Broadcast reserved opportunity assisted diversity relaying scheme and its performance evaluation

Relay-based transmission can over the benefits in terms of coverage extension as well as throughput improvement if compared to conventional direct transmission. In a relay enhanced cellular (REC) network, where multiple mobile terminals act as relaying nodes (RNs), multiuser diversity gain can be exploited. We propose an efficient relaying scheme, referred to as Broadcast Reserved Opportunity Assisted Diversity (BROAD) for the REC networks. Unlike the conventional Induced Multiuser Diversity Relaying (IMDR) scheme, our scheme acquires channel quality information (CQI) in which the destined node (DN) sends pilots on a reserved radio resource. The BROAD scheme can significantly decrease the signaling overhead among the mobile RNs while achieving the same multiuser diversity as the conventional IMDR scheme. In addition, an alternative version of the BROAD scheme, named as A-BROAD scheme, is proposed also, in which the candidate RN(s) feed back partial or full CQI to the base station (BS) for further scheduling purpose. The A-BROAD scheme achieves a higher throughput than the BROAD scheme at the cost of extra signalling overhead. The theoretical analysis given in this paper demonstrates the feasibility of the schemes in terms of their multiuser diversity gains in a REC network.