Research On Optimization Algorithms For Simultaneous Wireless Information And Power Transfer In Multi-Carrier Cooperative Communication

With the country's advocacy of green energy and the emphasis on energy scarcity,simultaneous wireless information and power transfer(SWIPT)has gradually been paid more attention.In the past SWIPT,most of the existing work is based on power splitting(PS)or time switching methods,which will lead to a reduction in subcarrier utilization and affect the quality of service.This paper studies the SWIPT scheme in multi-carrier cooperative communication.The main research contents of this paper are as follows:First,SWIPT for orthogonal frequency division multiplexing(OFDM)-based amplifyand-forward(AF)cooperative communication is proposed to save the relay's energy by harvesting the radio frequency(RF)energy from source node.In the first phase,the relay uses the subcarrier allocation method to receive information and energy from the source.In the second phase,the relay uses the energy harvested from the source to forward information from the source to the destination,while maximizing the rate of relay transmission to its own destination node.The simulation results show that our algorithm is 3% higher than the PSSWIPT algorithm,and 6% higher than the cooperative communication without energy harvesting.Second,the SWIPT in the OFDM-based decode-and-forward(DF)cooperative system is proposed.In the first phase,the relay receives information and energy from the source.In the second phase,the relay uses the energy harvested from the source to forward information from the source to the destination,while maximizing the rate of relay transmission to its own destination node.We allocate subcarriers by optimizing channel allocation and power allocation,thereby increasing the transmission rate of the relay itself under the constraints of energy harvesting and forwarding rate.Since the problem we are optimizing is non-convex,by using dual problems and iterative algorithms,the optimization problem is turned into a convex problem.The simulation results show that our algorithm is improved by 2.3% compared with the PS-SWIPT algorithm,and by 7% compared with the cooperative communication without energy harvesting.Finally,a time-frequency block allocation SWIPT(TFBA-SWIPT)system is proposed for OFDM-based DF cooperative communications,which allocates different time-frequency blocks for information decoding and energy harvesting at the relay and destinations.In the first phase,the relay uses the TFBA-SWIPT to decode information and harvest energy from the source.And in the second phase,the relay forwards the information both from source and itself to the corresponding destinations using the collected energy in the first phase.The joint allocation of time-frequency blocks and power is optimized to maximize the rate obtained by the destination node corresponding to the source,while ensuring the transmission rate and energy supply of the relay.Time-frequency block pairing algorithm and block power allocation algorithm are integrated to achieve the optimal solution.The simulation results show that our algorithm is 9% higher than the TFBA-SWIPT without block paring,12% higher than the subcarrier allocation algorithm,and 16% higher than the PS-SWIPT algorithm.