Ray-Traced Augmentation for Signal Strength Based Localization

Abstract

Indoor localization based on Wi-Fi typically relies on extensive collection of real-world received signal strength (RSS) fingerprints, making deployment costly and time-consuming. We present a ray-tracing-based framework that reduces this reliance by generating synthetic RSS fingerprints from a building model. We first calibrate the building model using a small amount of real RSS fingerprints through Bayesian optimization, followed by per-access-point calibration to account for residual errors in simulated RSS values. The calibrated model is then used to generate a large augmented dataset of synthetic RSS fingerprints at arbitrary locations. To effectively exploit these data for localization, we introduce novel binary and multivalued representations of RSS values and a ResNet-based localization architecture that supports cross-band fusion of 2.4 and 5 GHz measurements. We evaluate our localization method on a real campus building against a diverse set of four baselines. When trained exclusively on synthetic data, the proposed method with multivalued representation and upstream cross-band fusion achieves a mean localization error of 3.05m on a real-data test set, outperforming the best baseline by 33.6%. The results demonstrate that calibrated ray-tracing-based simulation can substantially reduce the need for real RSS fingerprints while enabling accurate deep-learning-based indoor localization.