Joint Optimization Scheme for Power Allocation and Subcarrier Pairing in OFDM-Based Multi-Relay Networks

We consider an OFDM-based multi-relay network in this letter, where a certain subcarrier pair can be forwarded by the source node and multiple relays to provide space diversity. A joint optimization scheme for power allocation (PA) and subcarrier pairing (SP) is proposed to maximize the total end-to-end transmission rate under a total power constraint. The optimization problem is simplified by introducing the definition of equivalent channel gain, and a new PA scheme based on the Cauchy–Schwarz inequality is provided in this letter. Then a suboptimal scheme, which can provide similar performance with lower computation complexity, is proposed. Simulation results show that the proposed schemes outperform other schemes with or without space diversity.