Network Verified NTN Positioning for 6G A Standards Oriented Survey of Hybrid TN NTN Localization

Abstract

Wireless positioning is evolving from legacy cellular and standalone satellite navigation toward hybrid, high-accuracy, three-dimensional (3D), and network-verifiable frameworks for 5G Advanced, 6G, and non terrestrial network (NTN) systems. This shift is driven by intelligent transportation, unmanned aerial vehicle (UAV) operation, low-altitude economy services, public warning, and regulated NTN use cases that require not only accurate location estimates, but also vertical awareness and verification confidence. This survey reviews the evolution from Long Term Evolution (LTE) and Global Navigation Satellite System (GNSS) positioning to New Radio (NR), Release-18/19 positioning enhancements, and NTN-enabled 3D positioning. It synthesizes observable families, 3rd Generation Partnership Project (3GPP) standard evolution, method-level tradeoffs, and open challenges for hybrid terrestrial network (TN) NTN designs, with emphasis on standardization impact, vertical observability, reliability-aware measurement selection, and network-side verification.