A survey on security threats in cognitive radio networks based on cooperative spectrum sensing

Cognitive radio networks (CRNs) are a technological revolution that allows unlicensed users (SUs) to opportunistically use the freely licensed spectrum bands of a primary user (PU). To avoid interference with the PU, SUs need to do accurate spectrum sensing. Spectrum sensing (SS) by a single SU user can be inaccurate in deep fading and multi-path environments. Cooperative spectrum sensing (CSS) is a technology implemented in CRNs to improve the results of SS in deep fading environments. But only the success of CSS is threatened by new forms of attacks on the physical layer, the main ones being the spectrum sensing data falsification attack (SSDF) and the primary user emulation attack (PUEA). In our paper, we present the CSS in detail. Subsequently, a relevant study on SSDF and PUEA attacks is carried out, and depending on the approach exploited, different research works to defend the CSS against these attacks are presented.