Earth is solitary among the rocky planets revolving in the solar system. It is the only planet that is 3/4 covered with oceans of liquid water. In today's era, wireless sensor network is used in almost places and also is an interesting topic for researchers too. But with the advancement in technology, a network similar to wireless sensor network can be deployed under the water with acoustic signals for data transmission. Because of harsh environment and some more challenges, underwater communication becomes tricky. Underwater wireless sensor networks (UWSNs) is an advanced technology for underwater explorations and have demonstrated their quality in underwater applications. UWSN is a blend of wireless technology with sensor technology that has some extraordinary features like smart sensing, intelligent computing, and communication capabilities. Further, to maintain the secure communication underwater, it becomes more and more tricky. This chapter presents an expansive analysis of challenges, attacks, and security techniques of UWSNs.
TopIntroduction
Wireless sensor network is a type of network in which many sensors are attached at different locations to make the communication possible from different locations wirelessly e.g. to sense anything, a sensor is situated at any place and information or data can be collected from that sensing device through a centralized network.
Wireless sensor network can be categorized in two sections:
In Organized WSNs, sensor nodes are distributed in pre-planned manner and less deployed that’s why maintenance cost is very low. On another side, in de-organized and unregulated WSNs; all the sensor nodes are densely collected and use Ad-hoc type of deployment that’s why maintenance of these type of network is a tough task and maintenance cost is also high.
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Underwater wireless sensor networks (UWSNs) is an advanced technology for underwater explorations and have demonstrated their quality in underwater applications e.g. Surveillance, resource exploration, ocean monitoring and military use in harsh underwater environments (Cui et al.,2005, Akyildiz et al.,2005).
UWSN is a wireless technology with micromechanical sensor technology having features like sharp sensing, intelligent computing, and communication capabilities.
Figure 1. Underwater wireless sensor network (UWSN) environment
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Figure1 (Yang et al., 2019) demonstrates the working environment of UWSNs. Data communication is performed in UWSNs by several components like underwater sensor nodes, underwater sink nodes, onshore sink, surface buoy station and surface sink which are elaborated as follows:
- a.
Initially, all the sensor nodes are dropped at the ocean floor. Every sensor nodes is in itself a standalone network which is responsible for sensing, processing and transmitting the information to the remote station.
- b.
Underwater sensor nodes monitor or sense water related physical or environmental conditions, such as pressure, sound, temperature, etc. and mutually transfer data to the underwater sink node. Different types of underwater sensor nodes are used as moored sensors, cabled seafloor sensors, acoustically connected sensors.
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Underwater sink nodes with horizontal transceivers collects data from sensor nodes and relays data to surface buoy with vertical transceiver.
Besides this, autonomous underwater vehicles (AUVs), satellite and vessel helps to grow the sense power and increase the communication range. The AUVs work as Power nodes in UWSN. With high energy level, AUVs move independently, and behaves like routers between fixed sensors. AUVs manage to reconfigure the network.
Figure1 shows the cluster-based network architecture. This architecture works not only to manage the nodes in an easy manner but also to extend the lifetime of the whole network.
Process: Among all the cluster member nodes, it is tricky to find any node as sink node. So, cluster-head (CH) node is assumed as the sink-node of the cluster which accumulates, broadcast packets within cluster and in-between clusters. Hence, the energy consumption of CH is greater than member nodes. To balance energy consumption as well as to extend the life-time of the whole network, sensor nodes are elected to be the CH. The protocol used behind the scene may be based on the best energy consumption (Wang et al., 2007), residual energy (Fang et al., 2007) and the optimal number of CHs (McGlynn et al., 2001).