Wireless Underwater Communications

The depths of the oceans have a high potential for future industrial development and applications. Robotic autonomous systems will greatly depend on a reliable communications channel with operators and equipment either performing joint operations or on the surface. However, communications must face harsh conditions that hinder the performance. Neither electromagnetic nor optical technologies are suitable for communication because of their short range in this medium. Due to this, acoustic equipment is envisaged as the most appropriate technology, even though it suffers several negative effects such as strong attenuation at high (ultrasonic) frequencies, Doppler shifts and a time-varying multipath. In this paper, we describe the characteristics of the acoustic underwater channel and how it impacts the mechanisms at the link and network layers.