Control of Cognitive Networks With Friendly Jamming as a Service

We consider a cognitive radio network with single antenna primary user (PU), destination and eavesdropper, and multi-antenna secondary users (SUs). SUs act as helper nodes transmitting noise to confound a passive eavesdropper while nulling the interference leakage at the destination. The jamming helper nodes are non-altruistic, and they gain access to the primary network by aiding in the confidential transmissions of the PU. We obtain the secrecy outage probability as a closed-form expression when PU and SUs have merely statistical information about the eavesdropper channel. For the delay-unlimited system, we derive the achievable confidential rates given the control strategies for bandwidth and power allocation. For the more practical delay-limited case, we formulate a network control problem with secrecy appearing as a quality of service constraint optimizing the confidential and open transmission rates of the PU and SUs, respectively. Finally, we develop a dynamic control algorithm obtaining asymptotically optimal solution and demonstrate its performance by numerical experiments.