Investigation of a short-range underwater acoustic communication channel for MAC protocol design

Mobile swarms of autonomous underwater vehicles (AUV) have exciting potential for extending current AUV applications and adding new possibilities to the working environment of the oceans. For swarm operations to occur, fast reliable communication between all vehicles within the swarm is needed. The challenge for underwater communication is the very different and unique characteristics of the channel compared to the terrestrial environment. Acoustic communication has been the typical physical layer technology used for underwater operations and has experienced significant research and progress over the last few decades, however this focus has been predominately on longer range acoustic channels. The work presented in this paper is to determine the critical parameters of an underwater acoustic communication channel for the evaluation and development of a new MAC Protocol designed for short range communication between vehicles operating within a swarm. This paper provides a review of the essential channel characteristics and the modelling currently in use for this purpose, highlighting the difference for short range operations. It then assesses the electro-acoustic interface with investigation into the parametric relationship between digital modulation requirements and short range channel characteristics.