OAM-Based Hybrid-Duplex Cognitive Frequency Hopping

Abstract

In cognitive radio networks, the jamming attacks, which have the same ability with secondary users (SUs) but access the licensed channels without considering the carrier sense multiple access protocol, can disguise a primary user (PU) or SU to occupy the licensed channels, thus resulting in failing to access the licensed channels for PUs and SUs. Employing full/half duplex cognitive frequency hopping (CFH), where users sense the occupancy of licensed channels and then dynamically adjust the hopping parameters, can mitigate the hostile jamming. However, due to the explosive growth of serves and data traffic, it is very difficult to significantly increase the anti-jamming results and achieve high capacities with full/half duplex CFH for both PUs and SUs in cognitive radio networks. To achieve efficient anti-jamming and high capacities for PUs and SUs, in this paper we propose the orbital angular momentum (OAM)-based hybrid-duplex CFH scheme, which jointly uses the half-duplex cooperative sensing and full-duplex transmission modes for PUs and SUs in cognitive radio networks. Using the OAM-based hybrid-duplex CFH scheme, PUs and SUs can identify the occupancy of licensed channels with half-duplex fashion, thus significantly reducing the probability of signals jammed. Then, based on the sensing results, the signals are allowed to be transmitted and received by the same time-slots, carrier frequencies, and OAM-modes. The average capacities of PUs and SUs are derived, respectively. Extensively numerical results show that our proposed OAM-based hybrid-duplex CFH scheme can significantly increase the capacities of PUs and SUs in cognitive radio networks under hostile jamming attacks.