Improvement of Energy, Lifetime and Delays in Underwater Wireless Sensor Networks by Effective Deployment of Relay Nodes
According to the importance of underwater exploration, the attention of many researchers has been attracted to underwater sensor networks (UWSNs). Problems of UWSNs are large propagation delay, low bandwidth, and limited energy. Because of these reasons, in this paper, we propose a new routing method in UWSNs that considers these factors and also achieves better load balancing in the network. In this method, relay nodes are used for routing. The relay nodes have a higher traffic load compared to the other nodes. They remove some burden from the overloaded nodes. The relay nodes shorten the transmission distance between source and destination. They have more energy compared to the other nodes. Our results show that the deployment of relay nodes in sensor networks helps to balance energy consumption and enhance the network lifetime. Nodes, after calculating the distance to the relay nodes and finding the nearest relay node, transmit packets to the nearest relay node for onetime immediately, so this method does not have holding time and it has less delay. The results are compared with DBR and CODBR. The results show that our method achieves more network lifetime, less delay and energy consumption compared to DBR and CODBR.
 M. Erol-Kantarci, H. T. Mouftah, and S. Oktug, "A Survey of Architectures and Localization Techniques for Underwater Acoustic Sensor Networks," IEEE Communications Surveys & Tutorials, vol. 13, no. 3, pp. 487-502, 2011.
 "Communications in Computer and Informatio Science," 2011.
 T. Khan et al., "Clustering Depth Based Routing for Underwater Wireless Sensor Networks," in 2016 IEEE 30th International Conference on Advanced Information Networking and Applications (AINA), 2016, pp. 506-515.
 H. Yan, Z. J. Shi, and J.-H. Cui, "DBR: Depth-Based Routing for Underwater Sensor Networks," in NETWORKING 2008 Ad Hoc and Sensor Networks, Wireless Networks, Next Generation Internet: 7th International IFIP-TC6 Networking Conference Singapore, May 5-9, 2008 Proceedings, A. Das, H. K. Pung, F. B. S. Lee, and L. W. C. Wong, Eds. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008, pp. 72-86.
 H. Nasir et al., "CoDBR: Cooperative Depth Based Routing for Underwater Wireless Sensor Networks," in 2014 Ninth International Conference on Broadband and Wireless Computing, Communication and Applications, 2014, pp. 52-57.
 P. Xie, J.-H. Cui, and L. Lao, "VBF: vector-based forwarding protocol for underwater sensor networks," in International conference on research in networking, 2006, pp. 1216-1221: Springer.
 A. Wahid and D. Kim, "An energy efficient localization-free routing protocol for underwater wireless sensor networks," International journal of distributed sensor networks, vol. 8, no. 4, p. 307246, 2012.
 N. Nicolaou, A. See, P. Xie, J.-H. Cui, and D. Maggiorini, "Improving the robustness of location-based routing for underwater sensor networks," in Oceans 2007-Europe, 2007, pp. 1-6: IEEE.
 J. Suomela, "Relay Placement in Sensor Networks," 2005.