Design Of Performance Improvement Scheme And Experimental Study Of Optical Wireless Communication System

Optical wireless communication(OWC)is an emerging communication technology in recent years,which use light as information carrier and free space as transmission medium to achieve communication.OWC have the advantages of large bandwidth,license-free operation,no electromagnetic radiation and anti-electromagnetic interference in traditional band.Hence,it has received more and more attention from domestic and foreign research scholars.This paper mainly studies on two typical kinds of OWC ways,visible light communication(VLC)and ultraviolet(UV)communication.So far,some domestic and foreign scientific research institutes have obtained some results in above two kinds of OWC technologies.With in-depth study,performance improvement of system is becoming important point that pay attention.In addition,considering practical application,implementation of real-time communication system is also noteworthy.Based on the National Natural Science Foundation of China(NSFC),this paper mainly focus on design of performance improvement scheme and experimental study of VLC system and UV communication system.The main work and innovation points of paper are as follows:Firstly,a real-time direct sequence spread spectrum(DSSS)VLC system scheme was proposed and implemented based on FPGA(Field Programming Gate Array).By building an experimental test-bed,the BER(bit error rate)performance of proposed system in multipath transmission environment was measured.The results show that DSSS technology is beneficial to suppress the multipath induced interference and offer enhanced performance in VLC system.Secondly,paper designed and implemented a driver scheme that could improve ultraviolet light emitting diode(UV LED)modulation performance.The measured results show that the designed driver circuit has smaller input reactance,could support narrower input signal pulse width and enhance the modulation bandwidth of transmitter effectively,hence make it could be applied to improve UV communication rate.Thirdly,a real-time multi-user UV communication scheme was proposed and implemented.By establishing an experimental system using self-designed multi-transmit driver circuit,we validated the feasibility of proposed scheme,measured and analyzed system BER performance.