Energy detection in full-duplex cognitive radios under residual self-interference

This paper investigates the possibility to exploit inband full-duplex wireless technology for simultaneous spectrum sensing and data transmission in cognitive radio terminals. The focus is especially on the receiver operating characteristics of basic energy detection. Full-duplex operation suffers from self-interference, even after cancellation since it is imperfect in prac-tice. The effect on the probability of missed detection is analyzed, and increasing sensing time is proposed as a countermeasure for residual distortion which, unlike in half-duplex operation, does not cause large overhead due to lost transmission opportunities. The study also compares the two- and single-antenna implementations of full-duplex radios and elicits a channel imbalance problem in the former due to which sensing provides different information than the transmitting antenna would observe.