1、Rec. 523-4 171 RECOMMENDATION 523-4 MAXIMUM PERMISSIBLE LEVELS OF INTERFERENCE IN A GEOSTATIONARY-SATELLITE NETWORK IN THE FIXED-SATELLITE SERVICE USING 8 BIT PCM ENCODED TELEPHONY, CAUSED BY OTHER NETWORKS OF THIS SERVICE (Question 50/4) (1978-1982-1986-1990-1992) The CCIR, considering a) that geos
2、tationary-satellite networks in the fixed-satellite service operate in the same frequency bands; b relative to its value in the absence of frequency sharing; that interference between networks in the fixed-satellite service degrades the bit error ratio performance c) different networks in that servi
3、ce should be such, as to give a reasonable orbit utilization efficiency; that it is desirable that the bit error ratio in networks in the fixed-satellite service caused by transmitters of d that the overall performance of a network should essentially be under the control of the system designer; e) n
4、etworks; that it is necessary to protect a network in the fixed-satellite service from interference by other such 0 that it is necessary to determine the maximum permissible interfering radio frequency power in a satellite system to establish space station and earth station characteristics such as r
5、equired protection ratios and minimum orbital spacing; s) into the earth station receiver; that networks in the fixed-satellite service may receive interference both into the space station receiver and h) be a controlled fraction of the total bit error ratio, as set out in Recommendation 522; that i
6、t is desirable that the increase in bit error ratio due to interference from other satellite networks should j) that where adjacent satellites serve networks with similar characteristics the largest interference contributions to a geostationary-satellite network will be from the networks using those
7、 adjacent satellites; but this may not be true where network characteristics are inhomogeneous; k) that the levels of interference between geostationary-satellite networks in the fixed-satellite service below 10 GHz are not expected to exhibit a large variation with time, and under these conditions
8、it is preferable to define the permissible interference limit as a fraction of the pre-demodulator noise power, as this allows multiple interference entries to be superimposed on each other on the basis of RF power addition; 1) that in frequency bands between 10 and 15 GHz where very high propagatio
9、n attenuation may occur for short periods of time, it would generally be desirable for systems to make use of adaptive up-link power control or earth- station site diversity or other techniques to counteract signal fading and that under these circumstances the levels of interference from other satel
10、lite systems would also not undergo a large variation with time; CCIR RECMN*523-4 72 H 4855232 05L8774 5T8 W 172 Rec. 523-4 m digital signal in the channel, that the carrier-to-interference ratio can be used to evaluate the degradation of the BER performance of a recommends 1. that networks in the f
11、ixed-satellite service operating in the same frequency bands below 15 GHz, and using geostationary satellites be designed and operated in such a manner that the total interference to an 1.2 in frequency bands in which the network practises frequency re-use, the interference power level, averaged ove
12、r any 10 min, should not exceed, for more than 20% of any month, 20% of the total noise power level at the input to the demodulator that would give rise to a bit error ratio of 1 in 106; 2. that the maximum level of interference power in any such 3. that the maximum level of interference noise power
13、 caused to that network should be calculated on the basis of the following values for the receiving earth station antenna gain, in a direction at an angle cp (in degrees) referred to the main beam direction: G = 32 - 25 log cp dBi for 1“ I cp 48“ G = -10 dBi for 48“ScpS 180“ except when the actual g
14、ain 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 regarded as part of this Recommendation: Note 1 -For the calculation of the limits quoted in 0 1.1, 1.2 and 2 it should be assumed that the total noise power at the inp
15、ut to the demodulator is of thermal nature. Note 2 - It is assumed in this Recommendation that the interference from other satellite networks is of a continuous nature; further study is required with respect to cases where interference is not of a continuous nature. Note 3 -The values quoted in 4 1
16、and 2 are not intended to apply: a) to networks for which a complete advance publication information was submitted to the IFRB by the time of the CCIR XIVth Plenary Assembly, 1978: for such networks the aggregate interference power level, averaged over any 10 min, should not exceed, for more than 20
17、% of any month, 10% of the total noise power level at the input to the demodulator which would give rise to a bit error ratio of 1 in 106; and the single- entry interference power level, averaged over any 10 min, should not exceed, for more than 20% of any month, 4% of the total noise power level at
18、 the input to the demodulator which would give rise to a bit error ratio of 1 in 106; b) to networks for which complete advance publication was submitted after the CCIR XIVth Plenary Assembly, 1978 and prior to the end of 1987: for such networks the aggregate interference power level, averaged over
19、any 10 min, should not exceed, for more than 20% of any month, 20% of the total noise power level at the CCIR RECMN*523-4 92 m 4855232 0538795 434 Rec. 523-4 173 input to the demodulator which would give rise to a bit error ratio of 1 in 106 for networks which do not practise frequency re-use, and 1
20、5% for those networks which do practise frequency re-use, and the single- entry interference power level, averaged over any 10 min, should not exceed, for more than 20% of any month, 4% (see Note 5) of the total noise power level at the input to the demodulator which would give rise to a bit error r
21、atio of 1 in 106. Note 4 - In some cases it may be necessary to limit the single entry interference value to less than the value quoted in $ 2 above in order that the total value recommended in Q 1 may not be exceeded. In other cases, particularly in congested arcs of the geostationary-satellite orb
22、it, administrations may agree bilaterally to use higher single entry interference values than those quoted in 8 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 $ 1 is exceeded. Note 5 - Th
23、e provisional single-entry value of 6% in 0 2 has provisionally replaced the 4% value, pending the results of studies to determine the most appropriate value, tng into account the increase in the effective number of interferers contributing to the aggregate interference because of the increasing use
24、 of spot becm antennas at space stations. Study of the relationship between the single-entry interference value quoted in Q 2 above and the aggregate interference values quoted in 0 1 is required as a matter of urgency. Note 6 - There is an urgent need for study of the acceptability of an increase i
25、n the maximum total interference noise values recommended in 8 1, since some studies have shown that the optimum interference allowances, from the point of view of GSO efficiency, could be greater than the present allowances for bandwidth and/or power limited satellite networks. Note 7 - In segments
26、 of the geostationary-satellite orbit not likely to be crowded, interference allowances less than those recommended in $ 1 above, may be utilized, ailowing a corresponding increase in other noise contributions within total acceptable noise limits. However, 8 1.1 and 1.2 above should normally be eval
27、uated with the assutnption that the total power noise level present is that which produces the specified bit error ratio under unfaded conditions of the received signal. Note 8 - Although this Recommendation has been extended to an upper frequency limit of 15 GHz, in the frequency r,ange from 10 to
28、15 GHz short-term propagation data are not available uniformly throughout the world and there is a continuing need to examine such data to confirm the appropriateness of the interference noise allowances. Note 9 - There is a need for urgent study to be given to the interference noise allowances appr
29、opriate to systems operating at frequencies above 15 GHz. Note 10 - The interference power levels indicated in 0 1 and 2 above apply only to the transmission of PCM telephony (see CCIR Recommendation 522 and CCIT Recommendation G.711). Further study by CCIR Study Group 4 is required regarding the pe
30、rformance objectives appropriate to the transmission of digital services other than PCM telephony, as information on the performance requirements of such services becomes available to the CCIR. Note I1 - Particularly in cases where interference is caused by transmitters using code-division-multiple-
31、access techniques, the interference from another fixed-satellite network referred to in 0 2 is the composite interference from dl tratismissions having overlapping spectra in that network. Note 12 - Methods to calculate the carrier-to-interference ratio are contained in Recoinmendation 741 and other relevant CCIR texts.
