Performance Analysis And Research Of Space-time Coding In Bistatic MIMO Backscatter Communication System Over Nakagami-m Fading

Backscatter communication has shown a good application prospect in the Internet of Things and other fields in recent years due to the advantages of close to zero maintenance because its mobile tag end does not need to be equipped with batteries.However,due to the bidirectional fading characteristics of the physical channel of backscatter communication,its channel fading is more dramatic than that of conventional wireless channels.A common solution is to introduce Multiple-Input Multiple-Output(MIMO)technology into backscatter communication to significantly reduce fading and improve performance.The joint design of Block-Level Unitary Query(BUTQ)and Orthogonal Space-Time Block Coding(OSTBC)is a MIMO technique that can fully exploit the gain of MIMO backscatter channel diversity,which can significantly improve the performance of MIMO backscatter communication.The performance of this technique has been demonstrated in Rayleigh fading,however,its performance under Nakagami-m fading is still unknown.This paper mainly analyzes and studies the performance of space-time coding in bistatic MIMO backscatter communication system under Nakagami-m fading,and the main contributions of this paper are as follows:(1)In this paper,the method of conditional Moment Generating Function(MGF)is used to analyze the performance of bistatic MIMO backscatter communication system in detail,and the closed expression of the asymptotic symbol error rate and diversity order using the BUTQ-OSTBC design pair is obtained through strict mathematical derivation.The results show that for the M×L×N bistatic MIMO backscatter communication system with M query antennas,L tag antennas,and N receive antennas,the diversity order can be achievedL×min(M m_d,Nm_u),where_dm is the fading parameter of the forward channel and_um is the fading parameter of the backscatter channel.This is significantly different from the diversity order m LN achieved by conventional MIMO channels under Nakagami-m fading,and this diversity order is a generalized form of the diversity orderL×min(M,N)for MIMO backscatter channels under Rayleigh fading.(2)This paper compares and verifies the performance of the bistatic MIMO backscatter communication system through a large number of simulation experiments.Including the joint design of various queries and codes,various channel correlations,various modulation methods and various channel parameters.The simulation results are completely consistent with the theoretical analysis,and it also verifies the optimality of BUTQ-OSTBC in the above joint design scheme of query and encoding.This conclusion provides a certain theoretical basis for the study of bistatic MIMO backscatter communication system,and also provides more ideas for the design and development of future backscatter communication system.