Research On Coverage Uniformity And Blind Equalization Algorithm In Indoor Visible Light Communication System

As the signal transmitter of indoor visible light communication system,LED should not only provide the whole indoor lighting,but also transmit information and data,so the lighting requirements and communication requirements should be considered when analyzing and designing the indoor visible light communication system.In practical application,the power distribution of indoor illumination and received light in traditional light source layout is extremely uneven,which not only causes eye discomfort,but also leads to a serious decline in communication quality.At the same time,due to the reflection of light from the wall and the influence of multiple light sources,serious inter symbol interference will occur in the communication process.Therefore,this paper will study and analyze these two problems based on intelligent optimization algorithm.The main work and research points are as follows:(1)The principle of illumination,received power and channel characteristics in VLC system with typical indoor light source layout are described and simulated.The results show that the illumination uniformity,received power uniformity and bit error rate on the receiving surface can't meet the lighting and communication standards,which points out the direction for the next optimization work.(2)Aiming at the shortcomings of early convergence and low precision of single intelligent optimization algorithm,a hybrid particle swarm optimization algorithm based on particle swarm optimization algorithm is proposed,and its performance test is carried out.The results show that the new algorithm has better performance than the basic particle swarm optimization algorithm in terms of convergence speed and convergence precision,which provides a theoretical basis for the next optimization of VLC system.(3)Aiming at the problem of uneven illumination and received power on the receiving surface in VLC system with typical indoor light source layout,a new layout scheme is proposed.On this basis,the concepts of position factor and power factor are introduced,and the hybrid particle swarm optimization algorithm is used to optimize the new layout.The results show that the optimized layout has improved the uniformity of illumination and received power obviously.(4)Aiming at the problem of inter symbol interference(ISI)in indoor VLC system,an amplitude transform CMA algorithm is proposed based on the traditional constant modulus algorithm.In order to alleviate the contradiction between the convergence speed and the steady-state error in the amplitude transform CMA algorithm,the idea of variable step size is introduced.The results show that the convergence speed of the new algorithm is faster in the early iteration,At the end of iteration,the steady-state error is reduced and the bit error rate of the whole system is reduced.Limited by the principle of CMA algorithm,the first part of the signal can't be well balanced,so this paper proposes a blind equalization algorithm based on hybrid particle swarm optimization algorithm.The results show that compared with the variable step size amplitude transform CMA algorithm,the new blind equalization algorithm has lower system error rate and clearer signal distribution.