Multi-Gbit/s LiFi Experiments With a VCSEL TX and an Enhanced Pulsed Modulation PHY

Due to its better power efficiency, pulsed modulation such as on-off keying (OOK) has the potential of maximizing reach and minimizing energy consumption for future high data rate optical wireless communication (OWC), especially LiFi systems. In this paper, we introduce enhancements of the OOK-based Pulsed Modulation Physical Layer (PM-PHY) defined in IEEE Std. 802.15.13-2023. Namely, we evaluate robust line-coding and equalization techniques with reduced overhead and complexity, and increase bandwidth by using vertical-cavity surface-emitting laser (VCSEL) arrays for transmission. With these enhancements, we demonstrate data rates up to $4.25 \,{\mathrm{Gbit}}/{\mathrm{s}}$ using large VCSEL arrays with a combined optical power of $350 \,\mathrm{m}\mathrm{W}$. These VCSEL arrays can cover an area of $4.32 \,\,\mathrm{m}^{2}\,$ at a distance of $2.5 \,\mathrm{m}$. Our results show that the large bandwidth, high power, and low energy consumption of low-cost VCSEL arrays, when combined with pulsed modulation, can reach Multi-Gbit/s data rates and enable user mobility in large areas.