Performance Analysis And Research Of Multi-Source Relay Cooperative System Based On Energy Harvesting

With the progress of science and technology,the demand of wireless communication in modern society is increasing;Meanwhile,people pay more attention to the more reliable and efficient communication services.Cooperation technology can realize spatial diversity and improve communication system performance,and effectively solve the problem of weak coverage of cell edges and prolong information transmission distance.Energy harvesting technology can harvest energy from surrounding radio frequncy(RF)signals to extend the life of system.Thus,the combination of Cooperation techniques and energy harvesting technology enables reliable green communications.This paper focuses on the analysis and research of the multi-source relay cooperation system based on energy harvesting.Two coding schemes which empoy low density parity check(LDPC)codes and repeat accumulate(RA)codes are used in the source and relay nodes.The performance of outage probability,bit error rate and complexity of the system is analyzed.The power allocation of the cooperation system is also studied.The main contents are as follows:(1)The multi-source coded cooperation system is studied.Firstly,the regular LDPC codes are used in the cooperation system.From the viewpoint of the destination,the overall parity-check matrix corresponding to the coded cooperation system is deduced,and the steps of decoding and the decision method under two different iterative decoding algorithms are analyzed.We also derive the outage probability in the ideal coded cooperation system.Secondly,for additive white gaussian noise(AWGN)channels,by introducing the notation of average signal-to-noise ratios(SNRs)in the destination,the Point-to-Point transmission model corresponding to the coded cooperation system is set up.The problems in the coded cooperation system may be transferred to the Point-to-Point transmission model,and the problems are simplified.Finally,on the basis of the above research,the coding steps,joint iterative decoding algorithm and outage probability of the multi-source coding cooperative system are studied.(2)A multi-source RA coded cooperation system based on energy harvesting and network coding is studied.Firstly,network coding technology is used to solve the information merge processing of multiple source nodes,and the advantages of network coding technology is highlighted.Secondly,RA codes are applied to the system,and its code words have the characteristics of systematic and differential coding.The bit error rate(BER)performance of the dual-source single-relay RA coded cooperation system is studied.The simulation results show that the proposed system is better than that of point-to-point system under the same conditions.Finally,The water-filling algorithm is adopted to the relay of the system,which solves the energy limitation problem of the relay node.Compared with the power average allocation algorithm and the antenna selection algorithm,this algorithm improves the system channel capacity,and reduces the system outage probability.(3)The optimization of power splitting factor for multi-source relay cooperation system based on energy harvesting is studied.For the case where there is no direct transmission link between the source node and the destination node in the cooperation system,the space-time coding cooperation mode is used to restore the original transmission information at the destination.Firstly,we consider the higher priority of a certain source node in the system,the power splitting factor of the relay node is optimized,and the channel capacity of the source node to the destination node is maximized.Secondly,the channel capacity of the two sources to the destination is further considered simultaneously,the two sources have no priority difference,and the channel capacity of the entire cooperation system is maximized by optimizing the power splitting factor.Finally,the simulation results show that the system channel capacity is improved by optimizing the power splitting factor;As the power conversion efficiency and signal-to-noise ratios increase,the channel capacity of the system is improved.