Research On Wireless Optical Communication Technology Based On White LED

LED lamps have the advantages of high brightness, long life, stable performance, energy savings, it will become the next generation of lighting tools. Due to the high sensitivity and linear modulation characteristics of the LED, LED lighting systems have the ability to transmit signals. Compared with the traditional infrared and radio communications, LED visible light communication has the advantages of high transmit power, no electromagnetic interference, no need to apply for spectrum resources no data leakage due to within room. LED lights and at the same time transmit information, is energy efficiency and reduce duplication of investment, therefore, the LED visible light communication system has significant valuable, has greater prospects for the future development, has been recognized as an emerging short-range high-speed wireless communication systems, and attracts the attention and study interest of scholars at domestic and foreign universities and research institutions.In this paper, we study from the characteristics of the structure and function of white LED, white LED light-emitting principle of volt-ampere characteristic, the photoelectric conversion characteristics, spectral characteristics. And indoor visible light communication channel include channel link, the chain of communication road, the channel model. Concerning system design, we investigate principle of PPM modulation and OOK&OFDM modulation, OOK Modem is also simulated, and we at the same time make comparison and choice of the photo-detectors, also analysis the white led and PIN response frequency by building visible light communication’s actual circuit. That is response frequency for white led and PIN tube were100KHZ and100HZ separately. Last, by using technology of OCDMA to achieve user’s uplink communication. Also simulation showed the curve for single user’s bit error rate with address code length, weight, number of user and threshold. That is the system’s bit error rate was in proportion with number of user, and the bit error rate was in inversely proportion with address code length, weight and threshold.