短波通信中迭代均衡与译码的低复杂度实现的分析.pdf

摘要
短波通信是广泛用于军事通信上的一种无线通信方式。克服短波信道的时变
特性,以及符号间干扰(ISI)和噪声的影响成为提高短波通信数据通过率的一个
重要内容。本文的目的是寻找一种在恶劣的短波信道条件下,能以较低复杂度进
行实际硬件实现的,仍然具有比较可靠的误码率的数据通信方法。
一般的短波接收机采用自适应均衡克服 ISI 干扰,采用编译码克服加性噪
声的影响。均衡器和译码器是分开的子系统。这种设计不是最优的,原因是均衡
器没有利用译码器引入的冗余信息,译码器也不能利用信道信息进行软输入输出
(SISO)译码。迭代均衡和译码(也称为 Turbo 均衡)概念的引入,使得译码
和均衡的信息得以相互充分利用。本文的仿真结果说明了迭代的均衡和译码方法
具有较大的优越性。
国外的 Tü 等学者比较多的说明了低阶调制下迭代均衡和译码方法。
本文论述了这种方法,并结合 Brink提出的迭代解映射和译码方法,阐述
了高阶调制下的迭代均衡和译码方法。另外 Tü 等阐述迭代方法时,假设
信道条件已经准确估计,引入了高复杂度的信道矩阵的求逆和乘积运算,这在实
际进行硬件的实现是比较困难的。本文阐述了使用时域简化和频域均衡实现低复
杂度迭代均衡和译码的方法。
关键词: 短波 turbo 码, turbo 均衡, 频域均衡, 低复杂度






I
Abstract
HF(High Frequency) communication is widely used in military wireless
communications. One of the important tasks to improve the throughput in HF
channel is to find the method to conquer the severe time-varying intersymbol
interference(ISI) as well as additive noise. The aim of the article is to find one
plexy digital method which is able to be applied on hardware and can get a
low bit-err-rate in severe HF channel.

Conventional HF receivers perform adaptive equalization to mitigate the ISI, perform
error-correcting coding (ECC) and error-correcting decoding (ECD) to mitigate
additive noise. The equalizater and decoder are apart sub-systems under that design
which is suboptimal because the equalizer does not make use of the redundancy
introduced by ECC and the ECC also can’t make use of the channel information to
perform soft-input-and-soft-output decoding. In my acticle, one outperformed system
is adopted to use iterative equalization and decoding (IED), Turbo equalization,
which has a mand of information transfer between the two sub-systems. The
simulated results illuminate the necessary of IED.

Tü, the foreign scholar, fully explained the IDE of low-level modulation. My
article addresses this method and the IDE of multilevel bined with the
iterative demapping and decoding (IDD) advanced