Blind Interference Alignment for Multiuser MISO Indoor Visible Light Communications

A filter-pair-based blind interference alignment scheme is proposed to improve the achievable degree of freedom (DoF) in multiuser multiple-input single-output indoor visible light communications. In the proposed scheme, the transmitter does not need to know channel state information. Different transmit sub-channels employ different pulse-shaping filters, and each user is equipped with multiple receive filters. The transmitter sends signals according to the predesigned strategy, and each user sets the receive mode by choosing the corresponding receive filter. Optical orthogonal frequency division multiplexing is employed in the proposed scheme to combat the intersymbol interference in high-speed transmissions, and the maximum achievable spectrum efficiency (SE) of the proposed scheme is analyzed. Simulation results validate that the proposed scheme can achieve higher SE and more DoF than the orthogonal multiple access schemes.