• Title/Summary/Keyword: Windowing system

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Fuzzy Control of Distturbance-added Servo System Using Modified Windowing Technique (수정 윈도잉 기법을 이용한 외란부가 서보 시스템의 퍼지 제어)

  • 이오걸;노중화;이준탁;우정인
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.17 no.12
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    • pp.1475-1483
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    • 1992
  • In this paper, a Fuzzy control approach of disturbance added servo system using MWT(modified windowing technique) was proposed. Because conventional windowing techniques adjust stepwisely a series of scale factors, even small disturbances make system unstable. But the proposed MWT adjusts exponentially. Therefore a servo system which applied this technique had coped excellenlty with internal and external disturbances, and also had decreased substantially steady-state deviation.

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Performance Analysis of a Noncoherent OOK UWB System Based on Power Detection in Indoor Wireless Channels (실내 무선 채널에서 전력검출 기반 Noncoherent OOK UWB 시스템의 성능 분석)

  • Oh Jongok;Yang Suckchel;Shin Yoan
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.11C
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    • pp.1498-1509
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    • 2004
  • In this paper, we evaluate the performance of a noncoherent OOK (On-Off Keying) UWB (Ultra Wide Band) system based on power detection with noise power calibration and noise power windowing for ubiquitous sensor network applications in typical indoor wireless channels. Utilizing noise power calibration and noise power windowing, the current noise information can be initially or adaptively provided to determine suitable detection threshold value for signal demodulation. Simulation results show that the noncoherent OOK UWB system using noise power calibration achieves good BER (Bit Error Rate) performance which is favorably comparable to that of the system using the ideal adaptive threshold, while maintaining simple receiver structure. However, despite the serious loss of the data transmission rate, the performance improvement by noise power windowing is not so remarkable. furthermore, these performance results are similarly maintained in BEE 802.15 Task Group 3a UWB indoor channel model, and it is also revealed that the BER performance can be significantly improved by increasing the pulse repetition rate.

A New Peak-Windowing Algorithm with Window-length Adaptation for PAPR Reduction of OFDM Systems (OFDM 시스템의 PAPR 저감을 위한 가변적인 윈도우 크기를 적용한 Peak Windowing 기법)

  • Lee, Sung-Eun;Bang, Keuk-Joon;Park, Myong-Hee;Lee, Young-Soo;Hong, Dae-Sik
    • Proceedings of the IEEK Conference
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    • 2005.11a
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    • pp.185-188
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    • 2005
  • This paper proposes a new peak-windowing algorithm with window-length adaptation for peak-to-average power reduction (PAPR) of orthogonal frequency division multiplexing (OFDM) systems. Conventional peak windowing algorithm has advantages, such as moderate system complexity with good spectral shape. However, adjacent peak signals within the length of window functions produce the distortion of signal amplitude since window functions might overap with each other. These undesired characteristics of conventional peak windowing algorithm result in the degradation of BER performance. The proposed algorithm outperforms the conventional one with the aid of window-length adaptation. Simulation results show the efficiency of the proposed algorithm under the environments of WiBro downlink systems.

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Sidelobe Suppression Technique in OFDM Systems for Spectrum Sharing (스펙트럼 공유를 위한 직교 주파수 분할 다중 (OFDM) 시스템에서의 사이드로브 억압 기법)

  • Hwang, Hu-Mor;Ahmed, Saleem
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.8
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    • pp.1633-1637
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    • 2009
  • We propose a new technique for sidelobe suppression in orthogonal frequency division multiplexing (OFDM) systems. Sidelobe suppression is an essential technique to design OFDM based overlay system. The proposed technique is based on the combination of the multiple choice sequence (MCS) with the conventional windowing of OFDM signal in time domain. The MCS is choosing the one sequence which has lowest power in sidelobes from the produced set of sequences. The main advantage of proposed technique is that it fully utilizes the available bandwidth to transmit data. Simulation results show that by combining MCS with conventional windowing technique, the sidelobes in OFDM system can be significantly reduced

WOI : Determining Area of Interest and Gaze Analysis for Task Switching in a Window Unit Behavior Measurement in Windowing System GUI (WOI : 윈도윙 시스템 GUI에서의 창 단위 작업 전환 행위 측정을 위한 관심영역 지정 및 시선 분석)

  • Ko, Eunji;Choi, Sun-Young
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.5
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    • pp.963-971
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    • 2016
  • This paper is a research of gaze analysis for measuring task switching behavior at multiple windows in GUI of windowing system. Previous methods that define area of interest for categorizing gaze had difficulties to define dynamic content that disappears or changes over time. On the other hand, this study suggests a new method to categorize gaze that defines Area of interest in a unit of window during the eye tracking experiment. In this paper, we constructed the conception of WOI(Window of Interest) in GUI of windowing system. Therefore, we developed a system using an eye tracker device and implemented a number of experiments. In addition, we analyzed the number of task switching and proportion of watched content. The method in the study comprehend from previous researches as it can measure and analyze the multi-tasking behaviors using multiple numbers of windows.

The Effects of Time Domain Windowing and Detection Ordering on Successive Interference Cancellation in OFDM Systems over Doubly Selective Channels (이중 선택적 채널 OFDM 시스템에서 시간 영역 윈도우와 검출 순서가 순차적 간섭 제거에 미치는 영향)

  • Lim, Dong-Min
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.6
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    • pp.635-641
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    • 2010
  • Time-varying channel characteristics in OFDM systems over doubly selective channels cause inter-carrier interferences(ICI) in the frequency domain. Time domain windowing gives rise to restriction on the bandwidth of the frequency domain channel matrix and makes it possible to approximate the OFDM system as a simplified linear input-output model. When successive interference cancellation based on linear MMSE estimation is employed for channel equalization in OFDM systems, symbol detection ordering produces considerable effects on overall system performances. In this paper, we show the reduction of the residual ICI by time domain windowing and the resultant performance improvements, and investigate the effects of SINR- and CSEP-based symbol detection ordering on the performance of successive interference cancellation.

Performance analysis of UWB receiver using PPM and BPSK modulation scheme in the LR-WPAN System (LR-WPAN 시스템에서 PPM+BPSK 변조 방식을 사용하는 UWB 송수신기의 성능 분석)

  • Lee, Kyoung-Tak;Lim, Dong-Guk;Sohn, Sung-Hwan;Kim, Jae-Moung
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.5 no.2 s.10
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    • pp.19-28
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    • 2006
  • In the IEEE 802.15.4a system, they require simple, economical and low power consumption transmitter and receiver to transmit low rate data and to identify distance and location. To meet these requirements, LR-WPAN system use transmitter and receiver with simple modulation and demodulation scheme. In this paper, use PPM+BPSK modulation and windowing scheme to overcome multipath fading effect. Then we apply this channel estimation scheme to LR-WPAN system and compare performance depends on transmitter scheme. Proposed method using preamble to find channel characteristic out and we compensate distorted data with that information. Therefore we can detect signal easily at the demodulation part. Simulation result shows that performance evaluation is greater at the NLOS channel than LOS channel no matter what the receiver scheme.

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Performance Evaluation of a Windowed-Sinc Function-Based PAPR Reduction Scheme for OFDM Polar Transmitters (OFDM polar transmitter를 위한 windowed-sinc 함수 기반의 PAPR 감소기법의 성능평가)

  • Seo, Man-Jung;Shim, Hee-Sung;Im, Sung-Bin
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.1
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    • pp.10-18
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    • 2010
  • The polar transmitter is applied to the narrowband communication systems such as GSM (Global System for Mobile Communications), EDGE (Enhanced Data Rates for GSM Evolution), and GPRS (General Packet Radio Service). To apply polar transmitter for the wideband communication like OFDM (Orthogonal Frequency Division Multiplexing) where the high PAPR (Peak-to-Average Power Ratio) problem occurs, this paper proposes a windowed-sinc function based PAPR reduction scheme. The proposed algorithm mitigates the effect of excessive suppression due to successive peaks or relatively high peaks of the signal. The BER (Bit Error Rate) and EVM (Error Vector Magnitude) performances are measured for various window types and lengths. The simulation results demonstrate that the proposed algorithm achieves significant improvement in terms of BER and PAPR reduction performance with similar spectrum performance to the conventional peak windowing scheme.

Performance Evaluation of Eureka 147 DAB System with Signal Distortion Techniques (Signal Distortion Techniques을 적용한 Eureka 147 DAB 시스템의 성능평가)

  • 정영호;박소라;이수인;김환우
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2001.11b
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    • pp.71-76
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    • 2001
  • OFDM(Orthogonal Frequency Division Multiplexing)의 단점인 높은 PAPR(Peak-to-Average Power Ratio)을 개선하기 위한 방법 중에서 SDT(Signal Distortion Technique)는 전송시스템의 규격 및 수신기의 변경 없이도 적용 가능한 이점이 있다. 본 논문에서는 SDT에 속하는 clipping과 peak windowing 기법을 Eureka 147 DAB(Digital Audio Broadcasting) 시스템에 적용하여 얻은 BER 및 PSD 성능결과를 토대로 PAPR 개선 정도에 따른 시스템의 요구 $Es/N_0$ 및 out-of-band의 PSD 열화 정도를 분석하였다. Hamming windowing을 적용한 경우, PAPR 4㏈에서 clipping에 비해 요구 $Es/N_0$는 비슷한 열화정도가 나타났으나, out-of-band의 PSD는 5dB 정도 개선되는 성능을 보였다.

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A Spectral Smoothing Algorithm for Unit Concatenating Speech Synthesis (코퍼스 기반 음성합성기를 위한 합성단위 경계 스펙트럼 평탄화 알고리즘)

  • Kim Sang-Jin;Jang Kyung Ae;Hahn Minsoo
    • MALSORI
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    • no.56
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    • pp.225-235
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    • 2005
  • Speech unit concatenation with a large database is presently the most popular method for speech synthesis. In this approach, the mismatches at the unit boundaries are unavoidable and become one of the reasons for quality degradation. This paper proposes an algorithm to reduce undesired discontinuities between the subsequent units. Optimal matching points are calculated in two steps. Firstly, the fullback-Leibler distance measurement is utilized for the spectral matching, then the unit sliding and the overlap windowing are used for the waveform matching. The proposed algorithm is implemented for the corpus-based unit concatenating Korean text-to-speech system that has an automatically labeled database. Experimental results show that our algorithm is fairly better than the raw concatenation or the overlap smoothing method.

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