A wireless sensor network (WSN) is comprised of a few hundred or thousand au-tonomous sensor nodes spatially distributed over a particular region. Each sensornode is equipped with a wireless communication device, a small microprocessor, anda battery-powered energy source. Typically, the applications of WSNs such as habitatmonitoring, re detection, and military surveillance, require data collection, process-ing, and transmission among the sensor nodes. Due to their energy constraints andhostile environments, the main challenge in the research of WSN lies in prolongingthe lifetime of WSNs.In this dissertation, we present four dierent topology management protocols forK-coverage and load balancing to prolong the lifetime of WSNs.First, we present a Randomly Ordered Activation and Layering (ROAL) protocolfor K-coverage in a stationary WSN. The ROAL suggests a new model of layer cov-erage that can construct a K-covered WSN using the layer information received fromits previously activated nodes in the sensing distance. Second, we enhance the faulttolerance of layer coverage through a Circulation-ROAL (C-ROAL) protocol. Us-ing the layer number, the C-ROAL can activate each node in a round-robin fashionduring a predened period while conserving reconguration energy. Next, MobilityResilient Coverage Control (MRCC) is presented to assure K-coverage in the presence of mobility, in which a more practical and reliable model for K-coverage with nodalmobility is introduced. Finally, we present a Multiple-Connected Dominating Set(MCDS) protocol that can balance the network trac using an on-demand routingprotocol. The MCDS protocol constructs and manages multiple backbone networks,each of which is constructed with a connected dominating set (CDS) to ensure a con-nected backbone network. We describe each protocol, and compare the performanceof our protocols with Dynamic Source Routing (DSR) and/or existing K-coveragealgorithms through extensive simulations.The simulation results obtained by the ROAL protocol show that K-coverage canbe guaranteed with more than 95% coverage ratio, and signicantly extend networklifetime against a given WSN. We also observe that the C-ROAL protocol provides abetter reconguration method, which consumes only less than 1% of the recongura-tion energy in the ROAL protocol, with a greatly reduced packet latency. The MRCCprotocol, considering the mobility, achieves better coverage by 1.4% with 22% feweractive sensors than that of an existing coverage protocol for the mobility. The resultson the MCDS protocol show that the energy depletion ratio of nodes is decreasedconsequently, while the network throughput is improved by 35%.

With the maturity of wireless network technologies, more and more real-time data and applications, such as video on demand, video teleconferencing, are being transmitted on the wireless environment. In the next generation high-speed wireless networks, the important issue is how to provide quality-of-service (QoS) guarantees as they are expected to support multimedia applications. Although the QoS provisioning problem arises in wireline network as well, scarcity of bandwidth, mobility of hosts, high bit error rate, etc., provisioning a challenging task in wireless network. It is important to reduce the dropping rate caused by lack of available bandwidth in the handoff target cell. Call admission control is a key component for real-time, continuous media connections to guarantee QoS for these applications. In this thesis, we proposed a new call admission control scheme in wireless network. The scheme is integration bandwidth reservation and reallocation strategy and more effective to reach that decrease the handoff call dropping probability (CDP), new call blocking probability (CBP) and increase the bandwidth utilization (BU). Furthermore, our scheme also considered aspects of multi-class and fairness when the system allocated resource to calls. Extensive simulation results show that our scheme outperforms the best previously known schemes to provide QoS guarantees for multimedia traffic.

When data streams transmitted on the networks include wire and wireless parts, the utilizations of bandwidth are usually not good on existing TCP protocol, that is because TCP is not designed for the wireless transferring at first. The SNOOP protocol suggests to cache the data streams from fixed stations to mobile hosts. And do local retransmissions when the data lost is still available on base stations. Our thesis supposes to modify the existing SNOOP protocol, then proving that it reduces many unnecessary timeout on the simulation result. Generating a loss notification back to the TCP sender when there is a packet loss on the wireless link. This notification makes TCP wait a short period of time while base stations is doing local retransmission. These series of mechanisms also avoid low transmit rate which occur when unnecessary timeouts. Besides we preserve the original advantages of SNOOP.

In wireless communication networks, power consumption is an important issue due to the limited battery power available at the mobile stations. Power management is addressed efficiently by the IEEE 802.11 standard. In this paper, we change the polling order in the polling list of AP (Access Point) to further save the power of CF-Pollable (Contention Free) stations in power saving mode. The proposed schemes can reduce the power consumption of stations in power saving mode or have balanced opportunity of polling.

This thesis describes research efforts toward the development of a wireless sensor node, which can be employed in durable and expandable wireless sensor networks for remote monitoring of soil conditions in areas conducive to slope stability failures. Commercially available soil moisture probes and soil tilt sensors were combined with low-power, wireless data transmitters to form a self-configuring network of soil monitoring sensors. The remote locations of many slope stability hazard sites eliminates the possibility of real-time, remote monitoring instrumentation that relies on AC power or land-based communication methods for operation and data transfer. Therefore, various power supply solutions and data transfer methods were explored during this research and are described herein. Additionally, sensor modification and calibrations are discussed. Preliminary evaluations of field durability of the pilot instrumentation were undertaken during this research. Geotechnical engineering instrumentation must be able to withstand extreme weather related conditions. The wireless, solar-powered soil moisture and tilt sensor node was installed on the Texas A&M University campus, allowing evaluation of system reliability and instrument durability. Lastly, potential future research and conclusions arising from this research are presented. This research has shown that commercially available wireless instrumentation can be modified for use in geotechnical applications. The development of an active power management system allows for sensors to be placed in remote locations and operated indefinitely, thus creating another option for monitoring applications in geotechnical and environmental problems.

In wireless sensor networks (WSNs), flooding is usually adopted by broadcast services to disseminate broadcast messages. However, flooding produces an excessive number of unnecessary control packets, markedly increasing overhead. This work proposes a new gossip-based scheme, in which nodes forward broadcast messages with dynamic probability to decrease the number of redundant messages and thereby improve energy efficiency. By using the novel probability table and adjustment mechanism based on neighbor conditions, nodes can obtain a suitable gossip probability. Furthermore, this work considers some special cases of uneven sensor deployment such as that contains nodes with a low degree. An efficient algorithm was also developed to maintain the stability of the proposed protocol. Hence, the proposed approach can deal with various topologies and node failure. Simulations demonstrate that applying the proposed scheme to control messages forwarding improves performance compared with that of existing gossip-based broadcasting schemes.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains ix, 116 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 94-96).

Thesis (Ph. D., Computer Science)--University of Idaho, March 11, 2009. / Major professor: Paul Oman. Includes bibliographical references (leaves 158-169). Also available online (PDF file) by subscription or by purchasing the individual file.

Thesis (M.S.)--University of Florida, 2000. / Title from first page of PDF file. Document formatted into pages; contains x, 78 p.; also contains graphics. Vita. Includes bibliographical references (p. 76-77).

Thesis (M.S.)--Naval Postgraduate School, 2002. / Thesis advisor(s): R. Clark Robertson, Tri T. Ha. Includes bibliographical references (p. 75-76). Also available online.