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ABSTRACT: Cooperation among wireless nodes has been recently proposed for improving the physical layer (PHY) security of wireless transmission
in the presence of multiple eavesdroppers. While existing PHY security literature answered the question “what are the link-level
secrecy rate gains from cooperation?”, this paper attempts to answer the question of “how to achieve those gains in a practical decentralized
wireless network and in the presence of a cost for information exchange?”. For this purpose, we model the PHY security cooperation
problem as a coalitional game with non-transferable utility and propose a distributed algorithm for coalition formation. Using
the proposed algorithm, the wireless users can cooperate and self-organize into disjoint independent coalitions, while maximizing
their secrecy rate taking into account the costs during information exchange. We analyze the resulting coalitional structures
for both decode-and-forward and amplify-and-forward cooperation and study how the users can adapt the network topology to
environmental changes such as mobility. Through simulations, we assess the performance of the proposed algorithm and show
that, by coalition formation using decode-and-forward, the average secrecy rate per user is increased of up to 25.3 and 24.4%
(for a network with 45users) relative to the non-cooperative and amplify-and-forward cases, respectively.
Keywordsphysical layer security–coalitional games–game theory–secure communication
Mobile Networks and Applications 04/2012; 16(2):231-245. · 0.84 Impact Factor
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ABSTRACT: The introduction of relay station (RS) nodes is a key feature in next
generation wireless networks such as 3GPP's long term evolution advanced
(LTE-Advanced), or the forthcoming IEEE 802.16j WiMAX standard. This paper
presents, using game theory, a novel approach for the formation of the tree
architecture that connects the RSs and their serving base station in the
\emph{uplink} of the next generation wireless multi-hop systems. Unlike
existing literature which mainly focused on performance analysis, we propose a
distributed algorithm for studying the \emph{structure} and \emph{dynamics} of
the network. We formulate a network formation game among the RSs whereby each
RS aims to maximize a cross-layer utility function that takes into account the
benefit from cooperative transmission, in terms of reduced bit error rate, and
the costs in terms of the delay due to multi-hop transmission. For forming the
tree structure, a distributed myopic algorithm is devised. Using the proposed
algorithm, each RS can individually select the path that connects it to the BS
through other RSs while optimizing its utility. We show the convergence of the
algorithm into a Nash tree network, and we study how the RSs can adapt the
network's topology to environmental changes such as mobility or the deployment
of new mobile stations. Simulation results show that the proposed algorithm
presents significant gains in terms of average utility per mobile station which
is at least 17.1% better relatively to the case with no RSs and reaches up to
40.3% improvement compared to a nearest neighbor algorithm (for a network with
10 RSs). The results also show that the average number of hops does not exceed
3 even for a network with up to 25 RSs.
IEEE Transactions on Communications 02/2012; · 1.68 Impact Factor
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Proceedings of the Global Communications Conference, 2010. GLOBECOM 2010, 6-10 December 2010, Miami, Florida, USA; 01/2010
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IEEE Transactions on Wireless Communications. 01/2010; 9:1277-1282.
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Proceedings of the Global Communications Conference, 2010. GLOBECOM 2010, 6-10 December 2010, Miami, Florida, USA; 01/2010
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ABSTRACT: Due to the limited energy supplies of nodes in wireless networks, achieving energy efficiency is crucial for extending the lifetime of these networks. Thus, we study efficient power allocations and transmission protocols for outage-restricted multihop wireless networks based on cooperative transmission. In such multihop networks, a number of nodes, acting as relays, can assist a source node in the transmission of its messages to a single destination. In this paper, several multihop transmission protocols with cooperative routing are proposed. Each of the proposed protocols offers a different rate and energy efficiency. Cooperative routing protocols are introduced using arbitrary distributed space-time codes for the purpose of energy savings, given a required outage probability at the destination. Three efficient cooperative multihop transmissions are proposed, and their corresponding distributed power allocation schemes, which depend only on the statistics of the channels, are also derived. The proposed cooperative protocols offer different degrees of energy efficiency, spectral efficiency, complexity, and signalling overhead. Simulations show that, using the proposed cooperative protocols, substantial energy savings are achievable, compared to non-cooperative multihop routing, in a network having an outage probability constraint.
Proceedings of the IEEE 21st International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2010, 26-29 September 2010, Istanbul, Turkey; 01/2010
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MSN 2009, The Fifth International Conference on Mobile Ad-hoc and Sensor Networks, Wu Yi Mountain, Fujian, China , December 14-16, 2009; 01/2009
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Frontiers of Computer Science in China. 01/2009; 3:263-271.
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ABSTRACT: Collaborative spectrum sensing among secondary users (SUs) in cognitive networks is shown to yield a significant performance improvement. However, there exists an inherent trade off between the gains in terms of probability of detection of the primary user (PU) and the costs in terms of false alarm probability. In this paper, we study the impact of this trade off on the topology and the dynamics of a network of SUs seeking to reduce the interference on the PU through collaborative sensing. Moreover, while existing literature mainly focused on centralized solutions for collaborative sensing, we propose distributed collaboration strategies through game theory. We model the problem as a non-transferable coalitional game, and propose a distributed algorithm for coalition formation through simple merge and split rules. Through the proposed algorithm, SUs can autonomously collaborate and self-organize into disjoint independent coalitions, while maximizing their detection probability taking into account the cooperation costs (in terms of false alarm). We study the stability of the resulting network structure, and show that a maximum number of SUs per formed coalition exists for the proposed utility model. Simulation results show that the proposed algorithm allows a reduction of up to 86.6% of the average missing probability per SU (probability of missing the detection of the PU) relative to the non-cooperative case, while maintaining a certain false alarm level. In addition, through simulations, we compare the performance of the proposed distributed solution with respect to an optimal centralized solution that minimizes the average missing probability per SU. Finally, the results also show how the proposed algorithm autonomously adapts the network topology to environmental changes such as mobility.
INFOCOM 2009. 28th IEEE International Conference on Computer Communications, Joint Conference of the IEEE Computer and Communications Societies, 19-25 April 2009, Rio de Janeiro, Brazil; 01/2009
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ABSTRACT: We consider a non-cooperative constrained stochastic games with N players with the following special structure. With each player there is an associated controlled Markov chain. The transition probabilities of the i-th Markov chain depend only on the state and actions of controller i. The information structure that we consider is such that each player knows the state of its own MDP and its own actions. It does not know the states of, and the actions taken by other players. Finally, each player wishes to minimize a time-average cost function, and has constraints over other time-avrage cost functions. Both the cost that is minimized as well as those defining the constraints depend on the state and actions of all players. We study in this paper the existence of a Nash equilirium. Examples in power control in wireless communications are given.
Oper. Res. Lett. 01/2008; 36:160-164.
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NETWORKING 2006 - Networking Technologies, Services, and Protocols; Performance of Computer and Communication Networks; Mobile and Wireless Communications Systems, 5th International IFIP-TC6 Networking Conference, Coimbra, Portugal, May 15-19, 2006, Proceedings; 01/2006
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ABSTRACT: In this paper 1 , we study the discrete power allocation game for the fast fading multiple-input multiple-output multiple access channel. Each player or transmitter chooses its own transmit power policy from a certain finite set to optimize its individual transmission rate. First, we prove the existence of at least one pure strategy Nash equilibrium. Then, we in-vestigate two learning algorithms that allow the players to converge to either one of the NE states or to the set of corre-lated equilibria. At last, we compare the performance of the considered discrete game with the continuous game in [7].
