1、 Rec. ITU-R BO.1504 1 RECOMMENDATION ITU-R BO.1504 Effective utilization of spectrum assigned to the broadcasting-satellite service (sound)*(Question ITU-R 219/10) (2000) The ITU Radiocommunication Assembly, considering a) that Resolution 528 (WARC-92) calls for the convening of a competent conferen
2、ce to plan the use of the bands allocated to the broadcasting-satellite service (BSS) (sound); b) that it is necessary to conduct the appropriate technical studies in ITU-R in order to prepare for such a conference; c) that the studies requested by Resolution 528 (WARC-92) are complex and require ur
3、gent answers, further considering a) the limited amount of available spectrum, the near omnidirectional nature of the receiving antennas, especially for vehicular reception, which translates into negligible spectrum reuse through orbital separation, the wide coverage area of typical systems and the
4、limitation in satellite antenna directivity at these frequencies due to practical physical size limitations, all this contributing to a potential for considerable intra-service interference; b) that various types of BSS (sound) will be implemented before such a conference is convened; c) the diversi
5、ty of technical characteristics for the systems so far notified to the Radiocommunication Bureau (BR); d) that administrations wishing to implement BSS (sound) could benefit from a set of spectrum management guidelines to enhance the effective use of the spectrum and provide equitable access, noting
6、 a) that there is a need to share the spectrum with other co-primary services and that many of these have a low tolerance to external interference and this will make management of the spectrum difficult; b) that BSS (sound) receivers may also have low tolerance to external interference, since the re
7、ceiving antennas need to be typically omnidirectional; c) that Appendix S3 to the Radio Regulations (RR) indicates the levels of spurious emission that space stations need to meet to avoid interference into passive services; _ *This Recommendation deals only with BSS (sound) intra-service sharing. 2
8、 Rec. ITU-R BO.1504 d) that the spectrum management of BSS (sound) is further complicated by the need to cater for both the satellite and complementary terrestrial sound broadcasting services, recommends 1 that in the interim period prior to the holding of a conference as per Resolution 528 (WARC-92
9、), the guidelines set out in Annex 1 be used by administrations planning to notify a BSS (sound) system in order to allow for the most efficient use of the spectrum/orbit resource and facilitate the management of the allocated BSS (sound) bands in the frequency range 1 400-2 700 MHz. The rationale f
10、or these guidelines can be found in Annex 2; 2 that the technical studies required in preparation for the conference continue as a matter of urgency, and the results be the subject of (a) further Recommendation(s), invites BR 1 to advise Working Party (WP) 6S (formely JWP 10-11S) on the possibility
11、of extending the request for the satellite transmit antenna pfd contours on the surface of the Earth, as part of the system notifications, down to 30 dB relative to the maximum power-flux density (pfd) in steps of 3 dB; 2 to advise WP 6S (formely JWP 10-11S) on the possibility of extending the reque
12、st for the RF spectrum mask expected for the emitted signal from the satellite, as part of the BSS (sound) system notifications, down to levels of 27 dBs relative to the in-channel power. ANNEX 1 Spectrum management guidelines for BSS (sound) 1 To the maximum extent possible, parameters should be ch
13、osen according to the values shown in this Table 1 (see Notes 1 and 2): TABLE 1 Maximum transmit antenna side-lobe gain relative to the maximum antenna gain 30 dB(1)Equivalent out-of-band (OoB) emission in the adjacent channelrelative to the in-channel power(2)27 dB Adjacent channel selectivity at t
14、he receiver 35 dB (1)This value might be relaxed for side lobes directed towards areas where no BSS (sound) using the same frequency band is expected to be implemented. (2)The variability of the channel bandwidth among the different sound BSS systems was taken into account by considering the integra
15、tion of the energy per unit bandwidth (4 kHz) of the interferer, over the extent of its channel bandwidth, over the overlapping portion of the bandwidth of the interfered-with signal (see Annex 2).Rec. ITU-R BO.1504 3 NOTE 1 This Table was developed assuming a spread of maximum pfd of 10 dB among th
16、e various BSS (sound) systems considered (see Annex 2). A reduced spread would be preferable since homogeneity in received pfd levels is an important factor in increasing the spectrum efficiency as described in Annex 2. If a system is outside the assumed range of maximum pfd: 128 to 138 dB(W/(m2 4 k
17、Hz), tighter or more relaxed values than those appearing in the Table would need to be considered NOTE 2 The values in Table 1 were established based on the following partitioning of the interference: 40% of the noise budget (equivalent to a 2.2 dB margin for interference) is set aside for the aggre
18、gate interference from: two co-channel interferers and two adjacent channel interferers each contributing for 10% of the noise budget (equivalent to 10 dB additional interference isolation) (see Annex 2). 2 Although first generation BSS (sound) system implementations may be aimed at wide coverage se
19、rvices due to satellite transmit antenna size limitations, narrower beam implementations should be considered as the preferred solution as the satellite technology develops. The use of narrower beams will enhance the prospect of more satellite systems operating over a given geographical area and per
20、mit greater frequency reuse especially if the antenna side lobes are well controlled thus increasing the possibility of greater access to the limited spectrum resource. ANNEX 2 Rationale for the guidelines to secure maximum spectrum efficiency in the introduction of BSS (sound) in the frequency rang
21、e 1-3 GHz The required discrimination between different BSS (sound) emissions to allow maximum frequency reuse and spectrum occupancy can be derived from four key factors. These are: the satellite transmit antenna directivity, the satellite transponder spectrum regrowth performance, the receiver cha
22、nnel selectivity and the receiver antenna directivity. With respect to the last factor, such receiving antenna directivity is minimal if the service is to be provided to vehicle and portable receivers. This receiving antenna directivity will therefore be neglected in the following discussion. The di
23、scrimination values available from the three first factors are compared to the isolation requirement between the various BSS (sound) systems. Given the required isolation among BSS (sound) systems, general guidelines can be deduced from such comparison. 1 Variables related to BSS (sound) intra-servi
24、ce sharing The BSS (sound) can rely on a limited number of means to maximize the efficiency and utilization of the frequency bands that were allocated to it by WARC-92 (40 MHz at 1.5 GHz, 50 MHz at 2.3 GHz and 120 MHz at 2.5 GHz). When a number of satellite broadcasting systems are used to provide t
25、he service, they can only rely on the following means to secure enough isolation to avoid mutual interference: very large satellite orbital separation so that the potentially interfering satellite is beyond the horizon in the service area of interest; 4 Rec. ITU-R BO.1504 satellite transmit antenna
26、discrimination: this translates into the possibility of reusing the spectrum if the two service areas of interest are geographically separated by the required minimum distance, reckoned as off-axis angle at the satellite antenna; receiver channel selectivity: adequate receiver selectivity will allow
27、 different systems covering the same area or adjacent areas to operate on channels closely spaced in frequency due to the adjacent channel rejection provided at the receiver; RF spectrum mask for OoB emission from the satellite transponder: this will also give the possibility of using channels close
28、ly spaced in frequency to cover the same service area or adjacent areas resulting in better use of the spectrum. Such OoB emissions, usually caused by satellite transponder spectrum regrowth, would be seen at the receiver as on-channel interference for which the receiver selectivity would be of no h
29、elp in improving the situation. Unlike in the case of many other satellite services, no discrimination can be assumed from the receiving antenna because, by nature, this antenna is to have minimum directivity since it is to be used in a portable environment and mobile environment where the vehicle c
30、an be moving in all directions. This antenna has to have a broad beamwidth to allow reception by mobile receivers and therefore cannot discriminate between satellites on a geostationary-satellite orbit (GSO) or any other orbit. More directional antennas could be used for fixed and portable reception
31、, and even for mobile reception if a tracking system is provided but the case of the near omnidirectional antenna should dictate the service constraints. In fact, some BSS (sound) system proponents plan to rely on the use of this broad receiving antenna beamwidth to secure some transmit diversity fr
32、om more than one satellite. This absence of directivity from the receiving antenna makes the process of maximizing the efficiency of the orbit/spectrum resource much simpler, as will be seen below. In order to identify the isolation required between different BSS (sound) systems to operate in a spec
33、trum efficient manner, some criteria have to be established. For the purpose of this exercise, it is assumed that the satellite reception is noise limited (which is quite realistic for satellite systems which are inherently power limited). The interference falling in each adjacent channel should not
34、 be allowed to represent more than 10% of the noise budget. Also, it is assumed that there would be a maximum of two other systems operating on the same frequency which would interfere with the wanted signal. Each of these co-channel interferers would not be allowed to contribute for more than 10% o
35、f the noise budget. This results in a 10 dB additional isolation requirement for each co-channel and adjacent channel interferer resulting in a total of 2.2 dB interference allowance to be included in the link budget. 2 Intra-system interference The four BSS (sound) systems for which most technical
36、details are available have been reviewed to establish a range of required isolation values. System parameters were taken from the ITU-R Special Publication on BSS (sound) currently being updated “Terrestrial and satellite digital sound broadcasting to vehicular, portable and fixed receivers in the V
37、HF/UHF bands”. Table 2 summarizes the process used to generate the isolation values needed between systems of the same kind to allow reuse of the spectrum. Rec. ITU-R BO.1504 5 TABLE 2 Total isolation requirement for intra-system interference These figures establish the discrimination required in or
38、der to allow frequency reuse for each of the systems considered assuming the worst-case reception condition where the interfering signal is line-of-sight (LoS) at the receiver while the wanted signal is faded to the point where the signal is received at threshold. Since the satellite transmit antenn
39、a discrimination is the only means of securing such isolation, the antenna pattern needs to produce such level of discrimination at the smallest possible off-axis angle. In order to maximize frequency reuse, the satellite transmit antenna needs to provide side-lobe rejection equal or better than the
40、 above isolation numbers. It means that the side-lobe plateau usually defined in reference antenna patterns has to be lower than 26.9 dB relative to the antenna gain at the edge of the beam in the case of System D. This value translates into a side-lobe rejection requirement of some 30 dB relative t
41、o the maximum antenna gain (gain differential is taken as typically 3 dB between centre and edge of beam). As can be seen, the information on the satellite transmit antenna side-lobe rejection is critical and should be provided to ITU-R as part of the application for any new system for comparison wi
42、th the required isolation values. 3 Inter-system interference This section covers the more complex situation where different systems are in operation and interfere with each other. Table 3 was developed to identify the maximum pfd levels produced by the four BSS (sound) systems documented in the ITU
43、-R Special Publication on BSS (sound) currently being updated so that any differential between these pfd levels can be taken into account to define the required isolation values to avoid mutual interference among these systems. Table 3 Systems(1) ParametersSystem A System B System D System E(2)Minim
44、um required Eb/N0(dB) 7.2 3.3 2.7 2.6 System implementation margin (dB) 1 1 0.5 0 Hardware implementation margin (dB) 0.5 0.5 1.8 2 Degradation due to uplink (dB) 0.4 0.4 0 0.1 Interference allowance (dB) 2.2 2.2 2.2 2.2 Fade allowance (dB) 5 5 9.7 8.1 Additional allowance to limit interference to 1
45、0% of the noise budget (dB) 10 10 10 10 Total isolation requirement (dB) 26.3 22.4 26.9 25.0 (1)The four systems used are described in Recommendation ITU-R BO.1130 (System C is used only for terrestrial broadcasting, broadcasting service (sound). (2)Interference value of System E is selected for cal
46、culation in this Table only. This value should not be used for any other purpose. 6 Rec. ITU-R BO.1504 gives the maximum spectral pfd produced at the centre of the beam for each system. The values to be used in the establishment of the isolation factors are actually a measure of the spectral density
47、 of the signal over 4 kHz. As an indication and for the purpose of comparison, the values declared to ITU-R as part of systems proposals, as given in the currently proposed ITU-R Special Publication on BSS (sound), were included. These isolation factors assume that the two interfering systems would
48、occupy the same equivalent spectrum bandwidth. If it is not the case, the isolation factor was corrected accordingly (i.e. if System X occupies only half of the bandwidth of System Y, the isolation figure of System Y interfered by X would need to be reduced by 3 dB whereas the isolation value in the
49、 reverse direction would not change since the reception of System X would see its full channel being interfered by the broader bandwidth of System Y). TABLE 3 Table of mutual isolation factors among BSS (sound) systems (single entry) A table of required discrimination values for the mutual interference among systems was developed from the intra-system discrimination values established in Table 2. These intra-system values actually appear (in bold) on the diagonal of the last rows of Table 3. This Table also includes all the inter-system isolation value
