49th IEEE Conference on Decision and Control (CDC), 2010
Abstract In this work, we analyze the problem of maintain-ing connectivity in a network of mobil... more Abstract In this work, we analyze the problem of maintain-ing connectivity in a network of mobile agents in the presence of a jammer. This is a variation of the standard connectivity maintenance problem in which the issue arises due to limitations in communications and sensing ...
2010 IEEE International Conference on Communications, 2010
The security issue in collaborative sensing in cognitive radio networks can be modeled as attacke... more The security issue in collaborative sensing in cognitive radio networks can be modeled as attackers and secondary users in a jamming and anti-jamming scenario. In this paper, we introduce a stochastic zero-sum game model to study the strategies. Primary users, secondary users and jammers are the three types of agents in the system. The primary users dictate the system states
Unlicensed secondary users (SUs) in cognitive radio networks are subject to an inherent tradeoff ... more Unlicensed secondary users (SUs) in cognitive radio networks are subject to an inherent tradeoff between spectrum sensing and spectrum access. Although each SU has an incentive to sense the primary user (PU) channels for locating spectrum holes, this exploration of the spectrum can come at the expense of a shorter transmission time, and, hence, a possibly smaller capacity for data transmission. This paper investigates the impact of this tradeoff on the cooperative strategies of a network of SUs that seek to cooperate in order to improve their view of the spectrum (sensing), reduce the possibility of interference among each other, and improve their transmission capacity (access). The problem is modeled as a coalitional game in partition form and an algorithm for coalition formation is proposed. Using the proposed algorithm, the SUs can make individual distributed decisions to join or leave a coalition while maximizing their utilities which capture the average time spent for sensing a...
Proceedings of the 40th IEEE Conference on Decision and Control (Cat. No.01CH37228)
The stability of a nonlinear stochastic dynamic system with singular perturbations is considered.... more The stability of a nonlinear stochastic dynamic system with singular perturbations is considered. Based on the notion of stochastic input-to-state stability and using time scale decomposition, a result of the "total stability" type is obtained, i.e. if the fast subsystem and the slow subsystem are both input-to-state stable with respect to disturbances, then this property continues to hold for the full-order system as long as the singular perturbation parameter is sufficiently small and a stochastic small gain condition is satisfied. The result is general in that it holds for a broad class of disturbances, and resembles similar results for deterministic systems.
Proceedings of the 2002 American Control Conference (IEEE Cat. No.CH37301), 2002
This paper describes a novel logic-based controller for the global asymptotic stabilization of an... more This paper describes a novel logic-based controller for the global asymptotic stabilization of an underactuated surface vessel, which has a larger degree-of-freedom than the number of control inputs. This system cannot be asymptotically stabilized using any time-invariant smooth feedback controller since the system violates the well-known Brockett's condition (1983). Thus, the proposed controller can be viewed as a time-varying controller devised to circumvent this limitation. It consists of a supervising logic unit and subordinate time-invariant controllers. The asymptotic stability is rigorously proven using Lyapunov analysis, and the practicality of the proposed algorithm is also demonstrated through the simulations of head-in parking and parallel parking.
2012 IEEE 51st IEEE Conference on Decision and Control (CDC), 2012
We consider a dynamic stochastic game with asymmetric information. Multiple controllers jointly c... more We consider a dynamic stochastic game with asymmetric information. Multiple controllers jointly control the evolution of a global state process and multiple local state processes. The global state affects every controller's cost while a controller's local state only affects its own cost. We assume that all controllers observe the global state, and in addition each controller observes its own local state. This information structure results in asymmetry of information among the controllers. In general, such asymmetry of information makes it difficult to find or characterize Nash equilibria. However, we show that a simple characterization of a class of Nash equilibria is possible under the assumption that the evolution of the local state processes depends only on the global state and control actions and not on the current or past values of local states. This class of equilibria and their characterization resemble the notion of Markov equilibrium and their characterization in games of symmetric information.
49th IEEE Conference on Decision and Control (CDC), 2010
Abstract In this work, we analyze the problem of maintain-ing connectivity in a network of mobil... more Abstract In this work, we analyze the problem of maintain-ing connectivity in a network of mobile agents in the presence of a jammer. This is a variation of the standard connectivity maintenance problem in which the issue arises due to limitations in communications and sensing ...
2010 IEEE International Conference on Communications, 2010
The security issue in collaborative sensing in cognitive radio networks can be modeled as attacke... more The security issue in collaborative sensing in cognitive radio networks can be modeled as attackers and secondary users in a jamming and anti-jamming scenario. In this paper, we introduce a stochastic zero-sum game model to study the strategies. Primary users, secondary users and jammers are the three types of agents in the system. The primary users dictate the system states
Unlicensed secondary users (SUs) in cognitive radio networks are subject to an inherent tradeoff ... more Unlicensed secondary users (SUs) in cognitive radio networks are subject to an inherent tradeoff between spectrum sensing and spectrum access. Although each SU has an incentive to sense the primary user (PU) channels for locating spectrum holes, this exploration of the spectrum can come at the expense of a shorter transmission time, and, hence, a possibly smaller capacity for data transmission. This paper investigates the impact of this tradeoff on the cooperative strategies of a network of SUs that seek to cooperate in order to improve their view of the spectrum (sensing), reduce the possibility of interference among each other, and improve their transmission capacity (access). The problem is modeled as a coalitional game in partition form and an algorithm for coalition formation is proposed. Using the proposed algorithm, the SUs can make individual distributed decisions to join or leave a coalition while maximizing their utilities which capture the average time spent for sensing a...
Proceedings of the 40th IEEE Conference on Decision and Control (Cat. No.01CH37228)
The stability of a nonlinear stochastic dynamic system with singular perturbations is considered.... more The stability of a nonlinear stochastic dynamic system with singular perturbations is considered. Based on the notion of stochastic input-to-state stability and using time scale decomposition, a result of the "total stability" type is obtained, i.e. if the fast subsystem and the slow subsystem are both input-to-state stable with respect to disturbances, then this property continues to hold for the full-order system as long as the singular perturbation parameter is sufficiently small and a stochastic small gain condition is satisfied. The result is general in that it holds for a broad class of disturbances, and resembles similar results for deterministic systems.
Proceedings of the 2002 American Control Conference (IEEE Cat. No.CH37301), 2002
This paper describes a novel logic-based controller for the global asymptotic stabilization of an... more This paper describes a novel logic-based controller for the global asymptotic stabilization of an underactuated surface vessel, which has a larger degree-of-freedom than the number of control inputs. This system cannot be asymptotically stabilized using any time-invariant smooth feedback controller since the system violates the well-known Brockett's condition (1983). Thus, the proposed controller can be viewed as a time-varying controller devised to circumvent this limitation. It consists of a supervising logic unit and subordinate time-invariant controllers. The asymptotic stability is rigorously proven using Lyapunov analysis, and the practicality of the proposed algorithm is also demonstrated through the simulations of head-in parking and parallel parking.
2012 IEEE 51st IEEE Conference on Decision and Control (CDC), 2012
We consider a dynamic stochastic game with asymmetric information. Multiple controllers jointly c... more We consider a dynamic stochastic game with asymmetric information. Multiple controllers jointly control the evolution of a global state process and multiple local state processes. The global state affects every controller's cost while a controller's local state only affects its own cost. We assume that all controllers observe the global state, and in addition each controller observes its own local state. This information structure results in asymmetry of information among the controllers. In general, such asymmetry of information makes it difficult to find or characterize Nash equilibria. However, we show that a simple characterization of a class of Nash equilibria is possible under the assumption that the evolution of the local state processes depends only on the global state and control actions and not on the current or past values of local states. This class of equilibria and their characterization resemble the notion of Markov equilibrium and their characterization in games of symmetric information.
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Papers by T. Basar