Reappearing primary user detection in FBMC/OQAM cognitive radios

This paper investigates the problem of detecting the reappearance of a primary user signal during ongoing secondary data transmission. The high frequency containment of filter bank multicarrier (FBMC) waveforms is exploited to construct, in spectrally efficient manner, continuous silent subbands within the transmission band for spectrum monitoring. Energy detection is carried out on these monitoring subbands in secondary receivers. The distribution of the test statistic is derived to characterize the detector performance in the transient phase where the reappearance of the primary signal falls arbitrarily within the integration window. The experimental data obtained from an FBMC/OQAM secondary multiplexing testbed verifies the derived analytic model. Further, the impact of the transmit power amplifier nonlinearity on the proposed spectrum monitoring scheme is discussed.