Research On MIMO Wireless Transmission Technology Based On Spatial Modulation

Spatial modulation(SM)belongs to the technical category of multiple input multiple output(MIMO).It transmits data not only in the time dimension but also in the serial number of the transmitting antennas(i.e.spatial dimension)based on the fact that there exist channel differences between different transmitting and receiving antennas.Compared with the traditional MIMO system,SM system only needs fewer radio frequency(RF)links,which can greatly reduce the implementation cost while keeping the system performance unchanged,and effectively overcome the problem of inter-channel interference(ICI)and possible unsynchronization between antennas.SM technology has become a new research direction of MIMO technology.Although SM technology has obvious advantages,the traditional SM technology only selects one of the antennas to transmit signals according to the antenna mapping results.Obviously,there is still much scope for improving the spectral efficiency through optimizing the system structure.Secondly,because the key idea of SM technology is to use the channel difference of antennas to carry the transmission information,when the number of available antennas is greater than that of the antennas actually needed,the antenna selection algorithm has a great impact on the performance of SM system,while the existing algorithm has the disadvantage of very high computational complexity,so it is necessary to reduce the complexity of the algorithm or compromise the complexity and system performance.In addition,the high peak-to-average power ratio(PAPR)of orthogonal frequency division multiplexing(OFDM)signals also exists in SM-OFDM systems.Furthermore,due to system differences,the PAPR suppression method of traditional OFDM systems cannot be directly applied to SM-OFDM systems,so it is very necessary to carry out special research on it.According to this,this paper focuses on the system structure,the selection of transmitting antenna and PAPR suppression of SM-OFDM system,and proposes corresponding improvement methods for the shortcomings of the current research results.The main work of this paper are as follows:1.The mathematical model,block diagram and working principle of SM system are established,and two extended spatial modulation technologies named quadrature SM(QSM)and generalized SM(GSM)are introduced.2.For QSM system,the existing antenna selection algorithm based on the maximization of the minimum Euclidean Distance(ED)is studied.The antenna selection process is mainly analyzed,and on this basis,a low complexity antenna selection algorithm is proposed.3.For single-carrier GSM system,the inadequate of the antenna selection algorithm based on ED criterion are analyzed,and two antenna selection algorithms based on module sorting and combination of module sorting and Euclidean distance are proposed.Theoretical analysis and simulation results show that the complexity of the antenna selection algorithm based on modular ordering is greatly reduced but the performance loss is large,while the antenna selection based on the combination of modular ordering and Euclidean distance can effectively reduce the computational complexity while maintaining the system performance.4.For multi-carrier GSM system,an antenna selection algorithm base on minimum modulus maximization criterion is proposed and compare with that antenna selection algorithm based on ED criterion.In addition,this paper also studies the relationship between system performance and subcarrier number,which can provide reference for system parameter design.5.Aiming at the problem of high PAPR in multi-carrier SM signals,PAPR suppression methods are studied from two ways of non-distortion processing and distortion processing respectively.In the non-distortion method,this paper proposes a preprocessing method of adding scrambling code to the transmitter.By adding scrambling code,the probability of constant phase signal is greatly reduced,thus changing its PAPR characteristics.In the distortion processing method,this paper analyzes the PAPR suppression method of clipping,focuses on how to effectively reduce the influence of clipping noise,and proposes a processing method of clipping noise extraction-noise reconstruction-noise cancellation,thus effectively reducing the loss of system performance caused by clipping processing.Through theoretical analysis and MATLAB simulation,the performance of the proposed algorithm is verified.