Research On Visible Light Communication Technology Based On Multi-ary Transmission Method

White LED is the main illuminator for the next generation.Compared to radio communication technology,wireless optical communication technology with white LED source has the advantages of high communication rate,lower energy consumption,no spectrum resource limitation,high security and no electromagnetic interference,etc.Therefore,the white visible light communication(VLC)technology has great development potential.White VLC is still at the initial stage and how to use the LED illuminator to implement light communication with high data transmission is the main subject of this dissertation.In order to increase communication rate,a method based on Mary Amplitude Shift Keying(M-ASK)is studied theoretically.The optimal number for the parameter M is finally found to be 8 based on series computation simulation.In the light of the theoretical result,light communication system based on 8-ASK modulation/demodulation is studied.Circuits for the 8-ASK optical communication system are designed to realize the octal signals.Modules including LED driver,light receiver,filter and decision-regeneration circuit are developed.In order to reduce the BER and race hazard,methods based on BCD code to Gray code conversion are studied.Experiment based on the 8-ASK VLC communication is completed in the final part.Comparing with the OOK modulation/demodulation technique,the 8-ASK technique can increase the communication rate more efficiently.