Smartphones may be our greatest tool for outdoor and indoor navigation
'GPS and its kindred Global Navigation Satellite Systems has taken over from the traditional compass.'
From the compass to positioning satellites orbiting earth, wayfinding tools have largely focused on helping us find our way through the outdoor world, but indoor navigation technology has also come a long way in its short history.
Use of the Global Positioning System (GPS) and more broadly, the Global Navigation Satellite System (GNSS), for civilian navigation largely began in 2000. Once people saw how this technology could give them a one or two-metre accurate position when they were outdoors, it started creating a demand for similar services indoors.
"Everyone is familiar with using GPS outside. And the trick with GPS is that it only works outside," Kyle O'Keefe, professor of geomatics engineering at the University of Calgary, told Spark host Nora Young. Its signals are too weak to penetrate buildings.
While early work in indoor positioning technology was largely motivated by the needs of emergency response services to automatically locate emergency calls, the demand for that service broadened. And the smartphone has proven essential in its development and accessibility — thanks to the built-in microphone, accelerometer and barometer.
"Improvements are being made using cell phone signals, to even be able to determine your position within a particular floor in a high rise building. But also which floor you're on," Richard Langley, professor of geodesy and geomatics engineering at the University of New Brunswick, told Young.
The most common method of indoor localization is measuring the signal strength of all of the WiFi access points in a space using a phone and comparing that with data from other users who have done the same in a big table to figure out the most likely location of the phone, says O'Keefe. Similar work is being done with Bluetooth, and ultrasound.
While promising, this technology also comes with potential privacy trade-offs. "The service providers can really benefit from knowing where we are, and use that information to sell us things more effectively," he said.
"I think that people, at least so far, have been willing to trade it for the convenience of having this free service that lets you find things easily."
Beyond its use limited to the outside world, satellite navigation signals can also be blocked by tall buildings and bounce off of them before they get to receivers, says Langley. So positioning accuracy in dense cityscapes can fall short. "You need at least four satellite signals in order to determine your three dimensional position… And those signals, preferably from the satellite, should be spread out in the sky," said Langley.
These signals can also be disrupted, both maliciously and by space weather caused by surface activity on the Sun.
In October 2022, the European Space Agency announced its plans for Low-Earth Orbiting satellites (LEOs) that provide navigation services. They can be anywhere between 400 kilometres and 2000 kilometres away from earth, he says. There are already satellites in low-Earth orbit being used for science, military operations and telecom — the International Space Station is one example.
"A number of countries are developing these worldwide webs in the sky to provide telecommunications, web access via satellites," he said. Now companies, like SpaceX, are leveraging these satellites' communication capabilities for positioning, navigation and timing (PNT) services.
Langley says these won't replace the GNSS, but rather complement it — to create a layered, more resilient constellation of navigation satellites and signals that are less vulnerable to jamming and other interference.
Navigation technology's roots
All of these technologies people depend on to take them from point A to point B, can be traced back to one of the earliest man-made navigation devices, the compass — which is still widely used today, says Gary Arndt, the host of the history podcast Everything Everywhere Daily.
"Certainly the creation of the Global positioning System was sort of the next logical step."
But the same basic principles of wayfinding still apply in the technologies we now use daily, especially because many of them, including phones and cars, have an electronic compass — technically known as a magnetometer — built into them, as standalone apps and complements to existing navigation systems, like Google Maps.
The electronic compasses on our smartphones are constructed microscopically onto an integrated circuit and can work with the built-in gyroscope to measure our magnetic field in three dimensions. And unlike the magnetic compass, which requires users to manually factor in the difference between magnetic and true north, electronic compasses can do that automatically.
"Knowing the navigational skills with the compass is still something that everybody needs to know," said Arndt, as GPS itself cannot tell you the direction you're facing.
"[If] you pull up your phone right now, it'll [only] show you where you are on a map... unless you move," he said. "If you're driving, you're going to have motion and you can compare two points and see the direction. But … if you've ever been in a large city and you want to know walking directions to a place, that's when a compass is still going to come in handy."
Mapping the future of indoor wayfinding
When it comes to accurate indoor positioning and wayfinding, there's still work to be done. Many of the tools, like ultra wideband ranging radios, are only available on the latest phones and little infrastructure is in place to change that. The goal, O'Keefe says, is to someday have seamless outdoor-to-indoor pedestrian navigation services.
"Once people are used to their very accurate outdoor position, they expect it to continue when they go inside," he said. That's possible in indoor environments that have a lot of signals to measure WiFi and Bluetooth and are already really well mapped, but less so in new buildings that no one has ever done the data collection on before.
"Providing that is a challenge that a lot of researchers and a lot of companies are spending quite a bit of effort making better now."