This paper compares different approaches for computing power products ∏ 1≤i≤k g ei i in commutative groups. We look at the conventional simultaneous exponentiation approach and present an alternative strategy, interleaving exponentiation. Our comparison shows that in general groups, sometimes the conventional method and sometimes interleaving exponentiation is more efficient. In groups where in...

In this paper, differential modulation diversity (DMD) is introduced. This diversity scheme is based on diagonal signal constellations which have been previously proposed for differential space–time modulation (DSTM). DMD can exploit both space and time diversity and DSTM, which is a pure space diversity scheme, results as a special case. A low– complexity noncoherent receiver originally design...

This paper describes two experiments designed to (1) ascertain whether the way in which architectural plans are displayed on a computer screen influences the quality of their correction by humans, and (2) identify the visual exploration strategies adopted in this type of task. Results of the first "spot the difference" experiment showed that superimposing the plans yielded better error correcti...

In this paper, we report on our TREC experiments with the ClueWeb09 document collection. We participated in the relevance feedback and web tracks. While our phase 1 relevance feedback run’s performance was good, our other relevance feedback and web track submissions’ performances were lacking. We suspect this performance difference is caused by the Category B document subset of the ClueWeb09 co...

Abstract. In this work we present a transcoding framework and an object-based technique to adapt live and stored videos to the user bandwidth and resources capabilities. Multiple transcoding policies are reviewed and a performance evaluation metric based on the Weighted Mean Square Error that allows different classes of relevance is presented. We present results for different transcoding polici...

The INET framework for the simulation tool OMNeT++ provides a TCP module, which can be used for evaluating various Internet applications. However, the implementation of this TCP module has not been state of the art. Some important features of modern TCP implementations – particularly Selective Acknowledgements (SACK) and a complete Flow Control – have been missing. In this paper, we first intro...

The estimation of the slope parameter of the linear regression model with normal error is considered in this paper when uncertain prior information on the value of the slope is available. Several alternative estimators are defined to incorporate both the sample as well as the non-sample information in the estimation process. Some important statistical properties of the restricted, preliminary t...

In this paper, we address the problem of estimating the second-order statistics of a frequency-selective Rayleigh channel in the context of the wideband CDMA mode of the UMTS. The data to be transmitted are sent over slots on which the channel is assumed to remain constant. Each slot contains a pilot symbol sequence from which it is possible to estimate the current value of the channel. The cov...

In this paper, we study the problem of non parametric estimation of the mean and variance functions b and σ2 in a model: Xi+1 = b(Xi) + σ(Xi)εi+1. For this purpose, we consider a collection of finite dimensional linear spaces . We estimate b using a mean squares estimator built on a data driven selected linear space among the collection. Then an analogous procedure estimates σ2, using a possibl...

Atmospheric turbulence can cause significant performance degradation in free space optical (FSO) communication system. Major effects on the beam such as beam wander and beam scintillation degrades the performance at the receiver. We investigate the impact of diversity technique and aperture averaging technique on the performance of FSO system. Performance evaluation is made in terms of average ...