Study On Elimination Method Of Multiple Access Interference In LED Visible Light Communication System

Visible Light Communication (Visible Light Communication (VLC) is a emerging wireless Communication mode that uses LED Light source for information transmission.It has the characteristics of high rate, no electromagnetic radiation, low cost, rich spectrum, good confidentiality and so on.Due to the multi-user VLC using address code is the unipolar code with poor correlation performance,exist more severe multiple access interference problems and reduces the size of the system.In this paper, combined with the development of the status quo at home and abroad, the algorithm of eliminating multiple access interference in indoor multi-user LED VLC is studied deeply. The main work includes:1. Analyzed the cause of the multiple access interference and the interference of different address code for the LED indoor VLC multi-access. Analyzed the LED light source layout on the effects of multiple access interference and the VLC indoor distribution of bite error rate.Light source layout optimization method is proposed, simulation Receive light power and bit error rate for the optimized layout of the light light source,to verify the effectiveness of the optimization method2. The OFDM-OCDMA system model is established, and the suppression effect of the correlation detection and the minimum mean square error detection on the multiple access interference in the static channel environment is analyzed. The feasibility of the linear detector to suppress the multiple access interference in the indoor VLC system is verified.3. A new RLS blind multiuser detection algorithm is proposed, and the expression of the adaptive forgetting factor is derived The effect of the algorithm on the suppression of multiple access interference in the indoor VLC system is simulated and analyzed.The results are shown that optimizing the layout of the light source can effectively improve the non-uniform distribution of multiple access interference and bit error rate.So the quality of communication is improved. Linear multiuser detection can effectively suppress multiple access interference and multipath interference in general indoor multiuser VLC system.An improved RLS blind multiuser detection algorithm for forgetting factor has the characteristics of fast convergence.