Performance analysis of optical wireless MIMO with optical beat interference

Previously, we have proposed the optical wireless multiple-input multiple-output communications (OMIMO) to achieve a high speed transmission with a compact transmitter and receiver. In OMIMO, the transmission signal is degraded by optical beat interference (OBI) when we use the same wavelength at the optical transmit antennas. However, the influence of OBI has not been clarified. In this paper, we evaluate the influence of OBI on OMIMO, where we consider the linear array and square array of optical transmit and receive antennas. We analyze the signal-to-interference-plus-noise ratio (SINR) and the bit error rate (BER) of OMIMO when the same wavelength is used at the optical transmit antennas. We employ on-off keying (OOK) and subcarrier multiplexing (SCM) for each optical transmit antenna. From the numerical result, we clarify the influence of OBI on OMIMO and show that by using zero-forcing (ZF) or singular-value-decomposition (SVD), we can reduce the size of transmitter and receiver compared to space division multiplexing (SDM).