Photonics Research, 2017, 5 (6): 06000588, Published Online: Dec. 7, 2017
Spectrally efficient multi-band visible light communication system based on Nyquist PAM-8 modulation
(060.0060) Fiber optics and optical communications (060.2605) Free-space optical communication (230.3670) Light-emitting diodes.
Abstract
High-speed multi-user access with high spectral efficiency is one of the key challenges for band-limited visible light communication (VLC) systems. In this paper, we propose a novel scheme for effective multiple-access VLC systems based on multi-band, Nyquist-filtered pulse amplitude modulation (PAM)-8 modulation. Within this scenario, the spectral efficiency can be improved from 1.5 to 2.73 b/s/Hz by implementing an appropriate Nyquist filter to suppress spectral bandwidth. We experimentally demonstrate a multi-band VLC system at 1.2 Gb/s after 1 m indoor free space transmission. The system performances have also been thoroughly investigated for different sub-band numbers, utilizing a rectangular filter in the frequency domain and a Nyquist filter based on square root raised cosine. The results show that the Nyquist-filtered PAM-8 signal can outperform a rectangular filtered signal. The maximum improvement of system capacity is up to 1.67 times for the Nyquist-filtered multi-band system. The results clearly show the advantage and feasibility of multi-band Nyquist PAM for high-speed multiple-access VLC systems.
Nan Chi, Mengjie Zhang, Jianyang Shi, Yiheng Zhao. Spectrally efficient multi-band visible light communication system based on Nyquist PAM-8 modulation[J]. Photonics Research, 2017, 5(6): 06000588.