• Title/Summary/Keyword: frequency comb

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Basic RF Characteristics of Fishbone-Type Transmission Line Employing Comb-Type Ground Plane (FTLCGP) on PES Substrate for Use in Flexible Passive Circuits

  • Yun, Young;Jeong, Jang-Hyeon;Kim, Hong Seung;Jang, Nakwon
    • ETRI Journal
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    • v.37 no.1
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    • pp.128-137
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    • 2015

  • In this work, a fishbone-type transmission line employing a comb-type ground plane (FTLCGP) was fabricated on polyethersulfone (PES) substrate, and its RF characteristics were thoroughly investigated. According to the results, it was found that the FTLCGP on PES showed periodic capacitance values much higher than other types of transmission lines due to a coupling capacitance between the signal line and ground, which resulted in a reduction of wavelength and line width. Using the theoretical analysis, we also extracted the bandwidth characteristic of the FTLCGP on PES. According to the result, the FTLCGP structure showed a cut-off frequency of 280 GHz.

  • https://doi.org/10.4218/etrij.15.0114.0244 인용 PDF KSCI KPUBS

Performance Analysis of PAPR and LS Estimation in OFDM Systems

  • Khan, Latif Ullah
    • IEIE Transactions on Smart Processing and Computing
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    • v.3 no.3
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    • pp.135-141
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    • 2014

  • The inherent feature of the highly efficient spectrum usage has made Orthogonal Frequency Division Multiplexing (OFDM) preferable for Communication Standards. This study evaluated the performance of a Least Square (LS) estimator for a comb-type pilot insertion scheme over a fast fading Rayleigh channel. A High Peak-to-Average Power Ratio (PAPR) is one of the major downsides of the OFDM. The effects of an increase in the number of subcarriers on PAPR and the performance of the LS Estimator were studied. Increasing the number of subcarriers while keeping the pilots overhead constant resulted in improved performance of the LS estimator but the PAPR increased with increasing number of subcarriers. Therefore some trade-off between the number of subcarriers and the performance of the OFDM system is needed. The Mean Square Error (MSE) expression was also derived for the LS estimator in the case of a comb-type pilot arrangement. The MSE expression clearly explains the effects of the number of subcarriers on the performance of the LS estimator.

  • https://doi.org/10.5573/IEIESPC.2014.3.3.135 인용 PDF KSCI

Enhanced Amplitude Panning for Virtual Source Imaging (가상 음원 이미징을 위한 향상된 진폭 패닝 기법)

  • Hyun, Dong-Il;Park, Young-Cheol;Youn, Dae Hee
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.3
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    • pp.139-145
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    • 2013

  • In this paper, the problems of the conventional amplitude panning method for a stereophonic panning system are analyzed. We observed that the distortion showed a feedforward comb filter response. As a remedy to this distortion, we propose a stereophonic panning system using a feedback comb filter. The comb filter is designed to minimize the difference between interaural level difference(ILD) of the proposed system and that of HRTF because ILD is most salient cue for the perception of the source direction. The proposed system is configured to operate selectively for the frequency band related to the source direction. The performance of the proposed system is verified by subjective listening tests.

  • https://doi.org/10.5573/ieek.2013.50.3.139 인용 PDF KSCI

An efficient Channel Estimation Technique for Space-Time Coded OFDM Systems (시.공간 부호화된 OFDM 시스템의 효율적인 채널추정기법)

  • Jeon, Won-Gi;Baek, Gyeong-Hyeon;Jo, Yong-Su
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.8B
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    • pp.1499-1509
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    • 2000

  • In this paper, we propose an efficient channel estimation technique for space-time coded orthogonal frequency-division multiplexing (OFDM) systems with transmitter and receiver diversity. The proposed technique estimates uniquely all channel frequency responses needed in a decoder of space-time coded OFDM systems using "comb-type" raining symbols. The computational complexity of the proposed technique is reduced dramatically, compared with the previous minimum mean-squared error (MMSE) technique, due to the processing is made all in the frequency-domain. Also, several other techniques for mitigating random noise effect and tracking channel variation are discussed to further improve the performance of the proposed approach. The performances of the proposed approach are demonstrated by computer simulation for mobile wireless channels. channels.

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