Abstract
To maximize the spectral efficiency of a Decode-and-forward (DF) cooperative Orthogonal frequency division multiplexing (OFDM) system, we first propose the optimal power allocation algorithm when perfect Channel state information (CSI) feedback is available. Since perfect CSI feedback is unrealistic, we further propose a power allocation scheme using limited feedback, where the power allocation vectors for the source and relay are limited in two finite power allocation tables respectively. In this scheme, the destination chooses the power allocation vectors for the source and relay, and feeds the indices of the vectors back. The power allocation tables are designed by using the Lloyd algorithm. Simulation results show that the perfect CSI feedback power allocation scheme achieves the best performance, and that the performance of the limited feedback scheme lies between the perfect CSI scheme and the scheme with no CSI.