Visible light communication system based on pre-distorted 4ASK modulation

The white LED is used not only for lighting,but also as the light source in communication systems.In recent years,as the performance of the optoelectronic devices improves,the indoor visible light communication system has attracted much attention of researches.But the efficient bandwidth of white LED used for illumination is around 1MHz due to its device characteristics.To improve the rate and the quality of the communication,a demodulation scheme is designed based on pre-distorted 4amplitude shift keying(4ASK)and the visible light communication transmitting system is constructed.To relieve the LED′s bandwidth deficiency,the RC equalization and pre-distorted circuit are used at transmitting terminal of the visible light communication system.The optimization parameters are got by simulation.The hardware circuit of the visible light communication system is built.The experimental results show that the maximum bit rate is up to 20Mbit/s,the bit error rate(BER)is less than 10-6,and the communication distance is about 1m.