Energy-Balancing with Sink Mobility in the Design of Underwater Routing Protocols
Underwater Wireless Sensor Networks (UWSNs) have been considered to provide efficient monitoring tasks and help in exploring aquatic environments. UWSNs composed of small size sensor nodes which are randomly or deterministically deployed in the desired sensing area. The focus of this thesis is energy balancing with sink mobility through the design of routing strategies for UWSNs. First and foremost, Dolphin and Whale Pods Routing (DOW-PR) routing, implements the adaptive transmission range adjustment into a number of power levels and at the same time select the next PFN from forwarding and suppressed zones. DOW-PR not only considers the packet upward advancement, but also takes into account the number of suppressed nodes and number of PFNs at the first and second hops. This research come up with another two schemes: geospatial division based geo-opportunistic routing for interference avoidance (GDGOR-IA) and Geographic routing for maximum coverage with sink mobility (GRMC-SM). The former one has opted depth based recovery and later one utilizes vertical and horizontal coordinate adjustment of deployed sinks to provide maximum coverage over an area. Furthermore, network field is divided into logical cubes by considering transmission range of sensor nodes. Both the schemes contribute to avoid fraction of local maximum nodes and improve packet delivery ratio (PDR). Also they can handle connectivity holes by their proposed recovery mechanisms. Additionally, Location Error resilient Transmission Range adjustment based protocol (LETR), Mobile Sink based LETR (MSLETR) and Modified MSLETR (MMS-LETR) for UWSNs are proposed. To successfully deliver data packets and maximize network throughput along with energy efficiency, LETR calculates Mean Square Error (MSE). This helps to cope with the inefficiency introduced by geographic routing (without considering location inaccuracy) in terms of energy consumption and network throughput. The packet delivery probability, packet advancement and MSE are used altogether in the selection of optimal forwarder node. Finally, an Energy Scaled and Expanded Vector-Based Forwarding (ESEVBF) scheme contributes the mitigation of duplicate packets generation due to imbalance of holding time difference and propagation delay between nodes. ESEVBF uses the residual energy of the node to scale and vector pipeline distance ratio to expand the holding time. Resulting scaled and expanded holding time of all forwarding nodes has a significant difference to avoid multiple forwarding, which reduces energy consumption and energy balancing in the network with less end to end delay.