Time Delay In Data Transmission Research Articles

Frequency regulation scheme in power system using an observer-based waiting event-triggered control with random features

Addressed in this paper is the observer-based waiting event-triggered control issue in multi-area load frequency control (LFC) power system subject to random communication delay and data packet dropout. In order to maintain the grid frequency stability of the multi-area LFC power system in an open communication network, an observer-based waiting event-triggered scheme (WETS) is proposed to deal with frequency fluctuation and extend the life of control equipments. Compared with the existing event-triggered mechanism, the proposed WETS has the merits of continuous event-triggered scheme and the periodic sampling event-triggered scheme in the both of theory and application. Then, by well considering the negative factors of data packet dropout and random time delay in data transmission, a stochastic delay-dependent multi-area LFC model is established, which involves the information of observer-based WETS, random communication delay and packet dropout in a unified structure. Further, an improved Lyapunov–Krasovskii functional (LKF) is constructed by dividing the interval of transmitted delay. Based on the constructed Lyapunov functional, Park’s theorem and Jensen’s integral inequality, some less conservative stabilization criteria are obtained. Finally, the validity of the proposed control method is verified via numerical examples.

LPLL-LEACH: A study of a low-power and low-delay routing protocol based on LEACH

For a series of problems, such as uneven energy consumption and long packet forwarding time of a low-energy adaptive clustering hierarchy (LEACH), an efficient routing protocol with low power and low latency based on LEACH (LPLL-LEACH) is proposed in this paper. In terms of energy, first, the optimal number of cluster heads (CHs) is calculated by quantitative analysis. Second, multiple factors are considered to redefine the threshold for electing CHs. In addition, ordinary nodes decide which cluster to join according to the cost function. Moreover, a forwarding function is utilized to determine the optimal next hop CH to forward the data. Last, the ordinary nodes are allowed to directly communicate with the base station (BS). In regard to latency, a hybrid mechanism of carrier sense multiple access and time division multiple access (CSMA_TDMA) is applied to minimize the time delay of data transmission. MATLAB is used to analyze the latency and energy of LPLL-LEACH and to compare it with LEACH, LEACH-C, ECH and EE-LEACH. The experimental results show that the time of all node deaths extended by 107%, 45%, 31.8%, and 8.8%. Similarly, the latency is greatly reduced, which improves the efficiency of data transmission.

Edge computing and its role in Industrial Internet: Methodologies, applications, and future directions

Proliferation of Industrial Internet has dramatically changed the way we live and work. It brings convenience to our society and sometimes requires real-time processing of dramatic data at the same time. However, traditional paradigm of computing on the center cloud can’t always meet such requirement, for the non-negligible time delay of data transmission and communication. Edge computing is a novel computing paradigm proposed to resolve such a problem. As a promising technology, it extends computing from cloud center to the edge of network. Edge computing has the advantage of low latency to achieve a shorter response time, as well as potential to address the concerns of energy consuming, bandwidth burden and security issue. In this paper, we give a survey about edge computing from the aspect of methodologies, application scenarios and its role in Industrial Internet. Some open issues of edge computing are also introduced in this paper. At the end of the manuscript, a discussion about future direction is proposed. The shallow network algorithms such as broad learning system (BLS), which have achieved great improvement in computing efficiency, show an optimistic outlook in this area. We propose our conceive about future applications when shallow network methods like BLS are applied in edge computing and hope the paper will inspire research in relative directions.

Bounded consensus for multiagent systems by event‐triggered data transmission, time delay, and predictor‐based control

SummaryThis paper investigates the consensus issue of multiagent systems with data transmission time delay. The state measurement of each local agent is directly sent to a private event‐trigger and further authorized to be broadcasted to its neighbors via communication network only when the threshold of the event‐trigger is violated. Since the controller always receives discrete‐time neighbor information with data transmission time delay, a predictor is employed to estimate the continuous‐time neighbor state. Based on the estimated state, a novel consensus protocol is mainly proposed for achieving the bounded consensus of the multiagent systems. By the proposed method, the asynchronous neighbor information is allowed and the margin of data transmission time delay is also given. Furthermore, it has been proved that the unwanted Zeno phenomena can be naturally excluded. Numerical example is provided to demonstrate the effectiveness of the proposed method.

Predictive Controller Design for Networked Control System

A networked control system where sensor ( ), controller ( ) and an actuator ( ) are interacting to the process model or system through a communication channel. The model reliability depends on time delay of data transmission from to , to , controller processing time and packet dropouts. In this proposed work, model based network system is designed to achieve the desired response of the controlled system by minimizing the network time delay and improves con-troller performance in term of stability. Time delay mainly occurs due to time sharing of the medium as well extra overload of signal coding and processing phase. The time delays could be steady, limited, or even random, depends upon protocol used in the network and hardware. The network predictive control tech-nique effectively works on random delay. The predictive controller is used to analyses the future output conditions of the system based on the previous values. The simulated result shows that if time delay increases, the response of the system degraded and therefore for improving it the correct choice of prediction and control horizon is needed. The designed networked control system based on predictive functional control is simulated using True Time tool on Matlab. The ob-tained outcomes from the proposed technique accomplishes that the technique is effective and feasible.

JamCatcher: A Mobile Jammer Localization Scheme for Advanced Metering Infrastructure in Smart Grid.

As the core component of the smart grid, advanced metering infrastructure (AMI) is responsible for automated billing, demand response, load forecasting, management, etc. The jamming attack poses a serious threat to the AMI communication networks, especially the neighborhood area network where wireless technologies are widely adopted to connect a tremendous amount of smart meters. An attacker can easily build a jammer using a software-defined radio and jam the wireless communications between smart meters and local controllers, causing failures of on-line monitoring and state estimation. Accurate jammer localization is the first step for defending AMIs against jamming attacks. In this paper, we propose JamCatcher, a mobile jammer localization scheme for defending the AMI. Unlike existing jammer localization schemes, which only consider stationary jammers and usually require a high density of anchor nodes, the proposed scheme utilizes a tracker and can localize a mobile jammer with sparse anchor nodes. The time delay of data transmission is also considered, and the jammer localization process is divided into two stages, i.e., far-field chasing stage and near-field capturing stage. Different localization algorithms are developed for each stage. The proposed method has been tested with data from both simulation and real-world experiment. The results demonstrate that JamCatcher outperforms existing jammer localization algorithms with a limited number of anchor nodes in the AMI scenario.

Reduction of Data Transmission Time Delay with Object Detection in Underwater Acoustic Sensor Network

Underwater acoustic sensor networks plays vital role in many applications such as monitoring underwater environment, location and object detection etc., In environment monitoring, the sensor nodes monitors the unwanted obstacles and transmits the information about the obstacles to Base Station(BS). The major problem is when sending data from two or more number of sensor nodes at same time the time delay in data transmission will be increased. In this project, to overcome the problem of end to end delay, mobile data collector is employed with waterproof ultrasonic sensor nodes in underwater acoustic Sensor network.

Spanning tree based topology control for data collecting in predictable delay-tolerant networks

In predictable delay tolerant networks (PDTNs), the network topology is known a priori or can be predicted over time such as vehicular networks based on public buses or trains and space planet network. Previous DTN research mainly focuses on routing and data access. However, data collecting are used widely in PDTNs and it is very important in practical application, how to maintain the dynamic topology of this type of PDTNs becomes crucial. In this paper, a spanning tree (ST) based topology control method for data collecting in PDTNs is proposed. The PDTN is modeled as layered space-time directed graph which includes spatial, temporal and energy cost information, which can be simplified as reduced aggregated directed graph. The topology control problem is defined as constructing a ST that the total energy cost of the ST is minimized and the time delay threshold is satisfied. We propose three heuristic algorithms based on layered space-time directed graph and reduced aggregated directed graph to solve the defined problem, and compare them in terms of energy cost and time delay. Extensive simulation experiments demonstrate that the proposed algorithms can guarantee data transmission effectively, reduce the network energy consumption significantly, and shorten the time delay of data transmission.

LPTA: location predictive and time adaptive data gathering scheme with mobile sink for wireless sensor networks.

This paper exploits sink mobility to prolong the lifetime of sensor networks while maintaining the data transmission delay relatively low. A location predictive and time adaptive data gathering scheme is proposed. In this paper, we introduce a sink location prediction principle based on loose time synchronization and deduce the time-location formulas of the mobile sink. According to local clocks and the time-location formulas of the mobile sink, nodes in the network are able to calculate the current location of the mobile sink accurately and route data packets timely toward the mobile sink by multihop relay. Considering that data packets generating from different areas may be different greatly, an adaptive dwelling time adjustment method is also proposed to balance energy consumption among nodes in the network. Simulation results show that our data gathering scheme enables data routing with less data transmission time delay and balance energy consumption among nodes.

Time-delayed decentralized H2/LQG controller for cable-stayed bridge under seismic loading

SUMMARY Consistency of real-time data transmission is an important factor in active and semi-active control of structures. Recent advances in wireless sensors and their reliable data communication have attracted many attentions in structural control engineering. Wireless sensors have been also preferred to wire-base types because of problems associated with installing extensive length of coaxial wires. In addition, embedded computing technologies in wireless sensors as local controller reduce size of transferring data and provide stable transmission. However, there are some issues in implementation of wireless connection like communication range and latency. This study presents the feasibility of developing a decentralized controller by using H2/LQG as robust-optimum algorithm in cable-stayed bridge. Because of large scale of structure, the order of model is reduced by using two different reduction methods in finite time and frequency. The controller is developed in centralized and decentralized solutions. The decentralized controller through developing a gradient-based method is designed to efficiently solve system of closed-loop H2 optimization problem. The structural responses in centralized and decentralized solutions are compared with each other under three different earthquake records considering time delay in data transmission. Results indicate that for large-scale bridges with time-delayed data communication issue, H2/LQG controller in decentralized solution gives maximum reduction of response indices in comparison with other strategies. Copyright © 2011 John Wiley & Sons, Ltd.

Research on the Character of a Synchronous Control System with Wireless Data Communication

It discusses the reasons of the data transmission time delay and packets loss based on the theory of net data transmission. Aimed to the question of the time delay of data transmission and packets loss, the control system models are set up to analyze their influence to the performance of the control system. Based on the synchronous control model analysis with wireless data transmission, a method to control the system is reached with the state prediction when the communication error or data loss appears. It can control constantly when communication errors appear, and also it can get the most error period by numerical analysis.

Distance Estimation Error Compensation of a Direct Control Type, Internet-based Mobile Robot System

This research is concerned with the development of an Internet-based mobile robot system, which is insensitive to the unpredictable Internet time delay in data transmission. For this purpose, the PPS (Position Prediction Simulator) is suggested and implemented to compensate for the time delay problem of the Internet. The PPS is divided into two parts, including the 3D virtual simulator and the robot position prediction part. The proposed PPS shows the visual information of a remote site, which is obtained from image processing and predicted position considering the time delay. The simulation results showed that the direct control using the PPS is insensitive to the time delay problem as in the indirect control. For the verification of the proposed PPS, the robot was moved and stopped following the planned path under various traffic conditions. The experimental results showed that the distance error could be reduced using the developed PPS.

Estimation of packet time belay in high-speed computer networks

Considered is one of the stages of analysis of high-speed computer networks - estimation of time delay of data transmission. Transmission medium is used as the routing network. Given and substained is the stochastic model of estimation of time delay in the data transmission network which is compared to relative model, allows take into account more fully the interaction of information flows. The received analytical dependencies can be used for increasing the efficiency of load control in computer networks