Routing plays an important role in energy constrained Wireless Sensor Networks (WSNs). To conserve energy in WSN, energy-efficiency of the routing protocol is an important design consideration. These protocols should maximize network lifetime and minimize energy consumption. In this thesis, a novel multipath routing protocol is proposed for WSNs, which constructs multiple paths based on residual energy of the nodes. The protocol allows the source node to select a path for data transmission from the set of discovered multiple paths based on cumulative residual energy or variance. Choosing a next-hop node based on energy, and using an alternative path for routing achieves load balancing. The results show that the proposed algorithm M-VAR has lower residual energy variance (96%, 90%, 72%, 12% less) and longer network lifetime (404%, 205%, 115%, 10%) than basic Directed Diffusion, load-balanced Directed Diffusion (LBDD-ED-RD), multipath Directed Diffusion (MDD-CRE), and the proposed algorithm M-CRE, respectively.

Routing plays an important role in energy constrained Wireless Sensor Networks (WSNs). To conserve energy in WSN, energy-efficiency of the routing protocol is an important design consideration. These protocols should maximize network lifetime and minimize energy consumption. In this thesis, a novel multipath routing protocol is proposed for WSNs, which constructs multiple paths based on residual energy of the nodes. The protocol allows the source node to select a path for data transmission from the set of discovered multiple paths based on cumulative residual energy or variance. Choosing a next-hop node based on energy, and using an alternative path for routing achieves load balancing. The results show that the proposed algorithm M-VAR has lower residual energy variance (96%, 90%, 72%, 12% less) and longer network lifetime (404%, 205%, 115%, 10%) than basic Directed Diffusion, load-balanced Directed Diffusion (LBDD-ED-RD), multipath Directed Diffusion (MDD-CRE), and the proposed algorithm M-CRE, respectively.

Thesis (Ph.D.)--George Mason University, 2008. / Vita: p. 124. Thesis directors: Sushil Jajodia, Sanjeev Setia Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Information Technology. Title from PDF t.p. (viewed Jan. 11, 2009). Includes bibliographical references (p. 120-123). Also issued in print.

Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 66-70).

Thesis (M.S. in computer science )--Washington State University, August 2009. / Title from PDF title page (viewed on Apr. 2, 2010). "School of Electrical Engineering and Computer Science." Includes bibliographical references (p. 65-73).

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 79-82). Also available on the World Wide Web.

Thesis (M.Sc.)--York University, 2008. Graduate Programme in Computer Science. / Typescript. Includes bibliographical references (leaves 147-152). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR51580

AN ABSTRACT OF THE THESIS OF ISMAIL GUNEYDAS, for the Master of Science degree in Computer Science, presented on 5th November 2008, at Southern Illinois University Carbondale. TITLE: ACTOR POSITIONING IN WIRELESS SENSOR AND ACTOR NETWORKS USING MATCHING THEORY. MAJOR PROFESSOR: Dr. KEMAL AKKAYA In most of the Wireless sensor and actor network (WSAN) applications, the locations for the actors are determined autonomously by the collaboration of actors and/or sensors in order to eliminate human intervention as much as possible. Particularly, sensors can collaborate in a distributed manner and elect cluster-heads (CHs) among them which will be taking into account the distribution of the sensors within the region. In such cases, the actors can then move to such sensor locations (i.e., replace them as cluster-heads) as they have the ability to move by talking to nearby sensors/actors. Such movement, however, should be done wisely in order to minimize the total distance that will be traveled by the actors so that their lifetimes can be extended. Nevertheless, this may not be possible since not all the actor and CH locations will be known to each actor. In addition, the actors may not be reachable to each other and thus conflicts in assignments can easily occur. In this thesis, we propose an actor-CH location matching algorithm which will detect the CH locations and assign the actors to such locations in a distributed manner with the minimized travel distance. We adapt the Gale-Shapley (G-S) stable matching algorithm from Matching Theory in order to prevent conflicts and minimize the travel distance. In this matching algorithm, actors are regarded as men and CHs are regarded as women. First, we detect the CH locations through running a quorum-based search within the sensor network. Later, G-S is run on actor and CH locations. Once the locations are determined, each actor moves to that location. We evaluated the performance of our approach through simulation and have shown that our approach can produce results very close to the brute force approach.

Wireless sensor network has been an area of interest among researchers. Designing a wireless sensor network involves multiple issues such as size and processing capacity of the sensors, number of the cluster heads, number of the base stations, routing protocols, battery of the nodes, layout of the system, etc. Battery is a critical factor, since sensor networks do not involve maintenance as they are situated in remote places. Hence the available battery must be utilized effectively to increase the efficiency. In our study we address issues associated with battery such that to increase the lifetime of the system. Existing standards for the sensors are implemented with each node having equal battery level `B' referred to as `Uniform system' in our study. Thus total amount of battery consumed by N nodes is `N * B'. In our approach we study the distribution of this `N * B' battery in non-uniform manner, referred as `Non-uniform system', such that each node would be allocated with different battery level depending upon its position and amount of information it receives and transmits. Initially we commence with the observation of the behavior of this approach on a chain of nodes. These nodes generate information at constant rate and transmit per cycle. We observed that there is a huge amount of increase in the lifetime as compared to lifetime of the uniform system. We step further in our experimentation by restricting the amount of battery each node can have and then quantizing it. Results indicate that only 3 levels of batteries instead of N, give us significant increase in the lifetime. These results validate our approach for practical implementation. We progressed by observing success of our approach on random topology where nodes are laid randomly in the area of experimentation. Approximately same increase in the lifetime as achieved initially without restricting battery levels can be achieved. Simulation results show that non-uniform system performs much better than uniform system. This approach of non uniform battery levels can be implemented in sensor networks such that system lives longer giving more throughput and thus increasing efficiency.

The coverage and energy issues are the fundamental problems which prevent the development of wireless sensor networks. In order to accurately evaluate the monitoring quality (coverage), one needs to model the interactive of sensors, phenomenons and the environment. Furthermore, in collaborative with scheduling algorithm and computer optimization, protocols can improve the overall monitoring quality and prolong the lifetime of network. This thesis is an investigation of coverage problem and its relative applications in the wireless sensor networks. We first discuss the realistic of current boolean sensing model and propose an irregular sensing model used to determine the coverage in the area with obstacles. We then investigate a joint problem of maintaining the monitoring quality and extending the lifetime of network by using scheduling schemes. Since the scheduling problem is NP hard, genetic algorithm and Markov decision process are used to determine an achievable optimal result for the joint problem of coverage-preserving and lifetime-prolong. In order to avoid the cost of centralized or distributed scheduling algorithms, a localized coverage-preserving scheduling algorithm is proposed by exploring the construction process of Voronoi diagram. Besides exploring the coverage characteristic in a static wireless sensor network, we investigate the coverage problem when the mobile elements are introduced into network. We consider the single-hop mobile data gathering problem with the energy efficiency and data freshness concerns in a wireless sensor network where the connectivity cannot be maintained. We first investigate the upper/lower bound of the covering time for a single collector to cover the monitoring area. Through our investigation we show that for a bounded rectangle area a hexagon walk could explore the area more efficiently than a random walk when the edges of area are known. We then propose a virtual force mobile model (VFM) in which the energy consumption for data transmission is modeled as a virtual elastic force and used to guide of mobile collectors to move to optimal positions for energy saving.