Opportunistic Relaying in Cooperative OFDM Networks for Throughput and Fairness Improvement

In this paper, we consider the downlink scenario of a cellular cooperative OFDM network, in which the vacant user in the cell could serve as relay for the base station and forward the downlink data streams. With the channel information of the users in the cell, the base station not only allocates the power and subchannels to the users, but also decides the relay strategy for each subchannel. We derive the optimal source-relay power distribution and the equivalent gain of the relay channel at first, then the opportunistic relaying strategy is given based on it. Further, we decompose the joint resource allocation problem into two subproblems of dynamic subchannel allocation (DSA) and adaptive power allocation (APA). A suboptimal algorithm with low computational complexity is proposed, and simulation results demonstrate that with the opportunistic relaying strategy and dynamic resource allocation, our algorithm greatly improves the throughput and fairness of the network.