Research On Optical Filtering Technology For Recever Of Outdoor Visible Light Communication

LED visible light wireless communication becomes an new type of communication technology and gradually applied to the LED lighting devices due to its green and low carbon,low energy consumption, no electromagnetic interference,etc. Nowadays the LED light source has been widely applied in automobile headlamps, traffic lights, street lamps and other equipments, makes it possible for visible light wireless communication to apply in Intelligent Transportation Systems and Internet of Vehicles. Outdoor visible light communication is seriously affected by the natural light and different weather conditions, which led to a decline in performance of the receiver.The outdoor visible light communication system in this paper, using the automobile LED headlamps as signal source, ground air as the transmission channel. For natural light background noise at the receiver, we use the optical filtering technology and design the induced transmission filter,the selector for incident light angle, make outdoor visible light communication system communication quality is guaranteed.Paper main work and innovation points:(1)In order to filter the sunlight noise, we design a new type of band pass filter. For automobile LED headlamps spectrum and sunlight spectrum analysis, According to the overlap and non-overlapping regions of automobile LED headlamps spectrum and sunlight spectrum, the filter pass band spectrum shape is determined. In view of the shape of the passband, we choose induced transmission filter. According to the optical film design calculation method, we design the membrane structure parameters of induced transmission filter and make simulation for the shape of the passband. Under the condition of the signal light could pass smoothly, the sunlight noise could be filtered effectively. Making analysis of induced transmission filter, results show that after using induced transmission filte the system signal-to-noise increased 1.44 times(2)Designig the selector for light Angle, to ensure the best angle of incidence of signal light and natural light. Making analysis of the relationship between LED headlamps signal light incident angle and the filter passband shape and the relationship between sunlight incident angle and sunshine noise power, determine the optimal incident angle of the LED headlamps signal light is 0 ~ 10°, sunlight optimal incident angle is 0 ~ 20°. Design the selector for LED headlamps signal light incident angle and sunlight incident angle, the selector consists of blocking layer, absorbing layer and transmission layer. Ensure the induced transmission filter passband deformation is minimized, the filter result is best and effectively reduce the sunlight noise.(3)Complete the overall structure design of the optical receiver. The optical receiver consists of the selector for sunlight incident angle, the selector for LED headlamps signal light incident angle, the induced transmission filter, Compound Parabolic Concentrator(CPC) and The silicon photodiode. Making analysis and simulation of the performance of the optical receiver.Results show that after using optical receiver not only improve the communication quality of the receiver and improve the effective distance of communication.