Resource Allocation for OFDMA Relay-Enhanced System with Cooperative Selection Diversity

The cooperative selection diversity (CSD) scheme which dynamically selects the best transmission scheme between decode-and-forward relaying and direct transmission outperforms the other complex cooperative diversity schemes in terms of throughput and implementation complexity. In this paper, we formulate the optimal resource allocation problem with a fairness constraint in the downlink of OFDMA relay-enhanced system when CSD based transmissions are considered. The problem is linearized into a binary integer programming problem by using a constant power allocation. To solve the linear programming problem, we proposed a heuristic joint path selection and sub-channel allocation algorithm. Moreover, a void filling algorithm is designed to make full use of the resources. Simulation results demonstrate that our path selection rule based on the end-to-end achievable data rate and the void filling algorithm achieve more system throughput especially when the proportion of the two zones used in the two-slot relaying pattern is far away from the optimal value. The heuristic resource allocation algorithm provides a suboptimal solution to gain a tradeoff between system throughput maximization and fairness.