A Hybrid Localization Scheme for Detection of Primary User Emulator in Cognitive Radio Networks

Abstract

Cognitive radio (CR) is an enabling technology for combating the problem of spectrum scarcity in the wireless world; however, some security challenges are threatening this emerging technology. The major security challenge to the deployment of the cognitive radio network (CRN) is the primary user emulation attack (PUEA). Since the primary user emulator (PUE) mimics the primary user (PU) signal to cause havoc in the network, to distinguish its signal from that of the PU, knowledge of the exact position of the PUE in the CRN is required. One of the methods to detect PUEs is via Localization, of which there are two major categories: range-based and range-free. The range-based class is reportedly more accurate but with higher complexity. Among this category are Angle of arrival (AoA), which uses angular measurements to localise the PUE, and the received signal strength (RSS), which uses only distance to localize the PUE. To improve performance and reduce the complexity of range-based methods, this paper proposes a hybrid of AoA and RSS methods to localize PUEs in TV white space. This scheme computes the angle at which the PU signal reaches the SUs and the distance between the transmitter and SUs in the CRN. Since in a TV white space, the PU’s location is known a priori, the computed AoA and the distance obtained from the RSS are thus used to determine the position of a PU signal transmitter. This position is compared with the location of the PU to ascertain the true source of the signal, thus detecting the PUE. The location estimation is carried out by the individual SUs. Computer simulations demonstrate that the hybrid scheme estimates the position of the PUE much faster and with a much lower root mean square error (RMSE) of 0.005, which greatly outperforms the methods considered individually. Thus, the hybrid scheme is faster, more accurate, and conserves energy better than considering the methods individually. This result is quite significant when attention is given to the fact that speed and accuracy are essential in the efficient operation of CRs and that energy-efficient operations are essential for wireless systems and especially in the currently looming global energy crisis.