment of the basic pattern relative to the available band is such that the higher capacity plan is significantly offset so that the spare spectrum is mostly to one e
7、nd of the band. In this case (Annex 3, Case 3), there would usually be no difference between the two methods. STD-CEPT ERC REPORT 4B-ENGL 1995 = 2326414 0013424 channel spacing: 7.0 MHz System C: 2 * 2 Mbits; channel spacing: 3.5 MHz The modulation scheme 4 FSK was applied to all three systems. The
8、IRF values are listed in Annexes 6 and 7. STD-CEPT ERC REPORT 48-ENGL 1995 = 2326434 00L342b b74 W ERC REPORT 18 Page 5 6 RESULTS TAKEN FROM THE EXAMPLE 6.1 Applicability of the test result In the example, 4 FSK-modulated radio relay systems with relatively low transmission rates (up to 8 * 2 Mbit/s
9、) taken from only one group of systems were tested. Nowadays, such systems are typically used in frequency ranges above approximately 13 GHz. They are basically suitable for the band re-use in the co- channel mode. To what extent the results taken from this example are applicable to comparable radio
10、 relay systems has to be studied in further detail (if necessary, in coordination with ETSI TM 4). Moreover, the conditions in the following cases need also be tested: * * * multi-carrier systems, * high-level modulated radio relay systems (e.g. 64 QAM), radio relay systems with high transmission ra
11、tes (e.g. 155 Mbit/s), concerning patterns in which adjacent channels have a different polarisation (alternated pattern). 6.2 Spectral decoupling between channels of one pattern In the case of the systems under test, the IFW is approximately 22 dB between adjacent channels of the same pattern indepe
12、ndent of the type of pattern arrangement (subdivision or interleaved). This value is by no means sufficient to be able to occupy adjacent channels in the same pattern within the same geographical area and without mutual coordination if it has to be ensured that no harmful interference is caused betw
13、een the channels. For instance, a radio relay operator “A“ cannot setup and operate a radio relay network in channel 4 without prior coordination with radio relay operator “B“ using, for example, channel 5 (see Annexes 8 and 9). 6.3 Conclusion regarding the spectral decoupling between channels of on
14、e pattern Independent of the type of pattern arrangement used (subdivision or interleaved), the adjacent channels of one pattern always have to be coordinated. Normally, even the channels with a larger frequency separation (“not-immediately adjacent channels“) have to be included in the coordination
15、. In Germany, a central and independent office of the Federal Office for Posts and Telecommunications is in charge of this task in order to ensure the highest possible degree of efficiency and frequency economy in terms of frequency assignments and coordination. If “guard bands“ are introduced betwe
16、en two operators by not using one or even several channels, a non- interference operation can also be achieved. A high degree of frequency economy, however, cannot be ensured by way of the latter possibility (Annex 10). Which of the two types of pattern arrangements is more effective than the other
17、has to be determined in each single case, depending on the required IRF value. STD-CEPT ERC REPORT 48-ENGL 1995 = 2326414 0013427 500 - ERC REPORT 48 Page 6 6.4 Spectral decoupling between the channels of two patterns The main differences between a subdivision and an interleaved arrangement of chann
18、el patterns are the frequency separations between the channel center frequencies of the two patterns under test (Delta f) and the resulting IRF values. These differences can best be illustrated if the channel spacing varies by a factor of 2. The following values concerning the systems A (8 * 2 Mbit/
19、s; channel spacing 14 MHz) and B (4 * 2 Mbits; channel spacing 7 MHz) were taken from the example: 6.5 Delta f O MHz +/- 3.5 MHz +/- 7.0 MHz +/- 10.5 MHz +/- 14.0 MHz +/- 17.5 MHz +/- 2 1 .O MHz +/- 24.5 MHz +/- 28.0 MHz +/- 3 1.5 MHz Subdivision - 2 channels; IRF = O dB 2 channels; IRF = 18 - 23 dB
20、 2 channels; IRF = 38 - 49 dB 2 channels; IRF = 56 - 61 dB 2 channels: IRF = 66 - 71 dB _-_ _-_ - - Table 2: Comparison of spectora Interleaved 1 channel; IRF = O dB .- 2 channels; IRF = 7 - 11 dB 2 channels; IRF = 3 1 - 35 dB 2 channels; IRF = 50 - 66 dB 2 channels; IRF = 61 - 71 dB iecoupling _- .
21、- _ - Conclusion regarding the spectral decoupling between channels of two patterns In order to be able to decide which of the two methods ensures a higher degree of frequency economy, the frequency distribution of the required IRF value should be tested in a radio relay network which has been expan
22、ded to full capacity. This test is very time-consuming and the result depends on the following factors (among others): * data of the antenna used, * structure of the network, * geographical and topographical conditions, * characteristics of the radio relay systems used. 7 ASPECTS OF COORDINATION WIT
23、HIN THE NETWORK OF ONE OPERATOR AND COORDINATION BETWEEN SEVERAL OPERATORS The aspects of coordination are illustrated by means of the example of a German mobile network operator (e- plus) and the frequency assignment criteria and principles that will be employed by the Radiocommunications Agency of
24、 the UK. 7.1 Coordination within the network of one operator (Example: e-plus) In order to ensure effective coordination all employees of the operator (e-plus) involved in the planning of the network make use of a planning tool providing information on the envisaged and established links of the mobi
25、le network. Moreover, several provisions concerning the priority of the frequency usage have been applied by the operator “e-plus in order to avoid problems in the border area between different network operators. Thus, a high degree of planning efficiency within the network of the operator “e-plus i
26、s ensured. STD-CEPT ERC REPORT 48-ENGL 3795 232bY34 0033428 447 9 ERC REPORT 48 Page 7 7.2 Coordination between several operators (Example: e-plus - MMO) The data of the envisaged “links“ of both operators (e-plus and Mannesmann Mobilfnk (MMO) are exchanged via diskettes in an agreed format. By mean
27、s of this data exchange the operators are enabled to recognise problems concerning the planning on time and to act accordingly, thus further increasing the efficiency in planning. The Federal Office for Posts and Telecommunications, however, is responsible for the actual and final assignment of freq
28、uencies. . In order to improve coordination between the frequency administration and the operators, efforts are being made to provide the operators with access to the data base of the BAPT, which contains all “links“ existing in a particular frequency band. Thus, an interference analysis including a
29、ll planned and existing “links“ could be carried out rendering the time-consuming coordination among operators unnecessary. Furthermore, all data of envisaged “links“ could be electronically and directly fed into the data base of the administration by the operators. This approach would further incre
30、ase the degree of efficiency in planning and ensure efficient coordination between the operators and the frequency administration. 7.3 Frequency assignment and coordination in the UK The following example gives the prospects for the frequency assignment criteria and principles that will be employed,
31、 by the Radiocommunications Agency, in the selection of frequencies for use by fixed radio services operating in the bands 12.75 GHz to 13.25 GHz and 14.25 GHz to 14.50 GHz. The 12.75 GHz to 13.25 GHz band has been divided into three sub-bands each having a low and high (go and return) group of freq
32、uencies. * The “first“ sub-band is primarily for private user digital links. * The “second“ sub-band is, at present, reserved for Mercury Communications Ltd, and operated in accordance with their own assignment criteria. In order to minimise interference between these channels and those in the acjac
33、ent sub-bands utilised by other users, partial coordination is carried out. Extending this process to full coordination is under consideration. * The “third“ sub-band is a shared band for analogue and digital links. The 14.25 GHz to 14.50 GHz band is a shared band for analogue and digital links and
34、has a low and high (go and return) group of frequencies. STDmCEPT ERC REPORT 48-ENGL 3995 232b434 0033429 383 = Minimum Capacity, Mbit/s 2 ERC REPORT 18 Page 8 WAJ (dB) Co-channel interference limit (dBW) 21 -140 7.3.1 Assignment of frequencies 8 2x8 34 i 40/ 1 55 The Radiocommunications Agency will
35、, as far as possible, assign frequencies on the basis that the estimated level of any individual CO channel and adjacent channel interference at the receiver input should not exceed the values shown in Table 3 and Table 4 for 99.9% of the time. 27 -135 21 -133 27 -130 39 -135 The W ratios in these t
36、ables are given for an unwanted interferer when the wanted signal is at a defrned sensitivity input level. Minimum Capacity, Mbit/s 2 2x2 WAJ (dB) Adjacent-channel interference limit (dBW) 3 -1 16 3 -1 14 8 2x8 34 140/155 3 -111 3 -109 3 -106 16 -1 12 Furthermore W-ratios, given by the matrices in A
37、nnex 11, for single entry interferes, for all digital systems (mixed capacities) have been calculated for various channel separations. The values listed in Annex 11 represent an overview of the spectral decoupling required to ensure non- interference operation of digital radio relay systems. Referrb
38、g to the example given in chapter 6 concerning the spectral decoupling of 4-FSK modulated systems, the latter values revealed the same tendency. As regards the problem which channel pattern arrangement method should be used, the selection of the method is based on the same variety of factors indepen
39、dent of whether 4-FSK or QAM modulated systems are concerned. However, if only the aspects of frequency assignment and coordination are taken into consideration, a coordination is required at all events no matter whether the frequencies are assigned and coordinated by a central body (e.g. BAPT, Germ
40、any) or whether the decentralized approach is used, Le. by means of the so- called block assignment, particular frequency ranges are assigned exclusively to certain operators who will then have to coordinate these frequencies among themselves. Frequency coordination is indispensable in any case in o
41、rder to ensure non-interference operation. STD-CEPT ERC REPORT YB-ENGL 3995 2326414 0033430 OT5 = ERC REPORT 48 Page 9 8 EQUIPMENT COSTS In order to be able to evaluate the problems concerning the method of pattern arrangement to be used in terms of the equipment costs involved, one of the manufactu
42、rers for radio relay equipment carried out a detailed study. The results of that study revealed that owing to the use of inexpensive and flexible technologies (fraction N components) the selected method of pattern arrangement did not have any significant impact on the resulting costs. Thus, in terms
43、 of the costs involved, none of the two methods has advantages over the other. In view of network and frequency planning, both methods are also considered equivalent. 9 PROS AND CONS OF THE TWO METHODS A superficial examination of the study reveals certain subjective advantages and disadvantages of
44、the two pattern arrangement methods (subdivision and interleaved). These advantages and disadvantages largely depend on the conditions under which one of the two methods is to be chosen. Major factors are the number of channels that can be implemented, the time and efort required for frequency coord
45、ination, network and Pequency planning aspecis cfiequency economy), and equipment costs. In view of the variety of these factors which arise in the planning and implementation of radio relay networks, the selection of the pattern arrangement method is always based on the case ai hand and its charact
46、eristics. When several individual cases are compared, it becomes obvious that the advantages of one case may well constitute disadvantages in another case. For this reason it is extremeb di$cult, ifnot impossible, to compile a list giving the definitive advantages and disadvantages of the two method
47、s ofpattern arrangement without referring to this specific problem. STD.CEPT ERC REPORT 4-ENGL 1995 W 232b414 OUI13433 T3L ERC REPORT 48 Page 10 . 10 SUMMARY In this study a comparison was drawn between the two methods of pattem arrangement: subdivision and interleaved. The following aspects were ex
48、amined * Number of channels which can be occupied Result: Which method of pattern arrangement provides for crucial advantages over the other has to be determined in each single case. * Frequency partitioning between several operators Result: No method of pattern arrangement has advantages over the o
49、ther. Both types of pattern arrangement require a coordination of frequencies between the operators. * Aspects of network and frequency planning (frequency economy) Result: Which of the two types of pattern arrangement is more effective than the other concerning the fiequency economy has to be determined in each single case, depending on the required IRF values to be used in a specific network (Le. at network hub points). * Equipment costs Result: No significant differences in the cost structure were revealed on the basis of a study of equipment costs. Both types
