物理层网络编码的符号时钟估计研究
发布时间：2018-10-23 13:08
【摘要】：物理层网络编码(PNC)作为一种新颖的中继传输技术,在频谱效率和吞吐量方面具有巨大优势而备受人们关注。目前,关于PNC的研究大多假设两个用户节点发送的符号在中继处完全对齐,即没有符号同步误差。然而,实际情况往往并不满足这一条件,造成系统性能下降。因此,PNC的符号时钟估计至关重要。本文研究双向中继信道PNC的符号时钟估计问题,基于CAZAC训练序列先后提出三种全新的适用于不同采样率下的时钟估计算法,分别是:过采样率(每个码元的采样点数)Q≥4的基于DFT插值的时钟估计算法、过采样率Q=2的低过采样率时钟估计算法,和波特率采样的时钟估计算法。论文首先根据PNC信号模型以及最大似然估计准则,利用训练序列的零自相关特性,得到两个端节点各自的时钟误差估计似然函数,进而提出运用基于DFT的插值算法来估计时钟误差。然后针对上述算法采样率过高的问题,提出一种Q=2下的低过采样率时钟估计算法。该算法根据似然函数的两个离散值之差与时钟误差是一一对应的关系,利用已知的发送脉冲形状和最小二乘法求一个拟合多项式来近似这种函数关系,从而实现时钟误差估计。最后为了进一步降低采样率,通过分析波特率采样下的接收信号,定义一种指示时钟误差大小的定时函数,并估计出该定时函数,实现波特率采样下的时钟估计。三种算法均在MATLAB平台上以均方误差(MSE)为性能指标进行仿真,同时探讨各种参数对算法性能的影响。仿真表明,三种算法都能取得较好的时钟估计结果,在32位的训练序列长度及18 d B的信噪比(SNR)条件下,MSE可达1×10~(-4)。
[Abstract]:As a novel relay transmission technology, physical layer network coding (PNC) has great advantages in spectrum efficiency and throughput. At present, most researches on PNC assume that the symbols sent by the two user nodes are completely aligned at the relay, that is, there is no symbol synchronization error. However, the actual situation often does not meet this condition, resulting in a deterioration of system performance. Therefore, the symbol clock estimation of PNC is very important. In this paper, the symbol clock estimation problem of bidirectional relay channel PNC is studied. Based on the CAZAC training sequence, three new clock estimation algorithms are proposed, which are suitable for different sampling rates. They are: the clock estimation algorithm based on DFT interpolation for oversampling rate (sampling points per symbol) Q 鈮，
本文编号：2289344
[Abstract]:As a novel relay transmission technology, physical layer network coding (PNC) has great advantages in spectrum efficiency and throughput. At present, most researches on PNC assume that the symbols sent by the two user nodes are completely aligned at the relay, that is, there is no symbol synchronization error. However, the actual situation often does not meet this condition, resulting in a deterioration of system performance. Therefore, the symbol clock estimation of PNC is very important. In this paper, the symbol clock estimation problem of bidirectional relay channel PNC is studied. Based on the CAZAC training sequence, three new clock estimation algorithms are proposed, which are suitable for different sampling rates. They are: the clock estimation algorithm based on DFT interpolation for oversampling rate (sampling points per symbol) Q 鈮，
本文编号：2289344
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