Capacity and Nonuniform Signaling for Discrete-Time Poisson Channels
The Poisson photon-counting model is accurate for optical channels with low received intensity, such as long-range intersatellite optical wireless links. This paper considers the computation of the channel capacity and the design of capacity-approaching, nonuniform signaling for discrete-time Poisson channels in the presence of dark current and underaverage and peak amplitude constraints. Although the capacity of this channel is unknown, numerical computation of the channel capacity is implemented using a particle method. A nonuniform mapper is coupled to a low-density parity check code and a joint demapper-decoder is designed based on the sum-product algorithm.