On the energy efficiency of IEEE 802.11 WLANs

Proceedings of: 2010 European Wireless Conference (EW2010), (April 12-15, 2010), Lucca, ItalyUnderstanding the energy consumption of wireless interfaces is critical to provide guidelines for the design and implementation of new protocols or interfaces. In this work we analyze the energy performance of an IEEE 802.11 WLAN. Our contributions are as follows: i) we present an accurate analytical model that is able to predict the energy consumption, ii) we present an approximate model that sacrifices accuracy for the sake of analytical tractability, iii) based on this simplified analysis, we derive the optimal configuration to maximize energy efficiency of a WLAN, and iv) finally, we also analyze the tradeoff between throughput and energy efficiency that IEEE 802.11 imposes. While most of these results consider a homogeneous WLAN scenario where all stations share the same energy features, we also discuss the case of heterogeneous environments, where different devices show different power consumption characteristics.European Community's Seventh Framework ProgramPartly funded by the Ministry of Science and Innovation of Spain, under the QUARTET project (TIN2009-13992-C02-01)Publicad

Fully dynamic and memory-adaptative spatial approximation trees

Hybrid dynamic spatial approximation trees are recently proposed data structures for searching in metric spaces, based on combining the concepts of spatial approximation and pivot based algorithms. These data structures are hybrid schemes, with the full features of dynamic spatial approximation trees and able of using the available memory to improve the query time. It has been shown that they compare favorably against alternative data structures in spaces of medium difficulty. In this paper we complete and improve hybrid dynamic spatial approximation trees, by presenting a new search alternative, an algorithm to remove objects from the tree, and an improved way of managing the available memory. The result is a fully dynamic and optimized data structure for similarity searching in metric spaces.Eje: Teoría (TEOR)Red de Universidades con Carreras en Informática (RedUNCI

Period Matrices Of Accola-Maclachlan And Kulkarni Surfaces

We compute the period matrices of the Riemann surfaces given by the equations w2 = z2g+