METHODS FOR THE REPEATED USE OF FREQUENCIES IN LOW-ORBIT SATELLITE-COMMUNICATIONS SYSTEMS

It is necessary to set up clusters of satellites in a particular struc ture that will include a specific number of satellites when designing satellite communications systems using low-orbit spacecraft for contin uous coverage of the service territory by radio visibility zones (RVZ) . As the satellites approach one another in orbit, their radio visibil ity zones overlap, thereby giving rise to mutual interference. To avoi d this, it is necessary to ensure that the signals from individual sat ellites are separated. A variety of signal separation methods are empl oyed, including frequency, time, waveform, spatial, polarization, etc. , separation. The problem here is to achieve maximum repeated use of f requencies by means of such methods on different spacecraft and thereb y minimize the total number of frequency bands required for each satel lite to transmit data with a specific carrying capacity without mutual interference. Note that these group frequency signal bands are determ ined not only by the number of partial channels and the transmission r ate but also by their type of modulation and the ''packing'' density o f channels on the frequency axis. However, this problem is not conside red in this paper.