Performance Enhancement of Multi-Cyclic Detector for Cognitive Radios with an OFDM Primary System

Minseok KIM
Kimtho PO
Jun-ichi TAKADA

IEICE TRANSACTIONS on Communications   Vol.E95-B    No.3    pp.950-960
Publication Date: 2012/03/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E95.B.950
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Terrestrial Wireless Communication/Broadcasting Technologies
cognitive radio,  spectrum sensing,  cyclostationarity,  cyclic detector,  maximum ratio combining,  OFDM,  IEEE 802.22,  

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Spectrum sensing, a key technical challenge in cognitive radios (CR) technology, is a technique that enables the spectrum of licensed systems to be accessed without causing undue interference. It is well known that cyclostationarity detectors have great advantages over energy detectors in terms of the robustness to noise uncertainty that significantly degrades the performance as well as the capability to distinguish the signal of interest from the other interferences and noise. The generalized likelihood ratio test (GLRT) is a recognized sensing technique that utilizes the inherent cyclostationarity of the signal and has been intensively studied. However, no comprehensive evaluation on its performance enhancement has been published to date. Moreover high computational complexity is still a significant problem for its realization. This paper proposes a maximum ratio combining multi-cyclic detector which uses multiple cyclic frequencies for performance enhancement with reduced computational complexity. An orthogonal frequency-division multiplexing (OFDM) signal based on the ISDB-T (integrated services digital broadcasting terrestrial), a Japanese digital television broadcasting standard, was used in the evaluation assuming this as a primary system in WRAN (wireless regional area network) applications like IEEE 802.22.