# Evaluation of the Ionospheric Corrections Generated by Smartphones with Different Real-Time Products

## TL;DR

This paper shows that smartphones can estimate ionospheric delays as accurately as expensive geodetic receivers, improving GNSS positioning when used with real-time corrections.

## Contribution

Demonstrates smartphone-based ionospheric estimation achieves meter-level accuracy comparable to geodetic receivers using real-time correction products.

## Key findings

- Smartphone-derived ionospheric delays match geodetic receiver accuracy within the meter level.
- Positioning performance improves by 74.7% and 54.9% using CNES and PPP-B2b corrections compared to conventional PPP.
- Smartphone corrections yield comparable positioning results to geodetic receivers after convergence.

## Abstract

Ionospheric delay is a dominant error source in global navigation satellite systems (GNSSs). Conventional ionospheric estimation relies on dense networks of expensive geodetic receivers, limiting accessibility and coverage. With the widespread availability of multi-frequency, multi-constellation smartphones capable of carrier-phase tracking, this study investigates smartphone-based ionospheric estimation. Using a single-reference Precise Point Positioning Real-Time Kinematic (PPP-RTK) framework, ionospheric delays are estimated from smartphone data and evaluated using real-time correction products from BeiDou PPP-B2b and Centre National d’Études Spatiales (CNES). Quality control is performed via solution separation testing with time-differenced carrier phase and time-differenced pseudorange. Field experiments with two Google smartphones and a geodetic receiver demonstrate that the estimated slant ionospheric accuracy is comparable to geodetic receivers within the meter level under both static and kinematic scenarios. Additionally, the horizontal positioning performance demonstrates that the positioning performance of the user smartphone with ionospheric corrections broadcast from the base smartphone is significantly improved, with 74.7% and 54.9% for CNES and PPP-B2b products compared with the conventional PPP solution. Furthermore, a comparison between ionospheric corrections generated from the smartphone and those obtained from the geodetic receiver reveals that the positioning performance of the user smartphone becomes comparable after convergence.