Signal Detection and Achievable Rates for Multiple Access Optical Wireless Scattering Communication

Due to the extremely large path loss of non-line of sight optical wireless communication, the received signal exhibits the characteristics of discrete photons. In this work we investigate the signal detection and achievable rates of OOK modulation for discrete Poisson multiple access channel (MAC), for both code division multiple access (CDMA) and non-orthogonal multiple access (NOMA). For the signal detection, we adopt the maximum likelihood (ML) criterion for the optimal detection, whose complexity grows exponentially with the number of users. Low computational complexity detection is proposed with ℳ-order correction algorithm that can perform closely to ML detection. Moreover, we address the achievable rates and rationalize the power allocation for discrete Poisson MAC for both NOMA and CDMA. Numerical and simulation results are presented to show the performance of the proposed detection, the achievable rate region as well as the optimal power allocation of two-user discrete Poisson NOMA and CDMA.