Android Smartphone Real-Time Instant PPP with Advanced QC Module to Mitigate GNSS Signal Blockage and Reflection

Precise smartphone GNSS (Global Navigation Satellite Systems) positioning is in strong market demand since it can facilitate numerous location-based services in smartphone applications. To improve the general smartphone positioning performance, Profound Positioning Inc. released a real-time instant PPP (Precise Point Positioning) AAR (Android Archive) library named IP3-Mobile for Android smartphones, capable of providing position solutions with sub-meter to meter level accuracy. IP3-Mobile enables access to accurate fast-convergence PPP solutions within a few seconds. Most smartphone positioning applications work mainly for open-sky or less challenging environments. There are still various difficulties in providing accurate and reliable position solutions in GNSS-challenging environments with signal blockage, multipath interference, low signal-to-noise ratio, etc. In this work, a QC (Quality Control) module has been developed and implemented into IP3-Mobile to minimize the impact of reflected and degraded GNSS signals on smartphone position determination. The key components of the QC module include a range error detector to filter out outliers based on statistical results, a GNSS observation classifier to detect the NLOS (Non-Line-Of-Sight) signals, and a solution validator to detect position solutions with large errors. These components work together to improve smartphone positioning accuracy in challenging environments with a significant number of reflected GNSS signals. The developed QC module has made several technological advancements to smartphone GNSS positioning. It can provide more accurate and reliable positioning performance in challenging environments because it can take advantage of all available GNSS observations. The field test results show that IP3-Mobile could achieve a Circular Error Probable 50% (CEP50) accuracy of around 1m in suburban areas. The performance degraded with increasing signal blockage and reflection in more challenging environments. In dense urban areas, CEP95 could still be maintained under 15 meters.