Human mobility prediction is a fundamental problem in spatio-temporal data mining with broad applications in urban computing and transportation systems. While large language models (LLMs) have demonstrated strong sequence modeling capabilities, directly adapting them to structured mobility data remains challenging due to long input sequences and efficiency limitations. In this study, we propose ELP-Mob, an efficient framework that reformulates mobility prediction as a language modeling problem. ELP-Mob employs an instruction-style prompt design that incorporates user mobility profiles, historical trajectories, and target future time slots, enabling LLMs to understand mobility patterns and make predictions. To further enhance efficiency, ELP-Mob includes a data selection strategy that reduces redundancy by sampling informative subsets of training users, and a dynamic splitting strategy with token-length control, which scales to long histories while reducing computational overhead. In the GISCUP 2025, ELP-Mob achieved 6th place on the official leaderboard. The source code is publicly available at https://github.com/chwang0721/ELP-Mob.

The rapid advancement of location and information technologies has generated a significant volume of human mobility data, which has been extensively utilized in spatiotemporal recommendation systems, including personalized point-of-interest recommendation, route recommendation, and location-aware event recommendation. Achieving high-quality recommendation results necessitates excellent quality of input trajectory data. However, trajectories obtained from GPS-enabled devices often contain missing and erroneous data that is unevenly distributed over time and highly sparse, which significantly hampers the effectiveness spatiotemporal data analytics. Therefore, trajectory recovery plays an important role in spatiotemporal recommendation systems. The objective of trajectory recovery is to utilize historical trajectories to restore missing locations, providing high-quality data for spatiotemporal recommendation systems. The development of an effective trajectory recovery mechanism faces three major challenges: 1) Complex and multi-granularity transition patterns among different locations; 2) Difficulty in discovering spatio-temporal dependencies; and 3) Data sparsity and noise. To address these challenges, we propose an attentional model with spatio-temporal recurrent neural networks, ARMove, to recover human mobility from long and sparse trajectories. In ARMove, we first design a spatio-temporal weighted recurrent neural network to capture users' long-term preferences. Next, we introduce a multi-granularity trajectory encoder to model complex transition patterns and multi-level periodicity of human mobility. An attention-based history aggregation module is proposed to leverage historical mobility information. Extensive evaluation results reveal that our model outperforms the state-of-the-art models, demonstrating its ability to reconstruct high-quality and fine-grained human mobility trajectories.

A trajectory is a sequence of timestamped point locations that captures the movement of an object such as a vehicle. Such trajectories encode complex spatial and temporal patterns and provide rich information about object mobility and the underlying infrastructures, typically road networks, within which the movements occur. A trajectory dataset is evolving when new trajectories are included continuously. The ability to detect anomalous trajectories in online fashion in this setting is fundamental and challenging functionality that has many applications, e.g., location-based services. State-of-the-art solutions determine anomalies based on the shapes or routes of trajectories, ignoring potential anomalies caused by different sampling rates or time offsets. We propose a multi-scale model, termed MST-OATD, for anomalous streaming trajectory detection that considers both the spatial and temporal aspects of trajectories. The model's multi-scale capabilities aim to enable extraction of trajectory features at multiple scales. In addition, to improve model evolvability and to contend with changes in trajectory patterns, the model is equipped with a learned ranking model that updates the training set as new trajectories are included. Experiments on real datasets offer evidence that the model can outperform state-of-the-art solutions and is capable of real-time anomaly detection. Further, the learned ranking model achieves promising results when updating the training set with newly arrived trajectories.