We propose a new routing protocol MobiSink (mobile sink) for underwater sensor networks (UWSNs). We deploy the sink mobility in four horizontal regions of the network. The mobile sink moves in its own region to collect data from the transmission range sensor nodes. The transmission range of a node is calculated after fixed interval of time for mobile sink. In MobiSink nodes also take help of transmission range neighbors to communicate with sink cooperatively, if sink is out of range. The mobility pattern of sink and cooperative routing achieved better results as compared with other depth based routing protocols. The MobiSink scheme is validated via simulation, which shows better performance compared with depth based routing (DBR) and energy efficient depth based routing (EEDBR) protocols in terms of network life time, throughput and energy consumption.

In this paper, we have proposed a two-tiered wireless sensor network (WSN) in which sensor nodes transmit data packets to their connected relay nodes (cluster heads). Each sensor node is associated with at least one relay node in the network. The proposed strategy determines the best set of relay nodes for upper-tier communication. These relay nodes are periodically reselected on the basis of residual energy information of sensor nodes. Relay node reselection mechanism balances the energy consumption of sensor nodes in a network. Moreover, greedy algorithm is used to create a set of possible routing solutions. With the help of genetic algorithm (GA), we find a best routing path from a set of possible routing solutions.

In this paper, performance of hydraulic pressure based routing protocol (HydroCast) is examined, and (Improved HydroCast) a technique for reliable HydroCast is proposed. Pressure level of sensor nodes is used to route data packet in greedy multi hop fashion to sinks deployed on the surface of water. The goal of this paper is to define reliable routing technique, that is applicable for both low and high density under water wireless sensor networks. In this paper, varying number of mobile sensor nodes are randomly deployed along with some fixed nodes at different strategic locations in the network. These few fixed nodes play important role in minimizing average number of transmissions for data packet delivery, and maximizing packet delivery ratio in sparse network. Simulation results validate that the proposed technique.

In this paper, we propose a region based cooperative routing protocol (RPCRP). This protocol performs analysis of amplify and forward technique over Rayleigh fading channels. The source node sends the sensed signal to the destination and available relay nodes. At the destination node, bit error rate (BER) is checked on the basis of which, either positive or negative acknowledgement (ACK or NACK) is sent to the source and relay nodes. If the positive feedback is received from the destination node, the relay nodes drop the packet. However, in case of negative feedback, the best relay node amplifies the signal. After the signal is amplified, it is forwarded to the destination node. Moreover, the mobile sinks (MSs) change their position after some time and cover the whole network are also deployed. The nodes that lie within the transmission range of MSs forward their data directly to the sink. Also, the mathematical equations for the total SNR gain and outage probability are verified by simulations. Results show that RBCRP outperforms incremental best ralay technique (IBRT) in terms of throughput and network lifetime. Also, the mathematical analysis for outage probability shows that RBCRP is 62 % more better than IBRT.

From few past years, researchers are attracted towards the unexplored region of earth due to is extreme usefulness and that region is water. As we know 70 % of earth surface is water and only 30 % is land that is already explored well. Due to the presence of useful resources in acoustic environment, researchers felt the need to explore the unexplored world of water. In order to explore the acoustic environment, many Underwater Wireless Sensor Network (UWSNs) routing protocols are already proposed. In UWSNs, small sensing nodes are deployed to monitor the desired area and mostly sinks (to gather information from nodes) are deployed on top of the water surface. But the sensing nodes in UWSNs posses limited battery for its operation. Due to harsh environmental conditions of acoustic life, it is impossible to replace or recharge the battery of nodes. Hence, energy is the main constraint in UWSNs. For this purpose, many energy efficient routing protocols are proposed, but it cannot completely solve the issue. In this paper we have proposed the energy balanced and interference avoidance technique due to which the network lifetime and through put increases. In EB-IAEEDBR we introduce the concept of energy balancing. The initial energy of all the nodes is divided into energy chunks, when the energy garde falls it informs its neighbor node about energy degradation by broadcasting the control packet. The node on receiving the control packet changes its transmission mode from multi hop to direct transmission mode as initially nodes are on multi-hop transmission mode. By this mechanism, energy consumption of node is evenly distributed in the entire network, results in better network lifetime, throughput and efficient energy consumption of nodes.

Energy is a main issue in Underwater Wireless Sensor Networks (UWSNs). The wireless sensor nodes in underwater network have limited source of energy (batteries) and replacement of their batteries is very difficult and costly. Hence, energy efficiency has always remained as a major concern in UWSNs. Moreover the variation in energy consumption of nodes reduces the network lifetime and creates network holes. Combination of multi-hop transmission and direct communication were proposed before to balance the energy consumption between nodes. Direct transmission of data packets to sink depletes more energy of sensor node as compared to multi-hop transmission. When The nodes which reside at a greater distance from the sink opt for direct communication, their energy rapidly decreases. Thus resulting in shorter network lifetime. This paper presents Energy Efficient Hybrid Routing Protocol (EEHR). This protocol is a hybrid between multi-hop and direct transmission to the neighbors residing in the sub neighbor region. In this paper the direct transmission distance is decreased and it is refined to a sub neighbor region, which increases the network lifetime and reduces the energy consumption of the network. There are 4 regions of different radii from the sink created in our proposed protocol. The regions are in the form of semi circles beneath the sink node. Equal number of nodes are deployed randomly in each region. Neighboring lists are created by the nodes on the basis of their optimum distance to the sink. Simulation results show improvement in the network lifetime and energy consumption of the network.

Recently, Underwater Wireless Sensor Networks (UWSNs) gained much attention of researcher due to its usefulness. Unlike terrestrial sensor networks, radio waves are not suitable for UWSNs due to harsh underwater environment. However, acoustic signals gained advantage over the radio waves for underwater communication. UWSNs have distinct characteristics i.e., high propagation delay, low frequency, high bit error rate and limited energy. Therefore, designing an efficient routing protocol for underwater sensor networks is quiet challenging. The major constraint of UWSNs is the limited battery of the sensor nodes. The replacement or recharging of batteries is a hectic job due to harsh underwater environment. Therefore we propose an energy efficient routing protocol, iIA-EEDBR, for UWSNs. iIA-EEDBR selects a forwarding node which has least depth, high residual energy and least number of neighbors. iIA-EEDBR improves the network lifetime by introducing sleep nodes in the UWSNs. When a node dies in the network, a sleep node takes over the performance of that particular dead node to avoid creation of routing holes. Due to the creation of the routing holes the network performances is affected and degraded. Therefore, iIA-EEDBR prevents the creation of routing holes.