Research On Key Techniques Of SWIPT In Multi-Carrier Communication System

With the development of wireless communication,energy consumption has become a main obstacle of wireless communication development.Simultaneous wireless information and power transfer(SWIPT)can compensate electric energy to receiver by using signal radio frequency energy and transmit information meanwhile.It provides the possibility of solving information and energy simultaneous transmission.Most existing algorithms of SWIPT for orthogonal frequency division multiplexing(OFDM)receiver are studied based on power splitting and time splitting,which lead to low subcarrier utilization.In this context,SWIPT algorithm in multi-carrier communication system is proposed in this paper.The theories analysis and performance simulation of proposed algorithm are also given.Firstly,the basic theories of multi-carrier SWIPT communication which contain multi-carrier,OFDM,SWIPT technique and cooperative relay communication are described in this paper.And then,optimization theories including convex optimization,Lagrange function and KKT conditions are also introduced.On the basis,the liner water-filling algorithm applying to traditional SWIPT communication which can allocation power adaptively is also introduced.Next,due to the low subcarrier utilization of power splitting and time splitting,an algorithm based on subcarrier allocation in multi-user OFDM system is proposed.The subcarriers in receiver are divided into two parts.One part is used for information decoding and the other part is used for energy harvesting.Under constraint of energy harvesting,the algorithm optimizes power and subcarrier allocation jointly by convex optimization and iterative calculation.Simulation results show that the proposed algorithm realizes resource optimization allocation.What's more,it can achieve higher sum rate than conventional algorithm and converges fast.Finally,considering when the channel condition of direct transmission is not good,an algorithm based on subcarrier allocation in cooperative OFDM communication is proposed.The algorithm adopts amplify-and-forward protocol.The relay node transmits information from source node to destination node by using a part of subcarriers.And remaining subcarriers are used for energy harvesting.In the premise of lowest energy harvesting,the algorithm optimizes subcarrier allocation and subcarrier power of relay node by establishing and solving optimization model.Simulation results show that the proposed algorithm not only realizes optimal allocation of subcarrier and power under situation of bad channel condition of direct transmission but also can achieve higher throughput and converges fast.