Research On Layout Schemes Of Lighting For Indoor Visible Light Communication System

Due to energy saving and environmental protection and high sensitivity,no electromagnetic pollution,etc,white LED is used more and more in life and commercial lighting.Visible Light Communication(VLC)is based on the use of the high-speed switching characteristics of white LED,VLC modulates the signal to the white LED for information transmission,so white LED achieves the dual functions of communication and lighting.The optical transmitting antenna and the optical receiving antenna are the main components in the indoor VLC system,and its performances directly affect the reliability of the whole system and the stability of the signal transmission.The layouts of the lighting determine the performances of the transmitting antenna to a great extent.Therefore,the effect of layouts of LED light sources on the performance of indoor VLC system are studied.Firstly,the principles of white light emission,optical characteristics and amplitude properties of white LED lighting are introduced.As well as,the direct link model and diffuse link model of indoor VLC system are narrated.Secondly,we propose a double elliptic layout of lighting,which is better relative to the grid,circular and elliptic layouts in signal-to-noise ratio,quality factor as well as illumination distribution,genetic algorithm is used to optimize the layout of light source and proving when the total transmitting power of the system is the same,double elliptic layout of lighting is better.Again,in this paper,an improving SNR distribution method is proposed under the condition of ensuring the total transmitting power of the VLC system constant in double elliptic layout of lighting for indoor VLC system,that is improving the transmitting power of the corner LED arrays.The simulation results show that this improved scheme in the distribution of illumination,the distribution of signal-to-noise ratio and the quality factor are better than the original scheme,and verify the improved scheme is also applicable in in the grid,circular as well as elliptic layouts of lighting.Finally,the distribution of signal to noise ratio and quality factor in the receiving region of the system under considering the LOS and NLOS are studied.The results further prove that the proposed scheme can also effectively improve the performance of the system.