Alternate Convex Search Method for Resource Allocation in OFDMA AF Relay Networks with Energy Harvesting

Joint optimization of the source transmission power, the relay transmission power, and the time switching (TS) ratio is investigated in orthogonal frequency division multiple access wireless powered relay networks. The relay does not have embedded energy supply and needs to first harvest energy from the received signals from the source before using amplify and forward transmission strategy for forwarding transmission. Time switching scheme is used by the relay for wireless information and power transfer. The resource allocation problem aims at maximizing the sum rate under the source transmission power, the relay harvested energy, and the TS ratio constraints. The joint resource allocation problem is formulated as an optimization problem, which is non-convex and generally difficult to solve. Then an alternate convex search algorithm, which alternately finds the optimal solution to one kind of variables by fixing the other two kinds of variables, is proposed. The convergence of the algorithm is proven as well. Simulations verify the better performance of the proposed algorithm compared with two related algorithms.