Wi-Fi expanding to indoor location services

Radios moving around a network is the best way to determine indoor location for assets and navigation, says certifier Wi-Fi Alliance, which introduced standards last week

Wi-Fi expanding role more to indoor location services
n.karim (CC BY 2.0)

The purpose of indoor Wi-Fi is no longer simply about providing internet connectivity. Indoor positioning services that enable asset tracking and visitor navigation functions are adding to the traditional access point feature set of spotty internet access.

GPS positioning doesn’t work as well indoors as out. And Wi-Fi equipment vendors are keen to point out that networks created with their equipment are better suited to indoor locationing—better than cellular, too, with its usually outdoor masts.

This has led to the newest Wi-Fi system: meter-level positioning.

The latest nod comes from the Wi-Fi Alliance, the certifier and association of Wi-Fi technology companies. It just launched a certified program for “meter-level accuracy for indoor device location data” using its technology.

“Measuring the time that it takes for the wireless signal to travel from one device to the other” is behind the newly standardized Wi-Fi approach. It’s known as the time-of-flight method. It’s better and is unlike how indoor positioning has worked in the past, the Wi-Fi Alliance claims in its press release.

How Wi-Fi Certified Location works

The Wi-Fi Alliance’s Wi-Fi Certified Location is rooted in the Fine Timing Measurement (FTM) protocol from IEEE 802.11-2016.

“Until now, devices typically determined indoor location by measuring received signal strength (RSSI), which has limited accuracy, or fingerprinting, which is more difficult to maintain,” the alliance says. Fingerprinting is a kind of RSSI collection with elaborate site surveys.

Tracking high-value equipment and stopping consumers from getting lost are among the uses for an improved system, Wi-Fi Alliance says. Geofencing also becomes practical. That’s where artificial boundaries prompt actions, such as an alert when a device crosses a cutoff point.

And, of course, advertising and marketing stand to benefit from it. Using “hyperlocal marketing,” businesses push targeted ads or special offers to consumers as they move around. That’s what may well pay for the increased workload in Wi-Fi location installation and testing.

The association says consumers are becoming more inclined to share their locations as they’ve gotten more comfortable with the idea. Ninety percent of U.S. smartphone users used some kind of location-based information in 2015, the group says on its website, quoting Pew Research published in 2017.

Problems with other indoor location services

The problem has always been the aforementioned issue in that incumbent satellite-driven GPS doesn’t work well indoors—roofs block the low power signal. Mobile networks and crowd sourcing is used in some location applications, along with GPS, but it all becomes less reliable indoors, the Wi-Fi Alliance claims. Beacons, too, are impractical. They’re too expensive because one needs a lot of them for large spaces, it says.

The Wi-Fi Alliance’s system functions when mobile devices and access points share data. Radio waves travel through the air at a predictable speed—the speed of light, Wi-Fi Alliance explains in its white paper. Therefore, to determine a location, all one has to do is calculate the time taken for a signal to travel between the sensing devices, say a smartphone and an access point, and factor in the speed of the radio transmission.

The key to getting it to work right is to synchronize the clocks accurately—something that’s only recently been made possible.

“Since nearly 100 percent of mobile devices ship with Wi-Fi capability and Wi-Fi networks exist globally, Wi-Fi stands out as the most viable solution to the indoor location issue,” the organization says optimistically.

CTIA, the U.S. wireless association, is working on mobile network indoor location systems, too, says RCR Unplugged, writing about the Wi-Fi Location announcement. The FCC has mandated better cellular location accuracy, it adds, which may create more options—and obvious competition for Wi-Fi Location.

Meanwhile, networking engineers should expect extra work in testing and installation of Wi-Fi access points.

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