Reliability Research Of MIMO Visible Light Communication System Based On Symmetric Matri

Traditional radio frequency communication leads to the shortage of spectrum resources,but visible light communication(VLC)can effectively use the new frequency band to alleviate this situation,and it has the advantages of high security,low cost,low electromagnetic radiation.However,visible light communication system has some problems such as low modulation bandwidth and small channel capacity,which lead to low transmission rate of the visible light communication system.In order to improve the transmission rate of the visible light communication system,researchers apply the multiple-input multiple-output(MIMO)technology to the visible light communication system to improve the transmission rate of the visible light communication system.The MIMO visible light communication system still has problems such as strong interference between channels that affect the communication reliability.In order to improve the reliability of the MIMO visible light communication system,the following studies are carried out in MIMO technology and precoding on the basis of symmetric matrix:Firstly,based on the low reliability of MIMO visible light communication system,a symmetric matrix based MIMO visible light communication system is proposed.In this paper,the basic principles of visible light communication technology and MIMO technology are described,and a MIMO scheme based on symmetric matrix is proposed.By using the repeatability of symmetric matrix elements,the minimum Euclidean distance between signals is extended to improve the reliability of MIMO visible light communication system.The theoretical and simulation results of the proposed scheme are compared in atmospheric channel and underwater channel,and the effectiveness of the proposed scheme to improve the reliability of MIMO visible light communication system is verified.By comparing with repeated coding(RC),spatial multiplexing(SMP)and spatial modulation(SM)schemes,it is proved that the proposed scheme can improve the reliability of MIMO visible light communication system better than other schemes.Then,for the MIMO visible light communication system based on symmetric matrix,because of the disadvantage that the subchannels obtained by singular value decomposition(SVD)have a big difference in signal-to-noise ratio,the geometric mean decomposition(GMD)scheme is introduced to obtain the subchannels with the same signal-to-noise ratio after decomposition.On this basis,a precoding scheme based on singular value decomposition and geometric mean decomposition and a symmetric matrix MIMO visible light communication system are proposed.The theoretical and simulation results of the proposed precoding scheme are compared in atmospheric channel and underwater channel,and the effectiveness of the proposed scheme improving the reliability of the MIMO visible light communication system based on symmetric matrix is verified.By comparing with the precoding scheme based on double singular value decomposition and the symmetric matrix assisted MIMO visible light communication system,it is proved that the proposed scheme can improve the reliability of MIMO visible light communication system based on symmetric matrix better than the precoding scheme based on double singular value decomposition.Finally,select different channel conditions in the atmospheric channel,underwater channel,atmospheric to underwater channel: transmission distance,water quality type,wind speed,change these conditions,respectively simulation of the two proposed schemes,the conclusion is: the shorter the transmission distance,the better the reliability of the system;The less particles contained in water,the better the reliability of the system.The lower the wind speed,the better the reliability of the system.