Study On Performance Of Visible Light Communication System With Indoor Shadow Occlusion

Visible Light Communication(VLC),as a new wireless communication technology with dual functions of illumination and communication,has been widely concerned by scholars at home and abroad in recent years because of its many advantages.In the indoor VLC environment,due to the short wavelength of visible light,when the visible light link encounters an obstacle,a shadow area will be generated,thus affecting the signal strength of the receiver in the shadow area.With the rapid development of the Internet of Things(IoT),more and more communication devices are connected to the visible light network,resulting in the shadow effect caused by obstacles.In order to specifically quantify the shadow effect of obstacles,this paper conducts systematic theoretical analysis on the shadow effect of human obstacles under single light source and multiple light source,so as to accurately evaluate the influence of shadow effect of human obstacles on the performance of indoor VLC system.The main research work of this paper is as follows:Aiming at the problem that the shadow effect of obstacles has a serious impact on the communication performance of VLC system,the shadow effect of obstacles under a single light source is quantitatively studied,and the calculation method of the shadow area of obstacles under a single light source is given according to the principles of geometric optics and mathematics.Then the visual function is used to process the receiver in the shadow area,and then the indoor VLC channel model of obstacle shadow occlusion under single light source is established.In view of the actual indoor VLC environment,the calculation methods of shadow area of obstacles are different due to the different number of LED light sources,and the obstacles will produce two different shadows(i.e.full shadow and half shadow)in the case of multiple light sources.The different shadow effects of obstacles under different number of light sources are deeply analyzed.According to the calculation method of obstacle shadow area under single light source,the calculation methods of obstacle full shadow area and half shadow area under multi-light source are derived respectively,so as to achieve the purpose of accurately quantifying different shadow effects of obstacle under multi-light source.The visual function is also used to classify receivers located in different shadow areas,and then the channel model of indoor VLC system with two different shadows blocked by obstacles under multiple light sources is established.Finally,the performance of the established indoor VLC system with shadow occlusion under single and multiple light sources is simulated and analyzed.The results show that in the case of a single light source,the presence of obstacle shadow effect will lead to a large area of communication blind area in indoor VLC system,and with the increase of the number of obstacles,the communication blind area will also increase,and the communication performance of the system will decrease significantly.Although increasing the number of light sources can reduce the influence of the full shadow and half shadow effect of obstacles,the influence of the half shadow generated by obstacles on the system performance is still large,so it cannot be ignored when exploring the shadow effect.Optimizing the layout of light source can effectively overcome the influence of total shadow effect of obstacles on indoor VLC system.The research results can provide a reference scheme for improving the performance of the communication system.