Journal of South China University of Technology (Natural Science Edition) ›› 2014, Vol. 42 ›› Issue (5): 16-22.doi: 10.3969/j.issn.1000-565X.2014.05.003

• Electronics, Communication & Automation Technology • Previous Articles     Next Articles

Channel Estimation- Assisted Demapping Algorithm of High- Order QAM within Shrunk Search Range

Xu Juan1 Yao Ru- gui2 Nan Hua- ni2 Gao Fan- qi2   

  1. 1.School of Electronic and Control Engineering,Chang'an University,Xi'an 710064,Shaanxi,China;2.School of Electronics and Information,Northwestern Polytechnical University,Xi'an 710072,Shaanxi,China
  • Received:2013-11-26 Revised:2014-02-26 Online:2014-05-25 Published:2014-04-01
  • Contact: 徐娟(1980-)，女，博士，讲师，主要从事先进信道编码、高速数据传输技术研究． E-mail:xuj@mail.nwpu.edu.cn
  • About author:徐娟(1980-)，女，博士，讲师，主要从事先进信道编码、高速数据传输技术研究．
  • Supported by:

    国家自然科学基金资助项目(61271416);航天支撑基金资助项目(2013- HT- XGD);西北工业大学基础研究基金资助项目(JCY20130132)

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Abstract:

QAM (Quadrature Amplitude Modulation) is broadly used in various communication systems thanks toits high power efficiency and bandwidth utilization.High- order QAM,because of its wide search range,may resultin high demapping complexity.In order to solve this problem,a novel concept of soft- decision contribution factor isintroduced to evaluate the contribution of reference constellation to the demapping,and a demapping algorithm ofhigh- order QAM within shrunk search range is proposed.Then,some boundary conditions of the algorithm are dis-cussed,and an adaptive selection scheme of search range is finally presented with the assistance of channel estima-tion.Simulated results indicate that (1) the proposed algorithm downsizes the search range without any sacrifice of BER performance; (2) 4096- QAM and 1024- QAM respectively shrink their search range to 12.7% and 19.7% ofthat of the whole constellation; and (3) as the proposed algorithm makes good tradeoff between performance anddemapping complexity.it has a good prospect of engineering application.

Key words: quadrature amplitude modulation, demapping, channel estimation, search range, contribution factor

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