Relay Aided Wireless Multicast Utilizing Network Coding: Outage Behaviour and Diversity Gain

Abstract

Broadcast nature of wireless networks can be exploited to provide a flexible transmission, especially in multicast service. The potential relay then is capable to participate in message forwarding. In this paper, we first presents a network coding based cooperative (NCBC) multicast scheme exploiting limited feedback, where the source transmits two separate signals to multiple destinations in two successive half slots. The relay may combine the signals if it received two signals correctly and forward it to destinations in the next half slot. The destinations, therefore, can recover signals either from direct transmission or the relay forwarding. The performance analysis on the developed NCBC multicast protocol is given in the viewpoint of physical layer, such as the outage probability and diversity order. It is demonstrated that the NCBC multicast scheme can work better than the source direct multicast in terms of outage probability. Meanwhile, the NCBC multicast scheme can achieve full diversity gain(diversity two for one relay case). Comparing with the known relay schemes, i.e., amplify-andforward (AF) and selection decode-and-forward cooperation schemes, it shows that the NCBC multicast scheme achieves almost the same outage performance with relatively less bandwidth and energy consumption.