5G NR Positioning Enhancements in 3GPP Release-18

TL;DR

Problem: GNSS-independent centimeter-level positioning is increasingly required for IIoT and smart-city applications. Approach: Rel-18 introduces carrier phase positioning (modeled by $d=\\lambda N + \\phi_{DL}$ with \\phi_{DL}=\\hat{\\phi}+\\phi_r-\\phi_t$), bandwidth aggregation, RedCap frequency hopping, LPHAP, and sidelink positioning, supported by UE/gNB coordination via the Location Management Function (LMF) and SL PRS resources. Contributions: standardized carrier-phase measurements, intra-band BW aggregation (granularity $k \\in \\{-6,...,-1\\}$; $T_c=0.5086~\\mathrm{ns}$), and SL PRS-based positioning across coverage scenarios. Impact: enables cm-level, GNSS-free positioning for industrial tracking, emergency response, and AR in 5G-Advanced networks, and sets a baseline for future enhancements across higher FR bands and unlicensed opportunities.

Abstract

New radio (NR) positioning in the Third Generation Partnership Project (3GPP) Release 18 (Rel-18) enables 5G-advanced networks to achieve ultra-high accuracy positioning without dependence on global navigation satellite systems (GNSS) with key enablers such as the carrier phase positioning technique, standardized for the first time in a cellular communications standard and setting a new baseline for future generations. In addition, Rel-18 NR supports positioning functionalities for reduced capability (RedCap) user equipment and bandwidth aggregation for positioning measurements. Moreover, the low power solutions are designed for low power high accuracy positioning use cases. Lastly, sidelink-based positioning is introduced in Rel-18. This article constitutes a comprehensive treatment of the Rel-18 NR positioning enhancements crucial for the development of next-generation networks.

Figures (6)

• Figure 1: Overview of 3GPP NR positioning
• Figure 2: Illustrative example of transmissions and receptions of DL PRS and UL SRS for carrier phase measurements.
• Figure 3: Illustrative example of DL PRS frequency hopping
• Figure 4: Illustrative example timeline of the DL PRS frequency hopping with RF retuning.
• Figure 5: Illustrative example of UL SRS frequency hopping with Zadoff-Chu sequence mapping.