Research On Indoor, High Data Rate Ultraviolet LED Communication System

Ultraviolet Communication (UV) is a new kind of communication technique,which has the advantages of good security, capability of high powerful anti-jamming, allweather and all wave work, non-line of sight communication, and so on. Therefore, itattracts the extensive attention and focus because of the potential of be applied inmilitary battlefield.This paper has a detailed analysis of Rayleigh scattering, and Mie scattering’seffect on UV communication system, establish the theoretical basis of non-line of sightcommunication in limited area. Furthermore, presents three channel transmissionmathematical models: line of sigh link, a single scattering model based on ellipsoidalcoordinates and a multiple scattering model based on Montecalo simulation.Single Pulse Position Modulation is used in UV communication system, which haslow average radiation. Considering the transmission efficiency and transmission rate,we take modulation length as16. In order to improve the bit-error-rate, CyclicRedundancy Code is also proposed to realize the function of data error detection andsingle bit error correction. CRC-CCITT is used as the generator polynomial.Modulation, demodulation and channel coding are implemented in Quartus II softwareusing Verilog HDL language, compared to the single-chip technology, fieldprogrammable logic arrays is debugging simply and good portability.The hardware circuit of system has also been designed: constant current sourcedrive circuit, photomultiplier readout circuit and signal processing circuit.The processes of the entire communication system are as follows: at the transmitter,modulated and coded signals are connect to the enable terminal of source drive circuit,and control the switching state of the LED to transmit different information; at thereceiver, photomultiplier readout circuit convert the detect current into the voltagesignal, through the filter, cascade amplifier, and shaper circuit, restored the originalsending signals, after decoding and demodulation, send to serial port, then, completedthe entire data communication processes.This paper built a UV LED wireless communication system prototype, repeatedlyexperiments indicate that: this system can transmit character information at the rate of115.2Kbps with a low bit error rate, within an area of5meters. Besides, it’s laid a goodfoundation of military utility. At the last of this article, made a summary of work, presents the difference between former communication systems, and discussed thesuggestion of improvement work.