XXX Simpósio Brasileiro de Telecomunicações

In this paper we compare the performance of three different restoration schemes for all-optical networks (link, subpath and path) upon a single link failure considering physical layer impairments. In addition, we propose two strategies for link or subpath restoration. Although the strategies based on subpath restoration present a better performance...

In this paper we propose a spatial diversity scheme for four transmit antennas and quantized feedback channel systems. We present a preprocessor design that enables this scheme to achieve full diversity order as well as a coding advantage. A quantized feedback analysis of the proposed scheme for quasi-static flat Rayleigh fading channels is also...

This article presents a method for automatically assessing the comfort associated with viewing stereoscopic videos based on the stereo vision geometry, to assist the camera stereo rig adjustment. The proposed method estimates, using SIFT and segmentation techniques, the extent of the frame on each scene which causes eye strain to the viewer.

This paper presents an analysis of radiation and absorption properties of cylindrical gold nanodipoles in the transmitting mode. The conventional antenna theory and the linear method of moments are used for the theoretical analysis of these antennas in the near-infrared and lower optical frequencies (100−500THz). Radiation and absorption parameters,...

This paper presents a speech enhancement technique based on the empirical mode decomposition method. The EMD-based filtering is evaluated in speech utterances corrupted with six acoustic noises and six different signal-to-noise ratios. The noises present different values of INS (index of nonstationarity). For comparison, another speech enhancement...

This article presents an empirical model for the noise of the acoustic underwater channel in shallow water from the analysis of field data measurements. A probability density function for the noise amplitude distribution is proposed and the associated likelihood functions are derived. As a result, an expression to the probability of symbol error for...

This paper presents the stochastic modeling of a well-known adaptive algorithm from the literature, the normalized least-mean-square (NLMS) algorithm. Considering a system identification problem with stationary plant and complex Gaussian input data, an accurate model obtained analytically is derived here. Such accuracy is mainly due to the form how...

The use of masks to limit the statistical behavior of interference is very common in communications. The ITU- R Radio Regulations has a number of examples of interference masks that are used to guarantee that the external interferences reaching a communication system would not prevent it from meeting its performance requirements. Each of these masks...

In this paper, we propose a new transmission scheme with two relay stations and phase feedback channels between the relays and the destination node. The preprocessor use in the relay stations is managed to achieve a full diversity order and also an array gain at the destination node. A phase feedback investigation for the proposed scheme is...

The use of electric grids for communication pur- poses may interfere with radio communication services. To offer new directions to avoid electromagnetic interference that reduces the effectiveness of electric power grids as a green and low- cost communication channel, this paper discusses and introduces spectrum sensing techniques for cognitive...