This paper studies the problem of active eavesdropping in fast fading channels. The active eavesdropper (Eve-A) is a more powerful adversary than the classical eavesdropper. It can choose between two functional modes: eavesdropping (Ex mode), and jamming (Jx mode)-Eve-A cannot function in full duplex mode. We consider the most conservative scenario, when the Eve-A can choose her strategy based on the legitimate transmitter-receiver pair's strategy-and thus the transmitter and legitimate receiver have to plan for the worst. We introduce a novel encoding scheme, based on very limited and unprotected feedback-the Block-Markov Wyner (BMW) encoding scheme-which outperforms any schemes currently available.
This paper studies the problem of active eavesdropping in fast fading channels. The active eavesdropper (Eve-A) is a more powerful adversary than the classical eavesdropper. It can choose between two functional modes: eavesdropping (Ex mode), and jamming (Jx mode)-Eve-A cannot function in full duplex mode. We consider the most conservative scenario, when the Eve-A can choose her strategy based on the legitimate transmitter-receiver pair's strategy-and thus the transmitter and legitimate receiver have to plan for the worst. We introduce a novel encoding scheme, based on very limited and unprotected feedback-the Block-Markov Wyner (BMW) encoding scheme-which outperforms any schemes currently available.
In this paper, we study the problem of half-duplex active eavesdropping in fast-fading channels. The active eavesdropper is a more powerful adversary than the classical eavesdropper. It can choose between two functional modes: eavesdropping the transmission between the legitimate parties (Ex mode), and jamming it (Jx mode)-the active eavesdropper cannot function in full duplex mode. We consider a conservative scenario, when the active eavesdropper can choose its strategy based on the legitimate transmitter-receiver pair's strategy, and thus, the transmitter and legitimate receiver have to plan for the worst. We show that conventional physical-layer secrecy approaches perform poorly (if at all), and we introduce a novel encoding scheme, based on very limited and unsecured feedback-the Block-Markov Wyner encoding scheme-which outperforms any schemes currently available.
In this paper we study the problem of active eavesdropping in fast fading channels. The active eavesdropper is a more powerful adversary than the classical eavesdropper. It can choose between two functional modes: eavesdropping the transmission between the legitimate parties (Ex mode), and jamming it (Jx mode) - the active eavesdropper cannot function in full duplex mode. In this paper we only consider the best-case scenario, when the transmitter knows the eavesdropper's strategy in advance - and hence can adaptively choose an encoding strategy. We show that, even under these most optimistic assumptions, an active eavesdropper can induce moderate to severe degradation of the achievable secrecy rate.
This work aims at addressing two critical security issues residing in the physical layer of wireless networks, namely intelligent jamming and eavesdropping. In the first two chapters we study the problem of jamming in a fixed-rate transmission system with fading, under the general assumption that the jammer has no knowledge about either the codebook used by the legitimate communication terminals, or the source’s output. Both transmitter and jammer are subject to power constraints which can be enforced over each codeword (peak) or over all codewords (average). All our jamming problems are formulated as zero-sum games, having the probability of outage as pay-off function and power control functions as strategies. We provide a comprehensive coverage of these problems, under fast and slow fading, peak and average power constraints, pure and mixed strategies, with and without channel state information (CSI) feedback. Contributions to the eavesdropping problem include a novel feedback scheme for transmitting secret messages between two legitimate parties, over an eavesdropped communication link, presented in Chapter 4. Relative to Wyner’s traditional encoding scheme, our feedback-based encoding often yields larger rate-equivocation regions and achievable secrecy rates. More importantly, by exploiting the channel randomness inherent in the feedback channels, our scheme achieves a strictly positive secrecy rate even when the eavesdropper’s channel is less noisy than the legitimate receiver’s channel. In Chapter 5 we study the problem of active eavesdropping in fast fading channels. The active eavesdropper is a more powerful adversary than the classical eavesdropper. It can choose between two functional modes: eavesdropping the transmission between the legitimate parties (Ex mode), and jamming it (Jx mode) – the active eavesdropper cannot function in full duplex mode. We consider two scenarios: the best-case scenario, when the transmitter knows the eavesdropper’s strategy in advance – and hence can adaptively choose an encoding strategy – and the worst-case scenario, when the active eavesdropper can choose its strategy based on the legitimate transmitter-receiver pair’s strategy. For the second scenario, we introduce a novel encoding scheme, based on very limited and unprotected feedback – the Block-Markov Wyner (BMW) encoding scheme – which outperforms any schemes currently available.
In this paper, we investigate secure short packet transmission from a legitimate transmitter to a receiver in the presence of an active eavesdropper. The aim is to gain more insights into how an active eavesdropper affects the secrecy throughput of short packet communications. The eavesdropper is assumed to have full-duplex (FD) capability, which enables performing eavesdropping and jamming simultaneously. All the communication links in the wiretap channel are assumed to be Rayleigh fading. An approximation of the average achievable secrecy throughput is proposed to measure the security of the system. The proposed approximation is examined and analysed in two different topology scenarios, which are triangular and line topologies. Then, Monte-Carlo simulations are performed to get an understanding of how good the approximation is. The results show that the closed-form expressions have a good match with Monte-Carlo simulations. We also investigate the impact of the eavesdropper's distance to the legitimate nodes as well as the different jamming power levels. Furthermore, self-interference influence on the eavesdropper is discussed.
We consider the secure transmission of information over an ergodic fading channel in the presence of an eavesdropper. Our eavesdropper can be viewed as the wireless counterpart of Wyner's wiretapper. The secrecy capacity of such a system is characterized under the assumption of asymptotically long coherence intervals. We first consider the full Channel State Information (CSI) case, where the transmitter has access to the channel gains of the legitimate receiver and the eavesdropper. The secrecy capacity under this full CSI assumption serves as an upper bound for the secrecy capacity when only the CSI of the legitimate receiver is known at the transmitter, which is characterized next. In each scenario, the perfect secrecy capacity is obtained along with the optimal power and rate allocation strategies. We then propose a low-complexity on/off power allocation strategy that achieves near-optimal performance with only the main channel CSI. More specifically, this scheme is shown to be asymptotically optimal as the average SNR goes to infinity, and interestingly, is shown to attain the secrecy capacity under the full CSI assumption. Remarkably, our results reveal the positive impact of fading on the secrecy capacity and establish the critical role of rate adaptation, based on the main channel CSI, in facilitating secure communications over slow fading channels.
We consider the secure transmission of information over an ergodic fading channel in the presence of an eavesdropper. Our eavesdropper can be viewed as the wireless counterpart of Wyner's wiretapper. The secrecy capacity of such a system is characterized under the assumption of asymptotically long coherence intervals. We analyze the full Channel State Information (CSI) case, where the transmitter has access to the channel gains of the legitimate receiver and eavesdropper, and the main channel CSI scenario, where only the legitimate receiver channel gain is known at the transmitter. In each scenario, the secrecy capacity is obtained along with the optimal power and rate allocation strategies. We then propose a low-complexity on/off power allocation strategy that achieves near-optimal performance with only the main channel CSI. More specifically, this scheme is shown to be asymptotically optimal as the average SNR goes to infinity, and interestingly, is shown to attain the secrecy capacity under the full CSI assumption. Remarkably, our results reveal the positive impact of fading on the secrecy capacity and establish the critical role of rate adaptation, based on the main channel CSI, in facilitating secure communications over slow fading channels.