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Pravin Varaiya - One of the best experts on this subject based on the ideXlab platform.

  • WTRP-wireless token ring Protocol
    IEEE Transactions on Vehicular Technology, 2004
    Co-Authors: Mustafa Ergen, Duke Lee, Raja Sengupta, Pravin Varaiya
    Abstract:

    The wireless token ring Protocol (WTRP) is a novel medium access control (MAC) Protocol for wireless local area networks (WLANs). In contrast with IEEE 802.11 networks, WTRP guarantees quality of service (QoS) in terms of bounded latency and reserved bandwidth, which are critical in many real-time applications. Compared to 802.11, WTRP improves efficiency by reducing the number of retransmissions due to collisions, and it is more fair as all stations use the channel for the same amount of time. Stations take turns transmitting and give up the right to transmit after a specified amount of time. WTRP is a Distributed Protocol that supports many topologies, as not all stations need to be connected to each other or to a central station. WTRP is robust against single node failures, and recovers gracefully from multiple simultaneous faults. WTRP is suitable for interaccess point coordination in ITS DSRC, safety-critical vehicle-to-vehicle communications, and home networking, and provides extensions to other networks and Mobile IP.

  • a wireless token ring Protocol for ad hoc networks
    IEEE Aerospace Conference, 2002
    Co-Authors: Anuj Puri, Raja Sengupta, Pravin Varaiya, R Attias, Stavros Tripakis
    Abstract:

    The wireless token ring Protocol (WTRP) is a medium access control Protocol for wireless networks in unmanned aerial vehicles. It supports quality of service in terms of bounded latency and reserved bandwidth. This quality of service guarantee is critical in mesh stability of the formation of the vehicles. The communication of the speed and the velocity of the lead vehicle to all other vehicles in the formation had been shown to be sufficient for mesh stability of the system. WTRP is efficient in the sense that it reduces the number of retransmissions due to collisions. It is fair in the sense that each station takes a turn to transmit and is forced to give up the right to transmit after transmitting for a specified amount of time. It is a Distributed Protocol that supports many topologies since not all stations need to be connected to each other or to a central station. It can be used with an admission control agent for bandwidth or latency reservations. WTRP is robust against single node failure. WTRP is designed to recover gracefully from multiple simultaneous faults.

  • a wireless token ring Protocol for intelligent transportation systems
    IEEE Intelligent Transportation Systems, 2001
    Co-Authors: R Attias, Raja Sengupta, Anuj Puri, Stavros Tripakis, Pravin Varaiya
    Abstract:

    The wireless token ring Protocol (WTRP) is a medium access control (MAC) Protocol for wireless networks in intelligent transportation systems (ITS). It supports quality of service (QoS) in terms of bounded latency and reserved bandwidth. The WTRP is efficient in the sense that it reduces the number of re-transmissions due to collisions. It is fair in the sense that each station takes a turn to transmit and is forced to give up the right to transmit after transmitting for a specified amount of time. It is a Distributed Protocol that supports many topologies since not all stations need to be connected to each other or to a central station. It can be used with an admission control agent for bandwidth or latency reservations. The WTRP is robust against single node failure. The WTRP is designed to recover gracefully from multiple simultaneous faults. It has applications to inter-access-point coordination in ITS dedicated short-range communication (DSRC) and to safety-critical vehicle-to-vehicle networking.

Carlos Borrego - One of the best experts on this subject based on the ideXlab platform.

  • A Distributed Token Passing Protocol for Time Constrained Data Gathering in VANETs
    Electronics, 2019
    Co-Authors: Francesco Chiti, Romano Fantacci, Francesca Nizzi, Laura Pierucci, Carlos Borrego
    Abstract:

    This paper proposes a novel approach for time constrained information gathering in a typical Vehicular Ad Hoc Network (VANET), based on a token passing scheme, adapted to wireless communications by creating a virtual ring where nodes are connected to a predecessor and a successor node. To address the typical fast topology changes of VANETs, we proposed a specific approach, called Tom Thumb that is a Distributed Protocol that node-by-node circulates a special packet, called token, which collects the information stored in each vehicle until returning to the first unit within a specified time constraint. The Protocol has been properly designed in terms of (i) the more effective hop-by-hop and Distributed heuristic implementing the objective function (ii) the token packet format, i.e., the syntax and semantics of its fields. Finally, the performance of the proposed approach is validated for different time constraints and numbers of vehicles, always pointing out a remarkable gain, especially in the presence of severe constraints, i.e., in terms of time deadline, collected information amount and success probability.

Karl Henrik Johansson - One of the best experts on this subject based on the ideXlab platform.

  • global consensus for discrete time multi agent systems with input saturation constraints
    Automatica, 2014
    Co-Authors: Tao Yang, Ziyang Meng, Dimos V Dimarogonas, Karl Henrik Johansson
    Abstract:

    In this paper, we consider the global consensus problem for discrete-time multi-agent systems with input saturation constraints under fixed undirected topologies. We first give necessary conditions for achieving global consensus via a Distributed Protocol based on relative state measurements of the agent itself and its neighboring agents. We then focus on two special cases, where the agent model is either neutrally stable or a double integrator. For the neutrally stable case, any linear Protocol of a particular form, which solves the consensus problem for the case without input saturation constraints, also solves the global consensus problem for the case with input saturation constraints. For the double integrator case, we show that a subset of linear Protocols, which solve the consensus problem for the case without saturation constraints, also solve the global consensus problem for the case with input saturation constraints. The results are illustrated by numerical simulations.

Xiaolong Liang - One of the best experts on this subject based on the ideXlab platform.

  • time varying formation control for second order discrete time multi agent systems with directed topology and communication delay
    IEEE Access, 2019
    Co-Authors: Lyulong He, Jiaqiang Zhang, Xiaolong Liang
    Abstract:

    Time-varying formation control Protocol design and analysis problems for the second-order discrete-time multi-agent systems with directed interaction topology and communication delay are investigated. A local information-based Distributed Protocol is designed by utilizing the delayed state information of neighbors. Through system decomposition and stability analysis, an explicit description of the feasible time-varying formation set is given. Necessary and sufficient conditions for the systems with the directed topology and communication delay to achieve time-varying formation are obtained, which are related to the topology of the interaction graph and the feasibility of the predefined formation. Necessary constraints on the gain parameters and the sampling period are proposed, so as to guide the design of parameters in the Protocol. The numerical simulation results indicate that the Protocol can steer the agents to accomplish the desired time-varying formation and effectively tolerate the relatively large bounded communication delay. Outdoor experiment with quadrotors is presented to demonstrate the effectiveness of the obtained theoretical results with one sampling period delay.

Karem A. Sakallah - One of the best experts on this subject based on the ideXlab platform.

  • i4 incremental inference of inductive invariants for verification of Distributed Protocols
    Symposium on Operating Systems Principles, 2019
    Co-Authors: Aman Goel, Jean-baptiste Jeannin, Manos Kapritsos, Baris Kasikci, Karem A. Sakallah
    Abstract:

    Designing and implementing Distributed systems correctly is a very challenging task. Recently, formal verification has been successfully used to prove the correctness of Distributed systems. At the heart of formal verification lies a computer-checked proof with an inductive invariant. Finding this inductive invariant, however, is the most difficult part of the proof. Alas, current proof techniques require inductive invariants to be found manually---and painstakingly---by the developer. In this paper, we present a new approach, Incremental Inference of Inductive Invariants (I4), to automatically generate inductive invariants for Distributed Protocols. The essence of our idea is simple: the inductive invariant of a finite instance of the Protocol can be used to infer a general inductive invariant for the infinite Distributed Protocol. In I4, we create a finite instance of the Protocol; use a model checking tool to automatically derive the inductive invariant for this finite instance; and generalize this invariant to an inductive invariant for the infinite Protocol. Our experiments show that I4 can prove the correctness of several Distributed Protocols like Chord, 2PC and Transaction Chains with little to no human effort.

  • towards automatic inference of inductive invariants
    Proceedings of the Workshop on Hot Topics in Operating Systems, 2019
    Co-Authors: Aman Goel, Jean-baptiste Jeannin, Manos Kapritsos, Baris Kasikci, Karem A. Sakallah
    Abstract:

    Distributed systems are notoriously difficult to design and implement correctly. Formal verification provides correctness proofs, and has recently been successfully applied to various Distributed systems. At the heart of a typical formal verification is a computer-checked proof with an inductive invariant. Finding this inductive invariant is the hardest part of the proof: a part that is currently undertaken manually by the developer and is responsible for most of the effort associated with formal verification. In this paper, we present a new approach: Incremental Inference of Inductive Invariants (I4), to automatically generate inductive invariants for Distributed Protocols. We start from a simple idea: the inductive invariant of a finite instance of the Protocol must be an instance of a general inductive invariant for the infinite Distributed Protocol. In I4, we instantiate a finite instance of the Protocol, work out the finite inductive invariant of this instance, then figure out the general inductive invariant as a generalization of the finite invariant. Our experiments show that I4 can finish the general proof of correctness of several systems with minimal human effort.