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arXiv 1111.4118math.OCstat.ML
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模拟稀疏逼近及其在压缩感知中的应用

Analog Sparse Approximation with Applications to Compressed Sensing

Adam S. Charles, Pierre Garrigues, Christopher J. Rozell

摘要:

最近的研究表明,信号处理任务的性能通常可以通过使用基于稀疏表示的信号模型来显着提高,其中使用来自固定字典的少量元素来近似信号。不幸的是,在这个模型中的推理涉及到解决非光滑的最优化问题,这是计算昂贵的。虽然大量的努力集中在专门针对该问题开发数字算法上,但是这些算法对于许多应用是不合适的,因为解决大的最优化问题所必需的时间和功率要求。基于最近的工作在计算神经科学,我们探讨了潜在的优势,连续时间动力系统解决稀疏逼近问题,如果他们在模拟VLSI实现。具体而言,在恢复通过压缩感知技术获取的合成和MRI数据的模拟任务中,我们表明这些系统可以在10-20μs的时间尺度执行恢复,支持50-100 kHz的数据速率(比数字算法快几个数量级)。此外,我们分析表明,广泛的稀疏近似问题可以解决在相同的基本架构,包括近似$\ell^p$规范,修改后的$\ell^1$规范,重新加权$\ell^1$和$\ell^2$,块$\ell^1$规范和经典的Tikhonov正则化。

英文摘要:

Recent research has shown that performance in signal processing tasks can often be significantly improved by using signal models based on sparse representations, where a signal is approximated using a small number of elements from a fixed dictionary. Unfortunately, inference in this model involves solving non-smooth optimization problems that are computationally expensive. While significant efforts have focused on developing digital algorithms specifically for this problem, these algorithms are inappropriate for many applications because of the time and power requirements necessary to solve large optimization problems. Based on recent work in computational neuroscience, we explore the potential advantages of continuous time dynamical systems for solving sparse approximation problems if they were implemented in analog VLSI. Specifically, in the simulated task of recovering synthetic and MRI data acquired via compressive sensing techniques, we show that these systems can potentially perform recovery at time scales of 10-20μs, supporting datarates of 50-100 kHz (orders of magnitude faster that digital algorithms). Furthermore, we show analytically that a wide range of sparse approximation problems can be solved in the same basic architecture, including approximate $\ell^p$ norms, modified $\ell^1$ norms, re-weighted $\ell^1$ and $\ell^2$, the block $\ell^1$ norm and classic Tikhonov regularization.

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