Environment-adaptive routing protocols for underwater acoustic sensor networks in the deep ocean

Abstract

Underwater Acoustic Sensor Networks (UWSNs) face challenges in communication such as limited bandwidth, high latency, high bit error probability, mobility, and energy draining due to underwater characteristics different from those of terrestrial environments. Also requirements of sensor networks can be various depending on kinds of applications in oceanographic data collection, pollution monitoring, tactical surveillance, disaster monitoring, assisted navigation and so forth. These applications can be classified into two groups: delay-sensitive applications and delay-insensitive applications. Each application group has different characteristics and requirements, so in this paper, we try to satisfy each requirement from the network layer point of view. Also, our proposed routing protocols for each application aim for 3-dimensional and deep-ocean environments. The main characteristic of our proposed routing protocols is the reflection of the property of environmental variables sensed by sensors on the routing protocols. In the deep ocean, several oceanic variables have different values depending on area. This fact can affect the behavior of acoustic communication, so we exploit this property to find routing paths. Moreover, our proposed protocols are based on the geographical routing algorithm. Since large-scale UWSNs are hard to know the whole network information, the geographical routing algorithm, which uses only position information of local area, should be used. The proposed routing protocols are introduced as follows. Firstly, we propose a routing protocol to find a low-latency path under 3-dimensional deep-ocean sensor networks. In deep-ocean conditions, underwater sound speed, which is determined by oceanic variables such as temperature, salinity, and pressure, has considerably different values depending on the location of measurement, so underwater sound speed affects the behavior of the acoustic communication under the sea. For this reason, we obtai...