Cooperative diversity avails MIMO-class benefits (e.g., improved BER,
outage behavior) to single-antenna wireless devices through
cooperative relaying. The MIMO-class benefit is enabled through
cooperative relaying where a single-antenna device act as a relay
to enhance communication between its partner and a destination. The
performance enhancements are envisaged with the inherent
assumption that relays adhere to the cooperation strategy at all
times. However, in a practical setting where relays might
exhibit malicious or selfish behavior the promised performance improvements might be curtailed
severely. As malicious and selfish relays constrain the
cooperation benefits differently, we treat them separately. A malicious behavior is characterized by a relay that
violates the cooperation strategy with the objective of
disrupting communication between source and destination at the
expense of its own power. In the absence of a mechanism to
detect malicious behavior, cooperative diversity exhibits
severe performance degradation depending on the degree of
As cooperation incurs cost, the relay has to expend its own resources (power and
bandwidth) to provide a reliable communication to cooperation
partner. In return, the helping partner is rewarded with the same
benefits when the partner reciprocates acting as a relay. However, in
practice, there are no mechanisms to ensure reciprocation in cooperative communication.
Due to lack of such a mechanism, especially power-limited partners may be tempted to refuse cooperation while
reaping benefits of it at no cost. The presence of such free-riders can degrade the envisaged
Due to the dependency on relays' conformance to rules of cooperation,
misbehaving relays can severely curtail the envisaged MIMO-class
benefits in the absence of a mechanism to enforce cooperation. Since inherently trusted relays cooperate by performing
physical-layer operation on source signal, cooperative diversity
presents a new security challenge at the physical layer. Existing
physical-layer security techniques are unable to mitigate such
malicious behavior as such schemes are primarily designed to prevent
signal detection and interception by unauthorized
We have shown both analytically and by simulation the
performance degradation in cooperative diversity in the presence
of misbehaving relays. We have also developed a statistical
detection scheme to mitigate effects of malicious behavior. The goal of cooperative communication security research
at ISIS, is to develop a
game-theoretic model where cooperation is conditioned based on past
behavior of partners. That is, cooperation will be confined to a group of wireless devices whose disposition to
cooperate is known a priori.
- Sintayehu Dehnie and Stefano Tomasin, “Misbehavior Detection in Cooperative Networks With ARQ Technologies”, submitted to IEEE Transactions on Communications
- Sintayehu Dehnie and Nasir Memon, "Modeling Misbehavior in Cooperative Diversity : A Dynamic Game Approach", sumitted to EURASIP Journal on Advances on Signal Processing, Special Issue on Game Theory in Signal Processing and Communications
- Sintayehu Dehnie and Nasir Memon,"A Dynamic Game Model for Amplify-and-Forward Cooperative Communications", submitted to ICASSP (Invited paper)
- Sintayehu Dehnie and Stefano Tomasin, "Misbehavior Detection in CSMA Cooperative Networks with HARQ", submitted to ICC'09
- Sintayehu Dehnie and Nasir Memon, “Cooperative Diversity as a Dynamic Game With Incomplete Information”, Proc. IEEE Military Communications 2008 (MILCOM’08), San Diego, CA
- Sintayehu Dehnie and Nasir Memon, “Detection of Misbehavior in Cooperative Diversity” Proc. IEEE Military Communications 2008 (MILCOM’08), San Diego, CA
- Sintayehu Dehnie and Stefano Tomasin, “Detection of Selfish Partners by Control Packets in ARQ-based CSMA Cooperative Networks”, to appear Proc. International Symposium on Spread Spectrum Techniques and Applications (ISSSTA’08), Aug. 2008, Bologna, Italy.
- Sintayehu Dehnie and Nasir Memon, “Cooperative Diversity In the Presence of Malicious Users”, under preparation to be submitted to IEEE Transactions on Wireless Communications
- Sintayehu Dehnie and Nasir Memon, “A Stochastic Model for Misbehaving Relays in Cooperative Diversity”, in Proc. Wireless Communications and Networking Conference (WCNC), Mar 31 – Apr. 3, 2008, Las Vegas, Nevada.
- Sintayehu Dehnie, Nasir Memon, “Cooperative Diversity with Selfish Users”, in Proc. Conference on Information Sciences and Systems (CISS’08), Mar 19-21, 2008, Princeton, New Jersey.
- Sintayehu Dehnie, Husrev T. Sencar, Nasir Memon, “Cooperative Diversity in the Presence of Malicious Relay : Performance Analysis”, in Proc. IEEE Sarnoff Symposium, Apr 30 – May 2, 2007, Pricenton,NJ.
- Sintayehu Dehnie, Husrev T. Sencar, Nasir Memon, “Detecting Malicious Behavior in Cooperative Diversity”, in Proc. Conference on Information Sciences and Systems, Mar, 2007, Baltimore,MD.
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