Robust detection of OFDM signals for cognitive UWB in low SNR with noise uncertainty

Sensing the weak signals of primary users by cognitive UWB devices greatly challenges the capability of energy detector under noise uncertainty. This paper presents a simple and robust statistic for detecting the primary signals of OFDM type. The statistic, constructed from the auto-correlation function of the received signal, is unsusceptible to the noise uncertainty since it avoids estimating the noise level. The detection and false alarm probabilities are then calculated. The comparison with energy detection demonstrates its superiority to the energy detector in case of low SNR and noise uncertainty.