Simultaneous Transmission and Spectrum Sensing in OFDM Systems Using Full-Duplex Radios

This paper studies the idea and performance of cyclostationary spectrum sensing in cognitive full-duplex radios, when secondary transmission and spectrum sensing are done simultaneously at the same channel. The paper starts by briefly introducing the ideas of cognitive full-duplex radio and the cyclostationary spectrum sensing in the presence of self-interference. The idea of changing the cyclic features of the secondary signal is then proposed and its impact on the spectrum sensing under self-interference is analysed. The cyclic features can be changed by changing the length of the cyclic prefix of the OFDM signal or by changing the amount of subcarriers. The effects of both approaches are evaluated with comprehensive performance simulations. It is shown that changing the cyclic features of the secondary signal can provide significant improvements in the sensing results of the primary signal, and that in general, reliable inchannel spectrum sensing while transmitting is feasible. This can enable enhance coexistence mechanisms, e.g., for LTE-Unlicensed technology at ISM band.