• Title, Summary, Keyword: time offset

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Neutral-Point Voltage Balancing Method for Three-Level Inverter Systems with a Time-Offset Estimation Scheme

  • Choi, Ui-Min;Lee, Kyo-Beum
    • Journal of Power Electronics
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    • v.13 no.2
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    • pp.243-249
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    • 2013
  • This paper presents a neutral-point voltage balancing method for three-level inverter systems using a time-offset estimation scheme. The neutral-point voltage is balanced by adding a time-offset to the turn-on time of the switches. If an inaccurate time-offset is added, the neutral-point deviation still remains. An accurate time-offset is obtained through the proposed time-offset estimation scheme. This method is implemented without additional hardware, complex calculations, or analysis. The effectiveness of the proposed method is verified by experiments.

Performance Evaluation and Offset Time Decision for Supporting Differential Multiple Services in Optical Burst Switched Networks (광 버스트 교환 망에서 차등적 다중 서비스 제공을 위한 offset 시간 결정 및 성능 평가)

  • So W.H.;im Y.C.K
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.41 no.1
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    • pp.1-12
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    • 2004
  • In this paper, we take advantage of the characteristics of optical burst switching (OBS) to support service-differentiation in optical networks. With the offset time between control packet and burst data, the proposed scheme uses different offset time of each service class. As contrasted with the Previous method, in which the high Priority service use only long offset time, it derives the burst loss rate as a QoS parameter in consideration of conservation law and given service-differential ratios and decides a reasonable offset time for this QoS finally Firstly proposed method classifies services into one of high or low class and is an algorithm deciding the offset time for supporting the required QoS of high class. In order to consider the multi-classes environment, we expand the analysis method of first algorithm and propose the second algorithm. It divides services into one of high or low group according to their burst loss rate and decides the offset time for high group, and lastly cumulates the offset time of each class. The proposed algorithms are evaluated through simulation. The result of simulation is compared with that of analysis to verify the proposed scheme.

Analysis of the Effect on Offset Time under Fault and Propose a New Restoration Scheme Considering QoS in OBS Networks (광 버스트 스위칭 망에서 망 고장에 대한 offset 시간 영향 분석 및 QoS를 고려한 장애 복구 기법)

  • 이해정;송규엽;소원호;김영천
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.12
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    • pp.94-105
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    • 2003
  • OBS(Optical Burst Switching) networks which decouple the burst from its header has characteristic one-way reservation. Therefore, the fault of a fiber link may lead to the magnitude of burst loss. Since sending a header packet and using an offset time before the transmission of the corresponding burst. In this paper, we analysis a offset time based on the burst loss rate resulting from only link failure and by applying the restoration schemes in an optical burst switching networks. The simulation results in terms of the effect of a offset time is evaluated in our network model to verify that comparing the numerical analysis with simulation result. Finally, and through these results, We propose the new restoration scheme based on offset time considered Quality of Service.

Design and Performance Evaluation of Offset Time Decision Algorithm for Guaranteeing the QoS in Optical Burst Switching Networks (광 버스트 스위칭 망에서 QoS 보장을 위한 Offset 시간 결정 알고리즘 설계 및 성능 평가)

  • So, Won-Ho;Cha, Yun-Ho;Roh, Sun-Sik;Kim, Young-Chon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.1C
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    • pp.1-10
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    • 2002
  • With the explosive growth of the number of Internet users and Internet-related services, the research on construction of broadband Optical Internet by using WDM technologies is actively is actively progressed. In this paper, we design the offset time decision (OTD) algorithm for supporting the QoS in optical networks based on optical burst switching (OBS), which is the new switching paradigm, and evaluate the performance of it. The proposed algorithm determines a reasonable offset time considering traffic load of network and the number of wavelengths to guarantee the burst loss rate (BLR) of high priority Internet traffic as a QoS parameter. In order to design the proposed OTD algorithm, firstly we make the new burst loss formula, which includes the effect of offset time. The decision of offset time corresponding to the requested BLR, however, should use the reverse formula of proposed one, thus we are not able to use it without any changes. In this paper, we define the heuristic loss formula (HLF) that can be changed into reversed formula by using the proposed formula and proportional equation considering its characteristics. Finally we show the OTD algorithm to decide the offset time by using HLF. We show that the requested BLR is guaranteed under various traffic load with the determinded offset time by using the proposed OTD algorithm.

Periodic Binary Sequence Time Offset Calculation Based on Number Theoretic Approach for CDMA System (CDMA 시스템을 위한 정수론 접근 방법에 의한 주기이진부호의 사건?? 계산)

  • 한영열
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.5
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    • pp.952-958
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    • 1994
  • In this paper a method calculates the time offset between a binary sequence and its shifted sequence based on the number theoretic approach is presented. Using this method the time offset between a binary sequence and its shifted sequence can be calculated. It has been recongnized that the defining the reference (zero-offset) sequence is important in synchronous code division multiple access(CDMA) system since the same spreading sequence are used by the all base station. The time offset of the sequence with respect to the zero offset sequence are used to distinguish signal received at a mobile station from different base stations. This paper also discusses a method that defines the reference sequence.

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A Study on System for Synchronization of Multiple UAVs and Ground Control System (무인이동체 및 지상국 컴퓨터 간의 시간 정보 동기화를 위한 시스템 연구)

  • Lee, Won-Seok;Lee, Woon-Sang;Song, Hyoung-Kyu
    • Journal of the Semiconductor & Display Technology
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    • v.19 no.1
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    • pp.11-16
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    • 2020
  • In this paper, system that includes multiple unmanned aerial vehicles (UAVs) are considered. The vehicles are equipped with a mission computer for a specific mission and equipment. The mission equipment operates based on the time of mission computer. Also, data collected by flight computer and mission computer is saved with the time of each operating system. Generally, time offset between multiple computers always exists, though the computers are connected to the Internet. When the data collected by multiple computers is combined, the time offset causes damage on reliability of the combined data. Computers that connected to the Internet are synchronized by network time protocol (NTP). This paper proposes a system that the time of multiple mission computers are synchronized by the same NTP server to minimize the time offset. In the results of the measurement, the system time offset of multiple mission computer is maintained within 10ms from the system time of the server computer.

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QoS Supporting Scheme Considering Service-Differentiation Ratio in Optical Burst Switching Networks (광 버스트 스위칭 망에서 서비스 차등률을 고려한 QoS 제공 기법)

  • 소원호;김영천
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.12C
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    • pp.1197-1206
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    • 2002
  • Recently, the research on the construction of optical Internet backbone networks using WDM has been actively progressed. In this paper, we propose the offset based service-differentiation scheme in optical burst switching (OBS) networks. We classify the services into two classes; high class and low class. The proposed scheme decides the offset time of high class so as to satisfy the required burst loss rate (BLR) of services according to the service-differentiation ratio (SDR). The SDR may be set depending on the environment of OBS network and user's requirements, our scheme decides the BLR of high class by using the required SDR and conservation law. Finally, we use the offset time decision (OTD) algorithm to determine the offset time of high class. The proposed scheme is evaluated through simulation. The result of simulation is compared with that of analysis to verify the proposed scheme.

Analysis for Time Offset of PN Sequence in CDMA System (CDMA 시스팀에서의 PN 부호 시간차 측정 기법)

  • 전정식;한영열
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.5
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    • pp.971-980
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    • 1994
  • The need increased capacity in the cellular system has resulted in the adoption of digital technology with CDMA as the channel access method. It has been recognized that the distinction of the base station is important for its performance in CDMA, since the same spreading sequences are used by the all base stations. Time offset of the pseudo-random noise binary code are used to distinguish signals received at a mobile station from different base station. But the start of the zero offset PN sequence is chosen arbitrary without the background of the systematic and mathematical elaboration. This paper proposes a mothed that define the start of the zero offset PN sequence mathematically. This paper also discusses a method that can easily calculate the time offset of the received spreading sequence with respect to the zero offset PN sequence.

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Detection of Onset and Offset Time of Muscle Activity in Surface EMG using the Kalman Smoother

  • Lee Jung-Hoon;Lee Hyun-Sook;Lee Young-Hee;Yoon Young-Ro
    • Journal of Biomedical Engineering Research
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    • v.27 no.3
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    • pp.131-141
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    • 2006
  • A visual decision by clinical experts like physical therapists is a best way to detect onset and offset time of muscle activation. The current computer-based algorithms are being researched toward similar results of clinical experts. The new algorithm in this paper has an ability to extract a trend from noisy input data. Kalman smoother is used to recognize the trend to be revealed from disorderly signals. Histogram of smoothed signals by Kalman smoother has a clear boundary to separate muscle contractions from relaxations. To verify that the Kalman smoother algorithm is reliable way to detect onset and offset time of muscle contractions, the algorithm of Robert P. Di Fabio (published in 1987) is compared with Kalman smoother. For 31 templates of subjects, an average and a standard deviation are compared. The average of errors between Di Fabio's algorithm and experts is 109 milliseconds in onset detection and 142 milliseconds in offset detection. But the average between Kalman smoother and experts is 90 and 137 milliseconds in each case. Moreover, the standard deviations of errors are 133 (onset) and 210 (offset) milliseconds in Di Fabio's one, but 48 (onset) and 55 (offset) milliseconds in Kalman smoother. As a result, the Kalman smoother is much closer to determinations of clinical experts and more reliable than Di Fabio's one.

Phase offset estimation scheme of using STBC with Turbo-code in Fading channel (페이딩 채널에서 STBC와 터보부호 기반의 위상오프셋 추정 기법)

  • Lee, Cheon-Ho;Ryu, Jung-Gon;Heo, Jun
    • Proceedings of the IEEK Conference
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    • pp.1047-1048
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    • 2006
  • In this paper, we present an iterative phase offset estimation algorithm based on a space-time block code and turbo coded system. External single phase estimator receives soft information from the turbo decoder and estimates phase offset with LMS algorithm. The estimated phase offset value is used for space-time decoder. Simulation results show the phase estimation gain in a flat fading channel.

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