Comparison and Selection of Spike Encoding Algorithms for SNN on FPGA

• Published in: IEEE transactions on biomedical circuits and systems Vol. 17; no. 1; pp. 129 - 141
• Main Authors: Wang, Kuanchuan, Hao, Xinyu, Wang, Jiang, Deng, Bin
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.02.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Approximation algorithms; Classification algorithms; Encoding; Field programmable gate array (FPGA); Field programmable gate arrays; Firing pattern; Hardware; Neural coding; Neural networks; Neuromorphics; Pulse duration; Resource consumption; Software algorithms; spike encoding algorithms; Spiking; spiking neural network; Square waves
• ISSN: 1932-4545; 1940-9990; 1940-9990
• DOI: 10.1109/TBCAS.2023.3238165

The information in Spiking Neural Networks (SNNs) is carried by discrete spikes. Therefore, the conversion between the spiking signals and real-value signals has an important impact on the encoding efficiency and performance of SNNs, which is usually completed by spike encoding algorithms. In order to select suitable spike encoding algorithms for different SNNs, this work evaluates four commonly used spike encoding algorithms. The evaluation is based on the FPGA implementation results of the algorithms, including calculation speed, resource consumption, accuracy, and anti-noiseability, so as to better adapt to the neuromorphic implementation of SNN. Two real-world applicaitons are also used to verify the evaluation results. By analyzing and comparing the evaluation results, this work summarizes the characteristics and application range of different algorithms. In general, the sliding window algorithm has relatively low accuracy and is suitable for observing signal trends. Pulsewidth modulated-Based algorithm and step-forward algorithm are suitable for accurate reconstruction of various signals except for square wave signals, while Ben's Spiker algorithm can remedy this. Finally, a scoring method that can be used for spiking coding algorithm selection is proposed, which can help to improve the encoding efficiency of neuromorphic SNNs.