Synchronization Technology For OFDM-Based Visible Light Communications

Recently, with the development of white LED lighting technology, as well as the continued growth of short-range communications bandwidth requirements, Visible Light Communication(VLC) is coming, using LED lights as transmission medium. The Visible Light Communication(VLC) is an optical wireless communication, is also a strong complementary technology for radio frequency (RF) in short-range communications. The OFDM technology in Visible Light Communication(VLC) can greatly improve the transmission performance of the system and its anti-interference ability. It also played a key role in the practical application of the system.This paper first introduces the Visible Light Communication(VLC) technology applications and research status. Then introduce the basic principle of the OFDM modulation and demodulation. Then discuss the OFDM synchronization principle and synchronization algorithm, as well as synchronization deviation effect to the system.Finally, this paper focuses on the two kinds of Visible Light Communication asymmetrically clipped optical OFDM system synchronization algorithm. The first synchronization algorithm is blind coarse symbol timing synchronization. By using a specific symmetry property of the ACO-OFDM time-domain signal, the method can achieve accurate symbol timing synchronization with very low implementation complexity. Second synchronization algorithm using a training symbol designed for the characteristics of ACO-OFDM are presented. On the basis of theoretical analysis, simulation of the two algorithms are performed, and the simulation results show that the two synchronization algorithms have very good timing synchronization performance.