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

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. This paper presents a network coding based cooperative (NCBC) multicast scheme exploiting limited feedback. In the developed NCBC multicast scheme, 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. In this paper, performance analysis is presented in terms of outage probability and diversity order. It is demonstrated that the NCBC multicast scheme can work better than direct source multicast in terms of outage probability. Meanwhile, the NCBC multicast scheme can achieve full diversity gain (diversity two for one relay case). Comparisons with amplify-and-forward (AF) and selection decode-and-forward cooperation schemes shows that the NCBC multicast scheme achieves almost the same outage performance as AF and selection decode and forward while consuming less bandwidth and energy resources.