Distributed Detection and Data Fusion
Distributed Detection and Data Fusion
ML estimation of time and frequency offset in OFDM systems
IEEE Transactions on Signal Processing
Doppler spread estimation for mobile OFDM systems in Rayleigh fading channels
IEEE Transactions on Consumer Electronics
Effect of quantization and channel errors on collaborative spectrum sensing
Asilomar'09 Proceedings of the 43rd Asilomar conference on Signals, systems and computers
Sequential and cooperative sensing for multi-channel cognitive radios
IEEE Transactions on Signal Processing
Cooperative sensing via sequential detection
IEEE Transactions on Signal Processing
Volume-based method for spectrum sensing
Digital Signal Processing
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This paper introduces a simple and computationally efficient spectrum sensing scheme for Orthogonal Frequency Division Multiplexing (OFDM) based primary user signal using its autocorrelation coefficient. Further, it is shown that the log likelihood ratio test (LLRT) statistic is the maximum likelihood estimate of the autocorrelation coefficient in the lowsignal-to-noise ratio (SNR) regime. Performance of the local detector is studied for the additive white Gaussian noise (AWGN) and multipath channels using theoretical analysis. Obtained results are verified in simulation. The performance of the local detector in the face of shadowing is studied by simulations. A sequential detection (SD) scheme where many secondary users cooperate to detect the same primary user is proposed. User cooperation provides diversity gains as well as facilitates using simpler local detectors. The sequential detection reduces the delay and the amount of data needed in identification of the underutilized spectrum. The decision statistics from individual detectors are combined at the fusion center (FC). The statistical properties of the decision statistics are established. The performance of the scheme is studied through theory and validated by simulations. A comparison of the SD scheme with the Neyman-Pearson fixed sample size (FSS) test for the same false alarm and missed detection probabilities is also carried out.