System Level Performance of Broadcast/Unicast Service Overlay using Superposition Coding

Abstract

System level performance of a broadcast/unicast superposition coding system is considered. Cellular network for unicast service only is considered as interference limited system, where increasing transmission power does not help improving network throughput. It is the case especially when frequency reuse factor is close to 1. In such case, the amount of power that does not contribute to improving throughput can be considered as "unused." This situation motivates to use the unused power for broadcast service, which can be efficiently provided in OFDM based single frequency network (SFN) as of the digital video/audio broadcast system. In this paper, we investigate the performance of such an overlay system where single frequency broadcast network is superimposed over unicast cellular service, namely, BC/UC superposition coded system (supercast). Alternative service multiplexing using FDM/TDM will also be investigated for comparison.