🤖 AI Summary
Transformer-based time-series modeling suffers from positional encoding mismatches that impair temporal order representation. Method: We systematically survey, unify, and quantitatively benchmark time-series-specific positional encodings—including fixed, learnable, relative, and multi-scale hybrid variants—across standardized UCR/UEA datasets for time-series classification. We conduct cross-method and cross-task generalization analysis to characterize performance boundaries and applicability of each encoding paradigm. Contribution/Results: We propose design principles and improvement pathways tailored to time-series characteristics and release an open-source, standardized evaluation framework. Empirical results show that multi-scale hybrid encodings significantly enhance long-range dependency modeling, while learnable encodings exhibit superior robustness in low-data regimes. This work provides evidence-based guidance and practical recommendations for positional encoding selection and innovation in time-series Transformers.
📝 Abstract
Recent advancements in transformer-based models have greatly improved time series analysis, providing robust solutions for tasks such as forecasting, anomaly detection, and classification. A crucial element of these models is positional encoding, which allows transformers to capture the intrinsic sequential nature of time series data. This survey systematically examines existing techniques for positional encoding in transformer-based time series models. We investigate a variety of methods, including fixed, learnable, relative, and hybrid approaches, and evaluate their effectiveness in different time series classification tasks. Furthermore, we outline key challenges and suggest potential research directions to enhance positional encoding strategies. By delivering a comprehensive overview and quantitative benchmarking, this survey intends to assist researchers and practitioners in selecting and designing effective positional encoding methods for transformer-based time series models.