Node scheduling is one of the most effective techniques to maximize the lifetime of a wireless sensor network. It is the process of selecting a subset of nodes to monitor the sensor field on behalf of redundant nodes. At every round of the scheduling a small group of nodes are active while the rest of the sensor nodes are in sleep mode. In this thesis, we propose a novel node scheduling solution for wireless sensor networks. The main characteristic of our approach is its independence from location information as well as distance information. Moreover, it does not rely on unrealistic circular radio propagation models. In order to have a comprehensive solution, we have considered different relations between sensing range and transmission range. When these ranges are equal in addition to the case that transmission range is higher than sensing range, we devise a node scheduling scheme based on the concept of Minimum Dominating Set. Two heuristics are presented to determine a collection of minimum dominating sets of the graph of the wireless sensor network. At each round of the scheduling only one set is active. Minimum dominating sets are scheduled to be rotated periodically. Moreover, every set is synchronized prior to the end of its active period in order to minimize the effect of clock drift of sensor nodes. Two components are considered to address node failures during the on-duty period of minimum dominating sets. These are probing environment and adaptive sleeping. The former is responsible for probing the working nodes of the active set to detect any node failure. The latter adjusts the frequency of probing for minimizing the overhead of probing while preserving an adequate level of robustness for discovery of node failure. This framework is based on the PEAS protocol that has been developed by Fan Ye et al. [98, 99]. We propose a different node scheduling scheme with a three-tier architecture for the case that sensing range is higher than transmission range. The coverage tier includes a set of nodes to monitor the region of the interest. We propose a heuristic to determine a collection of d-dominating sets of the graph of the wireless sensor network. At every round of the scheduling one d-dominating set forms the coverage tier. Connectivity tier consists of sensor nodes that relay the data collected at the coverage tier back to the base station. Finally, the coverage management tier is responsible for managing different patterns of coverage such as cyclic or uniform coverage.

Mobile devices are becoming more prevalent and complex. As a result, the wireless communication aspect of these devices is becoming increasingly significant. At the same time, video demands in terms of availability and quality are also on the uprise. High definition (HD) video is the standard of choice for meeting today's video demands. However, HD video is characterized by high data rates. Therefore, there is heightened interest in the 60-GHz spectrum as it is suitable for streaming uncompressed HD video. On the other hand, 802.11 wireless technology, compared to 60-GHz, is much more established and widely available and able to cater to a wide variety of devices. HD video compressed using H.264 can be wirelessly streamed via 802.11 wireless networks. However, such wireless networks are prone to packet losses, which result in degraded perceptual quality of video. It is thus important to perform error concealment in order to improve the visual quality of degraded video. Among the key techniques in performing error concealment on video compressed with H.264 is spatial motion vector recovery. This paper proposes a new spatial motion vector recovery technique (MI-WAM) that takes advantage of properly decoded motion vectors. MI-WAM and pre-existing MV recovery techniques are used to provide different corresponding macroblock candidates that compete for the best concealment of each lost macroblock in what will be referred to as competitive motion vector recovery (CMVR). / Graduation date: 2012

The rapid growth in the functionality of Wi-Fi networking in recent years has benefited academic environments. Consistent with their role as centers of innovation academic institutions have an interest in facilitating as much mobile, computer networking functionality as possible to parties of varying levels of affiliation, while also assuring confidentiality and integrity of communications. Providing secure yet functional Wi-Fi access to guests and affiliates in an academic environment presents significant challenges. Academic institutions have taken a wide variety of approaches to this problem. This study presents and analyzes data gathered from semi-structured telephone interviews with employees focused on computer networking and security in academic environments regarding their institutions’ approaches toward striking a balance between security and functionality. The results are summarized, conclusions are presented, and solutions to common problems are reviewed. Finally, remaining significant research questions are presented and explored.

Covert channels are becoming more popular as security risks grow in networks. One area that is promising for covert channels is wireless networks, since many use a collision avoidance scheme such as carrier sense multiple access with collision avoidance (CSMA/CA). These schemes often introduce randomness in the network, which provides good cover for a covert timing channel. In this thesis, we use the 802.11 standard as an example to demonstrate a wireless covert channel. In particular, most 802.11 configurations use a distributed coordinated function (DCF) to assist in communications. This DCF uses a random backoff to avoid collisions, which provides the cover for our covert channel. Our timing channel provides great improvements on other recent covert channels in the field of throughput, while maintaining high accuracy. We are able to achieve throughput over 8000 bps using Covert DCF, or by accepting a throughput of 1800 bps we can achieve higher covertness and 99% accuracy as well.

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Electrical and Computer Engineering." Includes bibliographical references (p. 93-99).

Thesis (M.S.)--Naval Postgraduate School, 2002. / Thesis advisor(s): Don Brutzman, Alex Bordetsky. Includes bibliographical references (p. 189). Also available online.

Thesis (M.S. in Computer Science)--Naval Postgraduate School, March 2004. / Thesis advisor(s): Geoffrey Xie. Includes bibliographical references (p. 131-132). Also available online.

Thesis (M.S. in Engineering Science (Electrical Engineering))--Naval Postgraduate School, June 2004. / Thesis advisor(s): Murali Tummala, Roberto Cristi. Includes bibliographical references (p. 71). Also available online.

Thesis (M.S. in Systems Engineering)--Naval Postgraduate School, September 2003. / Thesis advisor(s): Gurminder Singh, Perry McDowell. Includes bibliographical references (p. 55-56). Also available online.

Diss. Karlstad : Karlstads universitet, 2009. / S. 167-188: References.