Research On Spatial Modulation Signal Detection Technology In 5G Wireless Communication

Spatial modulation(SM)is a new type of multiple input multiple output(MIMO)technology,which has the characteristics of low radio frequecy overhead,simple hardware implementation,and reliable transmission performance,thus it becomes the physical layer technical proposal of fifth generation(5G)mobile communication.In order to adapt to 5G large-scale MIMO scenarios,it is necessary to develop multi-user and large-scale multi antenna systems with more transmit antennas.In order to be compatible with 5G multicarrier modulation,the concept of SM can be further extended to the frequency domain to form the orthogonal frequency division multiplexing with index modulation(OFDM-IM),which has the advantages of high spectral efficiency,strong resistance to multipath effect,low peak to average power ratio(PAPR)and less inter-carrier interference.In addition,the concept of SM and IM can also be extended to the orthogonal time frequency space(OTFS)technology.In this way,the above multidimensional modulation is endowed with both high frequency spectral efficiency and high diversity gain,thus it has became a candidate scheme for 5G high-speed mobile scenes.Against the above background,firstly,a series of low complexity and high performance detection algorithms are designed for the issues of spatial interference in multi-user and large-scale multi antenna systems;Secondly,the issues of frequency domain subcarrier interference elimination and time domain clipping interference elimination are studied for the multi-dimensional generalized space-time-frequency index modulation(GSTFIM);Finally,the new system is obtained by combining the SM and OTFS,the the signal detection in the system is studied.In general,the work of this paper mainly includes the following aspects:In the second chapter,the basic model of SM and the traditional detection algorithm are introduced.For multi-user SM systems,a pair of detection algorithms based on approximate message passing(AMP)are proposed: threshold-aided AMP(T-AMP)algorithm and probability-ranking-aided AMP(P-AMP)algorithm.Specifically,the T-AMP algorithm employs the threshold to reduce complexity,while the P-AMP algorithm improves the transmission performance of the system by reconstructing search space.In the third chapter of this dissertation,the threshold-aided layered message passing(T-LaMP),probability-ranking-aided layered message passing(PR-LaMP)and AMP detection algorithms are proposed for large-scale generalized spatial modulation(GSM)systems.Specifically,the T-LaMP algorithm judges the reliability of the estimated signal by the pre-set threshold,so as to reduce the number of iterations and the complexity;The PR-LaMP detection improves the detection performance by increasing search space;The AMP detection improves the system performance by reconstructing the non-Gaussian interference variables and reduces the complexity by avoiding the minimum mean-square error(MMSE)operations.In the fourth chapter,the carrier frequency offset(CFO)problem in the GSTFIM is researched,and two soft iterative detection algorithms based on MMSE criterion and message passing are proposed to eliminate the frequency domain interference,respectively.The proposed algorithms employ the prior information to reconstruct the interference,and then cancle the interference for the purpose of improving the system performance.On the other hand,for the clipping model of GSTFIM systems,two iterative interference cancellation detection algorithms based on symbol feedback and soft information are proposed,respectively.The proposed methods reconstruct the clipped noise by letting the hard decision GSTFIM symbols go through the same clipping process with the transmitted symbols,and then the interference cancellation operation is carried out to eliminate the clipping noise.Finally,in the fifth chapter,the generalized spatial modulation orthogonal time frequency space(GSM-OTFS)system is proposed by combining SM and OTFS.In order to solve the detecton problem of this new system,three detection algorithms are proposed by employing the space-time-frequency structure characteristics of the symbol,which are the decision feedback equalization algorithm based on the MMSE criterion,the detection algorithm based on generalized approximate message passing(GAMP)and the low complexity GAMP detection algorithm based on the diagonal characteristics of the channel matrix,respectively.The proposed algorithms are capable of effectively counteracting multipath interference and balancing the system performance and the complexity flexibly.