Signal Detection Based On Sphere Decoding In Quadrature Spatial Modulation

Multiple input multiple output(MIMO)technology could provide multiplexing gain and diversity by erecting multiple transceiver antennas at sender and receiver.And MIMO also effectively improves the transmission rate and reliability of system,so that it becomes more attracted in wireless communication.Spatial modulation(SM)could improve spectral efficiency by exploiting the spatial dimension to transmit information.Meanwhile SM technology requires only one RF chain at the transmitter,so the inter channel interference(ICI)and inter antenna synchronization(IAS)can be complete avoided.Quadrature spatial modulation(QSM)is a new digital MIMO transmission technique to further increase the spectral efficiency of SM.In QSM,the spatial constellation symbols are expanded to in-phase and quadrature components.The first dimension transmits the real part of a signal constellation symbol on the cosine carrier and the other one transmits the imaginary part of the constellation symbol on the sine carrier.Hence,QSM can further increase the spectral efficiency,as compared with the conventional SM system.Moreover,QSM system also overcomes conventional MIMO drawbacks including ICI since the two-transmitted data are orthogonal and modulated on the real part and the imaginary part of the carrier signal.These advantages make QSM technology become one of the hottest technology in wireless communication technology.The thesis mainly studies the signal detection algorithm in QSM system and aims to find the detection algorithm with the best performance and low computational complexity.This thesis focuses on the traditional Sphere Decoding(SD)detection algorithm.Firstly,traditional SD algorithm is studied and analyzed.Then,two improved algorithms are proposed based traditional SD algorithm.The main work of this thesis is summarized as follows:(1)Briefly introduce some classical detection algorithms and analyze the traditional SD detection algorithm in QSM System.(2)An algorithm called Based Sorting of Weighting Factor Sphere Decoding(BS-SD)is proposed to solve the problem that high computational complexity of the traditional SD detection algorithm in QSM System.(3)An algorithm called Based Sorting of Signal Vector Based Detection Sphere Decoding(BSVD-SD)is proposed to further reduce computational redundancy of the traditional SD detection algorithm in QSM System.(4)Apply the proposed two improved SD algorithms in SM.Simulation results show that the proposed two improved SD algorithms can effectively reduce computational complexity with no bit error rate(BER)loss compared to traditional SD algorithm.