1、I D 4855232 0522344 8T3 D Rec. ITU-R S.742-1 RECOMMENDATION ITU-R S.742- I * SPECTRUM UTILIZATION METHODOLOGIES (Question ITU-R 49/4 (1990)* 325 ( 1992- 1993) The ITU Radiocommunication Assembly, considering a the same part of the geostationary-satellite orbit (GSO); b) significantly in the next few
2、 years; c) networks in the frequency dimension; d) interference, and the more complex is the coordination process; e) additional users; f) frequency spectrum and the GSO, that interference may impose a limit on the number of satellites which operate in the same frequency band in that the number of s
3、atellites using the GSO for operational purposes has grown and will continue to grow that frequency band utilization methodologies are considered as a means of reducing inhomogeneity between that the more heterogeneous the types of carriers concerned, the higher are the levels of internetwork that m
4、ethods of spectrum utilization can, in some circumstances, increase the likelihood of accommodating that the use of frequency band utilization methodologies will lead to the most efficient use of the radio- recommends 1. far as possible, depending on their individual practicalities: that in internet
5、work coordination one of the following spectrum utilization methodologies should be used as I. 1 Rand segmentation methodologies Spectrum Segmentation can be achieved by several methods. The first method is designated as inacro- Segmentation, where frequency bands are segmented into large blocks, ty
6、pically many transponder banclwidihs wide resulting in only a few segments. Two different techniques for characterizing each of the segments c;ui he used, the first by carrier classification and the second by parameter values. Different sets of rules can be used with each technique. The macro-segmen
7、tation method would be most effective where the proportions of different types id cwricr or technical parameter values are the same in the satellite networks being coordinated. The second method of segmentation is micro-segmentation. For this method, the segmeiitation IS based o11 small blocks, typi
8、cally the size of a transponder. The micro-segmentation method would be most effective where Lhe transponder plans (bandwidths, polarization, etc.) of the satellite systems, operating in the orbital arc of coordi nation interest, are similar. 1.1.1 Macro-segmentation, carrier classification approach
9、 In this technique standard types of carriers are identified and several classifications (are dcfinctl. Table I - high-density carriers: FM-TV - low-capacity carriers: SCPC shows how 50 different carriers can be identified and placed in one of the following three classes: low-index FDM-FM low-capaci
10、ty or low-power analogue and digitil c,arriers * * Former CCIR Question 49/4. New version of CCIR Recommendation 742. 4855232 0522345 73T 326 Rec. ITU-R S.742-1 - average carriers: medium- to high-index FDM-FM TDMA wideband digital carriers This last type of carrier is compatible with either of the
11、two former types as regards mutual interference. Thus only the first two types of carrier - high density and low capacity - would have to be segregated under a rational set of spectrum utilization rules: the average carriers can be placed anywhere. To accomplish this, the band allocated (generally 5
12、00 or 250 MHz wide) is divided into low-capacity and high-density sub-bands. This can be done by allotting the lower parts of the bandwidth to low-capacity carriers and the upper parts to high-density carriers and only carriers of the assigned class could use the sub-band. The optimum segmentation p
13、rocedure will depend on the frequency bands in question. Figure 1 shows some of the required separation angles, obtained with the use of this method. I, 1.2 Macro-segmentation, parameter value approach In this technique a different approach for determining sub-band segments, based on limits on parti
14、cular values for parameters such as earth-station e.i.r.p., carrier bandwidth and various combinations of the WARC ORB-88 set of generalized parameters (A, B, C and D) are proposed. According to this approach the 6/4 GHz frequency band can be divided into two segments reducing the required satellite
15、s spacing to half, relative to the unsegmented case, and with the greatest improvement being achieved on the basis of carrier bandwidth, up-link e.i.r.p., and down-link e.i.r.p. (see Fig. i). 1.1.3 Micro-segmentation In this method, bands of the order of a transponder bandwidth are considered for su
16、b-division. A carrier classification approach is used such that sub-bands are identified for use by high-density carriers and for avoidance by low-capacity carriers. In contrast to macro-segmentation, the sub-bands are identified relative to a transponder bandwidth (e.g. 36 MHz) instead of an entire
17、 frequency band (e this to be the subject of further study. These methods can be augmented in some cases by alternating the polarization of overlapping high-density carriers in transponders off-set by approximately one-half of a transponder bandwidth. Using for example a 36 MHz transponder bandwidth, the spacing between the centres of the sub-band would then be 20 MHz.
