On the study of a quasi-synchronous CDMA-VLC system with two channels

In this paper, a new construction of optical zero correlation zone (OZCZ) code set pair is proposed for quasi-synchronous code division multiple access (QS-CDMA) visible light communication (VLC) system. Owing to its excellent correlation properties within zero correlation zone and greater code weight, the multi-user QS-CDMA-VLC system using the proposed code construction can obtain both good performance in illumination and communication. An experimental QS-CDMA-VLC system with two optical channels and two experiment setups is designed to evaluate the performance of the new OZCZ code set pair. When the free-space transmission distance difference is 1 m, we successfully achieve the 2-user and 14-user CDMA-VLC for 32.5 Mb/s and 24.1 Mb/s overall bit rate respectively, under the 7% forward-error-correction (FEC) limit of 3.8x10(-3). The experimental results indicate that, comparing to the other existing optical code sets, the proposed OZCZ construction can effectively reduce the impact of non-perfect synchronous problem, so that the bit error rate (BER) performance is improved. And dimming values and overall bit rates of the system can be significantly improved. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement