异方差多通道卷积模型函数导数小波估计的分块阈值法
Block thresholding for wavelet-based estimation of function derivatives from a heteroscedastic multichannel convolution model
摘要：
我们观察到$n$异方差随机过程$\{Y_v(t)\}_{v}$，其中对于任何$v\in\{1,\ldots,n\}$和$t \in [0,1]$，$Y_v(t)$是未知函数$f$和已知模糊函数$g_v$的卷积积高斯噪声破坏。在$g_1,\ldots,g_n$的一般光滑性假设下，我们的目标是从观测值估计$f$的$d$阶导数（弱意义下）.我们提出了一种基于小波块阈值的自适应估计器，即“BlockJS估计器”。以平均积分平方误差（MISE）为例，我们的主要理论结果研究了Besov光滑空间上的Minimax速率，并表明我们的块估计可以达到最佳的Minimax速率，或者至少是在最不利的情况下接近Minimax。我们还报告了一套全面的数值模拟，以支持我们的理论研究结果。我们的块估计的实际性能相比，非常有利的现有方法的文献上的一个大的测试功能。
英文摘要：
We observe $n$ heteroscedastic stochastic processes $\{Y_v(t)\}_{v}$, where for any $v\in\{1,\ldots,n\}$ and $t \in [0,1]$, $Y_v(t)$ is the convolution product of an unknown function $f$ and a known blurring function $g_v$ corrupted by Gaussian noise. Under an ordinary smoothness assumption on $g_1,\ldots,g_n$, our goal is to estimate the $d$-th derivatives (in weak sense) of $f$ from the observations. We propose an adaptive estimator based on wavelet block thresholding, namely the "BlockJS estimator". Taking the mean integrated squared error (MISE), our main theoretical result investigates the minimax rates over Besov smoothness spaces, and shows that our block estimator can achieve the optimal minimax rate, or is at least nearly-minimax in the least favorable situation. We also report a comprehensive suite of numerical simulations to support our theoretical findings. The practical performance of our block estimator compares very favorably to existing methods of the literature on a large set of test functions.
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