Research On White LED Intensity Distribution For Visible Light Communication

Based on the advantage of low power consumption,long lifetime,small size and environment-friendly,the LED has replaced the incandescent and fluorescent.Meanwhile,the LED owns a good modulation characteristic and a quick response time,which provide a possibility to transform communication signal.Recently,a novel wireless communication technology(visible light communication,VLC)has been proposed.Many researchers have been attracted by this technology,and mainly focus on the improvement of the communication rate and bandwidth,utilizing different modulation methods and coding methods,while the influence of the optical end to the visible light communication system still remains unclear.This paper study the characteristic of the visible light communication optical antenna,especially focus on influence of the optical design and the illumination distribution of the LED to the performance of visible light communication,as followed:1.The differences between traditional light source and the LED source and the advantage of the utilize of freeform surface for optical design are discussed.After reviewing the freeform surface optical design method,an advanced design method is proposed by integrating the freeform surface and the LED substrate.By applying this structure for optical design,the optics consumption can be reduced and a uniform lighting performance can be easily achieved,which is more suitable for visible light communication.2.Among the applications of visible light communication,indoor positioning causes most attention of the researchers.Based on the research on positioning influence of the LED light distribution,a positioning prototype is designed.What's more,by using CDMA coding,a positioning system with higher positioning accuracy is achieved.3 Applying the freeform surface,a collimating lens with 1.7 degree emitting angel is designed.And the optical signal can transform in a longer distance with the help of this collimating lens.And the long-range simulation model is built.The simulation shows that: by applyting a 1W LED as the light source,a 90 m visible communication system with 210Mbit/s is achieved.