通信工程专业论文--频选衰落信道下自适应均衡器的设计.doc

作者：邱海波 频选衰落信道下自适应均衡器的设计 摘要：数字通信由于其很多优点已经得到了广泛的应用，并且随着集成电路与计算机技术的发展，数字通信方式必将向着更高的速率和更高的可靠性方向发展。对于数字通信而言，误码率和频带利用率是两个主要的衡量指标。由于常用信道传输特性的非理想，数字信号经过传输以后，产生了严重的码间干扰，这对于正确的判决是非常不利的因素，从而增加了通信的误码率。这是不希望的，也是需要设法解决的问题。 自适应均衡从提出发展到现在，由于其良好的性能已经得到了广泛的应用。 论文首先简单介绍了自适应均衡技术以及其研究现状和发展等。由于信道的非理想特性是产生了码间干扰的主要因素，因此论文首先介绍了信道的概念，分析了理想状态和实际状态下通信信道的特性。论文还简要介绍了均衡的概念，同时为了方便于研究信道均衡器，定义一个离散时间信道模型。为了更有效的抑制码间干扰，分析了干扰产生的机理以及码间干扰的条件。对自适应均衡器的原理、性能及特点做了简单的介绍。对线性横向均衡器和线性格性均衡器结构进行了分析。然后对比和分析了迫零算法MMSE算法存在的优缺点，进行MATLAB仿真。在仿真过程中，发现迫零算法一般只适用于失真不太严重的信道，在深度衰落的信道中，迫零算法已经不能达到均衡的效果了。迫零算法对噪声是比较的灵敏，也就是说在小信噪比下，算法的性能比较差，有时不能完全跟踪住均衡器的最优解。而线性MSE均衡器的性能虽然比迫零均衡器有所改善，但是在克服严重的码间干扰方面具有较大的局限性。最后对全文进行总结。 关键词：自适应均衡，码间干扰，MMSE算法，MATLAB仿真 中图分类号：TN911 Design of Adaptive Equalization Over Frequency _Selective Fading Channel Abstract: Digital communication has been widely used because of its many advantages, and with the development of integrated circuit and compute technology, it is sure that digital communication will be developed with the much more fast and reliable direction. Toward digital communication, bit error and spectrum availability ratio are two main scale targets. Owing to non-ideal normal channel, serious Inter-Symbol Interference (ISI) is generated after the digital signal being transmitted, which is a very disadvantage for correct decision, sequentially communication bit error is increased. Which is not expected and measures should be taken to solve this problem. Adaptive equalization, from its bringing forward to now, has been widely employed because of its good performance. This paper simply introduces the Adaptive Equalization, and the status and development of Adaptive Equalization. As the non-ideal characteristics of Channel is the main factor of ISI, this paper firstly introduced the concept of Channel, and analysis the characteristic of communication channel that under the ideal and actual state. The paper also briefly introduced the concept of balance. And defined a discret