The Experts below are selected from a list of 130230 Experts worldwide ranked by ideXlab platform

Masayuki Fujita - One of the best experts on this subject based on the ideXlab platform.

  • Congestion control for TCP/AQM networks using state predictive control
    Electrical Engineering in Japan, 2006
    Co-Authors: Takehito Azuma, Tsunetoshi Fujita, Masayuki Fujita
    Abstract:

    The purpose of this paper is to design congestion controllers for TCP/AQM networks using state predictive control and to illustrate the effectiveness of the resulting congestion controllers via SIMULINK and the ns-2 simulator. Linearized models of TCP/AQM networks can be simply described as linear systems with Information Delay. Using state predictive control, these linear systems with an Information Delay are equivalent to linear systems with no Delay. Thus, congestion controllers (AQM mechanisms) can be designed by using linear control theory. In this paper, LQ control with an observer is adopted for linear systems with no Delay which describe linearized systems of TCP/AQM networks. Finally the designed state predictive controllers using LQ control with an observer are implemented and some simulation results obtained with SIMULINK and the ns-2 simulator are presented. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(3): 41–47, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20405

  • A scheduled controller design of congestion control considering network resource constraints
    Electrical Engineering in Japan, 2004
    Co-Authors: H. Naito, Takehito Azuma, Masayuki Fujita
    Abstract:

    In this paper, we consider a dynamical model of computer networks and derive a synthesis method for congestion control. First, we present a model of TCP/AQM (Transmission Control Protocol/Active Queue Management) as a dynamical model of computer networks. The dynamical model of TCP/AQM networks consists of models of TCP window size, queue length, and AQM mechanisms. Second, we propose to describe the dynamical model of TCP/AQM networks as linear systems with self-scheduling parameters, which also depend on Information Delay. Here we focus on the constraints on the maximum queue length and TCP window size, which are the network resources in TCP/AQM networks. We derive TCP/AQM networks as the LPV system (linear parameter varying system) with Information Delay and self-scheduling parameter. We design a memoryless state feedback controller of the LPV system based on a gain-scheduling method. Finally, the effectiveness of the proposed method is evaluated by using MATLAB and the well-known ns-2 simulator (Network Simulator Version 2). © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(1): 61–68, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10341

  • Scheduled Controller Design of Congestion Control Considering Network Resource Constraints
    IEEJ Transactions on Electronics Information and Systems, 2003
    Co-Authors: H. Naito, Takehito Azuma, Masayuki Fujita
    Abstract:

    In this paper, we consider a dynamical model of computer networks and derive a synthesis method for congestion control. First, we show a model of TCP/AQM (Transmission Control Protocol/Active Queue Management) as a dynamical model of computer networks. The dynamical model of TCP/AQM networks consists of models of TCP window size, queue length and AQM mechanisms. Second, we propose to describe the dynamical model of TCP/AQM networks as linear systems with self-scheduling parameters, which also depend on Information Delay. Here we focus on the constraints on the maximum queue length and TCP window-size, which are the network resources in TCP/AQM networks. We derive TCP/AQM networks as the LPV system (linear parameter varying system) with Information Delay and self-scheduling parameter. We design a memoryless state feedback controller of the LPV system based on a gain-scheduling method. Finally, the effectiveness of the proposed method is evaluated by using MATLAB and the well-known ns-2 (Network Simulator Ver.2) simulator.

  • Experimental verification of stabilizing congestion controllers using the network testbed
    Proceedings of the 2005 American Control Conference 2005., 1
    Co-Authors: Takehito Azuma, H. Naito, Masayuki Fujita
    Abstract:

    In this paper, we consider dynamical models of computer networks and derive a synthesis method for stabilizing congestion controllers. Moreover we verify the efficacy of the designed stabilizing congestion controllers using our developed network testbed. First we show dynamical models of TCP/AQM (transmission control protocol/active queue management) networks. The dynamical models of TCP/AQM networks consists of models of TCP window size, queue length and AQM mechanisms. Second we propose to describe the dynamical models of TCP/AQM networks as linear systems with self-scheduling parameters, which also depend on Information Delay. Here we focus on the constraints on the maximum queue length and TCP window-size, which are the network resources in TCP/AQM networks. Linear system with a self-scheduling parameter and an Information Delay are derived for dynamical models of TCP/AQM networks. We show a design method of memoryless state feedback controllers for derived linear system with a self-scheduling parameter and an Information Delay. Finally the effectiveness of the proposed method is evaluated by using ns-2 (Network Simulator Ver.2) simulator and our developed network testbed.

Gábor Orosz - One of the best experts on this subject based on the ideXlab platform.

  • Experimental Validation of String Stability for Connected Vehicles Subject to Information Delay
    IEEE Transactions on Control Systems Technology, 2020
    Co-Authors: Wubing B. Qin, Gábor Orosz
    Abstract:

    In this paper, we investigate the performance of communication-based controller design in connected vehicle networks. A testbed consisting of a group of ground robots that can mimic the dynamics of personal vehicles is built. We show that when incorporating time Delays in the modeling equations, which arise due to digital implementation and intermittent vehicle-to-vehicle (V2V) communication, the experimental results have a very good correspondence with the theoretical ones. Moreover, we demonstrate that by designing a controller for each individual vehicle in the chain plant stability and string stability can be guaranteed despite the time Delays in the control loop. Then, a series of experiments is conducted for a mixture of string stable and string unstable vehicles and the effects of penetration rate of string stable vehicles in maintaining smooth traffic are evaluated. The results lay a foundation for connected vehicle system design with flexible connectivity topologies.

Frédéric Le Mouël - One of the best experts on this subject based on the ideXlab platform.

  • Urban Infrastructure Deployment for Wireless On-Street Parking Sensor Networks
    Procedia Engineering, 2015
    Co-Authors: Trista Lin, Hervé Rivano, Frédéric Le Mouël
    Abstract:

    The deployment strategy of wireless applications in metropolitan areas is essential for their efficiency and functionality. In this paper, we introduce and study a deployment strategy for wireless on-street parking sensor networks. We define a multiple-objective problem in our analysis, and solve it with two real-world street parking maps. We present the results on the tradeoff among minimum energy consumption, sensing Information Delay and the amount of deployed mesh routers and Internet gateways, i.e., the cost of city infrastructure. These results yield engineering insights for appraising and deploying city mesh infrastructure to provide smart parking services to urban users. We also analyze these tradeoffs to see how different urban layouts affect the optimal solutions.

  • Router deployment of Streetside Parking Sensor Networks in Urban Areas
    2014
    Co-Authors: Trista Lin, Hervé Rivano, Frédéric Le Mouël
    Abstract:

    The deployment of urban infrastructure is very important for urban sensor applications. In this paper, we studied and introduced the deployment strategy of wireless on-street parking sensor networks. We defined a multiple-objective problem with four objectives, and solved them with real street parking map. The results show two sets of Pareto Front with the minimum energy consumption, sensing Information Delay and the amount of deployed routers and gateways. The result can be considered to provide urban service roadside unit or be taken into account while designing a deployment algorithm.

  • How to Choose the Relevant MAC Protocol for Wireless Smart Parking Urban Networks?
    2014
    Co-Authors: Hervé Rivano, Frédéric Le Mouël
    Abstract:

    Parking sensor network is rapidly deploying around the world and is regarded as one of the first implemented urban services in smart cities. To provide the best network performance, the MAC protocol shall be adaptive enough in order to satisfy the traffic intensity and variation of parking sensors. In this paper, we study the heavy-tailed parking and vacant time models from SmartSantander, and then we apply the traffic model in the simulation with four different kinds of MAC protocols, that is, contention-based, schedule-based and two hybrid versions of them. The result shows that the packet interarrival time is no longer heavy-tailed while collecting a group of parking sensors, and then choosing an appropriate MAC protocol highly depends on the network configuration. Also, the Information Delay is bounded by traffic and MAC parameters which are important criteria while the timely message is required.

  • Performance Comparison of Contention- and Schedule-based MAC Protocols in Urban Parking Sensor Networks
    2014
    Co-Authors: Hervé Rivano, Frédéric Le Mouël
    Abstract:

    Network traffic model is a critical problem for urban applications, mainly because of its diversity and node density. As wireless sensor network is highly concerned with the development of smart cities, careful consideration to traffic model helps choose appropriate protocols and adapt network parameters to reach best performances on energy-latency tradeoffs. In this paper, we compare the performance of two off-the-shelf medium access control protocols on two different kinds of traffic models, and then evaluate their application-end Information Delay and energy consumption while varying traffic parameters and network density. From the simulation results, we highlight some limits induced by network density and occurrence frequency of event-driven applications. When it comes to realtime urban services, a protocol selection shall be taken into account - even dynamically - with a special attention to energy-Delay tradeoff. To this end, we provide several insights on parking sensor networks.

  • Traffic Modeling and Analysis in the Performance of Parking Sensor Networks
    2014
    Co-Authors: Trista Lin, Hervé Rivano, Frédéric Le Mouël
    Abstract:

    Network traffic model is a critical problem for urban application, mainly because of its diversity and node density. As wireless sensor network is highly concerned with the development of smart cities, careful consideration to traffic model helps choose appropriate protocols and adapt network parameters to reach best performances on energy-latency tradeoffs. In this paper, we compare the performance of two off-the-shelf medium access control protocols on two different kinds of traffic models, and then evaluate their application-end Information Delay and energy consumption while varying traffic parameters and node density. From the simulation results, we highlight some limits induced by node density, occurrence frequency and non-uniform characters of event-driven applications. When it comes to real-time urban services, a protocol selection shall really be taken into account - even dynamically - with a special attention to energy-Delay tradeoff. To this end, we provide several insights on parking sensor networks.

Wubing B. Qin - One of the best experts on this subject based on the ideXlab platform.

  • Experimental Validation of String Stability for Connected Vehicles Subject to Information Delay
    IEEE Transactions on Control Systems Technology, 2020
    Co-Authors: Wubing B. Qin, Gábor Orosz
    Abstract:

    In this paper, we investigate the performance of communication-based controller design in connected vehicle networks. A testbed consisting of a group of ground robots that can mimic the dynamics of personal vehicles is built. We show that when incorporating time Delays in the modeling equations, which arise due to digital implementation and intermittent vehicle-to-vehicle (V2V) communication, the experimental results have a very good correspondence with the theoretical ones. Moreover, we demonstrate that by designing a controller for each individual vehicle in the chain plant stability and string stability can be guaranteed despite the time Delays in the control loop. Then, a series of experiments is conducted for a mixture of string stable and string unstable vehicles and the effects of penetration rate of string stable vehicles in maintaining smooth traffic are evaluated. The results lay a foundation for connected vehicle system design with flexible connectivity topologies.

Jeffrey S. Richardson - One of the best experts on this subject based on the ideXlab platform.

  • Comparison of Information Delay Types and Levels in Tactical TIC-TAC- TOE(T4)
    1993
    Co-Authors: Jeffrey S. Richardson
    Abstract:

    Abstract : The objective of this thesis is to design, conduct, and analyze a command, control, and communications conflict simulation to investigate the effects of differing types and quantities of Information Delay on mission outcomes using the computer simulation game Tactical Tic-Tac-Toe (T4). Three different types of Delay were compared: tactical, area, and communications. Each type of Delay was Delayed from zero to nine moves. The results indicate that tactical Delay had the greatest effect on mission outcome. Area Delay had less of an impact. Communications Delay had the least effect. Contrary to predictions, within each type of Delay, different levels of Delay did not significantly effect mission outcomes. This may be attributed to the high variability of the game scores. Generally, tactical and area Delays showed less mission impact at lower levels of Delay, however communications Delay indicated no trend in mission outcome at different levels of Delay.... C3, Command, Control, and Communication, Tactical Tic-Tac-Toe, T4, Information Delay, Experiments