5G Positioning Unleashed: Pioneering New Services

5G positioning and location technologies are the culmination of nearly three decades of advancements in mobile positioning technologies [see here for a very informative description]. What began as regulatory requirement for emergency services has expanded into requirements for positioning services in a host of industry verticals and use cases. To meet these new demands, 5G enhances positioning services through improved signalling schemes, robust solution architecture, and the implementation of diverse positioning techniques. As a result, for the first time ever, a mobile technology could become a competitive commercial positioning system, opening up new opportunities for mobile network operators to offer innovative services.

Comparative assessment

Positioning technologies each come with their own strengths and weaknesses. Key metrics include service availability, location accuracy, and confidence interval. Increasingly, the latency in determining the location has become crucial, especially for industrial applications. This need for reduced latency is a notable shift that 5G positioning technologies aim to address.

Technology	Accuracy	Coverage	Latency	Advantages	Disadvantages
Global Positioning System (GPS)	~5 meters (open sky), <1 meter with DGPS	Global	Low	Wide availability, high accuracy in outdoor environments	Limited indoor accuracy, dependent on satellite visibility
Wi-Fi Positioning System (WPS)	5-15 meters	Areas with Wi-Fi access points	Moderate	Effective indoors, leverages existing infrastructure	Variable accuracy, limited to areas with Wi-Fi coverage
Bluetooth Low Energy (BLE) Beacons	1-2 meters	Areas with beacon deployments	Low	High accuracy indoors, low power consumption	Requires beacon installation and maintenance, limited coverage
Ultra-Wideband (UWB)	Centimeter-level precision	UWB-enabled areas	Extremely low	Very high accuracy and reliability, suitable for real-time applications	Limited range and coverage, requires specialized hardware
5G NR Positioning	<1 meter horizontal, <3 meters vertical	Within 5G network coverage	Low	High accuracy, low latency, supports advanced applications like IIoT	Dependent on 5G deployment and density, still evolving with ongoing standardization
Inertial Navigation Systems (INS)	Varies, can drift over time	Independent of external signals	Very low	Works without external signals, effective in environments where GPS is unavailable, very low latency	Accuracy degrades over time without external correction, often requires integration with other systems for optimal results

5G positioning requirements

Release 16 specified the location and positioning requirements to meet regulatory standards for emergency services. Following this, Release 17 defined requirements for market verticals, distinguishing between commercial use cases and Industrial Internet of Things (IIoT) applications that require tighter specifications (See here blog post by the 3GPP). [Note: Release 18 brings further important enhancements for V2X and IIoT location services which I don’t cover in this post.]

Technically, 5G Release 16 network architecture introduces a new function called the location management function (LMF). The LMF manages location services and centralizes positioning calculations. It communicates with other network elements, such as the AMF and gNB, using a new control plane protocol called NR Positioning Protocol A (NRPPa). Practically, this means that some of the more advanced features of 5G positioning require a standalone 5G core network.

Release 16 introduces two physical layer reference signals: the positioning reference signal (NR PRS) for downlink or RAN-based techniques, and the sounding reference signal (SRS) in the uplink for device-based techniques. The PRS design ensures that reference signals from multiple base stations arrive at the mobile device with sufficient distinction and repetitiveness, enhancing the accuracy of downlink positioning techniques. In the uplink, multiple base stations receive the SRS, which is designed in a comb-like manner to minimize interference between reference signals from different mobile devices. While a full description of the PRS and SRS in 5G and their comparison to those in LTE is out of scope here, the key improvements lie in the enhanced structure, periodicity, duration, and repetition of the signals. These enhancements lead to a higher capacity, in number of mobile devices, for which we can accurately determining the location of. These enhancements lead to being able to accurately determining the location of a larger number of mobile devices.

	Horizontal accuracy	Vertical accuracy	Latency
Release 16 (Commercial use case)	Outdoor: < 10 m for 80% of mobile devices Indoor: < 3 m for 80% of mobile devices	Outdoor: < 3 m for 80% of mobile devices Indoor: < 3 m for 80% of mobile devices	Outdoor: < 1 second end-to-end Indoor: < 1 second end-to-end
Release 17 (Commercial use case in industry verticals and industrial use case / IIoT)	< 1 m for 90% of devices - commercial use < 0.2 m for 90% of devices - IIoT	< 3 m for 90% of devices - commercial use < 1 m for 90% of dvices - IIoT	< 100 msec end-to-end latency < 10 msec PHY latency
E911 [included for comparison; see here for full FCC specs]	Outdoor Network-based technologies: < 100 m for 67% of calls < 300 m for 90% of calls Outdoor Handset-based solutions: < 50 m for 67% of calls < 150 m for 80% of calls Indoor: 50 m	Within 3 meters above or below (plus or minus 3 meters) the handset for 80% of wireless E911 calls made from the z-axis capable device.	30 seconds max time-to-first fix

5G positioning technologies

Positioning technologies can be categorized into RAN-based technologies, where positioning is determined using uplink information, and mobile-based technologies, where positioning is determined using downlink information. Additionally, a distinction exists between technologies inherent to 5G and those relying on other networks such as GPS and Wi-Fi. However, I simplified this classification to include only two categories to describe the 5G positioning technologies in the table below.

RAN-Based Technologies	New Radio – Enhanced Cell Identity (NR E-CID)	The network reports the location of the serving cell site	High frequency bandwidth, e.g. 100 MHz FR1 or 400 MHz FR2
	Uplink Time Difference of Arrival (UL-TDoA)	The network measures the relative time of arrival of a mobile SRS signals at different cell sites	High frequency bandwidth, e.g. 100 MHz FR1 or 400 MHz FR2; larger sub-carrier spacing; beamforming to increase Rx power
	Uplink Angle of Arrival (UL-AoA)	The network measures the azimuth and zenith of arrival of a mobile’s SRS signals relative to a reference direction	Antenna arrays/massive MIMO; smaller sub-carrier spacing
	Multi-Round Trip Time (Multi-RTT)	The network measures the time difference of a mobile’s SRS signals at multiple cells Note: it also works in the downlink where the mobile measures the time difference of the PRS signals from multiple cells
Handset-Based Technologies	Downlink Time Difference of Arrival (DL-TDoA)	The mobile measures the time difference of arrival of the downlink PRS from different cells	High frequency bandwidth, e.g. 100 MHz FR1 or 400 MHz FR2; larger sub-carrier spacing; beamforming to increase Rx power
	Downlink Angle-of-Departure (DL-AoD)	The mobile measures the strength of the PRS in each beam from a beamforming cell site	Antenna arrays/massive MIMO; smaller sub-carrier spacing
	Assisted Global Navigation Satellite System (A-GNSS*)	Based on GPS and other GNSS systems (e.g. GLONASS, BeiDou, Galileo)	* Not applicable: Technology independent of 5G NR
	Wi-Fi Positioning System (Wi-Fi WPS)	Based on location of nearby Wi-Fi access points reported by databases	* Not applicable: Technology independent of 5G NR
	Bluetooth*	Based on Bluetooth beacons	* Not applicable: Technology independent of 5G NR
	Beacon Systems*	Other beacon-based positioning solutions	* Not applicable: Technology independent of 5G NR

Some inherent features of 5G significantly enhance positioning accuracy, as summarized in the last column of the above table. For example, the wider channel bandwidth of 5G (e.g., 100 MHz compared to 20 MHz in LTE) improves the accuracy of UL-TDoA and DL-TDoA positioning methods. For a more detailed explanation, see this blog post by Ericsson here.

Concluding remarks

5G’s advancements in positioning and location technologies mark a significant evolution from previous generations. With inherent features such as the LMF, wider channel bandwidths and advanced signal designs, 5G achieves higher accuracy and reliability in positioning. These improvements enable 5G to serve not only regulatory requirements for emergency services but also a wide range of commercial and industrial applications. As 5G continues to evolve (standalone networks and Release 17 compliance), it promises to open new opportunities for mobile network operators to deliver innovative services, leveraging its enhanced positioning capabilities. The continued development and refinement of these technologies will further solidify 5G’s role as a competitive commercial positioning system. However, this does not mean that 5G will replace other technologies, but it will be a powerful tool in the toolkit.

Finally, I focused on the technical aspects of 5G positioning. It is essential to validate the financial viability of these services by weighing the economic benefits against the implementation and operational expenses. For instance, GPS is available outdoors for free. Moreover, indoor coverage of 5G, especially in today’s mid-bands and future mmWave bands, is limited. Therefore, the cost of site densification and necessary upgrades to the network and user devices must be factored into the operator’s business case.