• Title/Summary/Keyword: Time synchronization

Search Result 284, Processing Time 0.1 seconds

A Time Synchronization Method of Sensor Network using Single Flooding Algorithm (단일 플러딩 라우팅 알고리즘을 활용한 센서 네트워크의 시간 동기화 기법)

  • Shin, Jae-Hyuck;Kim, Young-Sin;Jeon, Joong-Nam
    • The KIPS Transactions:PartC
    • /
    • v.18C no.1
    • /
    • pp.15-22
    • /
    • 2011
  • Usually time synchronization is performed after routing tree is constructed. This thesis proposes a time synchronization algorithm combined with single-flooding routing tree construction algorithm in a single path. TSRA (Time Synchronization Routing Algorithm) uses routing packets to construct a routing tree. Two types of time information are added to the routing packet: one is the packet receiving time, and the other is the packet sending time. Time offset and transmission time-delay between parent node and child node could be retrieved from the added time information using LTS (Lightweight Time Synchronization) algorithm. Then parent node sends the time offset and transmission time to children nodes and children nodes can synchronize their time to the parent node time along the routing tree. The performance of proposed algorithm is compared to the TPSN (Timing-sync Protocol for Sensor Networks) which is known to have high accuracy using NS2 simulation tool. The simulation result shows that the accuracy of time synchronization is comparable to TPSN, the synchronization time of all sensor nodes is faster than TPSN, and the energy consumption is less than TPSN.

TDoA-Based Practical Localization Using Precision Time-Synchronization (정밀 시각동기를 이용한 TDoA 기반의 위치 탐지)

  • Kim, Jae-Wan;Eom, Doo-Seop
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.38C no.2
    • /
    • pp.141-154
    • /
    • 2013
  • The technology of precise time-synchronization between signal receive devices for separation distance operation can be a key point for the technology with TDoA-based system. We propose a new method for the higher accuracy of system's time-synchronization in this paper, which uses OCXO and DPLL with high accuracy to achieve phase synchronization at 1 pps (pulse per second) of signal. And the method receive time value from a GPS satellite. Essentially, the performance of GPS with high accuracy refers to long-term frequency stability for its reliability. As per the characteristic, as the GPS timing signals are synchronized continuously, the accuracy of time-synchronization gets improved proportionally. Therefore, if the time synchronization is accomplished, the accuracy of the synchronization can be up to 0.001 ppb (part per billion). Through the improved accuracy of the time-synchronization, the measurement error of TDOA-based location detection technology is evaluated. Consequently, we verify that TDoA-based location measurement error can be greatly improved via using the improved method for time-synchronization error.

Development of Efficient Conservative Algorithm for Distributed Simulation (분산 시뮬레이션을 위한 효율적인 보수적 알고리즘 개발)

  • 이영해
    • Journal of the Korea Society for Simulation
    • /
    • v.8 no.1
    • /
    • pp.77-88
    • /
    • 1999
  • There are two approaches to handle the Causality Error in parallel and distributed simulation. One approach is based on the conservative time synchronization and the other is the optimistic time synchronization. In this paper an efficient null message reduction method for the conservative time synchronization approach is suggested with the experimental results, which could improve performance of simulation and avoid deadlock situations.

  • PDF

A Study on Time Synchronization for Programmable Electronic Systems of Train Control (열차제어 장치용 실시간 시스템의 시간 동기화에 관한 연구)

  • Kang, Shin Ju;Lee, Jong Woo
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.63 no.7
    • /
    • pp.1019-1023
    • /
    • 2014
  • The issue of safety insurance in PES(Programmable Electronic Systems) has been provoked because PES is difficult to define failure modes which are appeared in many different ways. But the PES applications extend rapidly in various areas. One of the solutions for PES safety insurance is voting which PES is used by comparing the outputs of several PES. The time synchronization of the PES is necessary for this reliable voting. The voting must be carried out with the outputs from same time inputs. There are several methods for time synchronization of the PES. In this paper, we discussed two modes of the time synchronization which are mutual synchronization of several PES and using UTC(Universal Time Clock).

Time Management System for Applications of UAV Network

  • Lee, Won-Seok;Jang, Jun-Yong;Song, Hyoung-Kyu
    • Journal of Positioning, Navigation, and Timing
    • /
    • v.9 no.4
    • /
    • pp.405-409
    • /
    • 2020
  • This paper proposes time management system for unmanned aerial vehicle (UAV) network. The computers of the UAVs need time synchronization that time offset does not exceed the minimum interval of data samples for errorless data blending between the computers. The proposed time management system is composed of time synchronization and general management systems for UAV control. The systems communicate each other for time information and control signals. The synchronization system uses improved version of existing time offset estimation that network time protocol (NTP) uses. The time synchronization is operated when the time offset of any UAV exceeds threshold that preconfigured by the general management system. The demonstration of prototype shows stable time synchronization satisfying preconfigured threshold.

A Survey on Time Synchronization Protocols for Wireless Sensor Networks (무선 센서 네트워크용 시각 동기화 프로토콜의 고찰)

  • Bae, Shi-Kyu
    • Journal of the Korea Society of Computer and Information
    • /
    • v.19 no.6
    • /
    • pp.61-69
    • /
    • 2014
  • Various Time Synchronization protocols considering for the characteristics of WSN(Wireless Sensor Network) have been developed, because a time relationship plays an important role in many WSN applications, as well. Synchronization accuracy as well as constraints of energy should be considered for WSN Time Synchronization protocols, especially. In this paper, I analyze Time Synchronization protocols for WSN after classifying these protocols with a new criteria (i.e. power consumption). So, this method will contribute to evaluating and comparing WSN Time Synchronization protocols in respect of power consumption.

Analysis and Compensation of Time Synchronization Error on SAR Image (시각 동기화 오차가 SAR 영상에 미치는 영향 분석 및 보상)

  • Lee, Soojeong;Park, Woo Jung;Park, Chan Gook;Song, Jong-Hwa;Bae, Chang-Sik
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.48 no.4
    • /
    • pp.285-293
    • /
    • 2020
  • In this paper, to improve Synthetic Aperture Radar (SAR) image quality, the effect of time synchronization error in the EGI/IMU (Embedded GPS/INS, Inertial Measurement Unit) integrated system is analyzed and state augmentation is applied to compensate it. EGI/IMU integrated system is widely used as a SAR motion measurement algorithm, which consists of EGI mounted to obtain the trajectory and IMU mounted on the SAR antenna. In an EGI/IMU integrated system, a time synchronization error occurs when the clocks of the sensors are not synchronized. Analysis of the effect of time synchronization error on navigation solutions and SAR images confirmed that the time synchronization error deteriorates SAR image quality. The state augmentation is applied to compensate for this and as a result, the SAR image quality does not decrease. In addition, by analyzing the performance and the observability of the time synchronization error according to the maneuver, it was confirmed that the time-variant maneuver such as rotational motion is necessary to estimate the time synchronization error adequately. In order to reduce the influence of the time synchronization error on the SAR image, the time synchronization error must be compensated by performing maneuver changing over time such as a rotation before SAR operation.

A Study on Time Synchronization Protocol to Cover Efficient Power Management in Ubiquitous Sensor Network (유비쿼터스 센서 네트워크를 위한 효율적인 시간 동기화 프로토콜 연구)

  • Shin, Moon-Sun;Jeong, Kyeong-Ja;Lee, Myong-Jin
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.11 no.3
    • /
    • pp.896-905
    • /
    • 2010
  • The sensor networks can be used attractively for various application areas. Time synchronization is important for any Ubiquitous Sensor Networks (USN) systems. USN makes extensive use of synchronized time in many contexts for data fusion. However existing time synchronization protocols are available only for homogeneous sensor nodes of USN. It needs to be extended or redesigned in order to apply to the USN with heterogeneous sensor nodes. Because heterogeneous sensor nodes have different clock sources with the SinkNode of USN, it is impossible to be synchronized global time. In addition, energy efficiency is one of the most significant factors to influence the design of sensor networks, as sensor nodes are limited in power, computational capacity, and memory. In this paper, we propose specific time synchronization based on master-slave topology for the global time synchronization of USN with heterogeneous sensor nodes. The time synchronization master nodes are always able to be synchronized with the SinkNode. Then time synchronization master nodes enable time synchronization slave nodes to be synchronized sleep periods. The proposed master-slave time synchronization for heterogeneous sensor nodes of USN is also helpful for power saving by maintaining maximum sleep time.

A Time Synchronization Protocol for Energy-Constrained Wireless Networks (에너지 제한적인 무선 네트워크에서 동작하는 시각 동기화 프로토콜)

  • Bae, Shi-Kyu
    • KIPS Transactions on Software and Data Engineering
    • /
    • v.4 no.9
    • /
    • pp.385-392
    • /
    • 2015
  • In IoT(Internet of Things), it is important for wireless networks to communicate data created among resource-constrained wireless nodes, where time synchronization is needed for meaningful data creation and transmission. Time Synchronization by flooding is one of the mostly used protocols for WSN(Wireless Sensor Networks). Even though this type of scheme has some advantages over other types (i.e. a simple algorithm and independency of topology and so on), too many data transmission is required, leading to large power consumption. So, reducing transmission data is an important issue for energy efficiency in this kind of networks. In this paper, a new Flooding-based time synchronization protocol is proposed to use energy efficiently by reducing a transmitted traffic. The proposed scheme's performance has been evaluated and compared with an representative scheme, FTSP(Flooding Time Synchronization Protocol) by simulation. The results are shown that the proposed scheme is better than FTSP.

Design of Time Synchronization Mechanism of Wireless USB over IEEE 802.15.6 (WUSB over IEEE 802.15.6 WBAN 프로토콜의 시각 동기 구조 설계)

  • Hur, Kyeong
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.18 no.7
    • /
    • pp.1619-1627
    • /
    • 2014
  • Wearable computer systems can use the wireless universal serial bus (WUSB) that refers to USB technology that is merged with WiMedia PHY/MAC technical specifications. In this paper, we focus on an integrated system of the wireless USB over the IEEE 802.15.6 wireless body area networks (WBAN) for wireless wearable computer systems supporting U-health services. And a communication structure that performs the time-synchronization is proposed for WUSB over IEEE 802.15.6 hierarchical protocol. Proposed time-synchronization mechanisms adopt the WBAN Polling Access and combine it with a time-synchronization middleware using time stamps. In our performance evaluations, time-synchronization performances with only WBAN Polling Access scheme are analyzed first. After that, performances combined with the time-synchronization middleware are analyzed to evaluate the effectiveness of proposed time-synchronization structure in WUSB over IEEE 802.15.6.