1、CCIR RECMN*4bb-b 92 4855232 0538788 2T4 166 Rec. 466-6 SECTION 4D: FREQUENCY S;YARNG BETWEEN NETWORKS OF THE FIXED-SATELLITE SERVICE - EFFICIENT USE OF THE SPECTRUM AND GEOSTATIONARY -SATELLITE ORBIT 4Dl: Permissible levels of interference RECOMMENDATION 466-6 MAXIMUM PERMISSIBLE LEVEL OF INTERFEREN
2、CE IN A TELEPHONE CHANNEL OF A GEOSTATIONARYSATELLITE NETWORK IN THE FIXED-SATELLITE SERVICE EMPLOYING FREQUENCY MODULATION WITH FREQUENCY-DIVISION MULTIPLEX, CAUSED BY OTHER NETWORKS OF THIS SERVICE (Question 4814) (1970-1974- 1978-l982-1986-1990-1992) The CCIR, considering a) that geostationary sa
3、tellite networks in the fixed-satellite service operate in the same frequency bands; b) that interference between networks in the fixed-satellite service contributes to the noise in the network; c) that it is desirable that the interference noise in the telephone channels of networks in the fixed-sa
4、tellite service caused by transmitters of different nehvorks in that service should be such as to give a reasonable orbit utilization efficiency; d) that the overall performance of a network should essentially be under the control of the system designer: e networks: that it is necessary to protect a
5、 network in the fixed-satellite service from interference by other such 0 determine space station and earth station characteristics; that it is necessary to specify the maximum permissible interference power in a telephone channel, to SI wide a minimum orbitai spacing; that the value selected for th
6、e maximum permissible single entry of interference noise should not result in too h) of interference in a telephone channel of the wanted network caused by transmitters of the other network: that for co-ordination between two satellite networks, it is necessary to know the maximum permissible level
7、j) into the earth station receiver: that networks in the fixed-sateiiite service may receive interference both into the space station receiver and k the hypothetical reference circuit; that the mean interference noise power should be an appropriate fraction of the total noise power permitted in 1) t
8、hat in many cases the largest interference contributions to a geostationary satellite network will be from the networks using geostationary satellites in orbit nearby and serving an overlapping coverage area. The value of interference from any other network will generally be less; d that the accumul
9、ation of interference from many entries from other satellite networks and from terrestrial stations is not likely to be equal to the arithmetic sum of the individual interference entries at their maximum value across the band, and the total interference noise level in any single channel may be signi
10、ficantly less; CCIR RECMN*4bb-b 92 4855212 0518789 130 a) to networks for which a complete advance publication was submitted to the IFRB by the time of the CCIR XIVth Plenary Assembly, 1978; for such networks the aggregate interference power in any telephone channel should not exceed 1 O00 pWOp psop
11、hometrically weighted one minute mean power for more thxi 20% of any month, and the single-entry interference noise power should not exceed 400 pWOp, psophometrically weighted one minute mean power, for more than 20% of any month; Rec. 466-6 167 n) in frequency bands below 10 GHz are not expected to
12、 undergo a large variation with time; that the levels of interference between geostationary satellite networks in the fixed-satellite service operating 0) that in frequency bands between 10 and 15 GHz where very high propagation attenuation may occur for short periods of time, it would generally be
13、desirable for systems to make use of adaptive up-path power control or earth- station site diversity or other techniques to counteract signai fading and that under these circumstances the levels of interference from other satellite systems would also not undergo a large variation with time; Pl that
14、the use of syllabic companding may be useful in reducing transmitter power requirements or increasing transmission capacity, but that companded transmissions have a sensitivity to interference which is different from that of uncompanded transmissions that the level of baseband degradation is inverse
15、ly proportional to the carrier-to-interference ratio, recommends 1. that different geostatioiiary-satelte networks in the fixed-satellite service operating in the same frequency bands, below 15 GHz, be designed in such a manner that the interference noise power at a point of zero relative level in (
16、my telephone channel of a hypothetical reference circuit of a network in the fixed-satellite service, employing frequency modulation, caused by the aggregate of the earth station and space station transmitters of other fixed satellite networks, should not exceed: 1.1 weighted one minute mean power f
17、or more than 20% of any month; in frequency bands in which the network does not practise frequency re-use: 2500 pWOp, psophometrically 1.2 one minute mean power for more than 20% of any month; in frequency bands in which the network practises frequency re-use; 2000 pWOp, psophometrically weighted 2.
18、 that the maximum level of the interference noise power at a point of zero relative level in any telephone channel of the hypothetical reference circuit of a geostationary-satellite network in the fixed-satellite service employing frequency modulation, caused by the transmitters of another fixed-sat
19、ellite network, should not exceed 800 pWOp, psophomekically weighted one minute mean power, for more than 20% of any month; 3. that the maximum level of interference noise power caused to that network should be calculated on the basis of the following values for the receiving earth station antenna g
20、ain, in a direction at an angle cp (in degrees) referred to the main beam direction: G=32-25logcp dBi for 1“Icp48“ G = -10 dBi for 48“Icp18Oo except when the actual gain is known and is less than the above value, in which case the actual value should be used; 4. that the following Notes should be re
21、garded as part of this Recommendation: Note I -The values quoted in Q 1.1, 1.2 and 2 are not intended to apply: CCIR RECMN*4bb-b 72 4855212 0518770 952 9 168 Rec. 466-6 b) for networks which have submitted complete advance publication after the CCIR XIVth Plenary Assembly, 1978 and prior to the end
22、of 1987, the aggregate interference power in any telephone channel should not exceed 2000 pWOp psophometrically weighted one minute mean power for more than 20% of any month for networks which do not practise frequency re-use and 1500 pWOp psophometrically weighted one minute mean power for more tha
23、n 20% of any month for networks which practise frequency re-use, and the single- entry interference noise power should not exceed 600 pWOp, psophometrically weighted one minute mean power, for more than 20% of any month. Note 2 - The pWOp values given in 0 1 and 2 apply to interfered with transmissi
24、ons which do not use syllabic companding. When a transmission uses syllabic companding, the equivalent values to be used result from multiplication of the values from 0 1 and 2 with the numerical companding gain for which the transmissions have been characterized. This is predicated on an overall su
25、bjective channel performance objective of 10 O00 pWOp. Note 3 - Only a small fraction of the channels of a network will experience the maximum value of interference from any single network and therefore the aggregate level for many channels will be less than the totals contained in 0 1. System desig
26、ners may provide for a lower value in their noise budgets for a large portion of the spectrum. The way in which the aggregate values are to be taken into account in the general noise objectives for networks in the fixed- satellite service is defined in Note 6 of Recommendation 353. Note 4 - In some
27、cases it may be necessary to limit the single entry interference value to less than the value quoted in 0 2 above in order that the total value recommended in 9 I may not be exceeded. In other cases, particularly in congested arcs of the geostationary-satellite orbit, administrations may agree bilat
28、erally to use higher single entry interference values than those quoted in 0 2 above, but any interference noise power in excess of the value recommended in 0 2 should be disregarded in calculating whether the total value recommended in 9 1 is exceeded. Note 5 - There is a need for study to be given
29、 to means of increasing the single entry interference level quoted in 0 2 above without causing the total interference noise level to exceed the values quoted in 0 1; this study should include, for example, the feasibility of overcoming problems of interference which result from inhomogeneous networ
30、k pcwatneters. Note 6 - There is a need for study of the acceptability of an increase in the maximum total interference noise values in 0 1, since some studies have shown the optimum interference allowances, from the point of view of GSO efficiency, could be greater than the present allowances for b
31、andwidth and/or power limited satellite networks. Note 7 - In segments of the geostationq-satellite orbit not likely to be crowded, an interference allowance less than that recommended iii 9 1 above, may be utilized, allowing a corresponding increase in other noise contributions within total accepta
32、ble noise limits. Note 8 - Although this Recommendation has been extended to an upper frequency limit of 15 GHz, in the frequency range from 10 to 15 GHz short term propagation data are not available uniformly throughout the world and there is a coiitinuing need to examine such data to confirm the a
33、ppropriateness of the interference noise allowances. Note 9 - There is a need for urgent study to be given to the interference noise c2110wances appropriate to systems operating at frequencies above 15 GHz. Note 10 - Particularly in cases where interference is caused by transmitters using code-divis
34、ion-multiple-access techniques, the interference from another fixed-satellite network referred to in 0 2 is the composite interference from all transmissions having overlapping spectra in that network. Note II - The expected level of carrier-to-interference ratio can be evaluated by using the methods provided in Recommendatiou 741 and other relevait CCIR texts.
