Experimental Validation of a 3GPP Compliant 5G-Based Positioning System

TL;DR

A 3GPP-compliant 5G positioning testbed is developed, incorporating gNodeBs (gNBs) and User Equipment (UE) and a calibration method is proposed for estimating time offsets affecting the inter-gNB and UE-gNB time offsets affecting the TOA estimates.

Abstract

The advent of 5G positioning techniques by 3GPP has unlocked possibilities for applications in public safety, vehicular systems, and location-based services. However, these applications demand accurate and reliable positioning performance, which has led to the proposal of newer positioning techniques. To further advance the research on these techniques, in this paper, we develop a 3GPP-compliant 5G positioning testbed, incorporating gNodeBs (gNBs) and User Equipment (UE). The testbed uses New Radio (NR) Positioning Reference Signals (PRS) transmitted by the gNB to generate Time of Arrival (TOA) estimates at the UE. We mathematically model the inter-gNB and UE-gNB time offsets affecting the TOA estimates and examine their impact on positioning performance. Additionally, we propose a calibration method for estimating these time offsets. Furthermore, we investigate the environmental impact on the TOA estimates. Our findings are based on our mathematical model and supported by experimental results.

Figures (9)

• Figure 1: 5G Positioning architecture as per 3GPP Release 16 10041419
• Figure 2: PRS configurations for the UE and three gNBs to transceive 5G positioning PRS signals.
• Figure 3: Testbed setup: Three gNBs and one UE are connected to an Octoclock for time and frequency synchronization.
• Figure 4: System Model with three gNBs and one UE with unknown time offsets between each other. $\tau_{i,j}$ can be positive or negative depending upon the values of $\phi$ and $\Delta_{j}$.
• Figure 5: TOA ($\tau_{i,2}$) is the location of the 'peak channel tap' obtained from the downlink channel estimate from gNB $2$.