Collaborative autocorrelation-based spectrum Sensing of OFDM signals in cognitive radios

Abstract

A simple and efficient spectrum sensing scheme for Orthogonal Frequency Division Multiplexing (OFDM) signals of primary user in cognitive radio systems is proposed in this paper. A detector exploiting the well-known autocorrelation property of cyclic prefix (CP) based OFDM signals is developed. The proposed scheme is then extended to the case of many secondary users collaborating in order to detect the primary user in the face of shadowing and fading. The amount of information each user sends to other users or fusion center is constrained by censoring scheme where only informative decision statistics are sent. Censoring allows reducing the power consumption in battery operated mobile terminals. The statistical properties of the decision statistics are established. Limits on the censoring region are found under constraints on false-alarm and transmission rates. The distribution of the test statistics for cooperative detection with censoring is approximated using characteristic functions. The performance of the scheme is studied by simulations.

IEEE Signal Processing Magazine - May 2006

“…For example, a perfect Fourier series representation of the signal shown in Figure 3 requires infinitely many Fourier coefficients. The autocorrelation-based detector of [17] and the cyclostationarity detector of [22] are compared in [24] for detection of an OFDM signal in AWGN. The results show that the cyclostationarity detector using two cyclic frequencies outperforms the autocorrelation detector, but that the autocorrelation detector is superior when only one cyclic frequency is used.…”

“…Note that [66] also takes reporting errors to the fusion center into account. In addition to energy detection, autocorrelation-based and cyclostationarity detection have also been used in combination with censoring [22], [24]. These works consider a soft decision rule, under a NP setting with a communication rate constraint per radio.…”

Spectrum Sensing for Cognitive Radio : State-of-the-Art and Recent Advances

“…In addition to energy detection, autocorrelation-based and cyclostationarity detection have also been used in combination with censoring [22], [24]. These works consider a soft decision rule, under a NeymanPearson setting with a communication rate constraint per radio.…”

“…The autocorrelation-based detector of [17] and the cyclostationarity detector of [22] are compared in [24], for detection of an OFDM signal in AWGN. The results show that the cyclostationarity detector using two cyclic frequencies outperforms the autocorrelation detector, but that the autocorrelation detector is superior when only one cyclic frequency is used.…”

Spectrum sensing of OFDM signals in the presence of CFO: New algorithms and empirical evaluation using USRP

“…All of these methods exploit properties of the autocorrelation of the received signal in different ways. They have been derived based on theoretical system models using more or less ideal assumptions, and the performance of these methods have been evaluated in simulations using channel models with a varying degree of realism [2,3,6].…”