A driver pulls into an underground car park in Xiongan New Area, north China's Hebei Province, taps "park" on a smartphone app and is guided directly to a vacant space. If the spot has already been taken, the system automatically recommends another. Behind this convenience is a technological breakthrough by a research team at the 54th Research Institute of China Electronics Technology Group Corporation (CETC54). Developed under the name "Xingyuan," the BeiDou micro-base-station system for underground positioning and navigation extends high-precision location services into spaces beyond the reach of satellite signals. The project behind the system has passed a national acceptance review by China's Ministry of Science and Technology, marking an important advance in the country's efforts to build an integrated spatio-temporal network for underground environments. CETC54 engineer Chen Chong said the system offers more than convenience, opening up new possibilities for intelligent transportation, mining and other sectors and reflecting the expanding use of high-precision positioning technology underground. Satellite navigation has long faced challenges in underground car parks because satellite signals cannot penetrate underground structures, making accurate positioning on ordinary smartphones difficult and leaving gaps in navigation services. Read More: China's Baidu launches AI model simulating road environment for robotaxis To address these challenges, the Xingyuan system deploys BeiDou micro base stations underground, enabling accurate positioning and navigation on ordinary smartphones. BeiDou, or the BeiDou Navigation Satellite System, is China's global navigation satellite system. Tests show the system can achieve static positioning accuracy better than 0.2 meters for pedestrians, with sub-meter navigation accuracy for high-speed unmanned vehicles. To make positioning reliable in complex underground environments, the team developed a digital-twin channel modeling method that combines real-time data collection with offline model optimization. The approach creates a "wireless environment map" that shows signal strength, signal delay and propagation direction, providing reliable support for underground positioning and navigation. The project has also produced China's first fully independently developed pulse positioning chip. Based on an original HNav-UWB signal standard, the chip achieves ranging accuracy better than 10 centimeters and angle accuracy better than 3 degrees, reducing reliance on foreign UWB positioning standards and core chips. Beyond parking, the Xingyuan system is being extended to underground coal mines. There, it supports personnel tracking, unmanned transportation and integrated surface and underground positioning, providing technical support for the intelligent upgrading of the coal industry.