Research On Low Complexity Detection Algorithms For Generalized Spatial Modulation Systems

Generalized Spatial Modulation(GSM),as an extension of Spatial Modulation(SM)technology,has been widely concerned by experts and scholars in the industry.Compared with SM technology,which only uses one antenna to transmit modulation symbols per time slot,GSM technology activates multiple antennas to transmit the same or different modulation symbols per time slot.It not only overcomes the disadvantages of SM technology,but also realizes spatial multiplexing and improves the frequency band efficiency.GSM system can get a better balance between hardware cost and spectrum efficiency by flexibly deploying the number of active antennas.Therefore,GSM technology occupies a very important part in the research of the new generation mobile communication technology.The GSM system that sends the same symbol is taken as the research object,and the signal detection problem at the receiving end of GSM system is mainly studied.The main contents and innovations are as follows:(1)Maximum likelihood(ML)detection algorithm in GSM system is very complex.In order to solve the high complexity problem brought by ML algorithm and improve the efficiency of detecting modulation symbols in GSM system,this thesis proposes an ordered block hard-limit decision maximum likelihood(OB-HLML)detection algorithm independent of modulation order M.The algorithm firstly sorts the possibility of transmitting antenna combinations,and then uses HLML detector combined with threshold to jointly detect antenna combinations and modulation symbols.Simulation results show that the proposed OB-HLML algorithm greatly reduces the computational complexity while ensuring almost the same detection performance as ML algorithm.(2)The difficulty and computational complexity of signal detection in large-scale GSM system with more antenna combinations are greatly increased.In order to improve the detection efficiency and symbol demodulation reliability of GSM system antenna combinations,two suboptimal detection algorithms are proposed in this thesis.One is the modified maximum ratio combining detection algorithm based on repetitive sorting strategy(MMRC-RS),which uses MMRC repetitive sorting strategy to select the most likely antenna combinations in detection.The other is the modified maximum ratio combining detection algorithm based on the iterative idea of the orthogonal matching pursuit(MMRC-MP),which screens out possible antenna combinations through limited iterations.(3)In the calculation of modulation symbols of MMRC-RS and MMRC-MP algorithms,the HLML algorithm(for M-QAM constellation)and LCML algorithm(for M-PSK constellation),which are suitable for SM systems and independent of modulation order M,are extended to GSM systems that send the same symbols.The simulation results show that for GSM systems with a large number of antenna combinations,the proposed MMRC-RS algorithm and MMRC-MP algorithm not only improve the detection efficiency of antenna combinations,but also achieve almost the same performance as ML algorithm,and the computational complexity is greatly reduced.