【作者】 李惠惠；

【导师】 杜栓义；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2011， 硕士

【摘要】 在短波通信系统中,多径时延会使信号产生符号间干扰(ISI),影响了数据传输的质量。Turbo均衡技术利用Turbo原理将信道均衡与译码结合起来,通过不断的迭代来消除ISI。首先介绍了几种比较经典的均衡器,以及一些常用的均衡算法。然后重点研究了Turbo均衡的基本原理,详细介绍了几种常见的Turbo均衡算法,并对均衡中输出的软信息进行了计算量的简化。基于常见算法在复杂度和性能方面的优缺点,重点对基于MMSE的近似算法、软干扰抵消(SIC)的改进算法以及两者的混合算法进行了研究,并对这些算法在典型信道下的性能进行了仿真。仿真表明,这些算法不但拥有线性的复杂度,而且经过几次迭代以后可以获得与线性MMSE均衡算法几乎相近的性能。最后,将Turbo均衡技术应用到实际的短波通信系统中,结合短波通信广泛应用的非线性数据检测算法(NDDE)得到了一种NDDE/SIC均衡算法,在短波信道模拟器上的测试表明该算法具有很好的性能。更多还原

【Abstract】 The serious inter-symbol interference (ISI) caused by multipath will degrade the performance of the HF communication system. Turbo equalization joints equalization and decoding to cancel ISI through an iterative approach.Firstly, some classical equalizers and its equalization algorithms are introduced. Then the principle of Turbo equalization is investigated and some Turbo equalization algorithms are studied to simplify its complexity of calculating the soft information. Considering the performance of these algorithms as well as their complexity, the approximate algorithms based on the minimum mean square error (MMSE) criterion、some modified algorithms of the conventional soft interference canceller (SIC) and the hybrid algorithm of MMSE and SIC are introduced and simulated in a typical ISI channel. The simulation and analytical results show that these algorithms exhibit similar performances as compared to the linear MMSE algorithm while providing the very low linear computational complexity.Finally, Turbo equalization is applied to the HF communication system. Combined with the nonlinear data detection algorithm (NDDE) widely used in HF communication, we obtain a NDDE/SIC algorithm. The results coming from the HF channel simulator show that the algorithm has a good performance.更多还原