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We consider a single-hop wireless sensor network in which each sensor node has an individual elastic data stream to transmit to each other node. We refer to this traffic pattern as unicast in this paper. The network has multiple slotted channels available for the data transmissions. To guarantee successful unicast within a bounded delay, we consider deterministic schemes that pre-assign each node a periodic schedule sequence to schedule transmitting and receiving at each time slot. The sequence period should be minimized since it upper bounds the unicast delay. We have investigated both synchronous TDMA sequences and asynchronous sequences. Since accurate time synchronization is difficult to achieve in sensor networks, we mainly present analysis and design for asynchronous sequences. In this paper, for a group-based channel assignment, we present a lower bound on the common period and propose a sequence construction method by which the period can achieve the same order as the lower bound. We also analyze optimal transmitting and receiving probabilities for two random schemes and compare their frequency utilization efficiency. Finally, unicast delay and energy consumption performance are compared by simulations. [ABSTRACT FROM AUTHOR]

This paper addresses the distributed consensus controller design approaches for one-sided Lipschitz nonlinear multiagents by employing relative state feedback. A new treatment for one-sided Lipschitz nonlinearity is rendered from the consensus control point of view. By employing the quadratic inner-boundedness and the one-sided Lipschitz constraints, a sufficient condition for asymptotic consensus of nonlinear systems under strongly connected communication topologies is provided. Further, a robust consensus protocol design scheme for the nonlinear multiagents is derived by ensuring the ${L_{2}}$ stability of the consensus error system. Furthermore, a novel robust consensus control scheme against amplitude-bounded perturbations is developed that guarantees asymptotic convergence of the consensus error into a compact set. Extensions to the proposed methodologies for the leader-following consensus for a spanning tree communication topology with the leader as the root are addressed. In contrast to the conventional consensus control methodologies, this paper is less conservative and can be applied to a broader class of nonlinear multiagent systems. Moreover, the proposed consensus control approach is less conservative for robustness against disturbances owing to its ability to handle amplitude-bounded disturbances and due to the relaxation of a balanced communication topology. A numerical simulation study is provided for the consensus control of eight mobile agents. [ABSTRACT FROM AUTHOR]

In this paper, the quantized control of networked control systems under stochastic clock offsets is considered. We assume that the clock offsets are caused by asynchronous clocks between sensors and controllers. A stochastic variable with a specific probability density function is used to describe the stochastic clock offsets. A quantized controller is designed to deal with quantization error such that the corresponding systems are stochastically stable. Finally, two numerical examples are used to show the validity of the proposed design method. [ABSTRACT FROM AUTHOR]

This paper addresses the leaderless consensus control for a network of multiagent systems with the one-sided Lipschitz and quadratic inner-boundedness nonlinear dynamics. A distributed dynamic consensus protocol as a function of relative state feedback of the neighboring agents with edge-based adaptive coupling weights is designed for an undirected communication graph to achieve asymptotic consensus among the nonlinear agents. Further, an extension of the proposed consensus protocol in the presence of external disturbance is devised to ensure the ${L_{2}}$ stability of the consensus error. This paper is less conservative and more general owing to its application to the systems with large Lipschitz constants and to a broad class of the nonlinear systems. In comparison to the previous consensus control schemes, the proposed approach can be employed to design consensus protocols for the one-sided Lipschitz systems with unknown communication topology. This feature enables the fully distributed consensus control as the communication graph information is not required for the consensus protocol design. Simulation results for a network of six mobile agents are provided to demonstrate the effectiveness of proposed consensus schemes in the absence or presence of an external disturbance. [ABSTRACT FROM AUTHOR]

Besides designing channel-hopping (CH) sequences, finding good methods of communication rendezvous is important for improving spectral efficiency and alleviating traffic load of cognitive radio (CR) networks. In this paper, new asynchronous-symmetric CH sequences are constructed and their (channel overlap, even-channel-use, and pairwise shift invariance) properties are investigated. Their operations in three transmission scenarios involving different basic collision-avoidance mechanisms are analyzed and compared in terms of maximum time-to-rendezvous, rendezvous-success (RS) rate, and RS variance. This paper shows that the new sequences have shorter period, larger cardinality, and smaller RS variations than other CH sequences, thus supporting greater number of secondary users and more frequent and uniform rendezvous in the CR networks. [ABSTRACT FROM PUBLISHER]

This paper studies quasi-synchronization in networked heterogeneous harmonic oscillators. By introducing a leader, two distributed synchronization protocols are first proposed for heterogeneous networks by utilizing continuous real-time information and aperiodic sampled-data information. Then, the sufficient conditions on quasi-synchronization are established for heterogeneous networks coupled with nonidentical harmonic oscillators. It is found that each follower oscillator can converge to a bounded region of the leader by adopting either a continuous-time protocol or sampled-data protocol. The upper bound of the region is solved for networked heterogeneous harmonic oscillators. Finally, an electrical network is provided to illustrate the applicability of the theoretical results, and two examples are provided to illustrate the effectiveness of the sufficient criteria. [ABSTRACT FROM AUTHOR]

This paper investigates the exponential synchronization of coupled Lur’e dynamical networks with multiple time-varying delays and derivative coupling. In order to synchronize the Lur’e dynamical networks to the corresponding Lur’e systems, we propose a kind of impulsive pinning control strategy, where different functions of impulsive effects are taken into account. Sufficient conditions are derived for the exponential synchronization of the derivative coupled Lur’e dynamical networks by jointly applying the contradiction proof method, the concept of an average impulsive interval, comparison principle, and the extended parameters variation formula. Simultaneously, the convergence rates of exponential synchronization are obtained according to the definition of the impulsive solution equation on different functions of impulsive effects. Furthermore, three numerical examples are presented to demonstrate the validity of the theoretical analysis and the control protocol. [ABSTRACT FROM AUTHOR]

The time synchronization in vehicular ad hoc networks (VANETs) has gained significant attention in recent times. In this paper, we focus on the time synchronization in large-scale VANETs and propose an adaptive beacon time synchronization (ABTS) algorithm to enhance timing message synchronization. ABTS algorithm selects the best time synchronization pairs to decrease the number of timing messages transmitted. To guarantee the reliability of synchronization, the clock offset of the connected vehicles periodically readjust to provide a better degree of synchronization accuracy with minimum energy consumption. Based on two-way timing message synchronization, we derive maximum likelihood (ML) estimation and its equivalent Cramer-Rao lower bound (CRLB) for clock offset design in the generalized sender-to-receiver system by assuming a Gaussian noise model. We propose node pair selection algorithms to improve pairwise beacon message timing synchronization. The simulation results validate that our proposed ABTS algorithm performs better than other protocols in terms of synchronization accuracy, the rate of convergence and energy efficiency. [ABSTRACT FROM AUTHOR]

This paper clearly demonstrates the architecture of time synchronization network of experimental advanced superconducting tokamak (EAST) poloidal field (PF) power supply control system and analyzes characteristics of the IEEE 1588 in detail at the same time. IEEE 1588 has unique advantages for this paper to utilize as protocol in order to improve the accuracy of the time synchronization network (TSN). Consequently, we design a time synchronization system based on PCI eXtensions for Instrumentation-6683H. This paper utilizes one master node to synchronize all slave nodes on the time network in each second. The result shows that the synchronization accuracy can be achieved within 50 ns. According to results of experiments, this system can perfectly meet the requirements of EAST PF power supply control system. [ABSTRACT FROM AUTHOR]

This paper studies the synchronization problem for mobile cellular device-to-device (D2D) networks. Depending on the number of devices that are in coverage of the base station, the D2D environment can be divided into three categories where the partial-coverage and out-of-coverage are challenging scenarios and thus are the focus of this paper. First, we discuss five main challenges imposed on the synchronization problem in mobile D2D networks. More specifically, there are different challenges in the two coverage scenarios, since they do not have exactly the same synchronization objectives. Second, we propose a low-complexity Adaptive distRibuted nEtwork Synchronization (ARES) algorithm to address the five challenges. The design principles and the theories behind the ARES scheme are also analyzed in detail. Finally, we provide comprehensive simulations to evaluate different synchronization schemes, where the proposed ARES mechanism shows very promising performance. [ABSTRACT FROM AUTHOR]

Clock synchronization is crucial for applications in wireless sensor networks, such as event scheduling and data fusion. In practical wireless networks, environmental changes cause the oscillator to be imperfect. Thus, it is necessary to track the nonlinear varying clock dynamically. In this paper, we propose a timestamp-free clock skew (frequency difference) and offset (time difference) joint tracking algorithm based on extended Kalman filter (EKF), which can be embedded into the general network data flow to achieve long-term synchronization without additional communication overhead. To further improve energy efficiency of clock synchronization, this paper develops an EKF clock skew tracking algorithm for silent nodes in receiver-only synchronization. For the situation that silent node overhears synchronization information from multiple active nodes, we present multi-information timestamp-free synchronization and multi-observation clock skew fusion scheme for silent nodes. Simulation results show the effectiveness of the proposed tracking algorithms. [ABSTRACT FROM AUTHOR]

This paper studies the problem of synchronization for a class of stochastic complex dynamical networks. It designs for the first time a distributed impulsive protocol based on pinning control that involves a constant signal transmission delay to tackle synchronization issues of such networks. Novel criteria on network synchronization are established by employing a time-dependent Lyapunov functional and a mathematical induction approach, where information on the state variables themselves and their neighbors is sufficiently utilized. Moreover, it is shown that the frequency of impulsive occurrence, impulsive input delays, stochastic perturbations, and the feedback control strength can significantly affect the synchronization performance. Numerical simulations are given to illustrate the effectiveness of the derived theoretical results. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of clock skew and offset estimation (CSOE) for the IEEE 1588 precision time protocol. Built on the classical two-way message exchange scheme, IEEE 1588 is a prominent synchronization protocol for packet switched networks. Due to the presence of random queuing delays in a packet switched network, the joint recovery of clock skew and offset from the received packet timestamps can be viewed as a statistical estimation problem. Recently, assuming perfect clock skew information, minimax optimum clock offset estimators were developed for IEEE 1588. Building on this work, we first develop joint optimum invariant clock skew and offset estimators for IEEE 1588 for known queuing delay statistics and unlimited computational complexity. We then show that the developed estimators are minimax optimum, i.e., these estimators minimize the maximum skew normalized mean square estimation error over all possible values of the unknown parameters. Minimax optimum estimators that utilize information from past timestamps to improve accuracy are also introduced. The developed optimum estimators provide useful fundamental limits for evaluating the performance of CSOE schemes. These performance limits can aid system designers to develop algorithms with the desired computational complexity that achieve performance close to the performance of the optimum estimators. If a designer finds an approach with a complexity they find acceptable and which provides performance close to the optimum performance, they can use it and know they have near optimum performance. This is precisely the approach used in communications when comparing to capacity. [ABSTRACT FROM AUTHOR]

In this paper, the problem of event-based synchronization of heterogeneous complex networks is investigated. Specifically, the influence of transmission delays on event-based synchronization is considered. The designed distributed controller for each nonidentical node in heterogeneous network includes reference generator (RG) and robust regulator. Event-based communication protocol is utilized to ensure the synchronization among the identical RGs and target leader. Meanwhile, the interevent intervals are lower bounded by a positive constant. Furthermore, the proposed high-gain output feedback and adaptive control law guarantee that all nonidentical nodes converge to their RGs. Based on these two steps, which are coincided with the separation principle, nonidentical nodes can track the target leader. In addition, theoretical results are demonstrated by a numerical example. [ABSTRACT FROM AUTHOR]

This paper investigates the cooperative tracking control problem of multiagent systems where each agent is described as a Lur’e system. We first consider the case where the leader’s control input is zero and design a distributed adaptive event-triggered protocol for the followers to track the leader. We then deal with the general case where the leader contains a bounded control input by proposing a novel event-based protocol, including a nonlinear term to restrain the effect of the leader’s input. Both of the proposed event-triggered protocols can guarantee the uniform ultimate boundedness of the tracking error and the adaptive gains without the requirement of any global information of the network. The relationship between the upper bound of the tracking error and the controller parameters is explicitly derived. [ABSTRACT FROM AUTHOR]

Over the course of the past two decades, a great deal of researchers has investigated synchronization of networked systems with determined node dynamics. However, in many realistic situations, noise is inevitable in man-made and naturally occurring networked systems. Therefore, dynamical networked systems with stochastic perturbations have gained substantial attention and have been extensively studied both in theoretical research and in practical applications. The primary goal of this paper is focused on the novel synchronization protocol design problem of nonlinear stochastic dynamical networked systems. Sufficient conditions are given to select protocol parameters. By employing stochastic analysis techniques and selecting appropriate Lyapunov functions, we proved that global synchronization of nonlinear stochastic dynamical networked systems can be reached in mean square. Numerical examples are depicted to demonstrate the efficiency of the theoretical results. [ABSTRACT FROM AUTHOR]

This paper is concerned with the optimal output synchronization control problem for a class of heterogeneous complex dynamical networks (CDNs) with partially unknown system dynamics. By defining a new quadratic performance index including the information of state couplings, an optimal controller consisting of a feedback control and a compensated feedforward control is then designed. A necessary and sufficient condition for the optimal control minimizing the quadratic performance index is established. Especially, an algebraic Riccati equation (ARE) associated with a discount factor is obtained, and a novel online iteration algorithm by iteratively solving the ARE is proposed to compute the optimal controller gain for the case that the CDNs are with partially unknown system dynamics. Moreover, it is proved that the output synchronization errors converge to zero asymptotically by applying the optimal control laws. Finally, two simulation examples are provided to verify the effectiveness of the proposed control method. [ABSTRACT FROM AUTHOR]

The IEEE 1588 protocol has received recent interest as a means of delivering sub-microsecond level clock phase synchronization over packet-switched mobile backhaul networks. Due to the randomness of the end-to-end delays in packet networks, the recovery of clock phase from packet timestamps in IEEE 1588 must be treated as a statistical estimation problem. A number of estimators for this problem have been suggested in the literature, but little is known about the best achievable performance. In this paper, we describe new minimax estimators for this problem, that are optimum in terms of minimizing the maximum mean squared error over all possible values of the unknown parameters. Minimax estimators that utilize information from past timestamps to improve accuracy are also introduced. Simulation results indicate that significant performance gains over conventional estimators can be obtained via such optimum processing techniques. These minimax estimators also provide fundamental limits on the performance of phase offset estimation schemes. [ABSTRACT FROM AUTHOR]

Recently, millimeter-wave (mmWave) 5G localization has been shown to be to provide centimeter-level accuracy, lending itself to many location-aware applications, e.g., connected autonomous vehicles (CAVs). One assumption usually made in the investigation of localization methods is that the user equipment (UE), i.e., a CAV, and the base station (BS) are time synchronized. In this paper, we remove this assumption and investigate two two-way localization protocols: (i) a round-trip localization protocol (RLP), whereby the BS and UE exchange signals in two rounds of transmission and then localization is achieved using the signal received in the second round; (ii) a collaborative localization protocol (CLP), whereby localization is achieved using the signals received in the two rounds. We derive the position and orientation error bounds applying beamforming at both ends and compare them to the traditional one-way localization. Our results show that mmWave localization is mainly limited by the angular rather than the temporal estimation and that CLP significantly outperforms RLP. Our simulations also show that it is more beneficial to have more antennas at the BS than at the UE. [ABSTRACT FROM AUTHOR]

The IEEE 1588 standard known as Precision Time Protocol (PTP) was developed to provide highly accurate and synchronized clocks for a wide range of applications. In particular, it is critical for latency-sensitive applications, such as enterprise-class financial transactions. In this paper, we analyze some of the security risks associated with this protocol, in particular, cyberattacks that disrupt the synchronization between multiple PTP devices or the synchronization between system clock and PTP hardware. We construct an experimental PTP test bed and perform the baseline measurements of synchronization between multiple clocks. We then demonstrate successful attacks that disrupt PTP synchronization, including vulnerabilities based on the lack of message authentication between master and slave clocks. Proposed mitigations of these vulnerabilities are discussed, in an effort to improve the next-generation implementations of this timing protocol or recommend additional external authentication devices in the network architecture. [ABSTRACT FROM AUTHOR]

This paper considers the consensus problem of multiagent systems with the input-based triggering condition. A model-based approach is first given to estimate the relative interagent states between intermittent communications instead of absolute states. A novel consensus protocol consisting of the relative interagent states is proposed for the consensus problem. Besides, compared with some results on the triggering condition consisting of state measurement error, a new triggering condition is constructed based on the control input. Then, the consensus protocol is executed by every agent in a fully distributed way, which has the advantage that the controller design is related to the number of agents instead of using global information. Moreover, the bounds of parameters of the controller and the triggering condition can be obtained by the proposed algorithm simultaneously, which depends on the total number of agents in multiagent networks. The proposed control scheme can ensure that states of all agents can achieve consensus. It is shown that “Zeno behavior” does not appear under the proposed algorithm. Finally, an illustrative example is given to verify the proposed method. [ABSTRACT FROM AUTHOR]

The recently proposed dual active protocol stack (DAPS) handover (HO) is one of the mobility enhancements that can effectively reduce the handover interruption time (HIT) in 5G networks. By using a DAPS solution, users can be connected to both the source cell and target cell during the HO execution phase, and thereby 0 ms of HIT becomes possible. However, the DAPS HO procedure may fail in 5G networks due to the channel characteristics of millimeter-wave (mmWave) signals. Since mmWave links are vulnerable to blockages, the received signal quality may degrade suddenly, which gives rise to an abrupt outage before DAPS HO can be completed. In this paper, a novel learning-based DAPS HO technology named intelligent DAPS (I-DAPS) HO is proposed to avoid sudden radio link failure (RLF) while providing a high data rate. The proposed I-DAPS HO uses a double deep Q-network (DDQN) deep reinforcement learning (DRL) framework, where blockage predictions are made based on past received signal data such that RLFs can be actively avoided. The performance evaluation demonstrates that the proposed I-DAPS HO scheme can effectively avoid RLF and improve the throughput performance compared to advanced 5G HO schemes. [ABSTRACT FROM AUTHOR]

In packet-based time synchronization protocols such as IEEE 1588, clock phase offsets are determined via two-way message exchanges between a master and a slave. Since the end-to-end delays in packet networks are inherently stochastic in nature, the recovery of phase offsets from message exchanges must be treated as a statistical estimation problem. Recently, minimax estimators for this problem were proposed by the authors, which are optimum in terms of minimizing the mean-squared estimation error over all values of the unknown parameters. In this paper, we consider a restricted class of estimators referred to as L-estimators, which are linear functions of order statistics. The problem of designing optimum L-estimators is studied under several hitherto unconsidered criteria of optimality. Our results address the case where the queuing delay distributions are fully known, as well as the case where network model uncertainty exists. Optimum L-estimators that utilize information from past observation windows to improve performance are also described. The derived L-estimators have a much lower computational complexity than minimax estimators, and also require lesser statistical knowledge of the queuing delays. Simulation results indicate that L-estimators exhibit a mean-squared estimation error very close to minimax estimators under many network scenarios. [ABSTRACT FROM AUTHOR]

This paper investigates the error bounds for distance estimation in visible light communication (VLC) systems. More precisely, we study the effect of signal-dependent shot noise (SDSN) on the estimation error bounds for both synchronous and asynchronous systems. Moreover, a bi-directional synchronization protocol is exploited, which can mitigate the effects of clock-biasing between the transmitter and receiver. The results demonstrate that SDSN negatively affects the distance estimation bounds for all considered scenarios. Furthermore, the bi-directional distance estimation protocol outperforms the directional estimation techniques even in the case of perfect synchronization between the transmitter and receiver. [ABSTRACT FROM AUTHOR]

Based on the reverse asymmetric time synchronization framework, we have proposed several schemes with a major focus on the energy efficiency and computational complexity of a large number of battery-powered, low-cost sensor nodes in wireless sensor networks (WSNs). To address the cumulative end-to-end synchronization error, we have also introduced an idea of compensating for the processing delays at packet-relaying gateways as an energy-efficient way of multi-hop extension of WSN time synchronization schemes. In this paper, we present a comprehensive analysis of the multi-hop extension of WSN time synchronization schemes based on packet-relaying gateways with the per-hop delay compensation and the results of extensive experiments for the energy-efficient time synchronization schemes based on the reverse asymmetric time synchronization framework together with the flooding time synchronization protocol as a representative of existing schemes. Experimental results based on a real testbed demonstrate that the multi-hop extension based on packet-relaying gateways with the per-hop delay compensation greatly improves the performance of time synchronization of all the schemes considered compared to the multi-hop extension based on the conventional time-translating gateways. [ABSTRACT FROM AUTHOR]

This paper is concerned with position-based synchronization of networked harmonic oscillators. Note that synchronization cannot be achieved via current-position-based protocols. The objective of this paper is to investigate the positive effects of network-induced delays on the synchronization of networked harmonic oscillators. That is, if taking network-induced delays into account, the motion of harmonic oscillators can be really synchronized via a proper position-based control protocol. In doing so, the harmonic oscillators are connected via a shared digital communication network. Different from some existing results, system measurements from oscillator nodes are sampled in an asynchronous way; and network-induced delays are assumed to be time varying and bounded, and they do not need to be synchronous with those from the other communication channels. At each oscillator node, a buffer is embedded into the controller to store the newest sampled-data packets transmitted from its neighboring nodes through communication channels. Then, based on the store of the buffer, the controller computes its control signal with its own period. As a result, the overall synchronization error system is modeled as a linear system with multiple interval time-varying delays. By employing the discretized Lyapunov–Krasovskii functional method, a sufficient condition on synchronization of networked harmonic oscillators is derived, which can ensure that the synchronization error system is asymptotically stable for network-induced delays falling into a certain closed interval whose lower bound is a positive real number. This condition is thus used to design suitable control protocols in terms of linear matrix inequalities with several tuning parameters. Finally, a multirobot platform is given to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Consider two remote nodes having binary sequences $X$ and Y$ , respectively. Y$ is an edited version of , where the editing involves random deletions, insertions, and substitutions, possibly in bursts. The goal is for the node with Y$ to reconstruct X$ with minimal exchange of information over a noiseless link. The communication is measured in terms of both the total number of bits exchanged and the number of interactive rounds of communication. This paper focuses on the setting where the number of edits is , where $n$ is the length of $X$ . We first consider the case where the edits are a mixture of insertions and deletions (indels), and propose an interactive synchronization algorithm with near-optimal communication rate and average computational complexity of $O(n)$ arithmetic operations. The algorithm uses interaction to efficiently split the source sequence into substrings containing exactly one deletion or insertion. Each of these substrings is then synchronized using an optimal one-way algorithm based on the single-deletion correcting channel codes of Varshamov and Tenengolts. We then build on this synchronization algorithm in three different ways. First, it is modified to work with a single round of interaction. The reduction in the number of rounds comes at the expense of higher communication, which is quantified. Next, we present an extension to the practically important case where the insertions and deletions may occur in (potentially large) bursts. Finally, we show how to synchronize the sources to within a target Hamming distance. This feature can be used to differentiate between substitution and indel edits. In addition to theoretical performance bounds, we provide several validating simulation results for the proposed algorithms. [ABSTRACT FROM PUBLISHER]

Cognitive radio (CR) networks are expected to offer a huge bandwidth to wireless users through dynamic spectrum access techniques. To realize this new network paradigm, effective distributed coordination schemes to exchange control information without assuming the availability of a prespecified common control channel (CCC) are needed. In this paper, we propose a distributed group-based spectrum-aware coordination scheme for carrier-sense multiple access with collision avoidance (CSMA/CA)-based CR networks, which is called virtual clustering distributed coordination (VCDC). By using a CSMA/CA access mechanism, VCDC allows neighboring CR users with a similar view to spectrum opportunities to asynchronously organize themselves into virtual clusters and coordinate their communications using locally available CCCs. VCDC differs from previous cluster-based schemes in that it exploits the discrete orthogonal frequency-division multiplexing (D-OFDM) technology to reduce neighbor-discovery time and facilitate intercluster communication and broadcasting. Three variants of the VCDC scheme are proposed, which are one-hop, two-hop, and constrained VCDC. These variants provide different cluster size based on the number of adopted local CCCs. We compare the performance of the VCDC scheme with existing clustering schemes. Simulation results show that VCDC constructs fewer larger size clusters with an appropriate number of common idle channels and introduces a lower percentage of clusters with no shared idle channels. Thus, VCDC performs better without imposing synchronization. [ABSTRACT FROM PUBLISHER]

The recent advances in cooperative and bio-inspired computing based on self-organizing sensor networks have been recognized as a very promising enabling technology for future smart grids (SGs). Although many papers outline the important role of these paradigms in decentralized SG monitoring and control, they do not explicitly consider the effect of the uncertainties that characterize the actual power system environment. The effects of these uncertainties could compromise the convergence of consensus-based algorithms in the form of unwanted changes in the convergence time, increasing the convergence errors and compromising the repeatability of the convergence. To address this problem, this paper proposes a new consensus protocol based on the use of affine arithmetic. The application of this reliable consensus protocol to decentralized SG computing is explained in detail. Furthermore, several numerical results are presented and discussed to demonstrate the effectiveness of the proposed methodology. [ABSTRACT FROM PUBLISHER]

Modern vehicles incorporate an increasing number of distributed compute nodes, resulting in the need for faster and more reliable in-vehicle networks. Time-triggered protocols such as FlexRay have been gaining ground as the standard for high-speed reliable communications in the automotive industry, marking a shift away from the event-triggered medium access used in controller area networks (CANs). These new standards enable the higher levels of determinism and reliability demanded from next-generation safety-critical applications. Advanced applications can benefit from tight coupling of the embedded computing units with the communication interface, thereby providing functionality beyond the FlexRay standard. Such an approach is highly suited to implementation on reconfigurable architectures. This paper describes a field-programmable gate array (FPGA)-based communication controller (CC) that features configurable extensions to provide functionality that is unavailable with standard implementations or off-the-shelf devices. It is implemented and verified on a Xilinx Spartan 6 FPGA, integrated with both a logic-based hardware ECU and a fully fledged processor-based electronic control unit (ECU). Results show that the platform-centric implementation generates a highly efficient core in terms of power, performance, and resource utilization. We demonstrate that the flexible extensions help enable advanced applications that integrate features such as fault tolerance, timeliness, and security, with practical case studies. This tight integration between the controller, computational functions, and flexible extensions on the controller enables enhancements that open the door for exciting applications in future vehicles. [ABSTRACT FROM PUBLISHER]

This paper describes the concept and analysis of virtualization technology and possible virtualization scenarios, which can be used to create a new generation of intelligent electronic devices (IEDs). The overview of the concept was based on solutions used in conventional IT systems. A fully operational working lab environment, in which simulated IED models were implemented, has been successfully tested. Problems associated with environment launch are described. An analysis of the influence of virtual device time synchronization and resynchronization on their correct operations is performed. Time delays of communication when sending GOOSE messages between the IEDs using GOOSE packages are verified. [ABSTRACT FROM PUBLISHER]

IEC 61850, which drives to digitalize information in the entire system, is being increasingly adopted in the power utility industry, since the last decade. It is necessary for all devices communicating with distributed digital data to have a common understanding of time. As protection and control devices are directly related to the safety of the power system, they are strictly required to have time accuracies. This paper describes the design of a hybrid slave clock with the transparent clock (TC) functionality defined in the IEEE 1588 precision time protocol. The design objective includes not only the synchronization of the time accuracy but also the transient time, as specified in the IEC/IEEE 61850-9-3 precision time profile for power utility automation. To comply with these objectives, we adopt a hardware–software co-design approach. The timestamp of each port is implemented by hardware. Also, they are connected by hardware to calculate the bridge time on the fly, enabling the design to have a one-step TC functionality with low latency. On the other hand, the synchronizing controller is implemented by software for adapting to the varying external conditions. The controller uses the linear quadratic Gaussian (LQG) to achieve stable steady-state performance. Simultaneously, the least-squares estimator is utilized to estimate the initial conditions of the LQG controller for reducing the transition time. Experimental results show the three-sigma time inaccuracies are 15.6 ns for the TC and 149 ns for the slave with an average transition time of 13.5 s, satisfying the IEEE/IEC 61850-9-3 criteria. [ABSTRACT FROM AUTHOR]

Current differential protection typically requires symmetrical communications channels—with equal latency in each direction—for correct operation. Conventionally, this has been delivered using protocols such as IEEE C37.94 over a time-division multiplexing wide-area network (WAN). Modern packet-based WANs offer improvements in efficiency, flexibility, and cost-effectiveness for utility applications. However, jitter is unavoidable in packet-based networks and, in extreme cases, jitter inevitably results in substantial asymmetrical latency in communications paths. This paper clearly defines how a new source of asymmetry arises due to the use of “de-jitter” buffers, which can jeopardize critical protection services. This is demonstrated using an analytical modeling approach, which precisely quantifies the degree of risk, and through real-time demonstration with actual devices, involving current differential protection over an IP/MPLS WAN. Using a novel method of real-time manipulation of Ethernet traffic to emulate large WANs, the modeling approach has been validated. It is shown how the sensitivity of relays to asymmetry depends on the protection settings and the magnitude of the measured load current. To address the risk of protection maloperation, a new approach for compensating for asymmetrical latency has been comprehensively validated. These developments will be of immediate interest to utilities operating, or migrating to, a packet-based infrastructure. [ABSTRACT FROM AUTHOR]

Under the mild assumption that only the sampled-data output information about the master system is available, synchronization of networked master–salve system consisting of a high-order master system and a low-order slave system is investigated in this paper. Specifically, the dynamics of the master system and those of the slave system are allowed to be characterized by heterogeneous nonlinear systems. The communication between these two systems are transmitted by multiple sensors over a communication network, while at each sampling instant, only one sensor is allowed to transmit its current information to the controller’s side according to some carefully designed scheduling protocols. To achieve master–salve synchronization, the stochastic scheduling and the Round-Robin scheduling protocols are, respectively, proposed and utilized. By appropriately designing observer and controller for the slave system, some sufficient synchronization criteria regarding to the gain matrices, sampling intervals and communication delays are derived for the closed-loop master–salve system under respectively the stochastic scheduling and the Round-Robin scheduling protocols. Last, two numerical examples are simulated to validate the effectiveness of the theoretical results. [ABSTRACT FROM PUBLISHER]

Cooperative awareness on the road is intended to support the road users by providing knowledge about the surroundings and relies on the information exchange enabled by vehicular communications. To achieve this goal the European telecommunication standard institute (ETSI) delivered the standard EN 302 637-2 for cooperative awareness messages (CAM). The CAM triggering conditions are based on the kinematics of the originating vehicle, which is checked periodically. In this paper, we show that the standardized ETSI protocol may suffer a decrease in communication performance under several realistic mobility patterns. The potential influence of the discovered phenomena on the IEEE 802.11p medium access control operation is studied. [ABSTRACT FROM PUBLISHER]