Performance Analysis Of Cooperative MIMO Backscatter Communication System

With the rapid development of modern society,the problems of large energy consumption and scarcity of spectrum resources in the traditional Internet of Things have become more and more serious.The emerging Ambient Backscatter Communication(AmBC)is one of the core technologies supporting the passive Internet of Things,and cooperative transmission with cellular communication systems can further improve communication efficiency.Based on the above problems,this paper studies the effectiveness and reliability of the communication transmission of the cooperative MIMO-AmBC system.The main work and innovation are as follows:First of all,the effectiveness of the cooperative MIMO-AmBC system was studied and the ergodic rates of the Parasitic Symbiotic Radio(PSR)scheme were analyzed.Firstly,the approximate expressions for the ergodic rate of the primary link and backscatter link by using the PSR scheme of the MIMO-AmBC system were derived,and the upper bound expression of the ergodic rate of the backscatter link was obtained.Secondly,the influence of backscatter on the performance of the MIMO-AmBC system is analyzed and verified.The experimental results verify the validity of the theoretical derivation.The main conclusions are as follows: 1)The backscatter link rate increases logarithmically with the number of receiving antennas,but not with the number of transmitting antennas;2)The backscatter can improve the ergodic sum-rate;at low SNR,the primary link rate is not affected by the introduction of BD,but at high SNR,the BD rate is increased at the expense of the primary link rate.3)Suitable AmBC symbiosis scheme can be selected according to practical application.Secondly,the reliability research of the cooperative MIMO-AmBC system is studied,and the bit error rate under the PSR scheme is researched and analyzed.First,a SIC-based MRC detector is designed for the cooperative receiver under the flat fading model.The main link is modulated by QPSK,the backscatter link is modulated by BPSK,and the Rayleigh fading channel is used for transmission.Second,derive the closed-form expressions of the bit error rate of the MRC-SIC detector for the main signal and the backscatter signal;finally,the simulation results verify the reliability of the theoretical derivation and compare it with the MRC detector to conclude: 1)Use The bit error rate performance of the main signal and backscattered signal of the MRC-SIC detector is better than that of the MRC detector;2)The bit error rate performance of the primary signal and backscatter signal is positively increased with the number of receiving antennas,and the backscatter signal is improved better.