Joint relay selection, subcarrier pairing and power allocation for OFDM-based cooperative networks

In this paper, relay selection, subcarrier pairing and power allocation are investigated jointly to maximize the channel capacity for OFDM-based cooperative networks under a total power constraint. The problem can be formulated as a mixed binary integer programming problem, which is NP-hard and very difficult to manipulate. In order to achieve an acceptable performance with a proper complexity, we first solve the relay selection and subcarrier pairing problem under equal power allocation. Then, power allocation is performed according to the equivalent channel power gains of the subcarrier pairs using water-filling. Simulations are carried out to validate our analysis and show that the proposed scheme can achieve an acceptable capacity with a proper complexity.