Intensity distribution-based multiplexing scheme for downlink LOS indoor optical wireless communication system

This paper proposes a novel spatial division multiplexing (SDM) scheme for downlink point-to-multipoint indoor line-of-sight optical wireless communication system consisting of an access point (AP) and multiple terminals. In the proposed scheme, the AP transmits on-off keying modulated optical signals from multiple light sources (LSs). Being spatially widespread, multiple optical signals cause mutual interference. Even under the interference, the terminal equipped with a receiver can identify the ON/OFF operation of the LSs by using the intensity distribution: spatial distribution of optical intensity formed by multiple optical signals and observed by the receiver with multiple photodiodes arranged on a 2-dimensional array. Numerical results show that proposed SDM scheme can be performed with less transmission power than allowable exposure limit when the receiver is appropriately designed to detect the spatially multiplexed optical signal.