Research On Multi-path Channel Estimation For Mobile Visible Light Communication In Vehicle Networking

Visible light communication(VLC)emerges as a promising candidate in vehicle networking since it is energy saving and has rich spectrum resources.However,most of them focus on the pointto-point static communication scenarios.For VLC downlink between street lamps and a moving vehicle,received signals tend to experience a time-varying multi-source and multi-path channel condition.Conventional channel estimation and equalization schemes in VLC cannot effectively solve the multi-path effects since they are mainly designed for the time-invariant scenarios.Therefore,this paper will focus on mobile multi-path channel estimation under the communication scenario between street lamps and moving vehicles,so as to reduce inter-symbol interference caused by multipath effects and improve system performance.The main research contents of this paper include:1.For outdoor VLC between LED street lamps and moving vehicles,a DCO-OFDM based mobile visible light communication multi-path channel model is established,and the time-varying characteristics of mobile visible light channel are analyzed from the perspective of time and frequency domain.At the same time,based on the proposed communication scenario,the distribution of the signal-to-noise ratio under different street light spacing and street height is analyzed.2.A decision feedback channel estimation scheme is proposed to track the time-varying channels so as to equalize the multi-path effects.Compared with the actual channel frequency response,it is found that the proposed method can significantly improve the accuracy of channel estimation compared with the conventional scheme using only training sequences.3.A mobile visible light communication system was setup through matlab,and the bit error rate(BER)performance of the decision feedback algorithm under different system parameters in the researched model was discussed.Simulation results show that compared with the conventional scheme based on training sequences,the proposed scheme can track the time-varying channels well under different system parameters,and significantly improve the system's BER performance.