Broadcast Overlay on Unicast via Superposition Coding and Interference Cancellation

There is an ever increasing interest in carrying point-to-multipoint broadcast/multicast services over existing and emerging cellular wireless systems. Techniques that provide increased spectral efficiency for broadcast services such as single frequency network operation by OFDM based transmission from multiple synchronized base stations are getting acceptance in wireless standards. In this paper, we propose and analyze a novel point-to- multipoint broadcast and point-to-point unicast traffic multiplexing and transmission approach based on broadcast traffic superposition and interference cancellation. The proposed approach superimposes the broadcast signal over the unicast traffic and cancels the broadcast signal before unicast demodulation and decoding. Using this approach, the broadcast interference to unicast traffic from own cell and neighboring cells can be eliminated thus improving the overall system capacity and efficiency by making full system bandwidth available to both unicast and broadcast traffic.