Performance evaluation of generalized optical spatial modulation with dimming support

In this paper, we propose a modified generalized spatial modulation (MGSM) scheme with dimming support for indoor optical wireless communication (OWC) systems. The spatial indices of the active LEDs and their transmitted optical power levels are utilized to modulate data in MGSM. The key property of the signal waveforms in MGSM is that it provides the same amount of optical power emitted at any time instant that corresponds to the dimming level requested. Consequently, MGSM prevents potential health and safety concerns related to the human eye such as flickering caused by intensity modulation. The upper bound on the symbol error rate (SER) of MGSM is derived theoretically using the union bound method, which is used to verify Monte-Carlo simulations. Numerical results show that MGSM achieves a full range of dimming with sufficiently high spectral efficiency compared to conventional techniques such as multiple pulse position modulation, overlapping pulse position modulation, on-off keying and generalized spatial modulation (GSM). In terms of error performance, the SER of MGSM is compared with GSM at several dimming levels, which shows that MGSM provides an advanced and efficient modulation scheme for indoor OWC systems.