• Title/Summary/Keyword: 대역폭 조절

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Network Monitoring Mechanism For High Quality Real-Time Streaming Service (고품질 실시간 스트리밍 서비스 제공을 위한 네트워크 모니터링 기법)

  • Kim, Yong-Sul;Kim, Hwa-Sung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.11B
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    • pp.969-978
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    • 2006
  • Recently, there has been explosive growth in Internet service contents, and we have witnessed the emergence of many real-time applications on the Internet. These types of applications require special support from the underlying network such as reliability, timeless, and guaranteed delivery, as well as different levels of service quality. Estimation network status and transcoding data rate are researching for QoS of multimedia service by using the RTP/RTCP. We propose two schemes that the way to calculate the one-way delay by expanding the structure of RTP/RTCP in Internet that provides us 'best effort' service and to estimate the network condition by using this in this paper. And we propose the dynamic RTCP mechanism based on one-way delay to deal with rapidly changed network situation immediately. In simulation, proposed monitoring schemes using the one-way delay has similar in performance to monitoring schemes using the GPS, proposed dynamic RTCP scheme obtain the desired result of decreased packet loss rate by sending RTCP RR packet lower than other schemes.

A Study on Fluorescence Imaging System Characteristics depending on Tilting of Band Pass Filter (대역통과필터의 기울임에 따른 형광 이미징 시스템 특성 분석 연구)

  • Kim, Taehoon;Cho, Sang Uk;Park, Chan Sik;Lee, Hak-Guen;Kim, Doo-In;Jeong, Myung Yung
    • Journal of the Microelectronics and Packaging Society
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    • v.23 no.2
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    • pp.85-89
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    • 2016
  • In this paper, we studied effects of tilting angle of band pass filter on the characteristics of fluorescence imaging system. Theoretical modeling showed that transmittance and filtering range are highly dependent on the tilting angle. Measurements on transmittance as a function of wavelength confirmed that changes in transmittance and the band filter range are in good agreement with theoretical prediction. Therefore, characteristics of band pass filter can be precisely tuned by altering tilting angle of band pass filter in order to enhance fluorescence signal in bio imaging system.

Frequency-Tunable Bandpass Filter Design Using Active Inductor (능동 인덕터를 이용한 주파수 가변형 대역통과 필터 설계)

  • Lee, Seok-Jin;Choi, Seok-Woo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.7
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    • pp.3425-3430
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    • 2013
  • The fast-growing market in wireless communications has led to the development of multi-standard mobile terminals. In this paper, a frequency-tunable active RC bandpass filter for multi-standards wireless communication system is designed using an active inductor. The conventional bandpass filter design methods employ the high order filter or high quality factor Q to improve the stopband attenuation characteristics and frequency selectivity of the passband. The proposed bandpass filter based on the high Q active inductor has an improved frequency characteristics. The center frequency and gain of the designed bandpass filter is tuned by employing the tuning circuit. We have performed the simulation using TSMC $0.18{\mu}m$ process parameter to analyze the characteristics of the designed active RC bandpass filter. The bandpass filter with Q=20.5 has 90MHz half power bandwidth at the center frequency of 1.86GHz. Moreover, the center frequency of the proposed bandpass filter can be tuned between 1.86~2.38GHz for the multi-standards wireless communication system using the capacitor of the tuning circuit.

Design of Triangular-Patch Type Low Pass Filter (삼각패치형 저역 통과 여파기의 구현)

  • Oh, Song-Yi;Hwang, Hee-Yong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.3
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    • pp.355-360
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    • 2012
  • In this paper, an stepped-impedance low pass filter(SI-LPF) of triangular-patch type is proposed. A SI-LPF designed according to the standard SI-LPF design procedure is folded as a right angled triangle. The figure of merits of this structure are the adjustabilities of the cut off frequency, the stopband and the attenuation pole frequency of the proposed LPF by varying the resultant slots after folding the SI-LPF compactly for miniaturization. The size of the fabricated LPF is $13.75mm{\times}6.875mm$, which is 24.4 % reduced one compared to that of the conventional SI-LPF. The measured results of the LPF show return loss of less than -10 dB at passband, insertion loss of less than -10 dB at stopband and wide stopband from 3.5 GHz to 10 GHz (about $3f_c$).

Implementation of Co-Channel Radio Relay System and Its Performance Evaluation with Synchronous Digital Hierarchy (동기식 디지틀 계위의 동일채널 무선 전송장치구현 및 성능분석)

  • 서경환
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.35D no.11
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    • pp.10-22
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    • 1998
  • In this paper, as a way of improving the availability and spectral efficiency of radio relay system, a co-channel radio relay system based upon the synchronous digital hierarchy is developed and its performance measured by 64-QAM with a never-seen multi-purpose ASIC chip is illustrated. This system provides a couple of transmission capacity compared with alternative channel arrangement. By adopting a powerful complex 13-tap adaptive time domain equalizer and cross-pol interference canceller, improvement of more than 1.5 ~ 2.0 dB in signature is obtained in comparison to 9 or 11-tap adaptive time domain equalizer, and about 22.5 dB in improvement factor of cross-pol interference canceller is achieved at C/N of 24.5 dB. In addition, digital filter makes it possible to optimize the occupied bandwidth by selecting an appropriate roll-off factor externally. It is expected that co-channel radio relay system with the powerful multi-purpose ASIC chip plays a key role in creating a value-added product, reliability, and reducing the outage time.

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Triple-band Compact Chip Antenna Using Parasitic Meander line and Stacked Meander line for GPS/IMT2000/Wireless LAN (기생 미엔더 라인과 적층 미엔더 라인을 이용한 GPS/IMT2000/Wireless LAN 삼중대역 소형 칩 안테나)

  • Kim Ho-Yong;Lee Hong-Min
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.5 s.347
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    • pp.156-161
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    • 2006
  • In this paper, GPS/IMT2000/Wireless LAN compact chip antenna is designed for mobile communication system. The proposed antenna size is $10.2mm{\times}21mm{\times}1mm$. It consists of three meander lines. dual resonance frequencies is achieved by two effective current paths using two meander lines and via. also The parasitic meander line structure is added. The coupling is adjusted by arranging parasitic meander line for triple-band. The fabricated antenna achieve triple-band. The resonance frequencies are 1.672GHz, 2.092GHz, 2.504GHz. The impedance bandwidths of each resonance frequencies are 156MHz, 272MHz, 64MHz. The maximum radiation gains of fabricated antenna are 0.08dBi, 1.67dBi, -1.44dBi. The proposed antenna achieve quasi monopole radiation pattern.

Adaptive Energy Detection for Spectrum Sensing in Cognitive Radio (인지 무선 시스템에서 스펙트럼 감지를 위한 적응 에너지 검파)

  • Lim, Chang-Heon
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.8
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    • pp.42-46
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    • 2010
  • Energy detection based spectrum sensing compares the energy of a received signal from a primary user with a detection threshold and decides whether it is active or not in the frequency band of interest. Here the detection threshold depends on not only a target false alarm probability but also the level of the noise energy in the band. So, if the noise energy changes, the detection threshold must be adjusted accordingly to maintain the given false alarm probability. Most previous works on energy detection for spectrum sensing are based on the assumption that noise energy is known a priori. In this paper, we present a new energy detection scheme updating its detection threshold under the assumption that the noise is white, and analyze its detection performance. Analytic results show that the proposed scheme can maintain a target false alarm rate without regard to the noise energy level and its spectrum sensing performance gets better as the time bandwidth product of the signal used to estimate the noise energy increases.

A Video Streaming Scheme for Minimizing Viewpoint Switching Delay in DASH-based Multi-view Video Services (DASH 기반의 다시점 비디오 서비스에서 시점전환 지연 최소화를 위한 비디오 전송 기법)

  • Kim, Sangwook;Yun, Dooyeol;Chung, Kwangsue
    • Journal of KIISE
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    • v.43 no.5
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    • pp.606-612
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    • 2016
  • The multi-view video service based on the DASH(Dynamic Adaptive Streaming over HTTP) switches the viewpoint or object which is selected by the user among the multiple video streams captured by multiple cameras. However, the problem is that the conventional DASH-based multi-view video service takes a long time to switch the viewpoint. The reason is that the conventional scheme switches to the new video stream after consuming all buffered segments of the previous video stream. In this paper, we propose a video streaming scheme for minimizing the viewpoint switching delay in the DASH-based multi-view video service. In order to minimize the viewpoint switching delay, the proposed scheme configures the video streams by controlling the GoP (Group of Pictures) size and controls the client buffer based on bandwidth estimation and playback buffer occupancy. Through the experimental results, we prove that the proposed scheme reduces the viewpoint switching delay.

A Low-pass Filter with Wide-stop Band Using Radial-shaped Open Stub (광대역의 저지대역을 갖는 부채꼴 형태의 개방형 스터브를 이용한 저역통과 여파기)

  • Yoon, Ki-cheol;Kim, Seong-cheol
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.7
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    • pp.1237-1242
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    • 2016
  • In this paper, the low pass filter with harmonics suppression and rejection using parallel coupled-line and radial type open stub is presented. And the resultant characteristic of the proposed low pass filter is that the harmonics are suppressed and rejected in wide bandwidth due to the parallel coupled-line structure. The open stub of a low pass filter is constructed in radial type which can be used to adjust the size of filter. The size of the proposed low pass filter is $6.98{\times}7.60mm2$ and the cut off frequency is 2.45 GHz. And the filter is economical in unit cost and can be constructed easily and has the merit of mass product because the filter is composed of distributed element. Also, the widely rejected harmonics is 128 % in the bandwidth and the insertion and return losses of the low pass filter are 1.07 dB and 19.5 dB, respectively.

Design of Improved DFT-s-SSB OFDM and Spectral Efficiency in Multiuser Environment (개선된 DFT-s-SSB OFDM 설계와 다수 사용자 환경에서의 스펙트럼 효율)

  • An, Changyoung;Lee, Jungu;Jang, Kyeongsoo;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.3
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    • pp.192-199
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    • 2018
  • This paper proposes an improved discrete Fourier transform spread single sideband(DFT-s-SSB) orthogonal frequency division multiplexing(OFDM) system that solves the problems of conventional DFT-s-SSB OFDM systems. Conventional DFT-s-SSB systems use pulse amplitude modulation(PAM) for applying SSB modulation. The higher the modulation level, the worse is the BER performance. Further, transmission is possible only through the lower sideband(LSB) spectrum. When transmitting using the LSB and upper sideband(USB) spectra simultaneously, interference occurs and spectrum recovery is not performed correctly. To solve this problem, the proposed system applies the 2/3 convolution coding to improve the bit error rate(BER) performance, adjusts the DFT size, and selects the USB spectrum to utilize the remaining spectrum resources. In addition, when using this system in an environment that supports multiuser or limited bandwidth, it uses only half of the spectrum; therefore, it can utilize the remaining spectrum resources and improve the spectral efficiency.