Coexistence of LTE and WLAN in unlicensed bands: Full-duplex spectrum sensing

Abstract

Problem of opportunistic use of the unlicensed 5-GHz band for LTE carrier aggregation (LTE unlicensed) is studied from the point-of-view of cognitive full-duplex transceivers. In this paper, an initial study of the impact of self-interference on the performance of cyclostationary spectrum sensing algorithm is given, in case where a full-duplex transceiver tries to opportunistically use parts of the band used by a WLAN signal. Effective sensing while transmitting is natively possible, because WLAN and LTE signals have different cyclic properties. The evaluation of the impact focuses on extensive system simulations and simulation analysis. It is concluded that the self-interference can indeed interfere with the cyclostationary spectrum sensing. However, the effect can be lowered by lowering the bandwidth of the aggregated signal and instead using higher spectral density for the lower bandwidth signal.