扩频通信系统中的Rake接收技术研究

发布时间：2018-11-25 13:55

【摘要】：无人机对地通信中的多径干扰较为严重,为解决这一问题,本文对扩频通信系统中Rake接收机技术进行了深入的研究。Rake接收机广泛应用于扩频通信系统中,以此来消除多径衰落对系统性能的影响。传统Rake接收机需要单独的搜索信道,占用信道资源,并且由于其采用的算法较为简单,对误码率性能提升不高。在本文,提出了一种低复杂度自适应Rake接收机——基于快速近似幂迭代子空间跟踪算法的自适应Rake接收机,和一种适合在低信噪比环境下应用的自适应Rake接收机——贝叶斯Rake接收机。论文详细分析了扩频通信中的关键技术,对扩频码序列、载波捕获与同步等进行了相应的仿真实验。对多径效应的产生,以及用抽头延迟线模型来抽象描述多径信道进行了深入的研究。在新型Rake接收机提出过程中,论文结合需要解决的问题,首先对已有的Rake接收机进行分类总结,然后从中找到可以创新的突破点。遵循这个思路,论文首先从低复杂度出发,提出了基于快速近似幂迭代子空间跟踪算法的自适应Rake接收机。这种新型的Rake接收机将子空间跟踪算法应用到Rake接收机中,降低了自适应Rake接收机在信道估计过程中的算法复杂度,并保证Rake接收机性能。然后论文又从改善低信噪比环境下Rake接收机性能出发,将贝叶斯思想应用到Rake接收机中,提出了贝叶斯Rake接收机。贝叶斯Rake接收机使得先验知识得以应用,并经过详细的推导,得到了贝叶斯Rake接收机的算法步骤。
[Abstract]:In order to solve this problem, the technology of Rake receiver in spread spectrum communication system is studied deeply in this paper. Rake receiver is widely used in spread spectrum communication system. In this way, the influence of multipath fading on system performance is eliminated. The traditional Rake receiver needs a single search channel, which takes up channel resources, and because of its simple algorithm, the performance of BER is not high. In this paper, an adaptive Rake receiver with low complexity is proposed, which is based on fast approximate power iterative subspace tracking algorithm. And a kind of adaptive Rake receiver, Bayesian Rake receiver, which is suitable for low signal-to-noise ratio (SNR) environment. In this paper, the key technologies of spread spectrum communication are analyzed in detail, and the corresponding simulation experiments on spread spectrum code sequence, carrier acquisition and synchronization are carried out. The generation of multipath effect and the abstract description of multipath channel by tap delay line model are studied. In the process of proposing a new Rake receiver, this paper combines the problems that need to be solved, firstly classifies and summarizes the existing Rake receiver, and then finds a breakthrough point that can be innovated. Following this idea, an adaptive Rake receiver based on fast approximate power iterative subspace tracking algorithm is proposed for low complexity. This new Rake receiver applies the subspace tracking algorithm to the Rake receiver, which reduces the complexity of the adaptive Rake receiver in the channel estimation process and ensures the performance of the Rake receiver. Then, in order to improve the performance of Rake receiver in low SNR environment, Bayesian theory is applied to Rake receiver, and Bayesian Rake receiver is proposed. Bayesian Rake receiver enables prior knowledge to be applied, and the algorithm steps of Bayesian Rake receiver are obtained through detailed derivation.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN914.42

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