Underwater Sensor Network Presented By: Sabbir Ahmed Khan

Contents What is Underwater Sensor Network Underwater Sensor Network: Why? Challenges Why sound is using as communication medium in UW-SN? 2D Under Water Sensor Network 3D Under Water Sensor Network Routing in UWSN Hop-by-Hop Dynamic Addressing-Based Routing (H2-DAB)

What is Underwater Sensor Network We can called Underwater sensor network simply a network that’s primary portion is built underwater. It consists of a number of underwater sensor nodes, underwater sink, surface station, Autonomous Underwater Vehicles (AUVs) that are deployed to perform collaborative monitoring and resource exploration tasks over a given area.

Underwater Sensor Network: Why? Undersea exploration Seismic monitoring Pollution monitoring Equipment monitoring and control Autonomous Underwater Vehicles (AUV) Mine reconnaissance

Challenges Communication via acoustic waves in underwater environment poses a number of main challenges Long and variable propagation delay The available bandwidth is severely limited Doppler Spread Multipath Noise and high path loss Limited Battery power (This is why Low radio frequency isn’t used in underwater transmission)

Why sound is using as communication medium in UW-SN? High Radio wave is extremely attenuated in salt water. So we can Use low radio frequency. Right?? But Low radio frequency requires a very large antenna and high transmission power. So, not practical at water medium. In addition, the optical waves are not efficient in underwater environments because they may be scattered.

2D Under Water Sensor Network Figure 1: 2D Underwater Sensor Network A group of sensor nodes are anchored to the bottom of the ocean. Underwater sensor nodes are interconnected to one or more underwater sinks (uw-sink). UW-sink is used to receive data from the ocean bottom network and send to a surface station. uw-sinks are equipped with two acoustic transceivers A vertical and a horizontal transceiver.

Figure 2: 3D Underwater Sensor Network In three-dimensional underwater networks, sensor nodes float at different depths. The depth of the sensor can then be regulated by adjusting the length of the wire that connects the sensor to the anchor

Routing in UWSN Conventional Proactive and Reactive routing does not work efficiently in the networks with high propagation delay and high dynamic topology such as UWSN. For example, a path from each node to other nodes is discovered and stored in the route table. This path is expired in a short period of time due to high movement of nodes.. We can divided routing protocols into two categories: Location-Based (Geographical) Routing Vector Based Forwarding Protocol (VBF) Hop-by-Hop Vector-Based Forwarding (HH-VBF) Location-Free (Non-geographical) Routing Hop-by-Hop Dynamic Addressing-Based Routing (H2-DAB)

Hop-by-Hop Dynamic Addressing-Based Routing (H2-DAB) Figure 4:Hop ID assigning process It is a location free routing protocol. H2-DAB is composed of two phases. i ) assigning dynamic address to sensor nodes. ii) data delivery.

Hop-by-Hop Dynamic Addressing-Based Routing (H2-DAB) (Cont.) In the first phase, all initial hop ID for sensor is equal to 99. Then sinks start to send hello packet and each node that receives the hello packet should update its hop ID according to the number of hops to the sink. Therefore closer sensors to sinks have smaller hop ID. For instance, the hop ID of node N11 is equal to 34 that indicate its hop distance from one sink is equal to 3 while its distance to another sink is equal to 4. In the second phase, the data is send to the sinks. Each forwarder node sends an inquiry request message to its neighboring nodes. Nodes in the communication range receive the message and send a reply message contains their node ID and their hop ID. The forwarder node selects a node with smallest hop ID as a next hop node. Hop ID is updated after an interval of time due to movement of nodes. In this way data is send to sink.

Hop-by-Hop Dynamic Addressing-Based Routing (H2-DAB)(Cont.) Pros: i ) Handles the node movement by water flow ii ) Employs the multi-sink structure, which reduces the congestion at closer nodes to sink. iii) It works without geographical information of nodes, extra hardware Limitations: i ) It doesn’t handles void communication ii) A single forwarder node strategy at each hop without considering the link quality of the nodes results in an increase in the number of packet loss and low reliability.

Thanks for your Patience and time QUESTION???

References http://en.wikipedia.org/wiki/Underwater_acoustics www.ee.gatech.edu/research/labs/bwn/surveys/underwater.pdf http://ftp.isi.edu/~johnh/PAPERS/Heidemann05b.pdf http://www.mit.edu/people/millitsa/resources/pdfs/royal.pdf http://www.ece.gatech.edu/research/labs/bwn/UWASN/ http://www.hindawi.com/journals/ijdsn/2013/701834/ I. F. Akyildiz, D. Pompili, and T. Melodia, “State-of-the-art in protocol research for underwater acoustic sensor networks,” in Proceedings of the 1st ACM International Workshop on Underwater Networks, pp. 7–16, September 2006. I. F. Akyildiz, D. Pompili, and T. Melodia, “Challenges for efficient communication in underwater acoustic sensor networks,” ACM Sigbed Review, vol. 1, pp. 3–8, 2004. M. Ayaz, I. Baig, A. Abdullah, and I. Faye, “A survey on routing techniques in underwater wireless sensor networks,” Journal of Network and Computer Applications, vol. 34, no. 6, pp. 1908–1927, 2011.