• Title/Summary/Keyword: Multiple Carrier Frequency Offset

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Performance Analysis and Compensation of FH/SC-FDMA System for the High-Speed Communication in Jamming Channel (재밍 채널에서 고속 통신을 위한 주파수 도약 SC-FDMA 통신 시스템의 성능 분석과 보상)

  • Kim, Jang-Su;Jo, Byung-Gak;Baek, Gwang-Hoon;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.6
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    • pp.551-561
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    • 2009
  • FH system is very robust to the jamming interference. OFDM system is very good for the high speed communication system. But, it has high PAPR. SC-FDMA system based on OFT-spread OFDM was proposed to reduce high PAPR. Therefore, in this paper, we like to introduce the FH system into SC-FDMA system, which can be best solution to the jamming hostile environment and for the high power efficiency. Also, OFDM is very sensitive to ICI. Especially, ICI generated by frequency offset and phase noise breaks the orthogonality among sub-carriers, which seriously degrades the system performance. We analyze the performance of the FH SC-FDMA system in the PBJ and MTJ channel. In this paper, the ICI effects caused by phase noise, frequency offset and Doppler effects are analyzed and we like to propose the PNFS algorithm in the equalizer to compensate the ICI influences. Through the computer simulations, we can confirm the performance improvement.

Performance Evaluation of MC-DS-CDMA Systems using STBC Antenna Diversity (STBC 안테나 다이버시티를 이용한 MC-DS-CDMA 시스템의 성능 분석)

  • Choi, Seung-Kuk
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.2
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    • pp.390-396
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    • 2009
  • MC-DS-CDMA is technique where a single data symbol is transmitted at multiple subcarriers which are orthogonal to each other. With this technique, frequency diversity can be achieved. The performance of PSAM MC-DS-CDMA system with the application of STBC antenna diversity is analyzed. The BER performance of this system over multipath fading environment is evaluated, considering the channel estimation ernr, carrier frequency offset, and the nonlinear high power amplifier.

Performance Evaluation of MC-DS-CDMA Transmission Technique using MRRC Antenna Scheme (MRRC 안테나 기법을 이용한 MC-DS-CDMA 전송방식의 성능 분석)

  • Choi, Seung-Kuk
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.14 no.4
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    • pp.817-823
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    • 2010
  • MC-DS-CDMA is technique where a single data symbol is transmitted at multiple subcarriers which are orthogonal to each other. With this technique, frequency diversity can be achieved. The performance of PSAM MC-DS-CDMA system with the application of MRRC antenna diversity is analyzed. The BER performance of this system over multipath fading environment is evaluated, considering the channel estimation error, carrier frequency offset, and the nonlinear high power amplifier.

Multiple Orthogonal Subcarrier Modulation based High-Speed UHF RFID System for Multiple-/Dense-Interrogator Environments (다중/집중리더 환경에 적합한 다중 직교 부반송파 변조 기반 고속 UHF RFID 시스템)

  • Park, Hyung Chul
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.9
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    • pp.67-74
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    • 2016
  • This paper presents a novel multiple orthogonal subcarrier modulation based UHF band RFID communication system. In tag-to-reader communication, the demonstration system can deliver 1.6 Mbps through four subcarriers. To improve data rate while suppressing increase in circuit complexity, tag employs square-waves as the subcarriers and uses individual load modulators for each subcarrier. By using multiple orthogonal subcarrier based modulation, proposed communication system can be operated under existing UHF band RFID regulation. In reader, an OFDM demodulator is used. Since the tag backscatters the reader's CW carrier, carrier frequency offset compensation is not necessary in reader demodulator. Experimental results show that the demonstration system achieves a bit error rate of 10-5 at an Eb/N0 of 10.8 dB.

Algorithm for the Improvement of Time and Frequency Synchronization Performance in OFDMA System (OFDMA 시스템의 시간 및 주파수 동기 성능 향상을 위한 동기화 알고리즘)

  • Noh Jung-Ho;Sun Tae-Hyoung;Chang Kyung-Hi
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.4A
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    • pp.402-411
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    • 2006
  • In OFDMA system, multiple users transmit signal through the subcarriers assigned to the user. Capabilities of high data-rate transmission in OFDMA system come from the ability to compensate the ICI (Inter Carrier Interference) using a single-tap equalizer and to implement transmitter and receiver by employing high speed FFT circuitry. Issues of time and frequency synchronization in OFDM system is quite essential to preserve the orthogonality among subcarriers not to produce ICI. In this paper, we Int analyze the preamble used in 802.16 d/e and WiBro system. Then we propose an effective timing synchronization algorithm, which is more accurate than the conventional one in the sense of timing position, and integral frequency offset estimation scheme for the simultaneouse estimation of the fractional and integral frequency offset. Through the simulation utilizing the proposed synchronization algorithm and structure, we show that the performance degradation due to the adjacent channel interference can be mitigated for the than conventional ones.

Performance Evaluation of MC-DS-CDMA Systems over Time Variant Channels (시변 채널 하에서의 MC-DS-CDMA 시스템의 성능 분석)

  • Choi, Seung-Kuk
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.14 no.3
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    • pp.581-586
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    • 2010
  • MC-DS-CDMA is technique where a single data symbol is transmitted at multiple subcarriers which are orthogonal to each other. With this technique, frequency diversity can be achieved. Time variant channels lead to interchannel interference which increases the bit error rate for MC-DS-CDMA systems. The performance of PSAM MC-DS-CDMA system over time variant channels is analyzed. The BER performance of this system over multipath fading environment is evaluated, considering the channel estimation error, carrier frequency offset.

A 2.4GHz Back-gate Tuned VCO with Digital/Analog Tuning Inputs (디지털/아날로그 입력을 통한 백게이트 튜닝 2.4 GHz VCO 설계)

  • Oh, Beom-Seok;Lee, Dae-Hee;Jung, Wung
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 2003.11a
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    • pp.234-238
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    • 2003
  • In this work, we have designed a fully integrated 2.4GHz LC-tuned voltage-controlled oscillator (VCO) with multiple tuning inputs for a $0.25-{\mu}m$ standard CMOS Process. The design of voltage-controlled oscillator is based on an LC-resonator with a spiral inductor of octagonal type and pMOS-varactors. Only two metal layer have been used in the designed inductor. The frequency tuning is achieved by using parallel pMOS transistors as varactors and back-gate tuned pMOS transistors in an active region. Coarse tuning is achieved by using 3-bit pMOS-varactors and fine tuning is performed by using back-gate tuned pMOS transistors in the active region. When 3-bit digital and analog inputs are applied to the designed circuits, voltage-controlled oscillator shows the tuning feature of frequency range between 2.3 GHz and 2.64 GHz. At the power supply voltage of 2.5 V, phase noise is -128dBc/Hz at 3MHz offset from the carrier, Total power dissipation is 7.5 mW.

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A 2.4 ㎓ Back-gate Tuned VCO with Digital/Analog Tuning Inputs (디지털/아날로그 입력을 통해 백게이트 튜닝을 이용한 2.4 ㎓ 전압 제어 발진기의 설계)

  • Oh, Beom-Seok;Hwang, Young-Seung;Chae, Yong-Doo;Lee, Dae-Hee;Jung, Wung
    • Proceedings of the IEEK Conference
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    • 2003.11c
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    • pp.32-36
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    • 2003
  • In this work, we have designed a fully integrated 2.4GHz LC-tuned voltage-controlled oscillator (VCO) with multiple tuning inputs for a 0.25-$\mu\textrm{m}$ standard CMOS process. The design of voltage-controlled oscillator is based on an LC-resonator with a spiral inductor of octagonal type and pMOS-varactors. Only two metal layer have been used in the designed inductor. The frequency tuning is achieved by using parallel pMOS transistors as varactors and back-gate tuned pMOS transistors in an active region. Coarse tuning is achieved by using 3-bit pMOS-varactors and fine tuning is performed by using back-gate tuned pMOS transistors in the active region. When 3-bit digital and analog inputs are applied to the designed circuits, voltage-controlled oscillator shows the tuning feature of frequency range between 2.3 GHz and 2.64 GHz. At the power supply voltage of 2.5 V, phase noise is -128dBc/Hz at 3MHz offset from the carrier. Total power dissipation is 7.5 mW.

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Performance Evaluation of Uplink MC-DS-CDMA Transmission Systems (상향링크 MC-DS-CDMA 전송 시스템의 성능 분석)

  • Choi, Seung-Kuk
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.14 no.12
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    • pp.2649-2656
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    • 2010
  • MC-DS-CDMA is technique where a single data symbol is transmitted at multiple subcarriers which are orthogonal to each other. With this technique, frequency diversity can be achieved. The performance of uplink MC-DS-CDMA systems with the application of MRRC antenna diversity over time variant channels is analyzed. Time variant channels lead to interchannel interference which increases the bit error rate in the receiver. The BER performance of this system over multipath fading environment is evaluated, considering the channel estimation error, carrier frequency offset, and the nonlinear high power amplifier.

A Research on the Bandwidth Extension of an Analog Feedback Amplifier by Using a Negative Group Delay Circuit (마이너스 군지연 회로를 이용한 아날로그 피드백 증폭기의 대역폭 확장에 관한 연구)

  • Choi, Heung-Gae;Kim, Young-Gyu;Shim, Sung-Un;Jeong, Yong-Chae;Kim, Chul-Dong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.10
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    • pp.1143-1153
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    • 2010
  • In this paper, we propose an alternative method to increase the distortion cancellation bandwidth of an analog RF feedback power amplifier by using a negative group delay circuit(NGDC). A limited distortion cancellation bandwidth due to the group delay(GD) mismatch discouraged the use of feedback technique in spite of its powerful linearization performance. With the fabricated NGDC with positive phase slope over frequency, the feedback amplifier of the proposed topology experimentally achieved adjacent channel leakage ratio(ACLR) improvement of 15 dB over 50 MHz bandwidth at wideband code division multiple access(WCDMA) downlink band when tested with 2-carrier WCDMA signal. At an average output power of 28 dBm, ACLR of 25.1 dB is improved to obtain -53.2 dBc at 5 MHz offset.