Maximizing achievable rate for improved AF-OFDM cooperative transmission

This manuscript develops an improved AF-OFDM (Amplify-and-Forward, Orthogonal Frequency Division Multiplexing) scheme where selective relaying policy is fully utilized to promote the spectrum efficiency of cooperative transmission, and presents an achievable rate maximizing resource allocation strategy subject to a sum-power constraint. The high computational complexity for optimization necessitates our investigation of suboptimal approaches. The proposed centralized algorithms can be implemented in a step-by-step manner. Specifically, the binary selective relaying policies are first decided for each subcarrier according to instantaneous or statistical channel state information. Then, relay selection might be conducted by those subcarriers who would like to choose a relay to assist their data transmission from network achievable rate maximization perspective, and finally power loading can be mathematically solved by employing standard Lagrange techniques. Numerical results are shown to illustrate the benefits of the improved AF-OFDM cooperative protocol with optimized resource allocation.