Detection Of Spatial Modulation Signals Based On Sphere Decoding

The classical Spatial Modulation(SM)technology can avoid inter-channel interference,inter-antenna synchronization,and multiple RF links in Multiple Input Multiple Output(MIMO)technology.Generalized Spatial Modulation(GSM)technology and Variable Active Antenna Spatial Modulation(VASM)technology are extension of the classical SM technologies,which improve the utilization of transmit antennas.Based on the basic principles of the classical SM,GSM and VASM schemes,this paper proposes a new type of spatial modulation scheme,which is called Modified Variable Active Antenna Spatial Modulation(MVASM).Compared to the other three spatial modulation systems,the MVASM system is more general,that is,the MVASM scheme provides a variety of alternative active antenna combinations.This paper presents an algorithm for MVASM scheme,which outputs multiple antenna combinations of MVASM scheme under the condition of the number of input transmitting antennas.From a variety of combinations,one of the SM,GSM or VASM schemes can be selected,and a more efficient active antenna combination scheme can be selected.In this paper,the theoretical upper bound formula of the bit error rate(BER),the upper limit formula of energy efficiency and the complexity calculation formula of the MVASM scheme under Maximum Likelihood(ML)detection are derived,and the above three are simulated by simulation.Formulas are validated.In view of the complexity of the MVASM-ML algorithm,this paper introduces the Sphere Decoding(SD)algorithm into the detection of the MVASM system,and designs the SD algorithm of two MVASM schemes: the transmitter-centered SD.(Tx)algorithm and improved SD(ITx)algorithm.In this paper,the complexity calculation formulas of these two algorithms are derived,and the BER performance and complexity of the two algorithms are simulated.The theoretical and simulation results of this paper show that the MVASM scheme is more flexible than the SM,GSM and VSAM scheme when using the SD algorithm.It can better achieve signal detection by selecting a suitable antenna combination.A good compromise between performance and detection complexity,where the MVASM-Tx algorithm is only suitable for high signal-to-noise ratios,and the MVASM-ITx algorithm can be applied for low signal-to-noise ratios.