Superposition coding and network coding for mixed multicast/unicast traffic on a time-varying channel

Military applications often require traffic to be multicast to a group of receivers. It has previously been shown that linear network coding is useful in conjunction with physical-layer multicasting for reliable multicast delivery over fading channels. Superposition coding is an effective way to deliver information to a single receiver over a fading channel. However, we have shown in previous work that if the channel statistics are known and the parameters of the network coding and superposition coding are optimized, superposition coding does not provide a significant additional benefit for multicast traffic over fading channels when the fading gain is unknown. In this work, we propose the use of simulcasting to deliver a mix of multicast and unicast traffic to receivers over time-varying fading channels. We show that simulcasting can provide additional performance gains over using just network coding for several different cases where the source has exact or delayed knowledge of the channel state.