Separate least mean square based equalizer with joint optimization for multi-CAP visible light communication

Abstract

Visible light communication (VLC) is expected to be a potential candidate of the key technologies in the sixth generation (6G) wireless communication system to support Internet of Things (IoT) applications. In this work, a separate least mean square (S-LMS) equalizer is proposed to compensate low-pass frequency response in VLC system. Joint optimization is employed to realize the proposed S-LMS equalizer with pre-part and post-part by introducing Lagrangian. For verification, the performance of VLC system based on multi-band carrier-less amplitude and phase (m-CAP) modulation with S-LMS equalizer is investigated and compared with that without equalizer, with LMS equalizer and with recursive least squares (RLS)-Volterra equalizer. Results indicate the proposed equalizer shows significant improved bit error ratio (BER) performance under the same conditions. Compared to the RLS-Volterra equalizer, S-LMS equalizer achieves better performance under low data rate or high signal noise ratio (SNR) conditions with obviously lower computational complexity.