Tracking of Rapidly Time-Varying Sparse Underwater Acoustic Communication Channels

Abstract : The long-term goal is to develop, for broadband short-range very shallow water environment, dynamic channel estimation and equalization algorithms that can improve the receiver performance for phase coherent acoustic communications. That the broadband short-range shallow water channels can be both rapidly fluctuating and sparse poses significant challenge to the problems of channel estimation and equalization. The primary scientific objectives of this task are to: 1. Understand and establish the connections between the channel characteristics (deterministic and stochastic dynamics caused by signal interactions with surface gravity waves, implicit and explicit multipath sparseness due to broadband transmission and correlated surface scattering) and the performance of dynamic channel estimation algorithms and channel estimate based equalization algorithms. 2. Develop dynamic channel estimation algorithms that have improved tracking capability and are also robust to the channel sparse structure; Analyze the performance of these algorithms as related to the channel characteristics. 3. Develop equalization algorithms that are based on or combined with the dynamic channel estimation algorithms in an iterative fashion, for phase coherent signal demodulation.