Channel estimation strategies for underwater acoustic (UWA) communication: An overview

Abstract

Underwater wireless communication techniques have played the most important role in the exploration of oceans and other aquatic environments. Underwater acoustic (UWA) communication faces a lot of hurdles such as environmental characteristics, variety of noises, temperature, pressure, salinity, etc which makes the UWA channel unique. UWA channel modeling is the most demanding task due to its time-varying property and due to its double dispersion property resulting in severe multipath spread and time variation. Accurate estimation and tracking of channel state information (CSI) are required for receiver design and channel capacity analysis in an underwater environment. The goal of this study is to provide a comprehensive survey on channel estimation of the latest researches in the field of UWA communication. The previous works are summarized, reviewed and compared according to their years of publication. This paper provides an overview on the channel model, methods, and algorithms for channel estimation and equalization in an underwater environment. It also includes a journey of channel estimation from time-varying UWA multipath model towards the estimation of a multipath underwater channel in the Multiple-input Multiple-output Orthogonal Frequency Division Multiplexing (MIMOOFDM) environment.