Study On Indoor Visible-Light Communication Based On OFDM

Visible Light Communication(VLC) is a new kind of wireless communication technology,that combines the function of illumination and communication by Light-Emitting Diode(LED). It has a lot of advantages over RF(Radio Frequency) communication, for example, we can use visible light spectrum freely without certification, and there is no electromagnetic interference between signals, furthermore, it’s relatively secure to transfer data via light path, so we can expect that one day in the future, VLC can be a strong complementary technology for RF. However, until now, studies on VLC are still in the stage of theoretical analysis and experiments, there is still a certain distance to practical application.This paper focuses on indoor visible light communication technology, and to design a practical VLC system. The main work of this paper is as follows:First, this paper studies the principle, research progress and technical difficulty of VLC technology. Based on the study, this paper proposes a feasible system framework. By introducing OFDM, to improve both transmission rate and anti-interference ability of the VLC system.Then it explains the details of OFDM modulation/demodulation schemes, analyses each module’s function and algorithm separately. According to the experimental environment, this paper uses LS channel estimation method based on block pilot, and proposes an improved frame synchronization algorithm based on Park algorithm. Besides, in this paper, normalized data structure of the physical layer is designed. Moreover, through matlab simulation, the correctness and performance of the system is preliminarily tested.Finally, this paper builds a real-time visible light communication system based on DSP(TMS320C6713) and FPGA (EP2C70F672C8).Under practical environment, the correctness and performance of the system is confirmed and improved. In addition, a computer monitoring software is designed to monitor the transmission of data between different PC.