石油学报 ›› 2014, Vol. 35 ›› Issue (3): 558-563.DOI: 10.7623/syxb201403019

• 石油工程 • 上一篇    下一篇

石油井下OFDM无线高速传输系统同步算法

罗仁泽1,2, 杨娇2, 戈勇华3   

  1. 1. 西南石油大学油气藏地质及开发工程国家重点实验室 四川成都 610500;
    2. 西南石油大学电气与信息学院 四川成都 610500;
    3. 深圳市云海通讯股份有限公司 广东深圳 518000
  • 收稿日期:2013-12-06 修回日期:2014-03-17 出版日期:2014-05-25 发布日期:2014-04-11
  • 通讯作者: 罗仁泽,男,1973年9月生,1992年获西南石油学院学士学位,2005年获电子科技大学博士学位,现为西南石油大学电气与信息学院教授、博士生导师、四川省"千人计划"特聘专家,主要从事通信信号处理、地震信号处理方面的研究工作。Email:lrzsmith@126.com
  • 作者简介:罗仁泽,男,1973年9月生,1992年获西南石油学院学士学位,2005年获电子科技大学博士学位,现为西南石油大学电气与信息学院教授、博士生导师、四川省"千人计划"特聘专家,主要从事通信信号处理、地震信号处理方面的研究工作。Email:lrzsmith@126.com
  • 基金资助:

    国家自然科学基金项目(No.61072073,No.61310306022)、四川省科技支撑项目(2012FZ0021)、四川省“千人计划”引进人才项目和西南石油大学油气信号检测与信息处理青年科研创新培育团队项目资金(No.2013XJZT007)资助。

Wireless downhole high-speed transmission system and its synchronization algorithm based on OFDM technique

Luo Renze1,2, Yang Jiao2, Ge Yonghua3   

  1. 1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University Chengdu 610500, China;
    2. School of Electrical Engineering and Information, Southwest Petroleum University, Chengdu 610500, China;
    3. Shenzhen Winhap Communications Inc., Shenzhen 518000, China
  • Received:2013-12-06 Revised:2014-03-17 Online:2014-05-25 Published:2014-04-11

摘要:

传统有线石油井下传输效率低,无法满足高速率传输井下数据的需求;采用插入训练序列及导频插入获得同步的方法,既浪费带宽效率又独占发射机功率。为了克服这两大缺陷,提出了OFDM油井高速无线传输系统及循环前缀叠加互补对称序列的时频同步方法。训练序列由互补序列对构成,具有反共轭对称性及良好自相关性。利用接收信号分别与本地序列前、后两部进行相关后,再进行一次循环能量累积来获取时间同步信息;同时,利用频率补偿的思想来获取精确的频偏估计。仿真表明,新算法与Chih-Peng Li提出的算法相比,时间同步和频偏估计均具有更低的均方误差,且算法复杂度较低。

关键词: 井下传输, OFDM, 叠加训练序列, 循环前缀, 同步

Abstract:

With low efficiency, conventional wired downhole transmission can't meet the requirement of high-speed downhole data transmission. The synchronization scheme obtained by inserting training sequence and pilot tone assisted modulation (PTAM) not only wasted bandwidth efficiency but also possessed all the transmitter power. To overcome the two defects, we proposed a timing -frequency synchronization scheme of orthogonal frequency division multiplexing(OFDM) high-speed transmission system of downhole data and superimposed complementary symmetrical training sequence in cyclic prefix. The training sequences are composed of complementary sequence couple with anti-conjugate symmetry and good auto-correlation. After received signals are correlated to the former and latter parts of training sequences respectively, they are recirculated for energy accumulation to finally obtain timing synchronization. At the same time, precise frequency offset estimation is achieved by the theory of frequency compensation. Simulation results demonstrate that, compared with Chih-Peng Li's algorithm, the novel algorithm has lower mean square error(MSE) and computational complexity both in timing synchronization and frequency offset estimation.

Key words: downhole transmission, orthogonal frequency division multiplexing (OFDM), superimposed training sequence, cyclic prefix, synchronization

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