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Indoor Positioning in 5G-Advanced: Challenges and Solution towards Centimeter-level Accuracy with Carrier Phase Enhancements

Jakub Nikonowicz, Aamir Mahmood, Muhammad Ikram Ashraf, Emil Björnson, Mikael Gidlund

TL;DR

The 5G positioning framework, measurements, and procedures are discussed before shifting the focus to recently identified carrier-phase (CP) measurements in Rel-18 as a complementary measure for time- and angular-based positioning methods.

Abstract

After robust connectivity, precise positioning is evolving into an innovative component of 5G service offerings for industrial use-cases and verticals with challenging indoor radio environments. In this direction, the 3GPP Rel-16 standard has been a tipping point in specifying critical innovations, followed by enhancements in Rel-17 and Rel-18. In this article, we elaborate on the 5G positioning framework, measurements, and procedures before shifting the focus mainly to recently identified carrier-phase (CP) measurements in Rel-18 as a complementary measure for time- and angular-based positioning methods. We discuss the associated challenges and potential solutions for exploiting CP, including integer ambiguity, multipath sensitivity, and signaling aspects. Furthermore, we study how phase-continuous reference signaling can counter noisy phase measurements using realistic simulations to achieve centimeter-level accuracy in indoor factory (InF) scenarios.

Indoor Positioning in 5G-Advanced: Challenges and Solution towards Centimeter-level Accuracy with Carrier Phase Enhancements

TL;DR

The 5G positioning framework, measurements, and procedures are discussed before shifting the focus to recently identified carrier-phase (CP) measurements in Rel-18 as a complementary measure for time- and angular-based positioning methods.

Abstract

After robust connectivity, precise positioning is evolving into an innovative component of 5G service offerings for industrial use-cases and verticals with challenging indoor radio environments. In this direction, the 3GPP Rel-16 standard has been a tipping point in specifying critical innovations, followed by enhancements in Rel-17 and Rel-18. In this article, we elaborate on the 5G positioning framework, measurements, and procedures before shifting the focus mainly to recently identified carrier-phase (CP) measurements in Rel-18 as a complementary measure for time- and angular-based positioning methods. We discuss the associated challenges and potential solutions for exploiting CP, including integer ambiguity, multipath sensitivity, and signaling aspects. Furthermore, we study how phase-continuous reference signaling can counter noisy phase measurements using realistic simulations to achieve centimeter-level accuracy in indoor factory (InF) scenarios.
Paper Structure (18 sections, 5 figures, 1 table)

This paper contains 18 sections, 5 figures, 1 table.

Table of Contents

  1. Introduction
  2. Basic positioning approaches
  3. Angle-based Positioning
  4. Time-based Positioning
  5. Investigated Hybrid Solutions/Enablers
  6. Carrier Phase (CP)-based Enhancements
  7. CP in Time-based Solutions
  8. CP in Angle-based Solutions
  9. Continuous-PRS
  10. Performance of Continuous-PRS in InF
  11. Open Challenges and Potential Solutions
  12. Integer Ambiguity
  13. Multipath and NLOS
  14. UE and gNB timing errors
  15. gNB/TRPs master-slave synchronization
  16. ...and 3 more sections

Figures (5)

  • Figure 1: The 5G positioning architecture and possible measurements/methods together with performance requirements across 3GPP releases for evolving needs of IIoT use-cases. Rel-17 and onward efforts are focused on accuracy enhancements by improving NR parameters (e.g., bandwidth, power, antennas), combination of measurements (e.g., CP with time/angle measurements), and other countermeasures (e.g., multipath resolution).
  • Figure 2: Illustration of carrier phase (CP) in angle/time-based solutions.
  • Figure 3: Carrier phase (CP) measurement in regular PRS vs. continuous-PRS.
  • Figure 4: Cumulative distribution function (CDF) of the 3D distance error for the InF FR1 scenario with 100 MHz bandwidth.
  • Figure 5: Cumulative distribution function (CDF) of the 3D distance error for the InF FR2 scenario with 400 MHz bandwidth.