• Title/Summary/Keyword: Frequency offset compensation

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Improvement of IEEE 802.15.4b LR-WAPN Frequency Offset with Multiple Differential Filter (다중 차분 필터에 의한 IEEE 802.15.4b LR-WPAN 주파수 옵셋의 개선)

  • Cheng, Cha-Keon;Kang, Sung-Min
    • The Journal of the Korea Contents Association
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    • v.9 no.2
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    • pp.10-17
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    • 2009
  • This paper analyze the effect of frequency offset for the IEEE 802.15.4b LR-WPAN(Low-Rate Wireless Personal Area Network) with 915MHz bandwidth noncoherent DSSS O-QPSK based receiver system, and presents a compensation method with addition of differential filter to the system for compensation of frequency offset problem. DSSS PSSS-ASK and DSSS O-QPSK modulation techniques are accepted within the regularization of IEEE 802.15.4b. These new method can obtain 250kbps transmission rate. The DSSS O-QPSK modulation method that is used in this paper has no BER variation below 40ppm(frequency offset 36.6kHz), but if the offset frequency become high above 40ppm, then the system cannot have stable receiving condition due to worse BER. To solve this problem, we present a more stabilized receiver system at maximum frequency offset ${\pm}80ppm$ using MDDF unti a correlator of DSSS O-QPSK modulator. Moreover computer simulation results will be presented to evaluate the performance of the proposed algorithm unde various AWGN and frequency offset environment.

A Study on Accurate Phasor Extraction Using a New DC Offset Elimination Filter (새로운 직류 옵셋 제거 필터에 의한 정확한 페이저 추출에 관한 연구)

  • Park, Chul-Won;Yoon, Hee-Whan
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.7
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    • pp.29-36
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    • 2013
  • In this paper, a new DC offset elimination filter is proposed for an accurate phasor extraction of fundamental frequency component. The proposed method can eliminate a DC offset component which is decayed exponentially. The proposed method uses only one cycle of data for phasor extraction computation, which does not need to preset the time constant of the DC offset component. Also, the other advantages of the proposed method is that gain compensation or phase compensation is not required after filtering. Simulations using ATP were performed to evaluate the performance of the proposed filter method, and the results were compared to the ones obtained by conventional methods.

Performance Analysis of Digital M/W Transmission System adopting Frequency Offset Compensation Algorithm in Multipath Fading Channel (다중경로 페이딩 채널에서 주파수 옵셋 보상 알고리즘을 적용한 디지털 M/W 전송 시스템의 성능 분석)

  • Park, Ki-Sik
    • Journal of the Korea Society of Computer and Information
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    • v.18 no.10
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    • pp.63-70
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    • 2013
  • In this paper, we investigated frequency synchronization through computer simulation of digital M/W transmission system in multipath fading channel. we suggested frequency offset correction algorithm against frequency offset between transmitter and receiver, then evaluated the degree of constellation performance enhancement. From the performance evaluation, in case of large frequency offset, although adopting frequency offset correction scheme, residual frequency offset degraded system performance. As a result, according to frequency offset value between transmitter and receiver residual frequency offset affects system performance significantly. The results of this paper should be utilized for frequency synchronization criterion when frequency band of broadcasting system is rearranged.

Efficient Estimation and Compensation of CFO and STO in Multi-carrier Communication System (다중 반송파 통신 시스템에서 효과적인 CFO와 STO추정 및 보상방법)

  • Lee, Hui-Kyu;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.5A
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    • pp.441-449
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    • 2011
  • Sample timing offset (STO) and carrier frequency offset (CFO) are caused by inter-symbol interference (ISI), inter-carrier interference (ICI) and phase error in orthogonal frequency division multiplexing (OFDM) system. OFDM characteristic is sensitive about STO and CFO. So when ICI occurs, compensation is hard and complex equalizer is needed. In this paper, we propose an effective correction method using feedback process with pilot and synchronization symbol. After feedback with estimated value in frequency domain, STO and CFO are corrected by control sample & and holder and oscillator. As a result of simulation, we confirm that STO and CFO can be corrected without equalizer through feedback.

DC offset Compensation Algorithm with Fast Response to the Grid Voltage in Single-phase Grid-connected Inverter (단상 계통 연계형 인버터의 빠른 동특성을 갖는 계통 전압 센싱 DC 오프셋 보상 알고리즘)

  • Han, Dong Yeob;Park, Jin-Hyuk;Lee, Kyo-Beum
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.7
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    • pp.1005-1011
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    • 2015
  • This paper proposes the DC offset compensation algorithm with fast response to the sensed grid voltage in the single-phase grid connected inverter. If the sensor of the grid voltage has problems, the DC offset of the grid voltage can be generated. This error must be resolved because the DC offset can generate the estimated grid frequency error of the phase-locked loop (PLL). In conventional algorithm to compensate the DC offset, the DC offset is estimated by integrating the synchronous reference frame d-axis voltage during one period of the grid voltage. The conventional algorithm has a drawback that is a slow dynamic response because monitoring the one period of the grid voltage is required. the proposed algorithm has fast dynamic response because the DC offset is consecutively estimated by transforming the d-axis voltage to synchronous reference frame without monitoring one cycle time of the grid voltage. The proposed algorithm is verified from PSIM simulation and the experiment.

A Study on an Integer Frequency Offset Estimation and Compensation for DOCSIS 3.1 Downstream

  • Bae, JaeHwui;Song, JinHyuk;Ra, Sang-Jung;Choi, Dong-Joon;Jung, Joon-Young;Hur, Namho
    • IEIE Transactions on Smart Processing and Computing
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    • v.6 no.1
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    • pp.39-46
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    • 2017
  • In this paper, we propose an integer frequency offset estimation and compensation method based on PLC preamble correlation in DOCSIS 3.1 Downstream system. The proposed method determines the PLC preamble subcarrier location recovered from PLC data and the one obtained from PLC preamble correlation. We showed the performance of PLC preamble detection in the received signal through the maximum value detection of PLC preamble correlation. Thus we can estimate and compensate for the integer frequency offset by computing the difference of PLC subcarrier locations.

Performance Improvement of an OFDM/QPSK System in Selective Fading and Frequency Offset Channel (비선택성 페이딩과 주파수 오프셋이 함께 존재하는 채널에서 OFDM/QPSK 시스템의 성능 개선)

  • 유기희;곽재민;박기식;안준배;조성언;조성준
    • Proceedings of the IEEK Conference
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    • 2001.06a
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    • pp.13-16
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    • 2001
  • In this paper, We have investigated the SER performance of a OFDM/QPSK system with carrier-frequency offset in a frequency non-selective fading channel. Adaptive linear equalizer is adopted to OFDH/QPSK systems for compensation of performance degradation according to the non-selective fading and carrier frequency offset. As a result of performance analysis, the more frequency offset is, the worse performance of OFDH/QPSK system is. However, when OFDH/QPSK system adopts the adaptive linear equalizer, the SER performance is enhanced to the limit range

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A Multiphase Compensation Method with Dynamic Element Matching Technique in Σ-Δ Fractional-N Frequency Synthesizers

  • Chen, Zuow-Zun;Lee, Tai-Cheng
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.8 no.3
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    • pp.179-192
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    • 2008
  • A multiphase compensation method with mismatch linearization technique, is presented and demonstrated in a $\Sigma-\Delta$ fractional-N frequency synthesizer. An on-chip delay-locked loop (DLL) and a proposed delay line structure are constructed to provide multiphase compensation on $\Sigma-\Delta$ quantizetion noise. In the delay line structure, dynamic element matching (DEM) techniques are employed for mismatch linearization. The proposed $\Sigma-\Delta$ fractional-N frequency synthesizer is fabricated in a $0.18-{\mu}m$ CMOS technology with 2.14-GHz output frequency and 4-Hz resolution. The die size is 0.92 mm$\times$1.15 mm, and it consumes 27.2 mW. In-band phase noise of -82 dBc/Hz at 10 kHz offset and out-of-band phase noise of -103 dBc/Hz at 1 MHz offset are measured with a loop bandwidth of 200 kHz. The settling time is shorter than $25{\mu}s$.

A Study on the Doppler Compensation Technique of 2-Step Kalman Filter in Mobile Satellite Communication System (이동위성 통신 시스템에서 2단 칼만필터에 의한 도풀러 보상기법에 관한 연구)

  • 강희조;고봉진;조성언
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.2
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    • pp.166-176
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    • 2000
  • In this paper, the LEO system signal degradation is mainly due to fading and doppler shift, so that the analysis of the signal degradation and compensation techniques are very important. This paper propose a Kalman filter based two step Automatic Frequency Control(AFC) to combat large and time variant frequency offset in low earth orbit satellite communication systems. The proposed Kalman AFC method estimates a frequency offset in two steps, I. e., coarse and fine estimations, extending the frequency acquisition range to even for than the symbol rate. Furthermore, it can track well a time variation of frequency offset. It is shown that the proposed compensator is able to compensate for doppler shift more than several KHz.

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Performance Analysis of Trellis Coded OFDM/M-ary PSK Systems in the presence of tarrier Frequency Offset (반송파 주파수 오프셋의 존재하에서 Trellis Coded OFDM/M-ary PSK 시스템의 성능 분석)

  • 조성언;박기식;오원근
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.4
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    • pp.684-691
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    • 2001
  • In this paper, the BER performance of OFDM/M-ary PSK systems is analyzed with considering carrier-frequency offset and TCM technique, which encodes and modulations simultaneously, is adopted to OFDWM-ary PSK systems for compensation of performance degradation according to carrier-frequency offset. As a result of analysis, the error performance of OFDM/M-ary PSK systems is degraded as the frequency offset is increased. And the frequency offset should be below 0.025 in order to achieve $BER= 10^{-3}$ with $E_b/N_o$ of 10 dB. Especially, when the TCM technique is adopted to OFDM/M-ary PSK systems, the performance improvement of about 4 dB is obtained in terms of $E_b/N_o$.

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