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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)
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 local-ization in(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)
—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)
Routing in multi-hop wireless networks is typically greedy, with every connection attempting to establish a path that minimizes its number of hops. However, interference plays a major role in limiting the capacity of such networks; this effect is ignored by most existing protocols. It is likely that approaches that coordinate routing to account for mutual(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)
In a Multi-hop Wireless Networks (MHWN), packets are routed between source and destination using a chain of intermediate nodes; chains are a fundamental communication structure in MHWNs whose behavior must be understood to enable building effective protocols. The behavior of chains is determined by a number of complex and interdependent processes that arise(More)
Radio environment maps are a promising architectural concept for storing environmental information for use in cognitive wireless networks. However, if not applied carefully their use can lead to large amounts of measurement data communicated over wireless links, causing substantial overhead. We propose enhancing the basic radio environment map concept by(More)
Carrier Sense Multiple Access (CSMA) protocols in Multi-hop Wireless Networks (MHWN) are known to suffer from different forms of hidden and exposed terminal problems, leading to inefficiency and unfairness. Recent studies have formally characterized the fundamental interactions in the IEEE 802.11 protocol by classifying and quantifying the possible(More)
Interference plays a complex and often defining role in the performance of wireless networks, especially in multi-hop scenarios. In the presence of interference, Carrier sense multiple access MAC protocols are known to suffer from the hidden terminal and exposed terminal problems, which can cause poor performance and unfairness. In this paper, we examine(More)