Design method for long-term evaluation of underwater acoustic communications and  networks in a Norwegian fjord environment

Abstract

Fjords often have difficult underwater acoustic propagation properties, such as the acoustic shadow zones created by highly dynamic bathymetry and thermocline/halocline. In addition, shallow-water coastal underwater acoustic horizontal communications are characterized by several reflections at the boundaries creating complex and timevarying multipath channel structures. We present an iterative simulation and experiment-based method for designing and evaluating an underwater acoustic communication system and the network layers built on it. First, we present the sound speed profiles collected throughout the year in the fjord at Austevoll in western Norway. Then we discuss the setup used to collect acoustic channel impulse responses in the frequency band 55-65 kHz in the same geographical area. We then provide the results of numerical modeling for the acoustic propagation and present the methodology that we plan to implement in the next few years for a long-term evaluation and improvement of acoustic sensor networks in fjord environments.