Transceiver Design For MIMO-VLC Svstems

Visible light communication(VLC)has many advantages,such as rich spectral resources,small radiance,good secrecy,low cost and low energy consumption.It is a new wireless transmission technology that is widely concerned.The introduction of MIMO technology can make the system get higher transmission rate.In this paper,the beamforming technology and adaptive equalization technology in indoor VLC system are studied deeply.The MIMO transceiver with light power constraint is designed and extended to multi-user situations.The main contents of this paper are as follows:Firstly,a transmission structure which combines the space time coding and beamforming is proposed for the MIMO-VLC system.First,according to the characteristics of the transmitted signal in the visible light system,the block coding technology in the traditional wireless communication is modified and applied to the MIMO-VLC system.Then,the beamforming of the coded signal is done again,and the receiver adopts the maximum likelihood decoding method.The simulation results show that the combination of the beamforming and space-time block coding can achieve full gain while obtaining a certain array gain.Secondly.Aiming at SISO-VLC system,an improved LMS receiver equalization algorithm based on exponential function and hyperbolic tangent function is proposed.Based on the introduction of adaptive equalization and classic LMS adaptive algorithm,the traditional LMS algorithm is improved to SISO-VLC system,which improves the convergence speed of the algorithm.Thirdly,according to the MIMO-VLC system in single user scenarios,the intensity of signal transmission of LED to satisfy the constraint conditions,the maximum SNR based on pre coding matrix gives the transmitting and receiving end joint optimization of equilibrium matrix;and through the method of pre coding matrix and equilibrium matrix iterative solution method,proposed the joint optimization problems.The simulation results show that the transceiver based on this optimization method has a significant advantage in the bit error rate performance.Lastly,according to the multi-user MIMO-VLC system,interference problems between different users,each user on SLNR as optimization object,the optical power constraints combined with the proposed conditions,the equilibrium matrix for the transmitter precoding matrix and the receiving end to carry out the optimization design.The simulation results show that the transceiver based on the proposed scheme has more advantages in the bit error rate performance.