A code division multiplexing scheme for satellite digital audiobroadcasting

摘要

Several systems are being considered for digital audionbroadcasting (DAB) and some of these systems will be deployed forncommercial use. In this paper, we consider a code division multiplexn(CDM) scheme for satellite DAB. For diversity purposes, this systemnmakes use of at least two satellites, and in urban areas, where thensatellite signals are shadowed by large structures, a terrestrialnnetwork is employed. We present a forward error protection (FEC) schementhat is robust under a variety of channel conditions, especially inncases where the received signal is severely attenuated because ofnhighway underpasses and tunnels. This FEC scheme makes use of timendiversity, and this introduces a large delay. Such delays will notnaffect the performance of broadcast systems; however, the delay will benan issue during tuning when a switch to another channel occurs. Wenintroduce a separate low-delay low-rate tuning channel to facilitatentuning. Extensive simulation results are given to examine thenperformance of the system, and it is shown that about 70 audio channels,neach with a rate of 96 kbit/s, can be satisfactorily supported in anbandwidth of approximately 12.5 MHz in most of the channel conditionsnconsidered