Communication Coverage Improvement of Indoor SDM-VLC System Using NHS-OFDM with a Modified Imaging Receiver

This paper proposes two techniques to improve the communication coverage of an indoor space division multiplexing visible light communication (SDM-VLC) system. One technique is a non-Hermitian symmetry orthogonal frequency division multiplexing (NHS-OFDM) scheme which can be achieved by parallelly transmitting the real (Re) and imaginary (Im) parts of a complex-valued OFDM signal via a pair of white light-emitting diode (LED) lamps, and the other is a modified imaging receiver (ImR) which utilizes tilted photodetectors (PDs) to improve the performance of a conventional ImR. Analytical and simulation results show that the communication coverage of an indoor 2 x 2 SDM-VLC system can be substantially improved by using NHS-OFDM with a modified ImR, compared with the system using Hermitian symmetry based OFDM (HS-OFDM) with a conventional ImR.