Browsing by Subject "Cognitive radio"
Now showing items 1-20 of 23
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The Analysis of Closed-form Solution for Energy Detector Dynamic Threshold Adaptation in Cognitive Radio
(Společnost pro radioelektronické inženýrství, 2017-12)Spectrum sensing is the most important process in cognitive radio in order to ensure interference avoidance to primary users. For optimal performance of cognitive radio, it is substantial to monitor and promptly react to ... -
A Broadband High Gain Circularly Polarized Antenna System for Cognitive Radio
(Společnost pro radioelektronické inženýrství, 2020-09)This paper proposes a broadband high gain LHCP (left hand circular polarized) antenna system using a microstrip line fed slot antenna, reflecting surfaces, and linear polarization (LP) to circular polarization (CP) transformer ... -
Effect of Location Accuracy and Shadowing on the Probability of Non-Interfering Concurrent Transmissions in Cognitive Ad Hoc Networks
(Společnost pro radioelektronické inženýrství, 2013-12)Cognitive radio ad hoc systems can coexist with a primary network in a scanning-free region, which can be dimensioned by location awareness. This coexistence of networks improves system throughput and increases the efficiency ... -
An Efficient Filter Banks Based Multicarrier System in Cognitive Radio Networks (invited paper)
(Společnost pro radioelektronické inženýrství, 2010-12)In cognitive radio techniques, OFDM is usually regarded as the physical layer candidate. However, the weaknesses of the OFDM technique, i.e., using plain FFT for spectral analysis , decreased bandwidth efficiency due to ... -
An Energy Efficient MAC Protocol for QoS Provisioning in Cognitive Radio Ad Hoc Networks
(Společnost pro radioelektronické inženýrství, 2010-12)The explosive growth in the use of real-time applications on mobile devices has resulted in new challenges to the design of medium access control (MAC) protocols for ad hoc networks. In this paper, we propose an energy ... -
Energy Harvesting-based Spectrum Access with Incremental Cooperation, Relay Selection and Hardware Noises
(Společnost pro radioelektronické inženýrství, 2017-04)In this paper, we propose an energy harvesting (EH)-based spectrum access model in cognitive radio (CR) network. In the proposed scheme, one of available secondary transmitters (STs) helps a primary transmitter (PT) forward ... -
Estimation of Time-Varying Channel State Transition Probabilities for Cognitive Radio Systems by means of Particle Swarm Optimization
(Společnost pro radioelektronické inženýrství, 2012-04)In this study, Particle Swarm Optimization is applied for the estimation of the channel state transition probabilities. Unlike most other studies, where the channel state transition probabilities are assumed to be known ... -
Generalized detector as a spectrum sensor in cognitive radio networks
(Společnost pro radioelektronické inženýrství, 2015-06)The implementation of the generalized detector (GD) in cognitive radio (CR) systems allows us to improve the spectrum sensing performance in comparison with employment of the conventional detectors. We analyze the spectrum ... -
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 ... -
Impact of Power Allocation and Antenna Directivity in the Capacity of a Multiuser Cognitive Ad Hoc Network
(Společnost pro radioelektronické inženýrství, 2012-12)This paper studies the benefits that power control and antenna directivity can bring to the capacity of a multiuser cognitive radio network. The main objective is to optimize the secondary network sum rate under the capacity ... -
The Impact of Sensing Range on Spatial-Temporal Opportunity
(Společnost pro radioelektronické inženýrství, 2013-06)In this paper, we study the impact of secondary user (SU) sensing range on spectrum access opportunity in cognitive radio networks. We first derive a closed-form ex- pression of spectrum access opportunity by taking into ... -
Improved Energy Detector for Wideband Spectrum Sensing in Cognitive Radio Networks
(Společnost pro radioelektronické inženýrství, 2014-04)In this paper, an improved energy detector for a wideband spectrum sensing is proposed. For a better detection of the spectrum holes the overall band is divided into equal non-overlapping sub-bands. The main objective is ... -
An Integrated Frequency Reconfigurable Antenna for Cognitive Radio Application
(Společnost pro radioelektronické inženýrství, 2017-09)A novel integrated antenna that consists of spectrum sensing and frequency reconfigurable antenna, printed on a single substrate is presented here. The integration of both antennas is based on the fact that reasonably large ... -
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 ... -
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 of a Cognitive Relay Network under AF Relay Selection Scheme with Imperfect Channel Estimation
(Společnost pro radioelektronické inženýrství, 2016-06)In this paper outage performance of a secondary user (SU) is evaluated under amplify and forward (AF) relay selection scheme with an imperfect channel state information (CSI)while sharing spectrum in an underlay cognitive ... -
Resource Allocation for Downlink Multi-Cell OFDMA Cognitive Radio Network Using Hungarian Method
(Společnost pro radioelektronické inženýrství, 2013-12)This paper considers the problem of resource allocation for downlink part of an OFDM-based multi-cell cognitive radio network which consists of multiple secondary transmitters and receivers communicating simultaneously in ... -
Robust Resource Allocation for OFDM-based Cognitive Radio in the Presence of Primary User Emulation Attack
(Společnost pro radioelektronické inženýrství, 2012-12)Cognitive radio (CR) is a promising solution to improve the spectrum efficiency in which some unlicensed users are allowed to exploit frequency bands which are not used by licensed network. However, CR technology imposes ... -
Sensing Task Allocation for Heterogeneous Channels in Cooperative Spectrum Sensing
(Společnost pro radioelektronické inženýrství, 2010-12)In the traditional centralized cooperative spectrum sensing, all secondary users sense the same channel. But, for a given channel, there exists detection performance diversity among all the users, due to the different ... -
Signal Detection for QPSK Based Cognitive Radio Systems using Support Vector Machines
(Společnost pro radioelektronické inženýrství, 2015-04)Cognitive radio based network enables opportunistic dynamic spectrum access by sensing, adopting and utilizing the unused portion of licensed spectrum bands. Cognitive radio is intelligent enough to adapt the communication ...