XXXI Simpósio Brasileiro de Telecomunicações

The collision channel without feedback (CCWFB) is a proposed channel model for situations in which a given number of users share the same communication channel for sending bit packets. In the CCWFB each user has a protocol sequence that determines the time intervals in which the user can send his packets. Cyclically permutable (CP) codes provide a...

This paper analyzes the complexity-performance tradeoff of relay selection (RS) methods for cooperative networks (CoopNet), specially applied to wireless sensor networks (WSNs). The performance-complexity of the classical RS methods such as opportunistic (O-RS), random (R-RS), maximum harmonic mean (MHM-RS), best-worse (BW-RS), max-generalized-mean...

This paper compares three methods for estimating the parameters of class of finite state Markov channels, specifically the Gilbert Elliot channel (GEC), so as to approximate a discrete fading channel. For this, the method proposed by Wilhelmsson and Milstein and the Baum-Welch algorithm, already used in the literature, are compared with the...

A new spiral square architecture antenna with unbalanced excitation was designed. Spiral antenna is formed by two arms, a ragged arousal in which one of the arms is powered by an inner conductor and the other is short-circuited with a ground plane by means of a cavity. The proposed antenna is able to generate a wide range of frequencies for...

The increasing demand from users for broadband services directly influences the attendance capacity of SMC. One of the main marketing strategies adopted by SMC operators, to upgrade the capacity of its BTS interconnection network has been renting the transmission links from other carriers. This technological support can be provided with the SDH...

Previous works have compared the performance of DCCP with standard transport protocols using the CBR pattern. In this paper, we compare the performance of DCCP (CCID2 and CCID3) with two TCP variants (CTCP and CUBIC), adopting VoIP and CBR traffic patterns. In the proposed scenarios, the protocols contend for the same link. Results show that...

This article presents the results of a partial implementation of the image compression standard recommended by the CCSDS, using parallel processing. The objective is to achieve a reduction in processing time of the Discret Wavelet Transform with the aid of a GPU. Through remote sensing images, the algorithm is tested and shows an acceleration around...

There are some Network Metrics that are very useful to analyze and model Complex Networks. These metrics, including the spectral-based ones, can be used to retrieve information from the network. As an example, the eigenvalues of the Laplacian matrix can present interesting information about the network topology. We observed that if one applies the...