LEISN: A long explicit–implicit spatio-temporal network for traffic flow forecasting

Abstract

Recent studies have shown that it is necessary to further improve the prediction accuracy of complex and dynamic traffic flow from two angles: temporal dependence and spatial dependence. Although many spatio-temporal networks are extracting features from both temporal and spatial dependencies, there are still two problems that need to be addressed. Firstly, existing methods often focus on modeling local spatial dependence relationship between adjacent nodes, but neglect non-local spatial dependence relationship between distant nodes. Secondly, while recent work has explored various methods such as convolutional and recurrent neural networks for modeling temporal dependence, they may not fully capture the long-term temporal dependence in traffic data. Therefore, addressing the challenges of long-term dependency, explicit spatial dependency, and implicit spatial dependency, this paper proposes a Long-term Explicit–Implicit Spatio-Temporal Network (LEISN) for traffic flow prediction. A Long-term Dependency Module has been designed to store hidden states generated from multiple previous time steps, facilitating the transmission of long-term features. Based on this, two graph convolution-based spatial feature extraction branches are designed to extract explicit spatial features based on the adjacency matrix generated by spatial topology and implicit spatial features based on the implicit adjacency matrix generated by trend similarity, respectively. Then all spatio-temporal features are fused to produce the next state. Additionally, a new encoder framework, LENSI-ED, was proposed based on LEISN. Comparative experiments are conducted on four datasets, and the results showed that our model has advantages over existing methods. The proposed model addresses the issues of local and non-local spatial dependence relationships and long-term temporal dependence in traffic flow forecasting.