Sensing UHF-TV Spectrum for Narrowband Cognitive Radios in a Malicious Presence

In this paper, we propose a robust spectrum sensing (SS) technique for cognitive radio receivers (CRRs) when a malicious CR user (MCRU) coexists in the network. The primary users (PUs) that we consider are the television (TV) broadcasters, who operate in an ultrahigh-frequency (UHF) band. Using multiple antennas of CRR, as a first step, we locate a narrower subband-within an UHF-TV range-at which the interference due to MCRU is least. Then, SS is implemented only at the chosen band, so that the detection of PU is not affected by the presence of MCRU. The finding of the apt band for SS is implemented through a table, which needs to know only the angle of arrival of signal from MCRU. We have shown the technique to estimate this angle of arrival as well. The simulation results show that the proposed method does not compromise the detection performance, unlike the energy detection scheme, which compromises severely when MCRU coexists.