Underwater sensor nodes will find applications in oceanographic data collection, pollution monitoring, o#shore exploration, disaster prevention, assisted navigation and tactical surveillance applications. Moreover, unmanned or autonomous underwater vehicles (UUVs, AUVs), equipped with sensors, will enable the exploration of natural undersea resources and gathering of scientific data in collaborative monitoring missions. Underwater acoustic networking is the enabling technology for these applications. Underwater networks consist of a variable number of sensors and vehicles that are deployed to perform collaborative monitoring tasks over a given area. In this

Underwater sensor networks consist of sensors and vehicles deployed to perform collaborative monitoring tasks over a given region. Underwater sensor networks will find applications in oceanographic data collection, pollution monitoring, offshore exploration, disaster prevention, assisted navigation, tactical surveillance, and mine reconnaissance. Underwater acoustic networking is the enabling technology for these applications. In this paper, an architecture for three-dimensional underwater sensor networks is considered, and a model characterizing the acoustic channel utilization efficiency is introduced, which allows investigating some fundamental characteristics of the underwater environment. In particular, the model allows setting the optimal packet size for underwater communications given monitored volume, density of the sensor network, and application requirements. Moreover, the problem of data gathering is investigated at the network layer by considering the cross-layer interactions between the routing functions and the characteristics of the underwater acoustic channel. Two distributed routing algorithms are introduced for delay-insensitive and delaysensitive applications. The proposed solutions allow each node to select its next hop, with the objective of minimizing the energy consumption taking the varying condition of the underwater channel and the different application requirements into account. The proposed routing solutions are shown to achieve the performance targets by means of simulation.

In this paper, architectures for two-dimensional and three-dimensional underwater sensor networks are discussed. A detailed overview on the current solutions for medium access control, network, and transport layer protocols are given and open research issues are discussed. Categories and Subject Descriptors:

In this paper, different deployment strategies for two-dimensional and three-dimensional communication architectures for UnderWater Acoustic Sensor Networks (UW-ASNs) are proposed, and statistical deployment analysis for both architectures is provided. The objectives of this paper are to determine the minimum number of sensors needed to be deployed to achieve the optimal sensing and communication coverage, which are dictated by the application; provide guidelines on how to choose the optimal deployment surface area, given a target region; study the robustness of the sensor network to node failures, and provide an estimate of the number of redundant sensors to be deployed to compensate for possible failures. Categories and Subject Descriptors:

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Surveillance wireless sensor networks are deployed at perimeter or border locations to detect unauthorized intrusions. For deterministic deployment of sensors, the quality of deployment can be determined sufficiently by analysis in advance of deployment. However, when random deployment is required, determining the deployment quality becomes challenging. To assess the quality of sensor deployment, appropriate measures can be employed that reveal the weaknesses in the coverage of SWSNs with respect to the success ratio and time for detecting intruders. In this article, probabilistic sensor models are adopted, and the quality of deployment issue is surveyed and analyzed in terms of novel measures. Furthermore, since the presence of obstacles in the surveillance terrain has a negative impact on previously proposed deployment strategies and analysis techniques, we argue in favor of utilizing image segmentation algorithms by imitating the sensing area as a grayscale image referred to as the iso-sensing graph. Finally, the effect of sensor count on detection ratio and time to detect the target is analyzed through

While self-deployment/reconfiguration of terrestrial wireless sensor networks (WSNs) has been studied extensively, such selforganization has just started to receive attention for Underwater Acoustic Sensor Networks (UWSNs). Particularly, self-deployment of sensor nodes in UWSNs is challenging due to certain characteristics of UWSNs such as three dimensional (3-D) environment, restrictions on node movement and longer delays in communication. Given these characteristics, self-deployment of sensor nodes should not only ensure the necessary coverage but also guarantee the connectivity for data transmission as in the case of terrestrial WSNs. In this paper, we propose a distributed node deployment scheme which can increase the initial network coverage in an iterative basis. Assuming that the nodes are initially deployed at the bottom of the water and can only move in vertical direction in 3-D space, the idea is to relocate the nodes at different depths based on a local agreement in order to reduce the sensing overlaps among the neighboring nodes. The nodes continue to adjust their depths until there is no room for improving their coverage. We tune the parameters of the algorithm to also provide connectivity of the network with a surface station. We compared the coverage and connectivity performance of this distributed scheme with distributed/semi-distributed baseline schemes and centralized schemes which can provide optimal coverage/connectivity. We also provide several observations regarding the coverage/connectivity performance and message/travel/time complexity of the proposed approach. Key words: UWSNs; underwater sensor deployment; self-organization; 3-D coverage; underwater mobility 1.

Wireless sensor networks (WSN) is tending towards becoming a complete solution in communication protocols, embedded systems and low-power implementations. However, the resource constraints which includes, limited communication range, limited energy, limited computing power, limited bandwidth and the fear of intruders have limited the WSN applications. Since lightweight computational nodes that are currently being used in WSN pose particular challenge for many security applications, the whole research therefore, is the investigation of new security techniques and appropriate implementation for WSN nodes, including various trade-offs such as implementation complexity, power dissipation, security flexibility and scalability. The goal of this research is to develop a network that has efficient and flexible key distribution scheme secured enough to prevent algorithmic complexity and denial of service attacks as well as the network able to conserve energy. A review of previous research to date in the area of security for WSNs was carried out and proposals are made based on security schemes that gather data in an energy-efficient mechanism through secured pre-allocation of keys, faster clustering routing algorithm and dynamic based rekeying implementation.

With current technologies submarines can thwart active or passive sonar detection. A viable alternative to detect submissible vessels is to use magnetic or acoustic sensors in close proximity to possible underwater pathways of them. This approach may require deploying large-scale underwater sensor networks to form barriers. We show new results for construction barriers in 3D sensor networks. First, we prove that barriers are unlikely to exist in a large 3D fixed emplacement sensor field where sensor locations follow a Poisson point process. We then derive the notion of 3D stealth distance to measure how far a submarine can travel in a sensor network without detection. Finally, we describe energy conserving approaches for constructing a 3D barrier using mobile nodes to detect intruders. We focus on developing an energy efficient matching of mobile sensors that move to cover gridpoints using auction algorithms. We compare our results of the auction approach to an optimal approach using simulations and show that the auction algorithm produces similar results to the optimal approach at a reduced computational expense. This provides a fruitful new approach to constructing barriers in 3D sensor networks. I.

Abstract — A radio network is a distributed system consisting of a large number of tiny sensors with low-power transceivers and no central controller. One of the most important problems in such networks is to minimize the energy consumption, and maximize the network lifetime. In the initialization problem (also known as naming) each of the n indistinguishable (anonymous) nodes in a given network is assigned a unique identifier, ranging from 1 to n. We consider a network where n nodes (processors) are randomly deployed in a square (resp. a cube) X. The network is assumed to be synchronous and the time to be slotted. Two nodes can communicate only if they are at a distance of at most r from each other (r is the transmitting/receiving range). Moreover, if two or more neighbors of a processor u are transmitting concurrently at the same time slot, u cannot receive either of their messages (collision). We suppose also n and |X | represent the only topological knowledge in each node. To solve the initialization problem, we propose an energy-efficient “ randomized algorithm running in at most O n 3/4 log (n) 1/4” awake for more than O time slots, with no station being n 1/4 log (n) 3/4” time slots. Index Terms — Multihop networks; self-configuration in ad hoc networks; randomized distributed protocols; initialization; naming; energy efficient algorithms. I.