Indoor optical wireless communication system with filters-enhanced generalized spatial modulation and carrierless amplitude and phase (CAP) modulation

The spatial modulation principle has been widely studied in indoor optical wireless communication (OWC) systems to provide high-speed connections to users by encoding part of data in the spatial domain. To further increase the speed and to eliminate the requirements of accurate channel state information (CSI) and low channel correlation, in this Letter we propose and demonstrate an indoor OWC system with a filters-enhanced generalized spatial modulation (FE-GSM) scheme and 16-carrierless amplitude and phase (16-CAP) modulation. The 16-CAP increases the data rate in symbol domain, and the FE-GSM scheme allows activating multiple transmitters simultaneously to increase data rate in the spatial domain. Experimental results show that using a 2.5 GBaud/s indoor OWC system with three transmitters, 15 Gb/s data rate is achieved even under identical channels without pre-known CSI. The demonstrated scheme provides a promising solution to increase data rate in indoor OWC systems.