Simultaneous Wireless Information and Power Transfer for OFDM-based Cooperative Communication

In cooperative communication, relay reduces the stored energy for its own transmission due to the energy consumption for forwarding the information from source node. In this paper, simultaneous wireless information and power transfer (SWIPT) for OFDM-based cooperative communication is proposed to save the relay's energy by harvesting the radio frequency (RF) energy from source node. Subcarrier allocation based SWIPT (SA-SWIPT) is designed to use different subcarrier sets for information decoding and energy harvesting. In the first phase, the relay uses the SA-SWIPT to receive information and energy from source node. And in the second phase, the relay forwards the information both from source node and itself to the destinations using the energy collected from source node. The transmission rates of the relay in DF and AF modes are maximized by jointly optimizing subcarrier allocations and subcarrier powers, respectively, while ensuring the required transmission rate of source node and the energy supply of relay. An efficient iterative optimization algorithm is proposed to solve the proposed optimization problem through Lagrangian dual decomposition. Simulation results show the convergence of the optimization algorithm after very few iterations and explains the potential benefits for using SA-SWIPT in the OFDM-based cooperative communication.