Now showing items 1-20 of 132

    • On the Gittins index in the M/G/1 queue 

      Aalto S.; Ayesta U.; Righter R. (Queueing Systems, 2009-12-31)
      For an M/G/1 queue with the objective of minimizing the mean number of jobs in the system, the Gittins index rule is known to be optimal among the set of non-anticipating policies. We develop properties of the Gittins ...
    • Optimal policy for multi-class scheduling in a single server queue 

      Osipova N.; Ayesta U.; Avrachenkov K. (21st International Teletraffic Congress, ITC 21: Traffic and Performance Issues in Networks of the Future - Final Programme, 2009-12-31)
      In this paper we apply the Gittins optimality result to characterize the optimal scheduling discipline in a multi-class M/G/1 queue. We apply the general result to several cases of practical interest where the service time ...
    • Heavy-traffic analysis of the M/PH/1 Discriminatory Processor Sharing queue with phase-dependent weights 

      Verloop I.M.; Ayesta U.; Núñez-Queija R. (Performance Evaluation Review, 2009-12-31)
      We analyze a generalization of the Discriminatory Processor Sharing (DPS) queue in a heavy-traffic setting. Customers present in the system are served simultaneously at rates controlled by a vector of weights. We assume ...
    • Convergence of trajectories and optimal buffer sizing for AIMD congestion control 

      Avrachenkov K.; Ayesta U.; Piunovskiy A. (Performance Evaluation, 2010-12-31)
      We study the interaction between the AIMD (Additive Increase Multiplicative Decrease) multi-socket congestion control and a bottleneck router with Drop Tail buffer. We consider the problem in the framework of deterministic ...
    • Convergence of trajectories and optimal buffer sizing for MIMD congestion control 

      Zhang Y.; Piunovskiy A.; Ayesta U.; Avrachenkov K. (Computer Communications, 2010-12-31)
      We study the interaction between the MIMD (Multiplicative Increase Multiplicative Decrease) congestion control and a bottleneck router with Drop Tail buffer. We consider the problem in the framework of deterministic hybrid ...
    • A modeling framework for optimizing the flow-level scheduling with time-varying channels 

      Ayesta U.; Erausquin M.; Jacko P. (Performance Evaluation, 2010-12-31)
      We introduce a comprehensive modeling framework for the problem of scheduling a finite number of finite-length jobs where the available service rate is time-varying. The main motivation comes from wireless data networks ...
    • Monotonicity properties for multi-class queueing systems 

      Verloop I.M.; Ayesta U.; Borst S. (Discrete Event Dynamic Systems: Theory and Applications, 2010-12-31)
      We study multi-dimensional stochastic processes that arise in queueing models used in the performance evaluation of wired and wireless networks. The evolution of the stochastic process is determined by the scheduling policy ...
    • Asymptotically optimal parallel resource assignment with interference 

      Verloop I.M.; Núñez-Queija R. (Queueing Systems, 2010-12-31)
      Motivated by scheduling in cellular wireless networks and resource allocation in computer systems, we study a service facility with two classes of users having heterogeneous service requirement distributions. The aggregate ...
    • Optimal routing in parallel, non-observable queues and the price of anarchy revisited 

      Anselmi J.; Gaujal B. (2010 22nd International Teletraffic Congress - Proceedings, ITC 22, 2010-12-31)
      We consider a network of parallel, non-observable queues and analyze the "price of anarchy", an index measuring the worst-case performance loss of a decentralized system with respect to its centralized counterpart in ...
    • Price of anarchy in non-cooperative load balancing games 

      Ayesta U.; Brun O.; Prabhu B.J. (Performance Evaluation, 2011-12-31)
      We investigate the price of anarchy of a load balancing game with K dispatchers. The service rates and holding costs are assumed to depend on the server, and the service discipline is assumed to be processor-sharing at ...
    • Competition yields efficiency in load balancing games 

      Anselmi J.; Ayesta U.; Wierman A. (Performance Evaluation, 2011-12-31)
      We study a nonatomic congestion game with N parallel links, with each link under the control of a profit maximizing provider. Within this 'load balancing game', each provider has the freedom to set a price, or toll, for ...
    • Properties of the gittins index with application to optimal scheduling 

      Aalto S.; Ayesta U.; Righter R. (Probability in the Engineering and Informational Sciences, 2011-12-31)
      We consider the optimal scheduling problem for a single-server queue without arrivals. We allow preemptions, and our purpose is to minimize the expected flow time. The optimal nonanticipating discipline is known to be the ...
    • The price of forgetting in parallel and non-observable queues 

      Anselmi J.; Gaujal B. (Performance Evaluation, 2011-12-31)
      We consider a broker-based network of non-observable parallel queues and analyze the minimum expected response time and the optimal routing policy when the broker has the memory of its previous routing decisions. We provide ...
    • Heavy-traffic analysis of a multiple-phase network with discriminatory processor sharing 

      Verloop I.M.; Ayesta U.; Núñez-Queija R. (Operations Research, 2011-12-31)
      We analyze a generalization of the discriminatory processor-sharing (DPS) queue in a heavy-traffic setting. Customers present in the system are served simultaneously at rates controlled by a vector of weights. We assume ...
    • Stability and asymptotic optimality of opportunistic schedulers in wireless systems 

      Ayesta U.; Erausquin M.; Jonckheere M.; Verloop I.M. (VALUETOOLS 2011 - 5th International ICST Conference on Performance Evaluation Methodologies and Tools, 2011-12-31)
      We investigate the scheduling of a common resource between several concurrent users when the feasible transmission rate of each user varies randomly over time. Time is slotted and users arrive and depart upon service ...
    • Load balancing in processor sharing systems 

      Altman E.; Ayesta U.; Prabhu B.J. (Telecommunication Systems, 2011-12-31)
      We investigate optimal load balancing strategies for a multi-class multi-server processor-sharing system with a Poisson input stream, heterogeneous service rates, and a server-dependent holding cost per unit time. Specifically, ...
    • Energy-aware capacity scaling in virtualized environments with performance guarantees 

      Anselmi J.; Verloop I.M. (Performance Evaluation, 2011-12-31)
      We investigate the trade-off between performance and power consumption in servers hosting virtual machines running IT services. The performance behavior of such servers is modeled through Generalized Processor Sharing (GPS) ...
    • A nearly-optimal index rule for scheduling of users with abandonment 

      Ayesta U.; Jacko P.; Novak V. (Proceedings - IEEE INFOCOM, 2011-12-31)
      We analyze a comprehensive model for multi-class job scheduling accounting for user abandonment, with the objective of minimizing the total discounted or time-average sum of linear holding costs and abandonment penalties. ...
    • Resource-sharing in a single server with time-varying capacity 

      Ayesta U.; Erausquin M.; Jacko P. (2011 49th Annual Allerton Conference on Communication, Control, and Computing, Allerton 2011, 2011-12-31)
      We investigate the problem of sharing the resources of a single server with time-varying capacity with the objective of minimizing the mean delay. We formulate the resource allocation problem as a Markov Decision Process. ...
    • Opportunistic schedulers for optimal scheduling of flows in wireless systems with ARQ feedback 

      Jacko P.; Villar S.S. (Final Program - 2012 24th International Teletraffic Congress, ITC 24, 2012-12-31)
      In this paper we study three opportunistic schedulers for the problem of optimal multi-class flow-level scheduling in wireless downlink and uplink systems. For user channels we employ the Gilbert-Elliot model of good and ...