VII International Telecommunications Symposium

Blind source separation (BSS) techniques have been extensively investigated in the last years, due to their large number of applications. There are two main approaches employed for such techniques: in the time-domain and in the frequencydomain. In this paper, we propose the use of a non-uniform DFT transform as a strategy for improving the behavior of...

We propose an energy-efficient algorithm for sensing a process f(x,y,t) using a multihop Wireless Sensor Network (WSN). The innovation-based algorithm aims at saving node energy by managing the transmission necessity. The nodes can also switch to an inactivity state, between innovative transmissions. When a node needs to send data, it transmits...

In this paper, we propose a different scheme based on user cooperation diversity, in which we obtain an increase in the data rate. In particular, we present performance analysis using conventional CDMA (code division multiple access) implementation for two users. Cooperation among users has been shown to achieve significant gains as compared to...

This article aims to establish a performance comparison between the Single Carrier with Cyclic Prefix (SCCP) and the Orthogonal Frequency Division Multiplexing (OFDM) systems in terms of the cutoff rate. We consider both linearly equalized SCCP (LE-SCCP) and the SCCP equalized with a decision feedback equalizer (DFE-SCCP). A theoretical approach to...

This paper investigates the influence of data loss in the performance of cooperative adaptive filters in distributed networks. The algorithms analyzed are those with and without data selection based on innovation. Our simulation results indicate that set-membership adaptation algorithms, which perform some form of innovation check prior to...

In this paper, a performance analysis for QPSK, 16- QAM and 64-QAM, modulations in the presence of co-channel interference is made. At first, an expression of the bit error rate (BER) for M-PAM as a function of the Eb=N0 ratio in the presence of K interferers is obtained. The formula from the BER gotten earlier is used to derive a simplified...

The Lombard effect is related to the change in the way people speak in noisy environments in order to compensate the degradation of the audio signal. There are significant changes in the duration of some types of phones and in the formant positions that can vary from a language to another. The construction of a speech database that isolates the...

Due to the increasing demand for data services in mobile networks, operators are observing the quality of data services to degrade as their packed switched (PS) resources become insufficient. Even though there are newer 3/4G technologies available, EGPRS is still a good solution for data services due to ubiquitous coverage, the availability of low...

This paper proposes user cooperation strategy using multiple antennas technology (MIMO). In a first model we used a Code Division Multiple Access (CDMA) system and in a second model we apply the techniques of the decorrelator and Singular Value Decomposition (SVD) to allow cooperation. We show how cooperation using different numbers of antennas can...

Wireless Sensor Networks (WSNs) offer data to Intelligence Ambient system, but, due the big number of sensor nodes and data heterogeneity, it can be overload by them. This paper proposes MIAD, a distributed autonomic inference machine which uses fuzzy logic to make ambient context and to self-configure sensing and dissemination rates and...