Research On Low Complexity Algorithms Of Spatial Modulation MIMO System

Spatial Modulation(SM)technology is an extension of Multiple-Input Multiple-Output(MIMO)technology.Its excellent performance has attracted widespread attention as soon as it is proposed.Compared with MIMO,SM has simple structure,and can effectively balance the spectrum efficiency and energy efficiency,and has great potential in meeting the needs of future wireless communication technology.After years of development,many SM evolution technologies have emerged.This article takes SM technology as the starting point and aims at low complexity,and studies SM and its evolution technologies.The main work innovations are as follows:(1)In order to solve the problem of high complexity of random search scheme in Space-Time Shift Keying(STSK)dispersion matrix optimization,a low complexity optimization scheme is proposed in this paper.Firstly,the elements in the dispersion matrix are discretized to reduce the search space of the candidate dispersion matrix set,thereby turning the optimization problem in the infinite space into the finite space;and the optimization problem of the saturation level in the process of generating discrete data is analyzed,the expression of the total quantization noise variance is derived.Secondly,based on the generated discrete data,an iterative optimization algorithm is proposed to optimize the dispersion matrix.The complexity and simulation analysis show that compared with the conventional random search scheme,the optimization scheme can significantly reduce the complexity of the dispersion matrix optimization process and can obtain the Bit Error Rate(BER)performance almost equal to that of the conventional scheme.(2)A low-complexity joint mapping table selection algorithm is proposed for the JM-GSM system.Different from most existing algorithms,the algorithm proposed in this paper uses the Channel State Information(CSI)fed back from the uplink to select the mapping table.The algorithm first builds a table for storing the Euclidean Distance(ED)between all vectors in the joint mapping table.In the process of constructing the table,it reduces the complexity by avoiding repeated calculations.During the execution of the algorithm,only the non-repeated elements in the table need to be operated.This method avoids the exhaustive search process and reduces the algorithm search steps.Compared with exhaustive search algorithm,this algorithm greatly reduces the complexity.The simulation results show that the algorithm can achieve excellent BER performance in different systems.(3)A low-complexity detection algorithm is proposed for the JM-VSM system.The algorithm first proposes a joint mapping vector sorting method based on the Modified Maximum Ratio Combining(MMRC)algorithm,which sorts all vectors in the joint mapping table according to the probability of being selected as a transmission vector,putting the vector with high probability at the front of the joint mapping table,and putting the vector with low probability at the back.Then the SD algorithm is used to detect the sorted joint mapping transmission vector set.Simulation and complexity analysis show that the algorithm can obtain the best detection performance,and at the same time can significantly reduce the detection complexity.