Security in Cognitive Radio Networks

In this paper, we investigate the information-theoretic security by modeling a cognitive radio wiretap channel under quality-of-service (QoS) constraints and interference power limitations inflicted on primary users (PUs). We initially define four different transmission scenarios regarding channel sensing results and their correctness. We provide effective secure transmission rates at which a secondary eavesdropper is refrained from listening to a secondary transmitter (ST). Then, we construct a channel state transition diagram that characterizes this channel model. We obtain the effective secure capacity which describes the maximum constant buffer arrival rate under given QoS constraints. We find out the optimal transmission power policies that maximize the effective secure capacity, and then, we propose an algorithm that, in general, converges quickly to these optimal policy values. Finally, we show the performance levels and gains obtained under different channel conditions and scenarios. And, we emphasize, in particular, the significant effect of hidden-terminal problem on information-theoretic security in cognitive radios.Comment: Submitted to CISS 201

Secure GDoF of the Z-channel with Finite Precision CSIT: How Robust are Structured Codes?

Under the assumption of perfect channel state information at the transmitters (CSIT), it is known that structured codes offer significant advantages for secure communication in an interference network, e.g., structured jamming signals based on lattice codes may allow a receiver to decode the sum of the jamming signal and the signal being jammed, even though they cannot be separately resolved due to secrecy constraints, subtract the aggregate jammed signal, and then proceed to decode desired codewords at lower power levels. To what extent are such benefits of structured codes fundamentally limited by uncertainty in CSIT? To answer this question, we explore what is perhaps the simplest setting where the question presents itself -- a Z interference channel with secure communication. Using sum-set inequalities based on Aligned Images bounds we prove that the GDoF benefits of structured codes are lost completely under finite precision CSIT. The secure GDoF region of the Z interference channel is obtained as a byproduct of the analysis.Comment: 34 pages, 10 figure