Joint subcarrier and power allocation for uplink relay-enhanced OFDM systems

There has been a lot of research works considering the resource allocation of the downlink multihop orthogonal frequency division multiplexing systems. However, due to the distributed nature of the uplink power constraints, the resource allocation in the uplink multihop systems, where multiple mobile stations transmit to one base station with the aid of one or many relay stations, has much difference and has not been well investigated so far. In this paper, we originally study the joint subcarrier and power allocation problem for the uplink dual-hop transmission with the aim to maximize the system transmit rate. The resource allocation problem is approximated to be a concave maximization problem. By using mathematical decomposition techniques, the problem is first decoupled and solved by the proposed near-optimal method, which has low-computation complexity. Then, our algorithm is extended to the case with subcarrier matching on the dual hops. Numerical results show that our proposed algorithm improves the system transmission rate. Compared with the equal power allocation schemes, our algorithm can achieve significant gain in system transmit rate. Copyright (C) 2010 John Wiley & Sons, Ltd.