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We analyze the performance of the IEEE 802.11b wireless local area networks. We have observed that when some mobile hosts use a lower bit rate than the others, the performance of all hosts is considerably degraded. Such a situation is a common case in wireless local area networks in which a host far away from an Access Point is subject to important signal(More)
We consider wireless LANs such as IEEE 802.11 operating in the unlicensed radio spectrum. While their nominal bit rates have increased considerably, the MAC layer remains practically unchanged despite much research effort spent on improving its performance. We observe that most proposals for tuning the access method focus on a single aspect and disregard(More)
We analyze in this paper the fairness of the 802.11 DCF (Distributed Coordination Function) access method. Shortterm fairness is an important property of a MAC layer for obtaining short delays. We show that contrary to the common wisdom, a 802.11 cell with two hosts does not exhibit shortterm unfairness. Many papers considered 802.11 as short-term unfair by(More)
An overwhelming part of research work on wireless networks validates new concepts or protocols with simulation or analytical modeling. Unlike this approach, we present our experience with implementing the <i>Idle Sense</i> access method on programmable off-the-shelf hardware---the Intel IPW2915/abg chipset. We also present measurements and performance(More)
HyPursuit is a new hierarchical network search engine that clusters hypertext documents to structure a given information space for browsing and search act ivities. Our content-link clustering algorithm is based on the semantic information embedded in hyperlink structures and document contents. HyPursuit admits multiple, coexisting cluster hierarchies based(More)
s digital video becomes ubiquitous and more video sources become available, applications will need to A deal with digital video as a new data model. However, since video has both temporal and spatial dimensions, it places different requirements on applications than existing data types such as text. Moreover, the volume and unstructured format of digital(More)
In this paper, we introduce and evaluate novel adaptive schemes for neighbor discovery in Bluetooth-enabled ad-hoc networks. In an ad-hoc peer-to-peer setting, neighbor search is a continuous, hence battery draining process. In order to save energy when the device is unlikely to encounter a neighbor, we adaptively choose parameter settings depending on a(More)
MAC protocols based on preamble sampling techniques like WiseMAC and BMAC offer significant energy savings for multihop wireless sensor networks. Although preamble sampling based techniques efficiently reduce idle listening in lowrate data networks, they introduce extra overhead due to possible reception of some irrelevant frames. In this paper, we identify(More)