• Title/Summary/Keyword: STFBC

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Phase Noise Compensation in OFDM Communication System by STFBC Method (OFDM 통신 시스템에서 STFBC 기법을 이용한 위상잡음 보상)

  • Li Yingshan;Ryu Heung-Gyoon;Jeong YoungHo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.10 s.101
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    • pp.1043-1049
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    • 2005
  • In OFDM system suitable for high capacity high speed broadband transmission, ICI caused by phase noise degrades system performance seriously by destroying the orthogonality among subcarriers. In this paper, a new STFBC method combining ICI self cancellation scheme and antenna, time, frequency diversity is studied to reduce ICI effectively. CPE and ICI are analyzed by the phase noise linear approximation method in the proposed STFBC OFDM system. CIR, PICR and BER are discussed to compare the system performance degraded by phase noise of PLL. As results, STFBC method significantly reduces ICI. Furthermore, the SCI that usually happens in the traditional STBC, SFBC diversity coding method can be easily avoided.

Block Coding Techniques with Cyclic Delay Diversity for OFDM Systems

  • Du, Ting;Hui, Bing;Chang, Kyung-Hi
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.9A
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    • pp.867-873
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    • 2008
  • Cyclic delay diversity (CDD) is considered as a simple approach to exploit the frequency diversity in OFDM system. In this paper, we apply CDD to the conventional STBC/SFBC/STFBC-OFDM transmit diversity schemes for Rayleigh fading channels. We compare the performances of STBC/SFBC/STFBC with and without CDD schemes. Simulation results show that the combination of block coding with CDD works well when using the ITU-R M. 1225 channel for both Pedestrian A (Ped A) channel with the mobility of 3 km/h, and Vehicular A (Veh A) channel with the mobility of 120km/h. For a BER of $10^{-3}$, compared to the conventional block coding schemes, a gain of 2dB, 4dB, and 5dB is obtained under the Ped A channel environment by STBC-OFDM, SFBC-OFDM and STFBC-OFDM with CDD, respectively Under the Veh A channel. gains by the combined schemes are 6dB, 2dB, and 4dB, respectivcly.

A Full Rate Quasi-orthogonal STF-OFDM with DAC-ZF Decoder over Wireless Fading Channels

  • Jin, Ji-Yu;Ryu, Kwan-Woong;Park, Yong-Wan
    • ETRI Journal
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    • v.28 no.1
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    • pp.87-90
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    • 2006
  • In this letter, we propose a quasi-orthogonal space-time-frequency (QOSTF) block coded orthogonal frequency division multiplexing (OFDM) that can achieve full symbol rate with four transmit antennas. Since the proposed QOSTF-OFDM cannot achieve full diversity, we use a diversity advantage collection with zero forcing (DAC-ZF) decoder to compensate the diversity loss at the receiving side. Due to modulation advantage and collected diversity advantage, the proposed scheme exhibits a better bit-error rate performance than other orthogonal schemes.

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Performance Evaluation of Fill Rate Quasi-orthogonal STF-OFDM with DAC-ZF Decoder for Four Transmit Antennas MIMO System (4개의 송신 안테나 MIMO 시스템을 위한 DAC-ZF 수신 기법과 결합된 Full Rate 준직교 QOSTF-OFDM 관한 연구)

  • Jin, Ji-Yu;Ryu, Kwan-Woong;Park, Yong-Wan
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.11A
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    • pp.1092-1100
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    • 2006
  • In this paper, we propose a full rate quasi-orthogonal space-time-frequency block coded orthogonal frequency division multiplexing(QOSTF-OFDM) that can achieve full symbol rate with four transmit antennas. Sincr: the proposed QOSTF-OFDM can not achieve full diversity, we use diversity advantage collection with zero forcing (DAC-ZF) decoder to compensate the diversity loss at receive side. At the same frequency efficiency, compared with linear orthogonal space-time codes which can not achieve full rate with four transmit antennas over complex constellations, low level modulation can be employed by proposed scheme due to its full rate, i.e., modulation advantage can be achieved. Due to modulation advantage and collected diversify advantage, the proposed scheme exhibits better BER performance than other orthogonal schemes.