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In this paper, we propose a new throughput analysis for IEEE 802.11 Distributed Coordination Function (DCF) considering the real channel conditions and capture effects under arbitrary load conditions employing basic access method. The aggregate throughput of a practical Wireless Local Area (WLAN) strongly depends on the channel conditions. In real radio(More)
The IEEE 802.11 protocol for Wireless Local Area Networks adopts a CSMA/CA protocol with exponential backoff as medium access control technique. As the throughput performance of such a scheme becomes critical when the number of mobile stations increases, in this paper we propose an Adaptive Contention Window mechanism, which dynamically selects the optimal(More)
—To satisfy the emerging need of wireless data communications , IEEE is currently standardizing the 802.11 protocol for wireless local area networks. This standard adopts a CSMA/CA medium access control protocol with exponential backoff. In this letter, we present a simple analytical model to compute the saturation throughput performance in the presence of(More)
— This letter presents a new approach to evaluate the throughput/delay performance of the 802.11 Distributed Coordination Function (DCF). Our approach relies on elementary conditional probability arguments rather than bidimensional Markov chains (as proposed in previous models), and can be easily extended to account for backoff operation more general than(More)
The IEEE 802.11e task group has reached a stable consensus on two basic contention-based priority mechanisms to promote for standardization: usage of different arbitration interframe spaces and usage of different minimum/maximum contention windows. The goal of this article is to provide a thorough understanding of the principles behind their operation. To(More)
It has been observed that different IEEE 802.11 commercial cards produced by different vendors experience different performance, either when accessing alone the channel, as well as when competing against each other. These differences persist also when thorough measurement methodologies (such as RF shielding, laptop rotation, etc) are applied, and alignment(More)
—With the popularity of the IEEE 802.11 standards, many analytical saturation throughput studies for the distributed coordination function (DCF) have been reported. In this paper, we outline a number of issues and criticalities raised by previously proposed models. In particular, a careful look at backoff counter decrement rules allows us to conclude that,(More)
Software Defined Networking envisions smart centralized controllers governing the forwarding behavior of dumb low-cost switches. But are "dumb" switches an actual strategic choice, or (at least to some extent) are they a consequence of the lack of viable alternatives to OpenFlow as programmatic data plane forwarding interface? Indeed, some level of(More)
—This paper describes the H.264 Scalable Video coding streaming Evaluation Framework (SVEF). This is the first open-source framework for experimental assessment of H.264 Scalable Video Coding (SVC) delivery over real networks. Effectively adapting of the transport of an H.264 SVC stream to time-varying, bandwidth constrained, and loss prone networks is an(More)
In addition to inhibition of the Na-K ATPase, ouabain activates a signal transduction function, triggering growth and proliferation of cultured cells even at nanomolar concentrations. An isomer of ouabain (EO) circulates in mammalians at subnanomolar concentrations, and increased levels are associated with cardiac hypertrophy and hypertension. We present(More)