Robust spectrum sensing in the presence of carrier frequency offset and phase noise for cognitive radio

In this paper we examine the spectrum detection performance of a matched filter (MF) in the presence of two system impairments: i.e., carrier frequency offset (CFO) and phase noise (PN). The results show that in the presence of CFO, the performance of the MF may be inferior to an energy detector (ED). So we propose three spectrum sensing techniques that are robust to CFO and outperform the MF over a certain range of CFO values. These three approaches are: the block-coherent detector (BLCD) with a suboptimal number (N/2) of blocks; the second-order matched filter-I (SOMF-I); and the second-order matched filter-II (SOMF-II), which is a modified version of SOMF-I. We show that the SOMF-II structure has the best detection performance of these three methods (in the presence of CFO). Finally, we examine the impact of PN on the detection ability of MF and SOMF-I. We will show that while PN will have some effect on the MF performance it does not impair the operation of SOMF-I.