Deep-Urban Unaided Precise Global Navigation Satellite System Vehicle Positioning

This article presents the most thorough study to date of vehicular carrier-phase differential Global Navigation Satellite System (CDGNSS) positioning performance in a deep urban setting unaided by complementary sensors. Using data captured during approximately 2 h of driving in and around the dense urban center of Austin, Texas, a CDGNSS system is demonstrated to achieve 17-cm-accurate 3D urban positioning (95% probability) with a solution availability greater than 87%. The results are achieved without the aid of inertial, electro-optical, or odometry sensors. The development and evaluation of the unaided, GNSS-based precise positioning system is a key milestone toward the overall goal of combining precise GNSS, vision, radar, and inertial sensing for all-weather, high-integrity, high-absolute-accuracy positioning for automated and connected vehicles. The system described and evaluated herein is composed of a densely spaced reference network, a software-defined GNSS receiver, and a real-time kinematic (RTK) positioning engine. A performance- sensitivity analysis reveals that navigation data wipeoff for fully modulated GNSS signals and a dense reference network are key to high-performance urban RTK positioning. A comparison with existing unaided systems for urban GNSS processing indicates that the proposed system has significantly greater availability or accuracy.