压缩感知框架下基于多模板解卷积的超宽带信道估计

发布时间：2019-02-10 19:51

【摘要】：脉冲超宽带(Impulse Radio-Ultra Wide Bandwidth,IR-UWB)是一种新兴的短距离无线通信技术。该技术凭借低功耗、抗干扰能力强等优点已经引起了广泛的关注和深入研究。然而,IR-UWB技术在应用领域也存在着难题,IR-UWB脉冲在时域上纳秒级的持续时间决定了其频域上占有极高的带宽,这就对数字化接收机设计过程中ADC的采样能力提出了很高的要求,如果严格按照Nyquist采样定律来设计接收机的采样部分将会带来高额的成本。压缩感知理论(Compressed Sensing,CS)是近年来应用数学领域的研究热点,该理论指出,在信号满足稀疏特性的前提下,利用远小于Nyquist采样定律的观测数量也可以高概率地重构原信号。超宽带信号的天然稀疏特性可以满足压缩感知理论的前提要求,因此CS理论就为打破传统思路的瓶颈设计IR-UWB数字化接收机提供了良好的契机。考虑到精确的信道估计是保障通信性能的重要环节,本文重点针对CS框架下IR-UWB系统信道估计进行研究。本文首先介绍CS的基本理论以及CS-UWB接收机的基本架构,然后基于CS-UWB信道估计方向已有的研究成果进行进一步的研究。超宽带接收机接收信号的一般形式为:g????n,其中?为本地模板矩阵、n为噪声向量、?即为待估计的信道冲击响应。IR-UWB信道估计的精确度受到n和?两方面的影响,本文针对这两方面的影响分别进行讨论并提出了在已有研究基础上进行改进的对应方法。传统的正交匹配追踪(Orthogonal Matching Pursuit,OMP)利用已知的接收信号g与本地模板?之间的迭代来得到信道估值,这种方法的抗噪声能力较差。本文在传统OMP算法迭代过程中加入噪声向量n的影响,基于公式的推导和证明提出了Anti-Noise OMP重构算法,并且通过仿真与原始OMP算法的信道估计性能作对比论证了推导的合理性。针对模板?改进的问题,本文首先对超宽带收发实验的实测数据进行分析,介绍了该实验的环境和参数,通过对不同点接收信号的分析来判断它们所受到失真的影响,根据分析结果构造包含波形失真信息的多模板字典MT?,并通过仿真验证了多模板较单模板的性能优越性。基于对超宽带信道特性的分析,本文利用部分信道先验信息(Channel Prior Information,CPI)来得到一个加权函数并利用它进一步改进模板,得到了一定的性能提升。最后,本文将所提出对针对噪声n和本地模板?的改进方法结合在一起,形成了系统的CS-UWB信道估计方案,在不同迭代次数下较原始方法的重构信噪比(Recovery Signal-to-Noise Ratio,RSNR)提升约为1d B。
[Abstract]:Pulse Ultra-wideband (Impulse Radio-Ultra Wide Bandwidth,IR-UWB) is a new short-range wireless communication technology. With the advantages of low power consumption and strong anti-interference ability, this technology has attracted extensive attention and deep research. However, there are still some difficulties in the application of IR-UWB technology. The duration of IR-UWB pulses in time domain determines the high bandwidth in frequency domain because of the duration of nanosecond pulse. This puts forward a very high requirement for the sampling ability of ADC in the design process of digital receiver. If the sampling part of the receiver is designed strictly according to the sampling law of Nyquist, it will bring high cost. Compression sensing theory (Compressed Sensing,CS) is a hot topic in the field of applied mathematics in recent years. The theory points out that the original signal can be reconstructed with a much smaller number of observations than the Nyquist sampling law if the signal satisfies the sparse characteristic. The natural sparse characteristic of UWB signals can meet the requirements of compression sensing theory, so CS theory provides a good opportunity to break the bottleneck of traditional thinking in designing IR-UWB digital receiver. Considering that accurate channel estimation is an important link to ensure communication performance, this paper focuses on channel estimation of IR-UWB systems under the framework of CS. In this paper, the basic theory of CS and the basic architecture of CS-UWB receiver are introduced, and then further research is carried out based on the existing research results of CS-UWB channel estimation direction. The general form of the UWB receiver receiving signal is: G / N, in which? Is the local template matrix, n is the noise vector,? That is, the channel impulse response to be estimated. The accuracy of IR-UWB channel estimation is affected by n and? In this paper, the influence of these two aspects is discussed and an improved corresponding method based on the existing research is put forward. Traditional orthogonal matching tracking (Orthogonal Matching Pursuit,OMP) uses known received signals g and local templates? This method has poor anti-noise capability. In this paper, the influence of noise vector n is added to the iterative process of the traditional OMP algorithm, and the Anti-Noise OMP reconstruction algorithm is proposed based on the derivation and proof of the formula. The rationality of the derivation is proved by comparing the channel estimation performance of the original OMP algorithm and simulation. For the template? This paper first analyzes the measured data of UWB transceiver experiment, introduces the environment and parameters of UWB transceiver experiment, and judges the effect of distortion on UWB transceiver by analyzing the received signals at different points. According to the analysis results, a multi-template dictionary MT?, with waveform distortion information is constructed, and the performance superiority of multi-template is verified by simulation. Based on the analysis of UWB channel characteristics, a weighting function is obtained by using partial channel priori information (Channel Prior Information,CPI) and the template is further improved, and the performance is improved to a certain extent. Finally, this paper proposes the proposed for noise n and local templates? Combined with the improved method, the CS-UWB channel estimation scheme of the system is formed, and the reconstruction signal-to-noise ratio (Recovery Signal-to-Noise Ratio,RSNR) of the system is improved to about 1dB under different iterations.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN925

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