On the Capacity of Intensity-Modulation Direct-Detection Gaussian Optical Wireless Communication Channels: A Tutorial

TL;DR

This tutorial reviews the capacity analysis of intensity-modulation direct-detection Gaussian optical wireless channels, covering single and multiple-input setups, capacity bounds, and multi-user scenarios, providing foundational insights into this specialized communication model.

Contribution

It offers a comprehensive overview of capacity results for IM/DD Gaussian optical wireless channels, including bounds and asymptotic behaviors, with extensions to multi-user configurations.

Findings

Capacity bounds for single-input single-output channels

Asymptotic capacity results at high SNR

Capacity bounds for multi-user optical wireless channels

Abstract

Optical wireless communication (OWC) using intensity-modulation and direct-detection (IM/DD) has a channel model which possesses unique features, due to the constraints imposed on the channel input. The aim of this tutorial is to overview results on the capacity of IM/DD channels with input-independent Gaussian noise as a model of OWC channels. It provides the reader with an entry point to the topic, and highlights some major contributions in this area. It begins with a discussion on channel models and how this IM/DD Gaussian channel model comes about, in addition to an explanation of input constraints. Then, it discusses the capacity of the single-input single-output channel, its computation, and capacity bounds and asymptotic capacity results. Then, it extends the discussion to the multiple-input multiple-output setup, and reviews capacity bounds for this channel model. Finally, it discusses multi-user channels modelled as a broadcast channel (downlink) or a multiple-access channel (uplink), with their associated capacity bounds.