Design And Optimization Of Constellations For Spatial Modulation Systems

Spatial modulation(SM)is a multiple input multiple output(MIMO)technology proposed in recent years.Compared with traditional MIMO technology,SM has the advantages of low cost and high energy efficiency.Spatial modulation is a kind of multi antenna modulation technology,which activates an antenna in each time slot to send information.At the same time,the index of the activated antenna is also used to carry some spatial bit information.Therefore,the spectral efficiency of the spatial modulation system has been greatly improved.Because spatial modulation is a single RF link structure,it can effectively avoid the problems of inter channel interference and antenna synchronization,so spatial modulation has drawn a significant amount of attention.Spatial modulation(SM)is a kind of index modulation in 5G communication system.It uses the number of transmitting antenna and the modulation symbol to carry the transmitting information together.Through the optimization design of the constellation for SM systems,the performance of the spatial modulation system can be significantly improved.Therefore,researchers put forward a unified concept of performance comparison,that is,introducing the minimization criterion of symbol error rate of SM system in theoretical analysis,and according to the minimization criterion,some new constellation design algorithms are proposed.According to the algorithm,the constellation of star space modulation system is composed of multiple rings,and the radius of each ring is determined before it is applied to the communication system,so as to reduce the extra cost.The simulation results show that the improved constellation has more advantages than the traditional amplitude phase modulation(APM).Based on this background,this paper proposes a constellation design scheme of spatial modulation system with good performance,and proposes a new low complexity detection algorithm for the phenomenon of high complexity of detection algorithm of spatial modulation system.The main contents of this paper are as follows:(1)Due to the high complexity of constellation design in spatial modulation system,we design a new hierarchical constellation.The constellation maps information bits to each antenna index,and the specific symbol bits are determined by other information bits.This kind of hierarchical constellation can not only satisfy the application of spatial modulation multiple antenna system,but also satisfy the layered transmission of different priority information bits of hierarchical constellation;And the structure is regular,so the algorithm of constellation design has low complexity.(2)Due to the high complexity of current optimal spatial modulation system detection algorithm,the performance of low complexity algorithm is poor.Therefore,we propose a low complexity spatial modulation detection algorithm.A low complexity spatial modulation detection algorithm is also designed in this paper.The algorithm detects the antenna sequence and transmission symbols step by step.Therefore,compared with other spatial modulation system detection algorithms,the proposed algorithm is more efficient,The algorithm has the characteristics of low complexity.And according to the simulation results,the performance of the proposed detection algorithm is very close to that of the current optimal detection algorithm under the condition that the complexity of the algorithm is 40%-60% lower than that of the existing algorithms.(3)Finally,a new hierarchical constellation and a new detection algorithm are applied to the spatial modulation system,and the performance of the spatial modulation system is simulated and compared.In each chapter,the simulation comparison experiments and discussion results under different parameter settings are given.