| 1. |
- Gabry, Frederic, et al.
(författare)
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Cooperation for secrecy in presence of an active eavesdropper : A game-theoretic analysis
- 2011
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Ingår i: 8th International Symposium on Wireless Communication Systems (ISWCS), 2011. ; , s. 281-285
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Konferensbidrag (refereegranskat)abstract
- In this paper, we investigate a four single-antenna node network, constituted of a transmitter, a receiver, a cooperative node and a wiretapper. The wiretapper has the ability to eavesdrop the communication or disrupt the transmission by jamming. This results in both cases in the decrease of the secrecy rate. The cooperative node on the other hand aims to improve secrecy by either relaying or jamming. We investigate the secrecy performance of the decode-and-forward and cooperative jamming strategies against this kind of adversary. To model the interaction between the helper and the wiretapper, we define an extensive form game, for which we derive the pure and mixed strategies equilibria. Finally, we compare the performance of the schemes and we analyze the equilibrium outcomes through simulation results.
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| 2. |
- Gabry, Frederic
(författare)
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Cooperation for Secrecy in Wireless Networks
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The growth of wireless networks has been considerable over the last decades. Due to the broadcast nature of these networks, security issues have taken a critical role in today’s communications. A promising direction towards achieving secure communications is information theoretic secrecy, which is an approach exploiting the randomness of the channels to ensure secrecy. Based on this approach, there has been a recent surge of interest in a potential cooperation between users to enhance the secrecy of communications. In this thesis we investigate the interaction between cooperation and secrecy. In particular the contributions of the thesis can be divided into two parts.In the first part, we study cooperative strategies for secrecy for wireless channels. Our goal is to evaluate the effect of fading and limited CSI on the eavesdropper’s channels. In that purpose we consider a scenario where a helper aims at increasing the secrecy of the communication between a source and destination in the presence of an eavesdropper. Several strategies are discussed for the helper, namely decode-and-forward, amplify-and-forward, and cooperative jamming. We introduce the secrecy outage probability, the conditional secrecy outage probability and the secure throughput as secrecy measures. For each measure, we investigate and compare the secrecy performance of cooperation. We furthermore elaborate a system optimization in terms of strategy selection, node positioning, power allocation and rate design.In the second part, we consider cooperation in the 4-node scenario against a more sophisticated adversary: an active eavesdropper, which can either passively eavesdrop, or jam the transmission. A game-theoretic perspective is a natural way to analyze the competitive interaction between the helper and the eavesdropper. Therefore we define several secrecy games, for which we find the Nash and Stackelberg equilibria as well as the corresponding secrecy rate outcomes. Another important consideration in this scenario is the interaction between the source and the helper, which we model and solve as a Stackelberg game, and we illustrate its impact on the achievable secrecy rates.
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| 3. |
- Gabry, Frédéric, et al.
(författare)
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Cooperation for Secure Broadcasting in Cognitive Radio Networks
- 2012
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Ingår i: Communications (ICC), 2012 IEEE International Conference on. - : IEEE. - 9781457720529 ; , s. 5613-5618
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Konferensbidrag (refereegranskat)abstract
- This paper explores the trade-off between cooperation and secrecy in cognitive radio networks. We consider a scenario consisting of a primary and a secondary system. In the simplest case, each system is represented by a pair of transmitter and receiver. We assume a secrecy constraint on the transmission in the sense that the message of the primary transmitter has to be concealed from the secondary receiver. Both situations where the secondary transmitter is aware and unaware of the primary message are investigated and compared. In the first case, the secondary transmitter helps by allocating power for jamming, which increases the secrecy of the first message. In the latter case, it can also act as a relay for the primary message, thus improving the reliability of the primary transmission. Furthermore, we extend our results to the scenario where the secondary system comprises multiple receivers. For each case we present achievable rate regions. We then provide numerical illustrations for these rate regions. Our main result is that, in spite of the secrecy constraint, cooperation is beneficial in terms of the achievable rates. In particular, the secondary system can achieve a significant rate without decreasing the primary rate below the benchmark rate achievable without the help of the secondary transmitter. Finally, we investigate the influence of the distances between users on the system's performance.
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| 4. |
- Gabry, Frédéric, et al.
(författare)
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Energy Efficiency Analysis of Cooperative Jamming in Cognitive Radio Networks with Secrecy Constraints
- 2015
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Ingår i: IEEE Wireless Communications Letters. - 2162-2337 .- 2162-2345. ; 4:4, s. 437-440
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Tidskriftsartikel (refereegranskat)abstract
- We investigate energy-efficient cooperation for secrecy in cognitive radio networks. In particular, we consider a four-node cognitive scenario where the secondary receiver is treated as a potential eavesdropper with respect to the primary transmission. The cognitive transmitter should ensure that the primary message is not leaked to the secondary user by using cooperative jamming. We investigate the optimal power allocation and power splitting at the secondary transmitter for our cognitive model to maximize the secondary energy efficiency (EE) under secrecy constraints. We formulate and analyze an important EE Stackelberg game between the two transmitters aiming at maximizing their utilities. We illustrate the analytical results through our geometrical model, highlighting the EE performance of the system and the impact of the Stackelberg game.
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| 5. |
- Gabry, Frédéric, et al.
(författare)
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High SNR performance of amplify-and-forward relaying in Rayleigh fading wiretap channels
- 2013
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Ingår i: 2013 Iran Workshop on Communication and Information Theory, IWCIT 2013. - : IEEE. - 9781467350235 ; , s. 6555771-
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Konferensbidrag (refereegranskat)abstract
- This paper investigates amplify-and-forward (AF) relaying for secrecy in quasi-static Rayleigh fading channels. We consider a four-node network where a helping node intends to enhance secrecy of the transmission between the source and the destination in presence of a passive eavesdropper. In this scenario, the common assumption of full CSI on the eavesdropper's channels is not realistic, and thus, we study the performance of cooperation from an outage perspective. Starting from the secrecy outage probability, we introduce a novel measure, the conditional secrecy outage probability to analyze the performance of AF. In particular, we derive closed-form expressions for AF for these two secrecy measures under a high SNR assumption. Moreover, we use numerical examples to illustrate our results and to characterize the effect of the nodes' geometry. We also show numerically how AF improves the secrecy performance in comparison to direct transmission in terms of outage probability and secure throughput.
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| 6. |
- Gabry, Frédéric, et al.
(författare)
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On the Optimization of the Secondary Transmitter's Strategy in Cognitive Radio Channels with Secrecy
- 2014
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Ingår i: IEEE Journal on Selected Areas in Communications. - 0733-8716 .- 1558-0008. ; 32:3, s. 451-463
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates cooperation for secrecy in cognitive radio networks. In particular, we consider a four-node cognitive scenario where the secondary receiver is treated as a potential eavesdropper with respect to the primary transmission. The cognitive transmitter can help the primary transmission, and it should also ensure that the primary message is not leaked to the secondary user. We consider two cognitive scenarios depending on whether the secondary transmitter knows the primary message or not. In the first case, the secondary transmitter is unaware of the primary transmitter's message and acts as a helping interferer to enhance the secrecy of the primary transmission, whereas in the second case, relaying of the primary message is also within its capabilities. First, we find achievable rate regions for these two scenarios in the case of AWGN channels. We then investigate three different optimization problems: the maximization of the primary rate, the maximization of the secondary rate and the minimization of the secondary transmit power. For these optimization problems, we find closed-form expressions in important special cases. Furthermore, we analyze the cooperation between the primary and secondary transmitters from a game-theoretic perspective. We model their interaction as a Stackelberg game, for which we define and find the Stackelberg equilibrium. Finally, we use numerical examples to illustrate the rate regions, the three optimizations, and the impact of the Stackelberg game on the achievable rates and on the transmission strategies of the secondary transmitter.
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| 7. |
- Gabry, Frederic, et al.
(författare)
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Outage Performance and Power Allocation for Decode-and-Forward Relaying and Cooperative Jamming for the Wiretap Channel
- 2011
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Ingår i: 2011 IEEE International Conference on Communications Workshops, ICC 2011 Workshops. - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- In this paper, we investigate the wiretap channel in the presence of a cooperative helping node. We derive a closed-form expression for the secrecy outage probability for the decode-and-forward (DF) relaying and cooperative jamming (CJ) strategies for the Rayleigh slow fading channel. We investigate the power allocation at the source and helping node, and compare the secrecy outage performance of the two schemes.
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| 8. |
- Gabry, Frederic, et al.
(författare)
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Outage Performances for Amplify-and-Forward, Decode-and-Forward and Cooperative Jamming Strategies for the Wiretap Channel
- 2011
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Ingår i: 2011 IEEE Wireless Communications and Networking Conference, WCNC 2011. - : IEEE. ; , s. 1328-1333
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Konferensbidrag (refereegranskat)abstract
- In this paper, we investigate the wiretap channel in the presence of a cooperative relay node. We analyze and compare the outage performance of three cooperatives schemes: cooperative jamming (CJ), decode-and-forward (DF), and amplify-and-forward (AF) for the Rayleigh slow fading channel. In particular, we derive a closed-form expression for the outage probability for the DF and CJ strategies, which allows an optimal strategy selection in terms of outage performance. We compare the three cooperative schemes through numerical simulations.
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| 9. |
- Gabry, Frederic, et al.
(författare)
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Secrecy Games In Cognitive Radio Networks with Multiple Secondary Users
- 2015
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Ingår i: 2015 IEEE CONFERENCE ON COMMUNICATIONS AND NETWORK SECURITY (CNS). - 9781467378765 ; , s. 143-148
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Konferensbidrag (refereegranskat)abstract
- In this paper we investigate secrecy games in cognitive radio networks with multiple secondary pairs and secrecy constraints. We consider the cognitive channel model with multiple secondary pairs where the secondary receivers are treated as eavesdroppers with respect to the primary transmission. For this novel network model, we derive achievable rate regions when secondary pairs are allowed to use the channel simultaneously. We then investigate the spectrum sharing mechanisms using several game theoretic models, namely 1) a single-leader multiple-follower Stackelberg game with the primary transmitter as the leader and the secondary transmitters as followers; 2) a non-cooperative power control game between the secondary transmitters if they can access the channel simultaneously; and 3) an auction between a primary auctioneer and secondary bidders which allows the primary transmitter to exploit the competitive interaction between the secondary transmitters. We illustrate through numerical simulations the equilibrium outcomes of the analyzed games and the impact of the competition between the secondary transmitters on the utility performance of every node in the cognitive radio network.
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| 10. |
- Gabry, Frederic
(författare)
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Secrecy in Cognitive Radio Networks
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With the considerable growth of wireless networks in recent years, the issue of network security has taken an important role in the design of communication devices and protocols. Indeed, due to the broadcast nature of these networks, communications can potentially be attacked by malicious parties, and therefore, the protection of transmitted data has become a main concern in today's communications. On the other hand the cooperation of nodes overhearing the transmission may potentially lead to a better performance. In this thesis we combine both fundamental concepts of cooperation and secrecy in wireless networks. In particular we investigate the cooperation between transmitters in a cognitive radio network where the secondary receiver is treated as a potential eavesdropper to the primary transmission. We study this novel model focusing on several fundamental aspects.First we derive achievable rate regions for different transmission schemes, such as cooperative jamming and relaying, with and without primary message knowledge at the secondary transmitter. For these schemes, we formulate and solve three relevant power allocation problems: the maximization of the achievable primary and secondary rates, and the minimization of the secondary transmitting power. We model the interaction between the transmitting users as a Stackelberg game corresponding to a more realistic power allocation problem. We solve the game and illustrate its impact on the achievable rates.Secondly we generalize our system model by introducing the multi-phase clean relaying (CR) scheme, which takes into account the message-learning constraint at the secondary transmitter, and we derive the achievable rate region for this scheme. We compare our CR scheme to other transmission strategies such as dirty paper coding, interference neutralization, and pure cooperative jamming. Thirdly we extend our model to the generalized scenario where multiple secondary transmitter-receiver pairs wish to access the spectrum. For this scenario, we define and study several types of games between the primary network and the secondary pairs, such as Stackelberg games, power control games, and auction games. We derive the equilibrium of each game considered, which allows us to predict the behavior of the users in the cognitive radio network with multiple secondary pairs.Moreover we consider the important concept of energy efficiency (EE) for the performance of the cognitive radio network and we derive the power allocation and power splitting maximizing the secondary transmitter's energy efficiency. An important EE Stackelberg game between the two transmitters is formulated, and the impact of the game theoretic interaction is analyzed. Finally we motivate and investigate information theoretic secrecy using key agreement techniques in wireless networks. In particular we derive achievable secret key rate regions for two different key agreement schemes in Gaussian channels using several transmission strategies such as power control and cooperative jamming. The interaction between transmitting users is analyzed from a game theoretic perspective using non-cooperative game theory.For every fundamental perspective considered for the analysis of the model studied in the thesis, our results are illustrated through numerical examples based on a geometrical setup, highlighting the impact of the node geometry on the achievable rates, the optimal strategies, the games' equilibria and the impact of the game theoretic interaction between transmitters on the system performance.
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