Wyniki wyszukiwania - Biblioteka Nauki

1

Implementation of Selected Spectrum Sensing Systems for Cognitive Radio Networks using FPGA Platform

100%

Abdullah H. N. , Abed H. S.

|

tom nr 4

81--87

EN

The energy efficient spectrum sensing method is very important in cognitive radio (CR), since high power drain may limit its implementation in mobile applications. The spectrum sensing feature consumes more energy than other functional blocks, as it depends on continuous detection of the presence or absence of the primary user (PU). In this paper, we proposed two methods to reduce energy consumption of the spectrum sensing feature. The ﬁrst is of a single stage variety with a reduced number of sensed samples. The other uses two stages. The ﬁrst stage performs coarse sensing for many subchannels, and the best subchannel is forwarded for ﬁne sensing in the second stage. The performance of the proposed methods is evaluated in AWGN channel and compared with the existing approach. The proposed methods are simulated using Matlab and ModelSim and are then hardware implemented using the Altera Cyclone II FPGA board. Simulation results show that the proposed methods oﬀer an improvement in energy consumption with an acceptable reduction in the probability of detection. At Eb/N0 Eb/N0 Eb/N0 of 0 dB, the energy consumption is reduced by 50% and 72% in the ﬁrst and second proposed method, respectively, compared to the traditional method (100% sensing).

2

Power Allocation for Energy-Harvesting-based Fading Cognitive Multiple Access Channels : with or without Successive Interference Cancellation

100%

Li Q. , Xu D.

|

2017

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tom Vol. 63, No. 1

65--72

EN

This paper considers a fading cognitive multiple access channel (CMAC), where multiple secondary users (SUs), who share the spectrum with a primary user (PU), transmit to a cognitive base station (CBS). A power station is assumed to harvest energy from the nature and then provide power to the SUs. We investigate the power allocation problems for such a CMAC to maximize the SU sum rate under the interference power constraint, the sum transmit power constraint and the peak transmit power constraint of each individual SU. In particular, two scenarios are considered: with successive interference cancellation (SIC) and without SIC. For the first scenario, the optimal power allocation algorithm is derived. For the second scenario, a heuristic algorithm is proposed. We show that the proposed algorithm with SIC outperforms the algorithm without SIC in terms of the SU sum rate, while the algorithm without SIC outperforms the algorithm with SIC in terms of the number of admitted SUs for a high sum transmit power limit and a low peak transmit power limit of each individual SU.

3

Optimal Voting Rule and Minimization of Total Error Rate in Cooperative Spectrum Sensing for Cognitive Radio Networks

100%

Ghosh S. K. , Trankatwar S. R. , Bachan P.

|

tom nr 1

43--50

EN

In cognitive radio technology, spectrum sensing is essential for detecting spectrum holes which may be allotted to secondary users. In this paper, an optimal voting rule is used for cooperative spectrum sensing while minimizing the total error rate (TER). The proposed spectrum sensing method is more energy-efficient and may be implemented in practice. It is relied upon in an improved energy detector whose utilization depends on the presence or absence of the primary user. Expressions for false alarm and missed detection probabilities are derived in the paper as well. Overall performance is analyzed both for AWGN and Rayleigh fading channels, in the presence of additive white Gaussian noise (AWGN). The optimum voting rule is applied to the cooperative spectrum sensing process in order to identify the optimum number of sensing nodes and the detection threshold. Finally, an energy-efficient spectrum sensing algorithm is proposed, requiring a lower number of cognitive users for a given error bound.

4

Energy-based spectrum sensing with copulas for cognitive radios

88%

Ilgin F. Y.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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tom Vol. 68, nr 4

829--834

EN

In this study, an energy-based spectrum sensing method combined with copula theory is proposed for cognitive radio systems. In the proposed spectrum sensing model, cognitive radio users first make their own local spectrum decision with energy-based spectrum sensing. Then, they forward their decision to the fusion center. In the fusion center, this decision is compared with the threshold value determined by copula theory and global spectrum decision is made. The test statistic at the fusion center were obtained with the Neyman Pearson approach. Thus, the fusion rule was created for the fusion center and necessary simulation studies were performed. According to the results of the simulation studies, the proposed detection method showed better results than the traditional energy based detection method.

5

An Efficient Cooperative Spectrum Sensing Method Using Renyi Entropy Weighted Optimal Likelihood Ratio for CRN

88%

Shrote S. B. , Poshattiwa S. D.

|

2023

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tom nr 3

41--48

EN

The main concept behind employing cognitive radio is to enable secondary users (SUs) or unlicensed users to utilize the available spectrum. Spectrum sensing methods detect the existence of primary users (PUs) and have become the main topic of research in the CRN industry and in academia. This paper proposes a new framework based on the Adam gradient descent (Adam GD) algorithm to develop a spectrum sensing mechanism used in CRNs and detecting the availability of free channels. The signal's components are extracted from the received signal and the spectrum is searched for availability which is detected through a fusion center using the proposed algorithm. The proposed Adam GD algorithm attains the maximum detection probability rate and the minimum false alarm probability of 0.71 and 0.39, respectively, for a Rayleigh channel.

6

Mobility-Aware, Correlation-Based Node Grouping and Selection for Cooperative Spectrum Sensing

88%

Cichoń K. , De Nardis L. , Bogucka H. , Di Benedetto M. G.

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tom nr 2

90--102

EN

Cooperative spectrum sensing has been proposed as a solution to increase the sensing function accuracy in cognitive radio networks, but the research has, so far, mainly focused on static scenarios, all but neglecting the impact of mobility on spectrum sensing. In this work a novel cooperative spectrum sensing scheme for mobile cognitive networks, based on a correlation-based, mobility-aware node selection algorithm is proposed. Correlation among sensing decisions is used to divide nodes into groups, and mobility is taken into account in the group leaders selection by means of a node selection metric that considers both sensing performance and mobility. Performance of the proposed algorithm is evaluated by computer simulations taking into account mobility and a detailed modeling of temporal and spatial correlation of fading and shadowing components in the channel path loss, going way beyond the performance evaluation carried out in previous works on correlation-based cooperative sensing schemes. Simulation results highlight that the proposed metric leads to a signicant increase of the update period required to maintain acceptable sensing performance, and correspondingly to a strong reduction in the overhead caused by the grouping and node selection procedure.

7

Spectrum Occupancy in Realistic Scenarios and Duty Cycle Model for Cognitive Radio

88%

López-Benítez M. , Casadevall F.

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2010

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tom Vol. 1, no. 1

26--34

EN

Most of the spectrum occupancy measurement campaigns performed to the date in the context of cognitive radio are based on measurements in outdoor high points such as building roofs, balconies and towers. Although these measurement scenarios enable a more accurate estimation of the primary transmitters’ spectral activity, they may not be representative of the spectrum occupancy perceived by a cognitive radio user in many other interesting practical situations where users are not placed in a static high point. In this context, this work presents the results obtained in a spectrum measurement campaign performed over a rich diversity of measurement scenarios of practical interest. The considered scenarios include not only high points but also indoor environments as well as outdoor locations at the ground level in open areas and between buildings. The ariety of considered measurement scenarios provides a broader view and understanding of dynamic spectrum occupancy under different practical scenarios of interest. The impact of considering various locations on the spectral activity perceived by a cognitive radio user is determined, analyzed and quantified. Moreover, a theoretical model for the occupancy levels observed at different locations is developed and verified with the obtained results.

8

Optimization of Spectrum Sensing Parameters in Cognitive Radio Using Adaptive Genetic Algorithm

88%

Chatterjee S. , Dutta S. , Bhattacharya P. P. , Roy J. S.

Journal of Telecommunications and Information Technology

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2017

|

tom nr 1

21--27

EN

Quality of service parameters of cognitive radio, like, bandwidth, throughput and spectral efficiency are optimized using adaptive and demand based genetic algorithm. Simulation results show that the proposed method gives better real life solution to the cognitive radio network than other known approach.

9

Deep Learning-based SNR Estimation for Multistage Spectrum Sensing in Cognitive Radio Networks

88%

Jeevangi S. , Jawaligi S. , Patil V.

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tom nr 4

21--32

EN

Vacant frequency bands are used in cognitive radio (CR) by incorporating the spectrum sensing (SS) technique. Spectrum sharing plays a central role in ensuring the effectiveness of CR applications. Therefore, a new multi-stage detector for robust signal and spectrum sensing applications is introduced here. Initially, the sampled signal is subjected to SNR estimation by using a convolutional neural network (CNN). Next, the detection strategy is selected in accordance with the predicted SNR levels of the received signal. Energy detector (ED) and singular value-based detector (SVD) are the solutions utilized in the event of high SNR, whilst refined non-negative matrix factorization (MNMF) is employed in the case of low SNR. CNN weights are chosen via the Levy updated sea lion optimization (LU-SLNO) algorithm inspired by the traditional sea lion optimization (SLNO) approach. Finally, the outcomes of the selected detectors are added, offering a precise decision on spectrum tenancy and existence of the signal.

10

Cooperative Spectrum Sensing in Cognitive Radio Networks: A Survey on Machine Learning-based Methods

88%

Khamayseh S. , Halawani A.

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2020

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tom nr 3

36--46

EN

The continuous growth of demand experienced by wireless networks creates a spectrum availability challenge. Cognitive radio (CR) is a promising solution capable of overcoming spectrum scarcity. It is an intelligent radio technology that may be programmed and dynamically conﬁgured to avoid interference and congestion in cognitive radio networks (CRN). Spectrum sensing (SS) is a cognitive radio life cycle task aiming to detect spectrum holes. A number of innovative approaches are devised to monitor the spectrum and to determine when these holes are present. The purpose of this survey is to investigate some of these schemes which are constructed based on machine learning concepts and principles. In addition, this review aims to present a general classiﬁcation of these machine learningbased schemes.

11

Suboptimal Approach to Distributed Detection in Cognitive Radio Networks

88%

Kumari S. , Praveena S.

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tom nr 1

32--36

EN

In this paper a dynamic spectrum access (DSA) concept is explored for mitigating the paucity of spectral bandwidth in cognitive radio (CR) for opportunistic, dynamic access of the spectrum without any interference. Dynamic spectrum access schemes are proposed for a distributed cognitive radio network consisting of one secondary user (SU) and many primary users (PUs). The SU has to make decisions for accessing PU channels within discrete time slots. The design of sensing and access strategies that govern channel choice in each slot for near-optimal throughput performance of the SU may be formulated as a partially observable Markov decision process (POMDP). Furthermore, it is considered that the SU incurs a cost whenever it switches to a different channel. The switching cost is expressed in terms of delay, packet loss and packet overhead. In this work, the SU access policy based on a myopic approach is proposed and evaluated.

12

Dual Port Antenna Combining Sensing and Communication Tasks for Cognitive Radio

75%

Nachouane H. , Najid A. , Tribak A. , Riouch F.

International Journal of Electronics and Telecommunications

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2016

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tom Vol. 62, No. 2

121--127

EN

Dynamic spectrum access has been proposed as the effective solution to overcome the spectrum scarcity issue, supported by cognitive radio technology. Sensing and communication functions are both the most important tasks in cognitive radio systems. In this paper, an antenna system combining sensing and communication tasks is proposed to be integrated into cognitive radio front-ends. The sensing task is performed by means of an ultra-wideband quasi-omnidirectional antenna. Whilst the communication task is ensured by using a narrowband antenna. Both antennas have been designed on the same layer of an FR4 substrate, for manufacturing cost constraint. Therefore, the isolation between them must take into consideration. The measured mutual coupling of less than -18 dB is achieved over the whole impedance bandwidth. The proposed sensing antenna covers a wide range frequency bands ranging from 2 to 5.5 GHz. While the communication antenna operates at 2.8 GHz, and by adding inductors to the antenna, the resonant frequency can be tuned from 2.6 to 2.7 GHz. The whole antenna system was designed, fabricated, and tested. Measurement and simulation results prove the feasibility of the proposed structure for cognitive radio applications.

13

Dynamiczne zarządzanie widmem w wojskowych sieciach bezprzewodowych

75%

Gajewski P. , Suchański M.

|

tom nr 1

27-31

PL

Gwałtowny wzrost zapotrzebowania na usługi dostępne drogą bezprzewodową powoduje potrzebę posiadania efektywnych metod dostępu do spektrum zarówno podczas planowania misji, jak i jej realizacji. Opisano dwie architektury (CJSMPT, DIMSUMNet), proponowane dla obecnie wykorzystywanych systemów, jak i systemów modernizowanych. Najbardziej obiecującą metodą, dla przyszłych sieci radia kognitywnego jest oportunistyczny dostęp do widma. Opisano zarówno koncepcję radia kognitywnego, jak również pewne prace standaryzacyjne w zakresie kognitywnego i dynamicznego zarządzania widmem częstotliwości.

EN

A rapidly growing demand for services accessed by wireless networks calls to have the efficient tools for spectrum allocation during mission planning and supervision. Two architectures (CJSMPT, DIMSUMNet) for legacy and modernized equipment are described. An opportunistic spectrum access is the most promising method for future cognitive radio networks (CRN) and therefore this paper deals with a general cognitive radio (CR) concept, as well as some standardization works concerning cognitive and dynamic spectrum access.

14

Sekwencyjny algorytm wykrywania transmisji użytkownika pierwotnego

75%

Cichoń K. , Kliks A.

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tom nr 8-9

640-645

PL

Przedstawiono algorytm sekwencyjny, umożliwiający skrócenie czasu wykrywania sygnału w widmie częstotliwościowym. W zaproponowanym rozwiązaniu skrócenie tego czasu jest możliwe przez kilkakrotne podejmowanie decyzji o obecności sygnału użytkownika pierwotnego. Efektywność algorytmu zbadano na drodze symulacyjnej w środowisku Matlab przy użyciu próbek odebranych za pomocą platformy USRP. Scharakteryzowano także projekt ACROPOLIS oraz zadania, które w ramach tej sieci doskonałości wykonuje Politechnika Poznańska.

EN

In this paper sequential energy detection algorithm has been investigated. The main aim of the analyzed solution is to shorten the sensing time by trying to mąke reliable decisions about the presence of the signal several limes in the considered period of time. Effectiveness of the algorithm has been verified twofold: first by means of computer simulations in the Matlab environment, and second by analysis of the real samples collected the dedicated software define radio platform named USRP Furthermore, the paper describes briefly the ACROPOLIS project and highlights the contributions of Poznań University of Technology.

15

Radio kognitywne - nowa koncepcja efektywnego wykorzystania zasobów widmowych

75%

Bugucka H.

|

tom nr 8-9

606-610

PL

Przedstawiono ideę nowoczesnej technologii radia kognitywnego, w szczególności jej potencjał do bardziej efektywnego wykorzystania zasobów widmowych, a także motywację podjęcia tej tematyki, którą stanowi z jednej strony obserwowany nadchodzący "kryzys widma", a z drugiej strony niedostateczne wykorzystanie zasobów przydzielonych różnym służbom w postaci licencji. Opisano mechanizm działania radia kognitywnego wykorzystującego wolne zasoby widmowe w sposób dynamiczny, czyli tzw. cykl kognitywny. Omówiono praktyczną realizację systemu radia kognitywnego wykorzystującego częstotliwości telewizyjne UHF w tzw. telewizyjnych białych obszarach (TVWS) uwzględniającą koncepcję brokera i wtórnego rynku widma.

EN

This work presents the idea of modern cognitive radio technology, In particular its potential for higher efficiency of radio resources usage. The motivation of research in this direction has been presented, which consists in the observed "spectrum crisis" on one hand and under-utilization of radio resources licensed to heterogeneous services on the other hand. Cognitive radio functionalities related to the dynamic spectrum access have been described based on the so-called cognitive cycle. Really, the practical implementation of a cognitive radio system using UHF frequencies in the television white spaces (TVWS) has been described, which introduces the concept of the secondary spectrum market and the spectrum broker.

16

Energy-based spectrum sensing with copulas for cognitive radios

75%

Ilgin F. Y. , Ilgin F. Y.

|

nr 4

17

Sensing kooperacyjny scentralizowany vs. lokalny w kognitywnych sieciach radiowych

63%

Skokowski P. , Malon K. , Łopatka J.

|

2017

|

tom nr 8-9

1072--1077, CD

PL

Monitorowanie widma (sensing) jest funkcjonalnością, które zapewnia możliwość tworzenia sieci w technologii radia kognitywnego. Sensing pozwala budować świadomość sytuacji elektromagnetycznej, dzięki czemu można lepiej wykorzystać dostępne zasoby radiowe oraz dostosować działanie sieci do zmiennych warunków środowiskowych ze względu np. na: pogorszenie jakości transmisji, unikanie interferencji czy zakłóceń celowych. W artykule przedstawiono wyniki badań porównania metody monitorowania widma lokalnej z kooperacyjną przez węzły radiowe sieci kognitywnej. Testy zostały przeprowadzone w symulatorze zbudowanym w środowisku Matlab/Simulink.

EN

Spectrum monitoring (signal sensing) is a functionality that enables creation of cognitive radio networks (CRNs). Signal sensing helps in building the situation awareness what is required for more efficient dynamic spectrum access and to adjust network parameters in case of jamming, interference from legacy systems or decreased link quality caused e.g. by changing positions of radio nodes. In this paper authors present results of comparison tests between cooperative centralized sensing and local sensing in CRN. All tests were performed in a simulator, which was developed in Matlab/Simulink environment.

18

Algorytm oceny przydatności kanałów radiowych wykorzystujący uczenie maszynowe Q-learning

63%

Malon K.

|

tom nr 7-8

259--262, CD

PL

W ramach artykułu zaproponowano algorytm oceny przydatności kanałów radiowych bazujący na metodzie uczenia maszynowego Q-learning oraz przedstawiono wyniki badań. Rozważany algorytm, wykorzystujący rezultaty monitorowania zasobów częstotliwościowych, może znaleźć zastosowanie w systemach dynamicznego dostępu do widma. W takich rozwiązaniach wtórni użytkownicy widma realizują transmisje radiowe w wolnych przestrzeniach czasowo–częstotliwościowych.

EN

In this paper, Q-learning based radio channels utility evaluation algorithm is proposed and tested. The considered algorithm, which takes into account the results of frequency resources monitoring, can be used in the dynamic spectrum access systems. In such solutions, secondary spectrum users transmit radio signals on the frequency channels that are temporarily not used by the licensed users.

19

Monitoring widma z wykorzystaniem platformy sprzętowej USRP-2920

63%

Grzesiak K.

|

2018

|

tom nr 8-9

738--742, CD

PL

Wykrywanie użytkownika pierwotnego jest jednym z najbardziej istotnych elementów radia kognitywnego. Stąd też zainteresowanie efektywnymi metodami detekcji sygnałów. W artykule przedstawiono wyniki badań detektora energii i cyklostacjonarności zbudowanego na platformie radia programowalnego USRP-2920.

EN

Primary User (PU) detection is a fundamental problem in cognitive radio. Therefore there is a lot of interest in the effective method of detection. In this paper were shown test results energy and cyclostationary detectors. Detectors were implemented and verified on USRP- 2920 platform.

20

The application of software defined radios in unmanned aerial vehicles

63%

Błachut M. , Pogorzelec P.

|

tom Vol. 54, No. 3(205)

375--396

EN

The article addresses the application of software defined radios (SDR) on modern battlefields. Above all, it focuses on the application of the SDR technology in communication with unmanned aerial vehicles. It also reviews some solutions applied in the armed forces of Finland, United States, Poland, Turkey, and Israel. It outlines the potential of these solutions and considers the main direction of development of the SDR technology, which is the cognitive radio.

PL

W artykule odniesiono się do wykorzystania na współczesnym polu walki radiostacji definiowanych programowo (SDR). Przede wszystkim skupiono się na wykorzystaniu technologii SDR do komunikowania się z bezpilotowymi środkami powietrznymi (BSP). Dokonano także przeglądu niektórych rozwiązań funkcjonujących w siłach zbrojnych Finlandii, Stanów Zjednoczonych, Polski, Turcji oraz Izraela. Po prezentacji możliwości wcześniej wspomnianych rozwiązań przedstawiono rozważania nad podstawowym kierunkiem rozwoju technologii SDR – radiem kognitywnym.