Abstract

This paper investigates a channel model describing optical
communication based on intensity modulation. It is assumed that the
main distortion is caused by additive Gaussian noise, however, with a
noise variance depending on the current signal strength. Both the
high-power and low-power asymptotic capacities under simultaneously
both a peak-power and an average-power constraint are derived.

The high-power results are based on a new firm (nonasymptotic) lower
bound and a new asymptotic upper bound. The upper bound relies on a
dual expression for channel capacity and the notion of
capacity-achieving input distributions that escape to
infinity
. The lower bound is based on a new lower bound on the
differential entropy of the channel output in terms of the
differential entropy of the channel input.

The low-power results make use of a theorem by Prelov and van der
Meulen.


Keywords

Channel capacity, direct detection, escaping to infinity, Gaussian
noise, high signal-to-noise ratio (SNR), low signal-to-noise ratio
(SNR), optical communication.



-||-   _|_ _|_     /    __|__   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 1 09:38:24 UTC+8 2011