High Speed WDM VLC System Based on Multi-Band CAP64 With Weighted Pre-Equalization and Modified CMMA Based Post-Equalization

• Published in: IEEE communications letters Vol. 18; no. 10; pp. 1719 - 1722
• Main Authors: Wang, Yiguang, Tao, Li, Wang, Yuanquan, Chi, Nan
• Format: Journal Article
• Language: English
• Published: IEEE 01-10-2014
• Subjects: Attenuation; Bit error rate; Image color analysis; Light emitting diodes; Modulation; Receivers; Wavelength division multiplexing; weighted pre-equalization; Visible light communication (VLC); carrierless amplitude and phase (CAP) modulation
• ISSN: 1089-7798; 1558-2558
• DOI: 10.1109/LCOMM.2014.2349990

Multi-user access is one of the key problems in the visible light communication (VLC). In this paper, we propose and experimentally demonstrate an approach for multi-user access based on multi-band CAP modulation over a wavelength division multiplexing (WDM) VLC system using a single RGB LED. In this scenario each wavelength will provide 3 sub-bands. Depending on the combination of the different wavelength and the sub-bands, a dynamic capacity can be achieved for up to 9 users access. At the transmitter a weighted pre-equalization method is proposed to overcome frequency attenuation of the LED, while at the receiver a post-equalizer based on modified cascaded multi-modulus algorithm (CMMA) is utilized. The experimental results show that the bit error rate (BER) for an over-all 1.35 Gb/s CAP64 signal over 30-cm transmission can be under the 7% forward error correction (FEC) limit of 3.8 × 10 -3 . The results clearly demonstrate the benefit and feasibility of the multi-band CAP modulation for the short range multi-user VLC systems.