多径衰落信道下QOTDM系统的盲均衡算法

J4 ›› 2009, Vol. 36 ›› Issue (5): 767-770+787.

多径衰落信道下QOTDM系统的盲均衡算法

王杰令¹;刘祖军¹;杨宏^1,2;易克初¹

(1. 西安电子科技大学综合业务网理论及关键技术国家重点实验室，陕西西安 710071；
2. 中国空间技术研究院，北京 100094)

收稿日期:2008-06-24 出版日期:2009-10-20 发布日期:2009-11-30
通讯作者: 王杰令
基金资助:
国家自然科学基金资助(60572148);高等学校学科创新引智计划资助(B08038)

Blind equalization algorithm for the QOTDM system in multi-path fading channels

WANG Jie-ling¹;LIU Zu-jun¹;YANG Hong^1,2;YI Ke-chu¹

(1. State Key Lab. of Integrated Service Networks, Xidian Univ., Xi'an 710071， China;
2. China Academy of Space Technology, Beijing 100094， China)

Received:2008-06-24 Online:2009-10-20 Published:2009-11-30
Contact: WANG Jie-ling

摘要/Abstract

摘要：

提出准正交时分复用系统的一种高效盲均衡算法．在发送端将一路准正交时分复用样点序列移频后与另外一路叠加，得到频谱白化的发送信号，接收机用梳状滤波器对接收信号和移频后的接收信号滤波得到两路样点序列．通过改进的恒模算法对两路样点序列初步均衡，下采样后再通过恒模算法处理，当输出误差低于门限后切换到结合判决反馈的最小均方误差算法均衡，可消除多径衰落带来的符号间干扰．Monte Carlo仿真表明，在地空通信的多径衰落信道下，新算法可以明显消除准正交时分复用系统存在的“地板效应”; 当信道的莱斯因子为10dB、误符号率为10^-3时，新算法比正交频分复用有4dB左右的性能改善．

关键词: 准正交时分复用, 正交频分复用, 恒模算法, 判决反馈

Abstract:

An efficient blind equalization scheme for the Quasi-Orthogonal Time Division Multiplexed (QOTDM) system is presented. At the transmitter, the transmitted signal with a white frequency spectrum can be obtained by adding one group of QTODM sample sequences with a frequency shift to the other group, and the receiver can get two group sample sequences by filtering the received signal and the received signal with a frequency shift using a comb filter. Firstly, two groups of sample sequences are equalized blindly by the modified constant modulus algorithm (MCMA), then the output of the primary equalizer is equalized by MCMA before the deferent error is larger than the gate, and finally the equalizer adopts the algorithm of lease mean square combined with the decision feedback technique. After equalization, the inter symbol interference (ISI) can be cancelled. It is shown by Monte Carlo simulation that the new scheme can cancel the “ground effect” of the QOTDM system in the ground-air multi-path fading channel. When the Rice fading factor is 10dB, the signal-to-noise ratio of 4dB or so for SER of 10^-3 can be achieved by the scheme proposed compared with OFDM.

Key words: quasi-orthogonal time division multiplexed, orthogonal frequency division multiplexed, constant modulus algorithm, decision feedback

中图分类号:

TN929

王杰令;刘祖军;杨宏;易克初. 多径衰落信道下QOTDM系统的盲均衡算法[J]. J4, 2009, 36(5): 767-770+787.

WANG Jie-ling;LIU Zu-jun;YANG Hong;YI Ke-chu. Blind equalization algorithm for the QOTDM system in multi-path fading channels[J]. J4, 2009, 36(5): 767-770+787.

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