From the Long-Range Channel in the Ocean to the Short-Range and Very Shallow-Water Acoustic Channel in Ports and Harbors

Micro Autonomous Underwater Vehicles (mu AUVs) and Underwater Wireless Sensor Networks (UWSNs) enable diverse underwater applications in ports and other shallow inshore waters. During the past, several acoustic underwater modems were developed, which have typical communication ranges of a few kilometers. Opposed to that, there is a growing demand of short-range communication (less than a kilometer) for the mentioned applications. This paper discusses the requirements of different acoustic communication devices and motivates the need of short-range and very shallow-water soundings. Typical observations of long-range channels do not apply. Afterwards, soundings in two locations are discussed. The soundings indicates quite different behavior and illustrates the diversity of acoustic transmission channels. Based on our findings, new modulation schemes can be developed.