• Title/Summary/Keyword: SF-OFDM

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Implementation of WLAN Baseband Processor Based on Space-Frequency OFDM Transmit Diversity Scheme (공간-주파수 OFDM 전송 다이버시티 기법 기반 무선 LAN 기저대역 프로세서의 구현)

  • Jung Yunho;Noh Seungpyo;Yoon Hongil;Kim Jaeseok
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.42 no.5 s.335
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    • pp.55-62
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    • 2005
  • In this paper, we propose an efficient symbol detection algorithm for space-frequency OFDM (SF-OFDM) transmit diversity scheme and present the implementation results of the SF-OFDM WLAN baseband processor with the proposed algorithm. When the number of sub-carriers in SF-OFDM scheme is small, the interference between adjacent sub-carriers may be generated. The proposed algorithm eliminates this interference in a parallel manner and obtains a considerable performance improvement over the conventional detection algorithm. The bit error rate (BER) performance of the proposed detection algorithm is evaluated by the simulation. In the case of 2 transmit and 2 receive antennas, at $BER=10^{-4}$ the proposed algorithm obtains about 3 dB gain over the conventional detection algorithm. The packet error rate (PER), link throughput, and coverage performance of the SF-OFDM WLAN with the proposed detection algorithm are also estimated. For the target throughput at $80\%$ of the peak data rate, the SF-OFDM WLAN achieves the average SNR gain of about 5.95 dB and the average coverage gain of 3.98 meter. The SF-OFDM WLAN baseband processor with the proposed algorithm was designed in a hardware description language and synthesized to gate-level circuits using 0.18um 1.8V CMOS standard cell library. With the division-free architecture, the total logic gate count for the processor is 945K. The real-time operation is verified and evaluated using a FPGA test system.

Efficient Symbol Detection Algorithm for Space-frequency OFDM Transmit Diversity Scheme (공간-주파수 OFDM 전송 다이버시티 기법을 위한 효율적인 심볼 검출 알고리즘)

  • Jung Yun ho;Kim Jae seok
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.4C
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    • pp.283-289
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    • 2005
  • In this paper, we propose two efficient symbol detection algorithms for space-frequency OFDM (SF-OFDM) transmit diversity scheme. When the number of sub-carriers in SF-OFBM scheme is small, the interference between adjacent sub-carriers may be generated. The proposed algorithms eliminate this interference in a parallel or sequential manlier and achieve a considerable performance improvement over the conventional detection algorithm. The bit error rate (BER) performance of the proposed detection algorithms is evaluated by the simulation. In the case of 2 transmit and 2 receive antennas, at $BER=10^{-4}$ the proposed algorithms achieve the gain improvement of about 3 dB. The symbol detectors with the proposed algorithms are designed in a hardware description language and synthesized to gate-level circuits with the $0.18{\mu}m$ 1.8V CMOS standard cell library. With the division-free architecture, the proposed SF-OFDM-PIC and SF-OFDM-SIC symbol detectors can be implemented using 140k and 129k logic gates, respectively.

Performance Evaluation of Space Time Frequency OFDM System using Super-Orthogonal Space Time Trellis Code Transmission Matrix (Super-Orthogonal STTC 전송 행렬을 이용한 STF-OFDM 시스템의 성능 평가)

  • Seo, Myoung-Seok;Shin, Chul-Min;Kim, Yoo-Mi;Kwak, Kyung-Sub
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.5 no.3 s.11
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    • pp.29-39
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    • 2006
  • In this paper, we propose an efficient method to detect the signal and evaluate performance of the system in frequency selective fading channel. We combine proposed system with OFDM (Orthogonal Frequency Division Multiplexing) to improve performance of the system. First, we study the SOSTTC-OFDM system using two transmit antenna and one receive antenna, and compare performance of the proposed space-time coded OFDM with that of previous system. We expand this system to the system using four transmit antennas with the proposed decoding method. Simulation results show that the proposed decoding method can detect the signal efficiently, and we identify that the performance of the proposed system is shown with varying doppler frequency in frequency selective fading channel.

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STF-OFDM Transmission Scheme with Frequency Diversity (주파수 다이버시티를 갖는 STF-OFDM 전송 기법)

  • 박상순;황호선;백흥기
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.2C
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    • pp.206-212
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    • 2004
  • In this paper, we propose a STF(Space-Time-Frequency) coded OFDM(Orthogonal Frequency Division Multiplexing) transmission scheme as an attractive solution for high bit rate data transmission in a multipath fading environment. STBC(Space-Time Block Coding) has been proposed as a simple diversity scheme using two transmit antennas. Also ST-OFDM(Space-Time Block Coded OFDM) and SF-OFDM(Space-Frequency Block Coded OFDM) transmission scheme, that the STBC is applied to the OFDM, has been proposed. In this paper, we propose STF-OFDM transmission scheme that to coded in time, space and frequency domain. The STF-OFDM transmission scheme that we propose in this paper is the way to improve a performance of conventional ST-OFDM, by using frequency diversity.

Performance Analysis of UWA Communication System by Diversity in UWA Channel (수중 음향 다중 경로 채널에서 수중 음향 통신 시스템 성능 분석)

  • Lee, Hojun;Kang, Jiwoong;Ahn, Jongmin;Chung, Jaehak
    • The Journal of the Convergence on Culture Technology
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    • v.3 no.4
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    • pp.191-198
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    • 2017
  • In this paper, we compare the transmission performance of Code Division Multiple Access (CDMA) and Orthogonal Frequency Division Multiplexing (OFDM) under long duration multipath channel environments. This paper generates underwater channels through Bellhop based on the underwater environmental data of the west sea. BER performance of CDMA and OFDM are analyzed through various underwater channels based on the channels. Computer simulations result show that CDMA has better performance than OFDM when multipath delay time of underwater channel is shorter than spreading factor (SF). However, OFDM has better BER performance than CDMA as multi-path delay time increases.