Subcarrier Pairing and Power Allocation Algorithm for OFDM Relay Systems with Delay QoS Guarantees

In this paper,the subcarrier pairing and power allocation algorithm for OFDM decode-and-forward(DF) relay systems with direct link is investigated.The goal is to maximize the system throughput while meeting the delay QoS requirements of transmission services.Firstly,by integrating the effective capacity model,the subcarrier pairing and power allocation problem is formulated as a mixed integer programming problem.Then,the problem is transformed into a continuous relaxed convex problem.By using the convex optimization theory,the optimal solution of the primal problem is obtained,and an alternative algorithm to achieve jointly optimal subcarrier pairing and power allocation is proposed.The derived analytical and simulation results show that both the optimal subcarrier pairing and power allocation depend on not only the channel quality of the subcarriers but also the delay QoS requirements of the service.Compared with the existing algorithms,our proposed algorithm achieves the highest effective capacity.