Optical Wireless Data Transmission System Based On LED

The wireless transmission technology play an important part of information society.As many traditional wireless transmission like Bluetooth,wifi have not only frequency band coincide themselves,but also coincide in different types of technologies,it is an urgent need to develop a new frequency band to save the crowd frequency band.It is more safety than traditional transmission way using the optical wireless transmission method based on LED in room.In the condition of saturated frequency band,optical band can leave out the annoyance of hertzian interface,and unlimited using frequency band by IEEE,therefore it have development prospect.The dissertation will conduct a study aimed at LED wireless data transmission.The dissertation firstly introduce the development and application in domestic and overseas.Then compare some typical traditional wireless transmission way.Analysis the merit and demerit,an optical wireless data transmission system based on LED is proposed which include the whole system diagram and data follow diagram.A new binary encoding of PWM is proposed for fitting both communication and visual lighting of LEDs which named pulse time delay(PTD-PWM).Compared with the traditional encoding scheme of PWM and OOK from encoding rules,structure and analysis the parameters from average transmitter power,bandwidth utilization,illuminance power utilization and bit error rate,respectively.A novel transmitter and receiver circuit design is described which can resist the ambient light effect aimed at LED wireless data transmission indoor.Signal to Noise Rate can be improved by this circuit.Thereby,Bit Error Rate reduced.A LED wireless transmission apply to USB on mobile terminal had been designed in allusion to popularize of mobile terminal,authoring a software program with C#of terminal applied to LED wireless image transmission.The transfer rate is 14.4Kbit/s on stabilization system,BER can decrease to 10-12 on the distance of 1m with the image and text file transmission.The experimental result shows that it is convenient to carry LED wireless data transmission for mobile transmission equipment as a supplement of traditional transmission for its ISM band interfere.The innovation point of the dissertation propose a new binary encoding of PWM fitting both communication and visual lighting of LEDs which named pulse time delay(PTD-PWM),using LED to realize reliable wireless transmission.