Investigation into an NFC-Based Monitoring Sensor Node for Electric Motor: Compression Algorithms for Baud-Rate Constraints

This paper presents an initial investigation aimed at expanding the effective baud rate of an NFC-based system. The study evolves from a single-parameter acquisition approach to an NFC-based multimodal sensor node designed for electric motor monitoring and, more generally, rotating machinery. The proposed system integrates temperature and torsional strain mea- surements directly on rotating components. Given the inherent limitations of NFC communication — specifically its constrained data rate due to RF channel speed — the study explores data compression algorithms to expand the effective bandwidth of the NFC channel. Four lossless compression techniques are evaluated: Huffman coding, Adaptive Rice coding, a hybrid Predictive+Huffman method, and S-LZW. These algorithms were selected based on their proven effectiveness in sensor network applications and assessed using real-world datasets. Experimental results demonstrate that Huffman-based algorithms achieve the highest compression ratios, ranging from 12.5% to 22.1%, signi- ficantly reducing the volume of transmitted data and enabling reliable real-time monitoring even in NFC scenarios where the effective speed has been assessed to 2.9 kBps.