Research On Spatial Modulation Technology Of MIMO-VLC System

VLC is a kind of communication technology that transmits data by modulating visible light.It has attracted close attention of academia and industry,because of its advantages such as abundant spectrum resources without authorization,green energy saving,harmless to human body,high security,low cost and small interference.This paper focuses on the space modulation in MIMO-VLC system,and studies the following four problems: the design of generalized space modulation symbol set,the optimization of generalized zero forcing precoding,the joint precoding and equalization,and the joint optimization of precoding and equalization under rate matching in imaging receiver and non imageing receiver.The specific work is as follows:?.This paper studies the design of the optimal symbol set when GSM modulation is used in MIMO-VLC system.The design of GSM symbol set with adaptive PAM order is proposed,that is,the order of the active LED is determined by the specific CSI,and the LED with better CSI obtains higher PAM modulation order.The mathematical model of adaptive symbol set design is established.Taking the PAM modulation order and symbol set of each LED as optimization variables,and taking the Euclidean distance after the symbol passes the channel as the objective function,the corresponding optimization problem is derived On this basis.The corresponding AICGSM algorithm is proposed to solve the optimization problem.The simulation results show that under the same SNR and symbol rate,the BER performance of GSM symbol set design based on adaptive PAM order is better than that of GSM symbol set design based on fixed PAM order.?.The optimization of GZF precoding in multiuser MIMO-VLC system is studied.An improved GZF precoding method based on the combination of channel pseudo inverse matrix and block diagonal matrix is proposed.Taking the weighted rate sum and the weighted power sum as the objective functions and the precoding matrix as the optimization variables,the corresponding mathematical model of precoding optimization problem is established.An algorithm with lower computational complexity is presented.Simulation results show that under the same performance requirements,the proposed scheme has obvious computational complexity advantage over the original SVD-BD method,and the larger the scale of MIMO-VLC,the more obvious the complexity advantage.?.The joint optimization of precoding and equalization for multiuser MIMO-VLC system under imperfect CSI is studied.The corresponding mathematical model is established.With precoding and equalization matrix as optimization variables and power as constraints,the optimization problems of minimizing MSE and DC bias are formed respectively.The corresponding step-by-step iterative algorithm is given.Simulation results show that the proposed IA based joint precoding and equalization method can achieve better performance.?.The receiver selection in MIMO-VLC system and the precoding and equalization in different receivers are studied.The joint optimization scheme of precoding and equalization under rate matching is proposed.The joint optimization problem is established with the number of data streams,precoding matrix and equalization matrix as the optimization variables,with MMSE as the objective function.The step-by-step iterative solution algorithm is given.The performance of four modulation modes in imaging and non imaging receivers is simulated and analyzed,including the relationship between SER and SNR,the influence of LED interval on the condition number of channel matrix,and the performance comparison between the joint precoding and equalization scheme under the speed-up matching and the original scheme.The experimental results show that when the total number of data streams is fixed,the proposed joint precoding and equalization scheme can significantly improve the performance of the system,and the performance of the imaging receiver is significantly better than that of the non imaging receiver.