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In existing directional MAC protocols a single queue is used at the MAC layer; this is inherited from omnidirectional implementations. However, while there is a single channel state in omnidirectional transmission (either the channel is busy or not), the state of the channel varies with the desired direction of transmission in directional antennas. Thus,(More)
Localization is a fundamental operation in mobile and self-configuring networks such as sensor networks and mobile ad hoc networks. For example, sensor location is often critical for data interpretation; moreover, network protocols, such as geographic routing and geographic storage require individual sensors to know their coordinates. Existing research(More)
The ability of a sensor node to determine its physical location within a network (Localization) is of fundamental importance in sensor networks. Interpretating data from sensors will not be possible unless the context of the data is known; this is most often accomplished by tracking its physical location. Existing research has focused on localization in(More)
Given the changing dynamics of mobility patterns and rapid growth of cities, transport agencies seek to respond more rapidly to needs of the public with the goal of offering an effective and competitive public transport system. A more data-centric approach for transport planning is part of the evolution of this process. In particular, the vast penetration(More)
Cognitive Radios have emerged as one the most promising methods to increase wireless system efficiency through dynamic spectrum access combined with other cross-layer optimization methods. Most of the research prototypes and demonstrations have so far focused on either general platforms or scenarios that are predominantly taken from military or emergency(More)
We consider the problem of target coverage in visual sensor networks with Pan-Tilt-Zoom (PTZ) cameras. The finely controllable movement in PTZ dimensions creates a large number of possible Field-of-View (FoV) settings, making it prohibitively expensive to consider them all in coverage algorithms. However, these FoVs are redundant as each group of targets is(More)
Directional antennas have been proposed to improve the performance and capacity of Wireless MAC protocols for use in Mobile Ad hoc Networks (MANETs). Such antennas focus their beams in the direction of their receiver, allowing more of the signal power to be used in the direction of the transmission and simultaneously reducing the interference in other(More)
Carrier Sense Multiple Access (CSMA) protocols are unable to effectively arbitrate the medium in wireless networks; problems such as hidden and exposed terminals occur frequently leading to collisions, poor performance and unfairness. CSMA networks can be optimized by careful tuning of transceiver parameters, such as transmission power and carrier sensing(More)
Chains or multi-hop paths are fundamental communication structures in Multi-Hop Wireless Networks (MHWNs). Understanding chain behavior is critical in order to build effective higher layer protocols. This paper examines the problem of how MAC level interactions influence chain behavior in a general MHWN where multiple chains coexist. We first classify(More)
Estimating the quality of wireless link is vital to optimize several protocols and applications in wireless networks. In realistic wireless networks, link quality is generally predicted by measuring received signal strength and error rates. Understanding the temporal properties of these parameters is essential for the measured values to be representative,(More)