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Optimized Hierarchical Cascaded Processing

Journal Contribution - Journal Article

© 2018 IEEE. Recently, there has been an increasing demand for advanced classification capabilities embedded on wearable battery constrained devices, such as smartphones or watches. Achieving such functionality with a tight power and energy budget has proven a real challenge, specifically for large-scale neural network-based applications. Previously, cascaded systems have been proposed to minimize energy consumption for such applications, either through using a single wake-up stage, or by using a linear-or tree based cascade of consecutive classifiers that allow early termination. In this paper, we expand upon these concepts by generalizing cascades to hierarchical cascaded processing, where a hierarchy of increasingly complex classifiers, each designed and trained for a specific subtask is used. This hierarchical approach significantly outperforms the wake-up based approach by up to 2 orders of magnitude in energy consumption at iso-accuracy, specifically in systems with sparse input data such as speech recognition and visual object detection. This paper presents a general design framework for such systems and illustrates how to optimize them toward minimum energy consumption. The text further proposes a roofline model for cascaded systems, derives system level trade-offs and proves the approaches validity through a visual classification case-study.
Journal: IEEE Journal on Emerging and Selected Topics in Circuits and Systems
ISSN: 2156-3357
Issue: 4
Volume: 8
Pages: 884 - 894
Number of pages: 11
Publication year:2018
Keywords:Electrical & electronic engineering