Power-line communication (PLC) deals with the challenge of transmitting data over a channel impaired by background and impulsive noises. In this paper, we provide evidence that the marginal distribution of the noise found in PLC systems exhibits some statistical properties that can be well captured by using -stable distribution. Motivated by this result, we present a practical application of the -stable model to synthesize noise in the power line. Furthermore, we also show that this family of distributions is a suitable alternative in order to model the PLC background noise that is commonly assumed as Gaussian. Finally, we study the performance of an orthogonal frequency-division multiplexing communication system under both kinds of background noise (i.e., Gaussian and -stable). From these experiments, we conclude that if highly impulsive background traffic is mistakenly assumed as Gaussian in evaluation studies, the system performance is largely overestimated.Index Terms--stable noise model, orthogonal frequency-division multiplexing (OFDM) performance, power-line communication (PLC), PLC noise modeling.

In this work we introduce a variable step-size normalized LMS algorithm for adaptive echo cancellation in a FIRstructure. In the proposed scheme, the step-size adjustment is controlled by using the square of the cross-correlationbetween the squared output error and the adaptive filter output. The proposed algorithm (that we call VSSSC aftervariable step size based on the squared cross-correlation) was evaluated using white noise and speech signals.Simulation results show that our proposal achieves better performance than similar algorithms in single and doubletalk. The proposed algorithm can be used in a number of applications such as in echo reduction for long-haul voicecommunications.

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Whereas there is a lot of work related to finding the location of users in WLAN and ad-hoc networks, guiding users in these networks remains mostly an unexplored area of research. In this paper we present the concept of node-to-node guidance and introduce a method that can be used to implement it. This method relies on the computation of a local gradient in the neighborhood of the moving node. We named this protocol GUIDE-gradient, which is a GPS-free and infrastructure-free node-to-node guiding system. In this paper we also discuss how the guiding algorithm can be generalized to node-to-node guidance in multihop ad-hoc networks.

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