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On Finding Spectrum Opportunities in Cognitive Radios: Spectrum Sensing and Geo-locations Database
KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.ORCID iD: 0000-0003-3860-5964
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The spectacular growth in wireless services imposes scarcity in term of the available radio spectrum. A solution to overcome this scarcity is to adopt what so called cognitive radio based on dynamic spectrum access. With dynamic spectrum access, secondary (unlicensed) users can access  spectrum owned by primary (licensed) users when it is temporally and/or geographically unused. This unused spectrum is termed as spectrum opportunity. Finding these spectrum opportunities related aspects are studied in this thesis where two approaches of finding spectrum opportunities, namely spectrum sensing and geo-locations databases are considered.

In spectrum sensing arena, two topics are covered, blind spectrum sensing and sensing time and periodic sensing interval optimization. For blind spectrum sensing, a spectrum scanner based on maximum minimum eigenvalues detector and frequency domain rectangular filtering is developed. The measurements show that the proposed scanner outperforms the energy detector scanner in terms of the probability of detection. Continuing in blind spectrum sensing, a novel blind spectrum sensing technique based on discriminant analysis called spectrum discriminator has been developed in this thesis. Spectrum discriminator has been further developed to peel off multiple primary users with different transmission power from a wideband sensed spectrum. The spectrum discriminator performance is measured and compared with the maximum minimum eigenvalues detector in terms of the probability of false alarm, the probability of detection and the sensing time.

For sensing time and periodic sensing interval optimization, a new approach that aims at maximizing the probability of right detection, the transmission efficiency and the captured opportunities is proposed and simulated. The proposed approach optimizes the sensing time and the periodic sensing interval iteratively. Additionally, the periodic sensing intervals for multiple channels are optimized to achieve as low sensing overhead and unexplored opportunities as possible for a multi channels system.

The thesis considers radar bands and TV broadcasting bands to adopt geo-locations databases for spectrum opportunities. For radar bands, the possibility of spectrum sharing with secondary users in L, S and C bands is investigated. The simulation results show that band sharing is possible with more spectrum opportunities offered by C band than S and L band which comes as the least one. For the TV broadcasting bands, the thesis treats the power assignment for secondary users operate in Gävle area, Sweden. Furthermore, the interference that the TV transmitter would cause to the secondary users is measured in different locations in the same area.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. , xiii, 61 p.
Series
TRITA-ICT-COS, ISSN 1653-6347 ; 1301
Keyword [en]
COgnitive Radio, Dynamic Spectrum Access, Spectrum Opportunity, Spectrum Sensing, GEo-locations database
National Category
Communication Systems
Identifiers
URN: urn:nbn:se:kth:diva-110107OAI: oai:DiVA.org:kth-110107DiVA: diva2:585976
Presentation
2013-02-07, 99:132, University of Gävle, Kungsbäcksvägen 47, Gävle, 13:00 (English)
Opponent
Supervisors
Projects
QUASAR
Funder
EU, FP7, Seventh Framework ProgrammeWireless@kth
Note

QC 20130114

Available from: 2013-01-14 Created: 2013-01-10 Last updated: 2015-02-09Bibliographically approved
List of papers
1. Maximum minimum eigenvalues based spectrum scanner for cognitive radios
Open this publication in new window or tab >>Maximum minimum eigenvalues based spectrum scanner for cognitive radios
2012 (English)In: 2012 IEEE I2MTC - International Instrumentation and Measurement Technology Conference, Proceedings, IEEE , 2012, 2248-2251 p.Conference paper, Published paper (Refereed)
Abstract [en]

In this paper we introduce a technique for spectrum scanning with the maximum minimum eigenvalue detection based spectrum sensing. The fundamental problem we address in this paper is the inability of using maximum minimum eigenvalue detection with filtering in time domain where the white noise becomes coloured. The solution we propose here is based on frequency domain rectangular filtering. By frequency domain rectangular filtering we take the spectral lines inside each sub-band and throw out the rest. After doing the frequency domain rectangular filtering, we generate the corresponding time domain signal and inject it to the maximum minimum eigenvalue detector. An experimental verification has been performed and the obtained results show that the technique is implementable with a performance better than the energy detector as a reference technique in terms of the probability of detection when both technique have the same probability of false alarm.

Place, publisher, year, edition, pages
IEEE, 2012
Series
IEEE Instrumentation and Measurement Technology Conference, ISSN 1091-5281
Keyword
Cognitive radio, maximum minimum eigenvalue detection, rectangular filtering, spectrum scanning, Spectrum sensing
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-101102 (URN)10.1109/I2MTC.2012.6229450 (DOI)000309449100427 ()2-s2.0-84864249987 (Scopus ID)978-145771771-0 (ISBN)
Conference
IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2012; Graz; 13 May 2012 through 16 May 2012
Projects
QUASAR
Funder
EU, FP7, Seventh Framework ProgrammeWireless@kth
Note

QC 20120904

Available from: 2012-08-23 Created: 2012-08-23 Last updated: 2015-02-09Bibliographically approved
2. Spectrum Sensing through Spectrum Discriminator and Maximum Minimum Eigenvalue Detector: A Comparative Study
Open this publication in new window or tab >>Spectrum Sensing through Spectrum Discriminator and Maximum Minimum Eigenvalue Detector: A Comparative Study
2012 (English)In: 2012 IEEE I2MTC - International Instrumentation and Measurement Technology Conference, Proceedings, IEEE , 2012, 2252-2256 p.Conference paper, Published paper (Refereed)
Abstract [en]

In this paper we present a new spectrum sensing technique for cognitive radios based on discriminant analysis called spectrum discriminator and compare it with the maximum minimum eigenvalue detector. The common feature between those two techniques is that neither prior knowledge about the system noise level nor the primary user signal, that might occupy the band under sensing, is required. Instead the system noise level will be derived from the received signal. The main difference between both techniques is that the spectrum discriminator is a non-parametric technique while the maximum minimum eigenvalue detector is a parametric technique. The comparative study between both has been done based on two performance metrics: the probability of false alarm and the probability of detection. For the spectrum discriminator an accuracy factor called noise uncertainty is defined as the level over which the noise energy may vary. Simulations are performed for different values of noise uncertainty for the spectrum discriminator and different values for the number of received samples and smoothing factor for the maximum minimum eigenvalue detector.

Place, publisher, year, edition, pages
IEEE, 2012
Keyword
Cognitive radio, maximum minimum eigenvalue detection, probability of detection, probability of false alarm, spectrum discrimination
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-101103 (URN)10.1109/I2MTC.2012.6229452 (DOI)000309449100428 ()2-s2.0-84864252477 (Scopus ID)978-145771771-0 (ISBN)
Conference
2012 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2012; Graz; 13 May 2012 through 16 May 2012
Projects
QUASAR
Funder
EU, FP7, Seventh Framework ProgrammeWireless@kth
Note

QC 20120830

Available from: 2012-08-23 Created: 2012-08-23 Last updated: 2015-06-10Bibliographically approved
3. Blind spectrum sensing for cognitive radios using discriminant analysis: A novel approach
Open this publication in new window or tab >>Blind spectrum sensing for cognitive radios using discriminant analysis: A novel approach
Show others...
2013 (English)In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 62, no 11, 2912-2921 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, we present a new spectrum sensing technique for cognitive radios based on discriminant analysis called spectrum discriminator. The presented technique uses the knowledge of the noise uncertainty and a probabilistic validation to overcome the limitations of the discriminant analysis. A comparative study between the proposed technique and the maximum-minimum eigenvalue detection has been performed based on two performance metrics: the probability of false alarm and the probability of detection. The spectrum discriminator has been further developed to a peel-off technique where all primary users can be detected. The performance of the spectrum discriminator and the peel-off technique has been tested on simulations and experimentally verified. The comparative study is based on simulations as well as measurements.

Place, publisher, year, edition, pages
IEEE, 2013
Keyword
Blind detection, cognitive radio, discriminant analysis, maximum-minimum eigenvalues detection, spectrum discriminator, spectrum sensing
National Category
Signal Processing
Identifiers
urn:nbn:se:kth:diva-111849 (URN)10.1109/TIM.2013.2267456 (DOI)000325820200004 ()2-s2.0-84885958005 (Scopus ID)
Note

QC 20131108. Updated from accepted to published.

Available from: 2013-01-14 Created: 2013-01-14 Last updated: 2017-12-06Bibliographically approved
4. A Novel Approach for Energy Detector Sensing Time and Periodic Sensing Interval Optimization in Cognitive Radios
Open this publication in new window or tab >>A Novel Approach for Energy Detector Sensing Time and Periodic Sensing Interval Optimization in Cognitive Radios
2011 (English)In: CogART '11 Proceedings of the 4th International Conference on Cognitive Radio and Advanced Spectrum Management, 2011Conference paper, Published paper (Refereed)
Abstract [en]

In this paper a new approach of optimizing the sensing time and periodic sensing interval for energy detectors has been explored. This new approach is built upon maximizing the probability of right detection, captured opportunities and transmission efficiency. The probability of right detection is defined as the probability of having no false alarm and correct detection. Optimization of the sensing time relies on maximizing the summation of the probability of right detection and the transmission efficiency while optimization of periodic sensing interval subject to maximizing the summation of transmission efficiency and the captured opportunities. The optimum sensing time and periodic sensing interval are dependent on each other, hence, iterative approach to optimize them is applied and convergence criterion is defined. The simulations show that both converged sensing time and periodic sensing interval increase with the increase of the channel utilization factor, moreover, the probability of false alarm, the probability of detection, the probability of right detection, the transmission efficiency and the captured opportunities have been taken as the detector performance metrics and evaluated for different values of channel utilization factor and signal-to-noise ratio.

Keyword
Energy detector, Sensing time, Periodic sensing interval, Probability of right detection, Transmission efficiency, Captured opportunities
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-101099 (URN)2-s2.0-84856325209 (Scopus ID)978-1-4503-0912-7 (ISBN)
Conference
4th international conference on cognitive radio and advanced spectrum management, CogART 2011
Projects
QUASAR
Funder
EU, FP7, Seventh Framework ProgrammeWireless@kth
Note

QC 20120919

Available from: 2012-08-23 Created: 2012-08-23 Last updated: 2015-02-09Bibliographically approved
5. On Spectrum Sharing and Dynamic Spectrum Allocation: MAC Layer Spectrum Sensing in Cognitive Radio Networks
Open this publication in new window or tab >>On Spectrum Sharing and Dynamic Spectrum Allocation: MAC Layer Spectrum Sensing in Cognitive Radio Networks
2010 (English)Conference paper, Published paper (Refereed)
Abstract [en]

One of the most critical issues regarding wireless networks regulation agencies is how to manage the available electromagnetic radio spectrum in a way that satisfies the needs of the huge growing in wireless systems both economically and technically, especially with the recent crowding in the available spectrum. Hence, building cognitive radio systems supporting dynamic access to the available spectrum has appeared recently as a novel solution for the wireless system huge expansion. In this paper we investigate the MAC layer sensing schemes in cognitive radio networks, where both reactive and proactive sensing are considered. In proactive sensing the adapted and non-adapted sensing periods schemes are also assessed. The assessment of these sensing schemes has been held via two performance metrics: available spectrum utilization and idle channel search delay. Simulation results show that with proactive sensing adapted periods we achieve the best performance but with an observable overhead computational tasks to be done by the network nodes.

Keyword
Cognitive Radio, Dynamic Spectrum Access, Reactive Sensing, Proactive Sensing, Spectrum Utilization Factor, Idle Channel Search Delay, Sensing Periods
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-110105 (URN)10.1109/CMC.2010.342 (DOI)2-s2.0-77953966817 (Scopus ID)
Conference
International Conference on Communications and Mobile Computing (CMC)
Note

QC 20130114

Available from: 2013-01-10 Created: 2013-01-10 Last updated: 2015-02-09Bibliographically approved
6. Geo-location Spectrum Opportunities Database in Downlink Radar Bands for OFDM Based Cognitive Radios
Open this publication in new window or tab >>Geo-location Spectrum Opportunities Database in Downlink Radar Bands for OFDM Based Cognitive Radios
2011 (English)Conference paper, Published paper (Refereed)
Abstract [en]

In this paper a model to investigate the spectrum opportunities for cognitive radio networks in three radar frequency bands L, S and C at a specific location is introduced. We consider underlay unaware spectrum sharing model. The Secondary System we assume is an OFDM based system. The followed strategy is built upon defining a specific co or adjacent channel as a spectrum opportunity if -and only if- the interference generated by the secondary system occupying that channel  into the radar system is less than the permissible interference defined by the value of Interference to Noise ratio (INR) and the radar receiver inherited noise level. The simulation results show that for the same transmission parameters C band offer more spectrum opportunities than S band which is itself offers more spectrum opportunities than L band.

Keyword
Geo-location based spectrum sharing, interference tolerance, downlink radar bands, INR, co and adjacent-channel interference
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-101098 (URN)
Conference
IEEE Conference on Communication, Science & Information Engineering CCSIE 2011 IEEE
Projects
QUASAR
Funder
Wireless@kthEU, FP7, Seventh Framework Programme
Note

QC 20120919

Available from: 2012-08-23 Created: 2012-08-23 Last updated: 2015-02-09Bibliographically approved

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Citation style
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  • ieee
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  • en-GB
  • en-US
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  • nn-NO
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Output format
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