Joint Subcarrier Pairing and Power Allocation for OFDM Two-Hop Systems

In this paper, we aim to maximize the weighted sum rate of Orthogonal Frequency Division Multiplexing (OFDM) relaying systems. In the considered system we jointly optimize subcarrier pairing in two consecutive time slots and power allocation on each subcarrier in each time slot. In addition, the destination combines the signals from the source and the relay pertaining to the same message in each two time slots. This is motivated by the lack of discussion in the literature on joint optimization with destination combining. It is assumed that the channel state information is known to the source. Decode-and-forward and half-duplex strategies are considered when the relay is used. Both total and individual power constraints for the source and the relay are investigated. Based on the optimization results, algorithms to achieve feasible solutions are also proposed. Simulation results show that the proposed algorithms almost achieve the optimal weighted sum rate, and outperform the existing methods in various channel conditions.