Have you ever hit a surprise pothole or other road obstruction? Do you wish your navigation app could provide more precise location or lane-level accuracy? These and other novel features are powered by smartphone positioning services. Machine learning and precision GNSS algorithms are expected to improve this accuracy and provide billions of Android phone users with a more fine-tuned positioning experience. Global Navigation Satellite System (GNSS) provides raw signals, which the GPS chipset uses to compute a position. Current mobile phones only offer 3-5 meters of positioning accuracy. While useful in many cases, it can create a “jumpy” experience. For many use cases the results are not fine nor stable enough to be reliable. This competition, hosted by the Android GPS team, is being presented at the ION GNSS+ 2021 Conference. They seek to advance research in smartphone GNSS positioning accuracy and help people better navigate the world around them. In this competition, you'll use data collected from the host team’s own Android phones to compute location down to decimeter or even centimeter resolution, if possible. You'll have access to precise ground truth, raw GPS measurements, and assistance data from nearby GPS stations, in order to train and test your submissions. If successful, you'll help produce more accurate positions, bridging the connection between the geospatial information of finer human behavior and mobile internet with much finer granularity. Mobile users could gain better lane-level coordinates, enhanced experience in location-based gaming, and greater specificity in the location of road safety issues. You may even notice it's easier to get you where you need to go. ### Acknowledgments The Android GPS team would like to show its appreciation to Verizon Hyper Precise Location Service and Swift Navigation Skylark Correction Service who provided assistance data for datasets in the challenge.