Masked Latent Prediction of CSI for Indoor Localization in Integrated Sensing and Communication Systems

Abstract

Channel State Information (CSI)-based fingerprinting can enable accurate indoor localization but suffers from domain shift, limited labeled data, and degraded performance in multipath-rich environments. To address these challenges, we propose a self-supervised localization framework built on a Joint Embedding Predictive Architecture (JEPA). Each CSI time snapshot is treated as a token, and the encoder is pre-trained by predicting the latent embeddings of masked snapshots from the visible ones, learning robust channel representations without any labels. The encoder is then frozen, and only a lightweight regression head is trained on a small set of labeled positions to estimate the user location. We evaluate the framework on the measured DICHASUS-005x dataset, a single-antenna transmitter received by a 32-antenna array in a multipath-rich indoor environment. With a 50% masking ratio, the proposed method reduces the mean localization error from 0.90 m to 0.42 m (a 53% reduction, or 0.48 m) relative to a supervised Convolutional Neural Network (CNN) baseline trained on raw CSI. Owing to its label-efficient, frozen-encoder design, the framework aligns with integrated sensing and communication (ISAC) objectives, enabling reliable sensing with minimal labeling and compute overhead.