Opportunistic relaying for wireless multicasting

In this paper, we consider relay-aided wireless multicasting where one source transmits the same information to multiple destinations. We assume that there is a half-duplex regenerative relay station (RS) which may cooperatively assist the source. Our underlying problems are two-fold: when and how should the source and the RS cooperate to improve the multicast rate? Firstly, we show the required conditions for using the RS for wireless multicasting and propose opportunistic relaying strategies where the RS, when in use, forwards only partial information of the source. Thus, the proposed opportunistic relaying strategies lead to an efficient use of the RS. Secondly, we explain how we can maximise the multicast rate by optimising both the source transmission rate and the time sharing between the source and the RS. It is shown that the proposed opportunistic relaying strategies improve the multicast rate of one-hop (direct links only) wireless multicasting and they outperform other benchmarked relaying strategies.