Joint subcarrier and power allocation method in wireless powered communication networks for OFDM systems

In this paper, we investigate wireless powered communication network for OFDM systems, where a hybrid access point (H-AP) broadcasts energy signals to users in the downlink, and the users transmit information signals to the H-AP in the uplink based on an orthogonal frequency division multiple access scheme. We consider a full-duplex H-AP which simultaneously transmits energy signals and receives information signals, and a perfect self-interference cancelation where the H-AP fully eliminates its self interference. In this scenario, we address a joint subcarrier scheduling and power allocation problem to maximize the sum-rate. In general, the problem is on-convex due to subcarrier scheduling, and thus it requires an exhaustive search method, which is prohibitively complicated to obtain the globally optimal solution. In order to reduce the complexity, we jointly optimize subcarrier scheduling and power allocation by applying the Lagrange duality method. Simulation results show that the proposed algorithm exhibits only negligible sum-rate performance loss compared to the optimal exhaustive search algorithm and a significant performance gain over conventional scheme.