LST-AGCN: A Novel Unified Lightweight Attention Framework for Efficient Skeleton-Based Action Recognition

While Graph Convolutional Networks (GCNs) have revolutionized skeleton-based action recognition, existing methods face a critical efficiency–accuracy dilemma: state-of-the-art approaches achieve high performance through computationally expensive multi-stream fusion (joint, bone, joint motion, and bone motion) and deep architectures, limiting real-world deployment on resource-constrained devices. We propose LST-AGCN (Lightweight Spatial–Temporal Attention Graph Convolutional Network), introducing three technical contributions that address this challenge: (1) Unified Attention Module (UAM)—a framework that integrates channel, spatial, and temporal attention through a single compact operation, significantly reducing attention parameters compared to separate attention mechanisms; (2) Depthwise Separable Attention Mechanism (DSAM)—a factorization using depthwise separable convolutions that achieves linear complexity reduction from O(C2) to O(C) in attention operations; and (3) Efficient Topology-Aware Fusion (ETAF)—an adaptive Joint-wise Attention strategy that captures fine-grained spatial relationships without quadratic complexity growth. Extensive experiments on NTU RGB+D 60 and NTU RGB+D 120 datasets demonstrate that LST-AGCN achieves strong performance using only joint modality (86.14%/94.0% and 79.5%/82.0% Top-1 accuracy with 99.0% Top-5 on cross-view) while requiring 14.11 M parameters and 19.02 GFLOPs, delivering efficient inference suitable for edge deployment.