Bluetooth for Geolocation? - A Tragic Misuse Shows Why this is a Bad Idea

In a recent, tragic case, a Bluetooth tracker that was advertised as having a wide area geolocation capability has failed to locate a lost Alzheimer’s patient after 17 days. 17 days and counting. And they still can’t find him.

Harold Cantrell Missing - Public Invited to Help; Image Credit: WFLA

Bluetooth isn't bad for finding low-value items wedged beneath your living room seat cushions, like your car keys or wallet. And Bluetooth has many other valuable applications in IoT, but geolocation over a wide area isn't one of them. If you want to pretend that you really do love your mother-in-law’s spoiled dog, give her a Bluetooth tracker as a gift and then feign shock when she can’t find him when he goes missing. (OK — that wasn’t nice.)

Marketing a short range technology like this as a wide area tracking device and allowing (or at a minimum, not warning against) its use on human is both misleading and dangerous. I don’t know the fate of this Alzheimer’s patient and hope and pray he will be found safe and sound, but folks in the Bluetooth tracking business should be paying attention.

So Why Isn't Bluetooth Good For Geolocation?

With an average range of about 30 feet, using Bluetooth to track something — especially something very valuable — over wide areas is just usually not done. Bluetooth is a Personal Area Networking technology — as in, a Fitbit or a Sonos speaker — and certainly not a Wide Area Networking technology.

In my experience, the handful of people I have seen putting Bluetooth trackers on dogs or bikes are doing so based on utter technical naiveté, bad marketing hype, or hearsay from other uninformed users. Like “My brother-in-law told me I could use it on my dog and if she went missing the Bluetooth tracker would find her via satellite. Or via the cell phone network.”

In the article, it mentions a community finding feature which uses Bluetooth on phones of anyone with the app to locate objects. It's basically crowdsourced geolocation. If you walk within range of the lost object, your phone will recognize it and let the person who lost the object know. This is what's used to "support" the wide area networking claims. (There are other Bluetooth folks out there doing the same thing, last time I checked.)

Unfortunately, without massive numbers of concurrent users actively invoking their tracking app, the probability of a detection is — as the 17-day delay in locating the missing patient demonstrates — very, very small.

How small?

Covering the city of Daytona Beach (where the Alzheimer’s patient went missing) requires enough active users — each with ~2,800 square feet (that’s 30 feet² x π) of Bluetooth “coverage” — to cover 65 square miles of the city (1.8 billion square feet). Or about 647,000 concurrent users just in Daytona Beach. All distributed evenly throughout the city, all with ~30 feet of Bluetooth coverage, all with their phones turned on and the tracking app enabled. And all of this assumes the patient didn’t run off to another town nearby.

And this is made somewhat more problematic by the U.S. Census Bureau, which says the total population of Daytona Beach is 63,000 people.

End user confusion about how wireless technologies work (like WiFi, Bluetooth, LPWANs, cellular IoT, etc.) is pretty rampant. High powered cellular technology is the paradigm that I have observed makes some of this possible. Misconceptions about how GPS works are even more abundant.

Bluetooth radio spec sheets claim certain capabilities, often based on “best case” conditions that don’t reflect a real world environment. And in a rush to turn Bluetooth into a relevant Internet of Things technology, hacks were invented to make it sound more compelling as a tracking technology than it really is.

It's possible the Bluetooth tracking company here warned their customers against tracking humans with their product, but when you market a community finding feature replete with “success stories” of objects like lost bicycles, and then claim that the range is potentially “limitless”, people are going to take your word for it and get creative.

If you want real-time tracking over wide areas using a device that provides multi-year battery life and GPS-based location, there are much better technologies out there than Bluetooth.