Armour, SMD

Fan, Z

Kaleshi, D

Subramani, S

English

Underutilization of the limited spectrum sparked the need for dynamic spectrum access and flexible spectrum policies. Accurate estimation of spectrum occupancy is an essential step for spectrum access in distributed networks. This paper analyzes a bidirectional and dual scanning method that scans multiple spectrum bands to find a suitable free-channel. Moreover, secondary users' access to available spectrum could be interrupted by the arrival of primary spectrum users, forcing the well-behaved secondary users to switch to another free-channel. A pointer and adaptive reserve channel mechanism is proposed in this paper to facilitate quicker and smoother channel switching. Simulation results for both techniques show improved overall connectivity is maintained for varying primary users' arrival rate

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                          Subramani, S., Armour, S. M. D., Kaleshi, D., & Fan, Z. (2008). Spectrumscanning and reserve channel methods for link maintenance in cognitiveradio systems. In IEEE Vehicular Technology Conference, 2008 (VTCSpring 2008), Singapore. (pp. 1944 - 1948). Institute of Electrical andElectronics Engineers (IEEE). doi: 10.1109/VETECS.2008.440,10.1109/VETECS.2008.440Link to published version (if available):doi: 10.1109/VETECS.2008.44010.1109/VETECS.2008.440Link to publication record in Explore Bristol ResearchPDF-documentUniversity of Bristol - Explore Bristol ResearchGeneral rightsThis document is made available in accordance with publisher policies. Please cite only the publishedversion using the reference above. Full terms of use are available:http://www.bristol.ac.uk/pure/about/ebr-terms.htmlTake down policyExplore Bristol Research is a digital archive and the intention is that deposited content should not beremoved. However, if you believe that this version of the work breaches copyright law please contactopen-access@bristol.ac.uk and include the following information in your message:• Your contact details• Bibliographic details for the item, including a URL• An outline of the nature of the complaintOn receipt of your message the Open Access Team will immediately investigate your claim, make aninitial judgement of the validity of the claim and, where appropriate, withdraw the item in questionfrom public view.Spectrum Scanning and Reserve Channel methods for Link Maintenance in Cognitive Radio NetworksSiva Subramani, Simon Armour, Dritan Kaleshi, Zhong Fan*, University of Bristol, UK, *Toshiba Research, UKMOTIVATIONSpectrum bands are expected to be non-contiguous channels distributed over wide range of spectrum• Need efficient multi band spectrum scanning that is capable of scanning deeper parts of spectrum and including user’s preference Spectrum access disruption or disconnection due to unexpected events such as primary user arrival and interference• Need a mechanism to facilitate link maintenance during such unexpected events.Spiral – Bidirectional Spectrum ScanningINTRODUCTIONTo exploit the Cognitive Radio’s ability to switch between channels (spectrum agility/mobility) to improve performance,  wepresent the framework consisting of Multi-band Scanning• Spiral-Bidirectional scanning mechanism• Dual scanning mechanismLink Maintenance• Adaptive Reserve Channel• PointerSPECTRUM SCANNING1. Spiral- Bidirectional scanning mechanism• The cognitive radio pair share the scanning tasks in either direction• The scanning steps are Cx+1, Cx-1, Cx+2, Cx-2, … so on2. Dual scanning mechanism• Two different bands are selected by the pair (combination of random and sequential scanning techniques)• The channels are checked alternativelyPERFORMANCE RESULTSScanning Mechanism• Bidirectional scanning mechanism ensures the nearest free-channel available• Number of steps is asymptotical to sequential CONCLUSIONIn the scenarios of unexpected events (i.e shorter than the scanning time), the secondary user’s link is maintained throughReserve Channel• Some channels reserved frequency for smooth transfer of links if necessary• In shared spectrum regime, no fixed reserve channels; the RCsare adaptivePointer• A reference to a valid and regularly checked backup channel • During unexpected events, pointers serve as first stepDual scanning techniqueCxCmCx+1Cm+1channelschannelsLINK MAINTENACELink Maintenance: Adaptive Reserve Channel• Even with 1% of channels as RC, connectivity improved by 77%Adaptive Channel MechanismIllustrating simple example:• Analyzed bidirectional and dual scanning mechanism to scan deeper and non-contiguous spectrum• Proposed adaptive reserve channel and pointer mechanism for link maintenance in the event of primary user arrival• Performance results demonstrate the ability to produce the nearest channel available without compromising complexity• Even with 1% of channels as reserve, the connectivity improve by 77%• Other parameters influencing connectivity such as lease period and PU arrival rate are illustrated• Scanning mechanism controls the sequence of scanning• Conventional scanning techniques are sequential Link Maintenance performance with adaptive reserve channelPerformance of bidirectional scanning mechanism

Spectrum scanning and reserve channel methods for link maintenance in cognitive radio systems

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Spectrum Scanning and Reserve Channel Methods for Link Maintenance in Cognitive Radio Systems

https://research-information.bris.ac.uk/files/3010834/siva_IEEE_VTC_spring 2008.pdf

Spectrum scanning and reserve channel methods for link maintenance in cognitive radio systems

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