Filter-Enhanced Spatial Modulation and Multiplexing in Indoor Optical Wireless Systems

Optical wireless communication (OWC) systems have been widely studied to provide high-speed connections in indoor environments. In this letter, we propose a filter-enhanced indoor OWC system with hybrid spatial modulation (SM) and spatial multiplexing (SMUX) to further increase the data rate. The filter-enhanced SM enables extra information be transmitted via the spatial indices of OWC transmitters, and the SMUX further increases the data rate via the parallel transmission of multiple signals even under highly-similar channels. The proposed scheme is experimentally demonstrated. Up to 35 Gb/s data rate can be achieved with 2.5 GBaud/s symbol rate and four transmitters. Compared with the filter-enhanced SM scheme, the achievable data rate can be increased by 100%. Compared with the conventional SM and SMUX, the bit-error-rate (BER) is improved by over two orders-of-magnitude.