Skyline queries are a class of preference queries that compute the pareto-optimal tuples from a set of tuples and are valuable for multi-criteria decision making scenarios. While this problem has received significant attention in the context of single relational table, skyline queries over joins of multiple tables that are typical of storage models for RDF data has received much less attention....

WiMAX (Worldwide Interoperability for Microwave Access) is a promising technology which can offer high speed voice, video and data services upto the requirements at the customer’s end. The objectives of this paper is to evaluate the Performance evaluation of a WiMAX system under various diversity schemes (Selection combining, Maximal ratio combining and Equal gain combining), employing differen...

Two concurrent factors challenge the evaluation of large-scale cache networks: complex algorithmic interactions, which are hardly represented by analytical models, and catalog/network size, which limits the scalability of event-driven simulations. To solve these limitations, we propose a new hybrid technique, that we colloquially refer to as ModelGraft, which combines elements of stochastic ana...

This article examines spectrum allocation and partitioning schemes to mitigate cross-tier interference under downlink beamforming environments. The enhanced SIR owing to beamforming allows more femtocells to share their spectrum with the macrocell and accordingly improves overall spectrum efficiency. We first design a simplified centralized scheme as the optimum and then propose a practical dec...

This paper presents novel extensions to our earlier system for streaming perceptually coded audio over error prone channels such as mobile IP. To improve error robustness while maintaining bandwidth efficiency, the new extensions combine the strength of an error resilient coding scheme in the sender, a prioritized packet transport scheme in the network and a compressed domain error concealment ...

using modern irrigation methods such as border irrigation is one way for an optimum usage of water. potato, for this study, was cultured in a farm located at kermanshah faculty of agriculture to evaluate the efficiency of border irrigation. the culture potato was the agria variety and the applied treatment were 50, 75, and 100 percent of potato plant`s water requirement. tapes were 12 m and the...

Future wireless networks need to address the predicted growth in mobile traffic volume, expected to have an explosive growth in the next five years mainly driven by video and web applications. Transmission schemes based on Orthogonal Frequency Division Multiple Access (OFDMA) combined with Space Division Multiple Access (SDMA) techniques are key promising technologies to increase current spectr...

Novel closed-form expressions for the probability density function and the average output signal-to-noise ratio at the output of a selection combiner in Weibull fading are derived. Using these expressions, the spectral efficiency of a direct sequence code division multiple access system is analytically obtained and performance evaluation results are presented. r 2004 The Franklin Institute. Pub...

Cognitive Radio generates a big interest as a key cost-effective solution for the underutilization of frequency spectrum in legacy communication networks. The objective of this work lies in conducting a performance evaluation of the end-to-end message delivery under both Markovian and Poissonian primary traffics in lossy Cognitive Radio networks. We aim at inferring the most appropriate conditi...