As 5G devices and networks begin to emerge and expand through the early 2020s, location and positioning technologies are some of the most interesting areas of advancement. That’s because many of the most exciting new use cases, from autonomous vehicles to real-time remote control, simply won’t happen without significant improvements in the accuracy, speed, and availability of positioning information. 5G is stepping up to the plate with enhancements to current 4G positioning techniques such as A-GNSS and OTDOA, as well as completely new techniques (such as using beamforming information to determine vertical position).
It’s critical, though, to perform testing of these new technologies to ensure the location performance of new 5G devices and services. It’s also critical in the near term, though perhaps less obvious, to test 4G positioning performance within 5G devices.
Here, we review positioning technology as it relates to cellular networks. The next installment will look at how 5G and other technologies such as Wi-Fi are expanding the positioning toolkit and Spirent’s solutions for testing and assuring the high performance that 5G can deliver.
It’s critical to perform testing of these new technologies to ensure the location performance of new 5G devices and services. It’s also critical in the near term, though perhaps less obvious, to test 4G positioning performance within 5G devices.
Cellular Positioning Technology—It’s not just GPS satellites
If you ask most smartphone users how their iPhone or Android device performs tricks like turn-by-turn navigation, they are likely to say, “it’s just GPS.” While satellite positioning does form the foundation for cellular location, GPS—or for much of the world outside the U.S., GNSS, the Global Navigation Satellite System—alone cannot meet the most important cellphone location requirement: rapidly and accurately identifying a caller’s location during an emergency call.
Here’s why. When an emergency call is placed from a mobile handset, it can take several minutes for the handset to find signals from the appropriate GNSS satellites and to receive a sufficient amount of positioning information to calculate its position. This startup time, known as Time to First Fix (TTFF), is a critical performance parameter in emergency situations.
To help the handset get a faster TTFF, the cellular network steps in. The cell network takes what it knows about the location of the user (such as the location of the base station that the user is currently connected to), looks up instantaneous satellite positions in a real-time database, and sends the handset information about which satellites to listen for. This is called A-GNSS (Assisted GNSS). A-GNSS’s “assistance data” reduces TTFF down to a handful seconds, instead of minutes.
Cellular has a couple of other tricks up its sleeve to determine location even when satellite signals are weak or unavailable, including ECID (Enhanced Cell ID) and OTDOA (Observed Time Difference of Arrival). Wi-Fi has also been extended to act as a viable indoor positioning technology, and is already being mandated by some major U.S. carriers (including AT&T) to meet U.S. Federal Communications Commission (FCC) requirements.
The proliferation of public and private Wi-Fi access points (APs) provides an abundance of equipment to control positioning information. Since almost all new devices are equipped with Wi-Fi, this is an inexpensive and fast-to-market addition to supplement location-based services.
Taken together, A-GNSS, ECID, OTDOA, and Wi-Fi form a “hybrid” positioning system that provides location information both indoors and outdoors.
The regulatory push for greater location accuracy and availability
As cool as they may be, GNSS and LTE-based hybrid technologies are becoming insufficient to meet increasing location demands and regulatory requirements. The most influential driver for mobile location accuracy is the regulatory requirements for mobile emergency calls (E911) set by the FCC. Other entities piggy-back on the FCC requirements, such as the European Union for E112 and, for automotive, eCall.
The FCC has been driving increasing location accuracy for almost two decades. E911 Phase 1, defined in 1995, required only the caller’s phone number and cell tower ID. This progressed in the early 2000s to a requirement of 300-meter accuracy within six minutes. The FCC has continued to evolve its safety requirements as our lifestyles have become so intertwined with and dependent on wireless connectivity. In 2017, the FCC required that operators demonstrate 50-meter accuracy for 40% of mobile E911 calls.
By mid 2021, operators will need to show that they are delivering 50-meter accuracy for 80% of all outdoor and indoor mobile emergency calls, according to the FCC.
Worldwide, the industry as a whole benefits from global handsets that meet these FCC-driven mandates.
Commercial drivers for improved accuracy
The second driver for location accuracy and “anywhere-availability” is economic. As wireless technologies have exploded over the past several decades, the opportunities for new applications dramatically increased. A long list of new and envisioned human-to-machine and machine-to-machine use cases require spot-on precision—augmented reality, fitness wearables, real-time location-based advertising, transportation, package tracking, asset tracking, factory vehicles, shared bikes, and many others.
Locating a trusted partner for position testing
All of these bring a need for accurate performance testing. Network providers and device manufacturers are already working to understand the potential challenges and design test methodologies to ensure that location-based systems work as intended. In 3GPP, for example, there are several working groups and work items related to 5G positioning technology (See the RAN#80 Study on NR positioning support).
Spirent is at the center of these developments. Having led the GNSS test industry almost since its inception, our experts are a key driving force in industry-wide innovations – as demonstrated by our 2016 Royal Institute of Navigation Award for Technical Achievement.
For a complete, in-depth discussion of 5G and location technologies, check out The Impact of 5G on Location Technologies: Fulfilling the Promise of Positioning and Location Accuracy.
How 5G and other technologies are expanding the positioning toolkit
In Part 2, we’ll look at how 5G and a variety of other technologies are stepping in to fill the gaps in location accuracy.