Search results for "Algorithm"
showing 10 items of 4887 documents
Dynamic MAC Parameters Configuration for Performance Optimization in 802.11e Networks
2006
Quality of service support in wireless LAN is a theme of current interest. Several solutions have been proposed in literature in order to protect time-sensitive traffic from best-effort traffic. According to the EDCA proposal, which is a completely distributed solution, the service differentiation is provided by giving probabilistically higher number of channel accesses to stations involved in real-time applications. To this purpose, the MAC parameter settings of each contending stations can be tuned dynamically. In this paper, we face the problem of tuning the EDCA MAC parameters in common scenarios in which a given number of low-rate delay-sensitive traffic flows share the channel with so…
Remarks on IEEE 802.11 DCF Performance Evaluation, IEEE Communication Letters, Vol. 9, Issue 8, Aug 2005 pp:765 - 767
2005
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 DCF's one
On the accuracy of some common modeling assumptions for EDCA analysis
2005
Several models have been discussed in literature in order to evaluate the performance of the EDCA differentiation mechanisms. Despite of the exponential back off rules, usually the EDCA protocol has been modeled as a persistent slotted access protocol, and summarized into a set of access probabilities. These models often show a very different complexity and accuracy, according to the basis assumptions. In this paper, we propose a new modeling approach for EDCA, in which the medium access is described in terms of backoff counter comparisons, contention by contention, and no restrictive hypothesis is considered. Through our model, we verify the applicability of the most common protocol simpli…
Network Capacity Estimators Predicting QoE in HTTP Adaptive Streaming
2022
The aim of adaptive HTTP streaming technology is preserving the best possible video streaming quality for viewers in heterogeneous network conditions. This can be achieved by making multiple quality versions of the video available. Switching between versions during playback should be imperceptible and fluent. The decision about quality-level switching is typically based on network capacity estimation and buffer occupancy, which predict the risk of stalling. Since quality-level switching and stalling are directly evident to the user, they are often classified as influence factors of quality of experience (QoE). In this paper, we observe different network capacity estimators and buffer behavi…
Utilisation et traitement des données saisies sous EndNote avec des scripts PHP/MySQL
2010
National audience; Cet article présente la façon d’exploiter ou de traiter des données de références bibliographiques saisies ou importées dans EndNote en dehors de leur logiciel natif en utilisant des scripts PHP/MySQL. Deux raisons nous ont amenés à utiliser ce traitement : soit EndNote ne pouvait pas faire des opérations particulières, soit il le pouvait mais de façon trop fastidieuse. Dans ce but nous exposerons dans un premier temps la façon dont les données sont organisées par EndNote, puis la méthode pour les exploiter et enfin nous donnerons quelques exemples d’utilisation.
Normal, Abby Normal, Prefix Normal
2014
A prefix normal word is a binary word with the property that no substring has more 1s than the prefix of the same length. This class of words is important in the context of binary jumbled pattern matching. In this paper we present results about the number \(\textit{pnw}(n)\) of prefix normal words of length n, showing that \(\textit{pnw}(n) =\Omega\left(2^{n - c\sqrt{n\ln n}}\right)\) for some c and \(\textit{pnw}(n) = O \left(\frac{2^n (\ln n)^2}{n}\right)\). We introduce efficient algorithms for testing the prefix normal property and a “mechanical algorithm” for computing prefix normal forms. We also include games which can be played with prefix normal words. In these games Alice wishes t…
Less Data Same Information for Event-Based Sensors: A Bioinspired Filtering and Data Reduction Algorithm
2018
Sensors provide data which need to be processed after acquisition to remove noise and extract relevant information. When the sensor is a network node and acquired data are to be transmitted to other nodes (e.g., through Ethernet), the amount of generated data from multiple nodes can overload the communication channel. The reduction of generated data implies the possibility of lower hardware requirements and less power consumption for the hardware devices. This work proposes a filtering algorithm (LDSI&mdash
Topological ranks reveal functional knowledge encoded in biological networks: a comparative analysis
2022
Abstract Motivation Biological networks topology yields important insights into biological function, occurrence of diseases and drug design. In the last few years, different types of topological measures have been introduced and applied to infer the biological relevance of network components/interactions, according to their position within the network structure. Although comparisons of such measures have been previously proposed, to what extent the topology per se may lead to the extraction of novel biological knowledge has never been critically examined nor formalized in the literature. Results We present a comparative analysis of nine outstanding topological measures, based on compact vie…
AN ANALYSIS OF CONTINENT-WIDE PATTERNS OF SEXUAL SELECTION IN A PASSERINE BIRD
2006
Patterns of selection are widely believed to differ geographically, causing adaptation to local environmental conditions. However, few studies have investigated patterns of phenotypic selection across large spatial scales. We quantified the intensity of selection on morphology in a monogamous passerine bird, the barn swallow Hirundo rustica, using 6495 adults from 22 populations distributed across Europe and North Africa. According to the classical Darwin-Fisher mechanism of sexual selection in monogamous species, two important components of fitness due to sexual selection are the advantages that the most attractive males acquire by starting to breed early and their high annual fecundity. W…
Selection and long-term cultures of high-yielding Digitalis obscura plants: RAPD markers for analysis of genetic stability
1996
Fifteen wild-growing plants of Digitalis obscura collected in three differents regions were characterized according to their capacities to biosynthesize cardenolides and to proliferate in vitro. Great genotype-dependent variabilities were found in both parameters. Selected genotypes were differentiated using randomly amplified polymorphic DNA (RAPD) markers. Once an elite genotype with high-yielding properties was isolated and micropropagated during 2 years, identity of the donor plant and the regenerants was confirmed by RAPD analysis.