Browsing 2010/4 by Title
Now showing items 16-35 of 39
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Guest Editorial: Cognitive Radio Communications and Software Defined Radio
(Společnost pro radioelektronické inženýrství, 2010-12) -
Impact of Noise Power Uncertainty on the Performance of Wideband Spectrum Segmentation
(Společnost pro radioelektronické inženýrství, 2010-12)The objective of this work is to investigate the impact of noise uncertainty on the performance of a wideband spectrum segmentation technique. We define metrics to quantify the degradation due to noise uncertainty and ... -
Improvement of RF Vector Modulator Performance by Feed-forward Based Calibration
(Společnost pro radioelektronické inženýrství, 2010-12)RF Vector Modulator enables independent control of a narrowband RF signal amplitude and phase. Unfortunately practical realization of an analog vector modulator suffers from misbalances and imperfections in the I and Q ... -
Influence of Sea Surface Roughness on the Electromagnetic Wave Propagation in the Duct Environment
(Společnost pro radioelektronické inženýrství, 2010-12)This paper deals with a study of the influence of sea surface roughness on the electromagnetic wave propagation in the duct environment. The problem of electromagnetic wave propagation is modeled by using the parabolic ... -
Investigating the Behavior of Compact Composite Descriptors in Early Fusion, Late Fusion and Distributed Image Retrieval
(Společnost pro radioelektronické inženýrství, 2010-12)In Content-Based Image Retrieval (CBIR) systems, the visual content of the images is mapped into a new space named the feature space. The features that are chosen must be discriminative and sufficient for the description ... -
Key Information Retrieval in Hyperspectral Imagery through Spatial-Spectral Data Fusion
(Společnost pro radioelektronické inženýrství, 2010-12)Hyperspectral (HS) imaging is measuring the radiance of materials within each pixel area at a large number of contiguous spectral wavelength bands. The key spatial information such as small targets and border lines are ... -
LMS Based Adaptive Channel Estimation for LTE Uplink
(Společnost pro radioelektronické inženýrství, 2010-12)In this paper, a variable step size based least mean squares (LMS) channel estimation (CE) algorithm is presented for a single carrier frequency division multiple access(SC-FDMA) system under the umbrella of the long term ... -
Log-Polar Quantizer with the Embedded G.711 Codec
(Společnost pro radioelektronické inženýrství, 2010-12)In this paper a new two-dimensional vector quantizer for memoryless Gaussian source, realized in polar coordinates, is proposed. The G.711 codec is embedded in our vector quantizer, and therefore our vector quantizer is ... -
Modeling of the Secondary System's Generated Interference and Studying of its Impact on the Secondary System Design
(Společnost pro radioelektronické inženýrství, 2010-12)In this paper we study how much capacity a cellular secondary system can achieve if the interference to the TV system is kept under control. The interference is modeled and controlled in a slow fading environment. The ... -
Modeling of the Simultaneous Influence of the Thermal Noise and the Phase Noise in Space Communication Systems
(Společnost pro radioelektronické inženýrství, 2010-12)Our work deals with studies of a noise behavior in space communication systems. Two most important noise types the additive thermal noise and the multiplicative phase noise, respectively, are included. A simple model of ... -
Modular Filter Structures Using Current Feedback Operational Amplifiers
(Společnost pro radioelektronické inženýrství, 2010-12)The concept of the wave filtering is followed in the derivation of high-order filter topologies by employing Current Feedback Operational Amplifiers as active blocks. For this purpose, the wave equivalent of an appropriate ... -
Modulation Schemes for Cognitive Radio in White Spaces
(Společnost pro radioelektronické inženýrství, 2010-12)In this paper we give an overview and a comparison of the possible waveforms for white space applications. Four physical layer schemes for cognitive radio are selected for study: Orthogonal Frequency Division Multiplexing ... -
New Squarer Circuits and a Current-Mode Full-Wave Rectifier Topology Suitable for Integration
(Společnost pro radioelektronické inženýrství, 2010-12)In this paper, three squarer configurations and a current-mode (CM) full-wave rectifier circuit are suggested. The first and second squarer configurations respectively use two PMOS and two NMOS transistors while the third ... -
A New Technique of Frequency Hopping with Collision Avoidance
(Společnost pro radioelektronické inženýrství, 2010-12)This article proposes a new technique of frequency hopping with collision avoidance (FH/CA). Currently there are well-known systems of frequency hopping which adapt their behavior based on previously measured data (such ... -
On the Effect of Channel Impairments on VANETs Performance
(Společnost pro radioelektronické inženýrství, 2010-12)The primary means of studying the performance of vehicular ad hoc networks (VANETs) are computer simulations. Nowadays, the development of analytical models and the use of hybrid simulations that combine analytical modeling ... -
Optimization of the Gaussian Kernel Extended by Binary Morphology for Text Line Segmentation
(Společnost pro radioelektronické inženýrství, 2010-12)In this paper, an approach for text line segmentation by algorithm with the implementation of the Gaussian kernel is presented. As a result of algorithm, the growing area around text is exploited for text line segmentation. ... -
Optimum Detection Location-Based Cooperative Spectrum Sensing in Cognitive Radio
(Společnost pro radioelektronické inženýrství, 2010-12)Cognitive radio arises as a hot research issue in wireless communications recently, attributed to its capability of enhancing spectral efficiency and catering for the growing demand for bandwidth. As a good embodiment of ... -
Performance Analysis of Multiradio Transmitter with Polar or Cartesian Architectures Associated with High Efficiency Switched-Mode Power Amplifiers (invited paper)
(Společnost pro radioelektronické inženýrství, 2010-12)This paper deals with wireless multi-radio transmitter architectures operating in the frequency band of 800 MHz – 6 GHz. As a consequence of the constant evolution in the communication systems, mobile transmitters must be ... -
Performance Bounds of DPSK and OOK for Low Elevation Optical LEO Downlinks
(Společnost pro radioelektronické inženýrství, 2010-12)Optical wireless LEO downlinks are seen as an emerging solution to increase available bandwidth to multigigabits per second. One of the biggest challenges is the impact of the atmosphere on the optical signal. The atmosphere ... -
Performance of Pilot Aided Channel Estimation Technique in 2D Spreading Based Systems
(Společnost pro radioelektronické inženýrství, 2010-12)It has recently been observed that the combination of the OFDM (Orthogonal Frequency Division Multiplex) and the CDMA (Code Division Multiple Access) can achieve notably lower BER (Bit Error Rate) performance in comparison ...