Optimization Algorithm For Resource Allocation In Simultaneous Wireless Information And Power Transfer(SWIPT) System

In recent years,more and more scholars pay close attention to the technology of simultaneous wireless information and power transfer(SWIPT).SWIPT refers that a receiving node both have the ability of energy harvesting and information reception.The RF signal transmitted by the transmitting node carries energy information.After receiving the RF signal,the terminals use parts of the received RF signal to decode the information and the others are stored in the battery.This is a promising solution of energy storage for terminals and extending the battery life.The relay cooperative network plays an important role in improving the spectrum utilization and increasing the capacity.SWIPT and relay cooperative network provide a new solution for wireless communication system.The contributions of this paper are as follows:First,consider the downlink,multi-input single-output system and using PS mode for SWIPT,the design of the second-order convergence optimization algorithm(SOCP)to solve the non-convex problem.It can be seen from the experimental results that compared with the greedy algorithm,the convergence of the algorithm is faster and the performance is improved greatly.While the terminals' battery capacity is limited,we designed the battery model for the terminal to update energy.We maximize the user rate and the iterative updating of each time slot of the battery is taken into account,considering of the relationship between the maximum user rate and the battery model.Secondly,we consider the SWIPT in two-hop AF relay transmission,two-hop DF relay transmission and deeply analyzed outage probability optimization problem.The Lagrangian duality algorithm and the one-dimensional search are used to obtain the optimal power splitting factor.Transmit Power,SNR and power divider factor of two-hop AF relay transmission and DF relay transmission are given,and the relationship between the actual value and the theoretical value of the optimal power splitting factor is verified by simulation.In addition,the relationship between the transmission distance and the outage probability between the two hops is verified,and the optimal location of relays and the optimal power allocation scheme are proposed.The feasibility of the proposed algorithm is proved by simulation.The optimized placement of the optimized relay is obtained,which proves that the optimal power splitting factor is almost the same as the actual experimental value.Thirdly,when we used two-hop DF relay transmission in SWIPT,the SNR ratio received by the first hop affects the SNR reception of the second hop.The outage prob?ability expression in the simplified process encounters the non-integrable form,so the Taylor approximation method is used to calculate,finally,the error of the approximate method is analyzed experimentally.At the same time,the scheme of relay probability selection based on outage probability is proposed to maximize the terminals' user rate.At present,some relay cooperative networks that adopt DF mode work in the grid-powered scenario mostly,and the relay power isn't influenced by the power of base station.While in transmission scenario,the relay can receive both energy and information,and it is the same RF signal.The energy received by the relay is used to energy storage and provide the power of forwarding information.Therefore,the amount of energy received will affect the subsequent information forwarding.In this paper,the relationship between outage probability and power splitting factor,base station transmit power,and the distance be-tween two hops is deduced by Taylor approximation.The advantages of the proposed transmission protocol can also be seen from the simulation.