VII International Telecommunications Symposium

Compressive sampling is a new framework that exploits sparsity of a signal in a transform domain to perform sampling below the Nyquist rate. In this paper we investigate the applicability of the Compressed Sensing Framework to audio compression by searching for a good sparsity basis and a reconstruction technique fit to audio applications. We also...

In this article, we discuss about link adaptation (LA) for multiple-input multiple-output (MIMO) wireless systems. We present a cross-layer approach that takes into account a hybrid automatic repeat request (HARQ) information which is a medium access control layer (MAC) layer information. The expected throughput is then used in order to...

In this work, we propose a feedback-assisted version of the Adaptive Network Coded Cooperation (ANCC) scheme, recently proposed by Bao and Li for a network consisting of M users having independent information to send to a common base station. The aim is to increase the system rate without compromising its error performance, based on a small...

Wireless data usage is growing now faster than ever before. In order to attend the increasing demand for wireless services and considering that frequency spectrum is a scarce and expensive resource, wireless are required to operate as efficiently as possible. In this context, the application of mathematical optimization methods in the study and...

Whenever a document is written on both sides of translucent paper there is a back-to-front interference, also known as bleeding or show-through. In the literature there are many algorithms to filter out the back-to-front interference in documents. This paper presents a new quantitative method to assess those algorithms. This method is based on the...

This paper discusses a coding scheme for the 2- user binary adder channel (2-BAC) employing a pair of distinct turbo convolutional codes, not necessarily forming a uniquely decodable code pair, in the presence of additive white Gaussian noise. The decoder is able to separate the binary data for each user by exploiting the code structure to combat...

Recently a new technique that used parametric amplification in optical fibers to combine two binary signals into a single quaternary amplitude-shift keying (4-ASK) signal, at frequency of signal to be amplified, was proposed. In this paper, other new technique with use of parametric amplification, also to combine two binary signals into a...

A performance analysis in terms of the bit error rate for digital systems with co-channel interference is done. In order to evaluate the effects of the interference on systems performance, expressions for the bit error rate are obtained for different scenarios. In these scenarios we consider one, two or K interferers that have the same power. If K is...

Nowadays, implement security in P2P systems is a great challenge. The possibility of building an infrastructure of public keys (PKI) operating in P2P environments represents a great advance. In this context, this paper presents an implementation of a P2P application with trust-based reputation using the JXTA platform.

In the context of space-time block codes (STBCs), the theory of hyperbolic lattices over totally real number field is presented, as well as theoretic criteria to check if such algebras are division algebras from arithmetic Fuchsian groups. These can be used to obtain families of 2 × 2 STBCs that satisfies the properties of linear dispersion, full...