Primary User authentication of cognitive radio network using underlay waveform

Primary User Emulation (PUE) attack is one of the major concerns and problems in cognitive radio networks. Essentially, an intruder who tries to interfere and occupy the vacant spectrum of the primary user (PU) can emulate or impersonate the primary user by mimicking certain characteristics and features of the primary user signal. As a direct result, it may seem to secondary users (SUs) as though the primary user is still using the spectrum when in reality the intruder has unleashed a PUE attack denying SU spectrum access. In this paper, we propose a novel primary use authentication scheme to solve the PUE attack problem by employing an underlay RF fingerprint in the primary users signal. Specifically, we intentionally introduce an underlay waveform on top of the header of the legitimate primary users signal. This underlay waveform is consisted of wider bandwidth and higher baud rate than those of the original primary users signal. As a direct result, the underlay waveform exhibits a unique and different cyclostationary feature than that of the primary user signal. At the CR, a sophisticated cyclostationary analysis algorithm, combined with a primary user signal cancellation, is capable of revealing this unique cyclostationary feature to authenticate and validate the identity of the legitimate PU. The PUE attack signal, on the other hand, will not reveal this cyclostationary feature and fail to pass the authentication.