Design of efficient channel estimation techniques for underwater communication

Abstract

Precise underwater channel estimation (CE) is necessary for efficient and reliable newlineunderwater acoustics (UWA) communication. This study presents novel channel estimation newlineschemes tailored for underwater acoustic communication, highlighting key distinctions from traditional radio frequency (RF) counterparts. Underwater channels pose unique challenges, including high attenuation, time-varying sound speed profiles, and complex multipath effects. The proposed schemes account for these underwater-specific characteristics, providing a robust foundation for accurate channel estimation in challenging aquatic environments. The methods have been presented in this thesis with focus on estimating sparse UWA communication channels. The broadband underwater channel can be characterized by three distinct features. Firstly, the CIR is characterized by an excessively long delay spread. Secondly, the channel exhibits fast temporal variation created by scattering from the mobile sea surface. Finally, the channel structure is sparse, owing to the presence of resolvable paths. Conventional least square (LS) estimation methods do not effectively exploit the sparsity of the channel structure and are constrained in their ability to estimate high-dimensional channels with fast variations like that in underwater channel. The motivation behind this work is the need for better estimation techniques for UWA communication. The main contribution of this study is to present the precise UWA CE and propose modified and novel schemes for better performance newline