The capacity of the discrete time Poisson channel is studied. This
channel law describes optical communication with a direct-detection
receiver, where the output models the receiving photons due to the
transmitted laser signal and due to surrounding light. For battery
issues and safety reasons the inputs are simultaneously constrained on
both their average and peak power.

We try to find an upper and a lower bound on the capacity. Applying
some recent results on the Poisson distribution and a dual expression
of channel capacity, the bounds are partially analytic and partially
numerical, where the computation complexity is very low. The gap
between our bounds is not large, i.e. we ave succeeded in narrowing
the range of the capacity.

-||-   _|_ _|_     /    __|__   Stefan M. Moser
[-]     --__|__   /__\    /__   Senior Researcher & Lecturer, ETH Zurich, Switzerland
_|_     -- --|-    _     /  /   Adj. Professor, National Chiao Tung University (NCTU), Taiwan
/ \     []  \|    |_|   / \/    Web: http://moser-isi.ethz.ch/

Last modified: Thu Sep 2 06:07:21 UTC+8 2010