Low PAPR Coding Scheme for Uniform Illumination in MIMO VLC

Abstract

For visible light communications many coding schemes like space shift keying (SSK), generalized space shift keying (GSSK), spatial multiplexing, spatial modulation, generalized spatial modulation, dual-LED complex modulation, and quad-LED complex modulation have been proposed. These existing schemes achieve various trade-offs between spectral efficiency and bit error rate (BER) performance. Except SSK and GSSK, a common issue in all these existing schemes has been that the total power transmitted across different time slots by the light emitting diodes is not constant, resulting in non-uniform illumination. In this paper, we propose a novel coding scheme with varying number of active antennas to maintain uniform illumination. Though SSK, GSSK, and proposed scheme achieve same peak to average power ratio (PAPR) of unity, the spectral efficiency achieved by the proposed scheme is higher compared to SSK and GSSK for a given number of transmit antennas. The proposed scheme is compared with several existing schemes in terms of BER, mutual information, PAPR, and spectral efficiency. The proposed scheme performs close to the existing schemes in error performance while providing consistent illumination as SSK and GSSK, with spectral efficiency higher than SSK and GSSK.