On suitability of PSD method for opportunity detection in OFDM(A) based cognitive radio systems

Sultan Aldirmaz*, Asli Birol, Ibrahim Demirdogerr, Huseyin Arslan, Lutfiye Durak

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

In this study, orthogonal frequency division multiple access (OFDMA) based primary and secondary usage in a cognitive radio system is considered and conventional power spectral density (PSD) based technique is used to detect the opportunities in the spectrum. Primary user employs block-based or scattered subcarrier allocation scheme and the overlay system aims to utilize the spectral gaps. Comparison of the allocation schemes and effect of windowing are presented in terms oftrue detection andfalse alarm rates. It is observed that when block-based allocation is employed, the unlicensed user will be able to detect more opportunities in the spectrum compared to the case in which the scattered allocation is employed. Simulation results show that threshold selection is crucial since it is the main factor in determining the false alarm and true detection rates. It has been shown that, for either ofthe schemes all possible spectral gaps cannot be found when PSD is used. Questioning the suitability of PSD method results in that a new definition of opportunity is needed, forming a basis for the second part of this study.

Original languageEnglish
Title of host publication2009 International Conference on Ultra Modern Telecommunications and Workshops
DOIs
Publication statusPublished - 2009
Externally publishedYes
Event2009 International Conference on Ultra Modern Telecommunications and Workshops - St. Petersburg, Russian Federation
Duration: 12 Oct 200914 Oct 2009

Publication series

Name2009 International Conference on Ultra Modern Telecommunications and Workshops

Conference

Conference2009 International Conference on Ultra Modern Telecommunications and Workshops
Country/TerritoryRussian Federation
CitySt. Petersburg
Period12/10/0914/10/09

Keywords

  • Cognitive radio systems
  • OFDMA
  • Opportunity search
  • Subcarrier allocation

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