Research On Visible Light Communication System Based On Polar Codes

At present,with the development of wireless communication technology,people's communication demand is increasing,but the spectrum resources of wireless electromagnetic wave are decreasing,which forces people to find new wireless communication technology.Fortunately,visible light has a wealth of spectrum resources that have not been exploited yet,and has excellent confidentiality.Because of these advantages of visible light communication,people begin to study visible light communication and make full use of visible light band.As a new type of error correcting code,polar code has been widely concerned since it was put forward because of its clear encoding and decoding structure and Shannon capacity,and has become a research hotspot in the field of communication.Based on the basic principle of polar code,this paper applies polar code to visible light communication system to improve the reliability of the system.The channel polarization principle of polar code points out that the reliability of each polarized sub-channel is arranged by channel merging and channel splitting operation,and the sub-channel with the best reliability is selected for information bit transmission.In this paper,we propose an improved construction method of Bhattacharyya parameters method for Nakagami-m channel,which has general and universal significance.By using the transmission characteristics of Nakagami-m channel,the initial value of Bhattacharyya parameters is recalculated.According to boundary conditions of Bhattacharyya parameters proposed by Arikan,the Bhattacharyya parameters of each polarized subchannel are calculated.In theory,as long as all the parameters satisfying the boundary conditions of the Bhattacharyya parameters are obtained and sorted,the best information bit selection scheme for different Nakagami-m channels can be obtained.On this basis,according to the boundary conditions of Bhattacharyya parameters,three kinds of calculation schemes of Bhattacharyya parameters are put forward in order to obtain the better scheme of information bit selection.The simulation results show that the polar code constructed by this scheme can significantly improve the transmission performance of Nakagami-m channel,and even surpass LDPC code under certain conditions,which has good applicability.As an outdoor application of visible light communication,marine communication is the focus of this paper.In view of the transmission channel of the maritime visible light communication system,the marine atmospheric turbulence channel,the polar code construction scheme proposed in this paper is used to construct the polar code.Through the simulation of different code length,code rate,decoding scheme and turbulence intensity on the performance of the constructed polar code,it is proved that the polar code has good application performance in the maritime visible light communication system and can improve the transmission performance of the system.In addition,the simulation results also show that under some conditions,the performance of polar code is better than LDPC.Under the condition of signal-to-noise ratio greater than 8 d B,polar code can even replace LDPC code in the maritime visible light communication system.