Blind carrier phase estimation based on geometric projection for the multi-band VLC system

Abstract

The carrier phase offset induced by the mismatch between the signal subcarrier frequency and arbitrary waveform generator (AWG) reference clock is a key problem for high-speed multi-band visible light communication (VLC) system. In this paper, we propose a blind carrier phase estimation (CPE) algorithm based on geometric projection for multi-band Nyquist pulse amplitude modulation (PAM) system. Compared with traditional CPE algorithms, the proposed method does not contain any feedback loop and the Mth power operation. Therefore, the lower computational complexity and simpler system structure are both achieved. Furthermore, we experimentally validate the proposed CPE algorithm in a three-band PAM-8 VLC system. The measured results show the system performance can be greatly improved. And compared with the Viterbi and Viterbi (V&V) algorithm using training symbols (20% of the total symbol length), the proposed CPE algorithm can slightly outperform. However, the scheme is a blind estimation without any assistant training sequences. Thus higher bandwidth efficiency is achieved.