When you think about Bluetooth, you probably think about things like wireless headphones, computer mice, and other personal devices that utilize the short-range, low-power technology. That’s where Bluetooth has made its mark, after all—as an alternative to Wi-Fi, using unlicensed spectrum to make quick connections between devices.
But it turns out that Bluetooth can go much farther than the couple of meters for which most people rely on it. Apptricity, a company that provides asset and inventory tracking technologies, has developed a Bluetooth beacon that can transmit signals over 32 kilometers (20 miles). The company believes its beacon is a cheaper, secure alternative to established asset and inventory tracking technologies.
A quick primer, if you’re not entirely clear on asset tracking versus inventory tracking: There’s some gray areas in the middle, but by and large, “asset tracking” refers to an IT department registering which employee has which laptop, or a construction company keeping tabs on where its backhoes are on a large construction site. Inventory tracking refers more to things like a retail store keeping correct product counts on the shelves, or a hospital noting how quickly it’s going through its store of gloves.
Asset and inventory tracking typically use labor-intensive techniques like barcode or passive RFID scanning, which are limited both by distance (a couple of meters at most, in both cases) and the fact that a person has to be directly involved in scanning. Alternatively, companies can use satellite or LTE tags to keep track of stuff. While such tags don’t require a person to actively track items, they are far more expensive, requiring a costly subscription to either a satellite or LTE network.
So, the burning question: How does one send a Bluetooth signal over 30-plus kilometers? Typically, Bluetooth’s distance is limited because large distances would require a prohibitive amount of power, and its use of unlicensed spectrum means that the greater the distance, the more likely it will interfere with other wireless signals.
The key new wrinkle, according to Apptricity’s CEO Tim Garcia, is precise tuning within the Bluetooth spectrum. Garcia says it’s the same principle as a tightly-focused laser beam. A laser beam will travel farther without its signal weakening beyond recovery if the photons making up the beam are all as close to a specific frequency as possible. Apptricity’s Bluetooth beacons use firmware developed by the company to achieve such precise tuning, but with Bluetooth signals instead of photons. Thus, data can be sent and received by the beacons without interfering and without requiring unwieldy amounts of power.
Garcia says RFID tags and barcode scanning don’t actively provide information about assets or inventory. Bluetooth, however, can not only pinpoint where something is, it can send updates about a piece of equipment that needs maintenance or just requires a routine check-up.
By its own estimation, Apptricity’s Bluetooth beacons are 90 percent cheaper than LTE or satellite tags, specifically because Bluetooth devices don’t require paying for a subscription to an established network.
The company’s current transmission distance record for its Bluetooth beacons is 38 kilometers (23.6 miles). The company has also demonstrated non-commercial versions of the beacons for the U.S. Department of Defense with broadcast ranges between 80 and 120 kilometers.
This article appears in the November 2020 print issue as “30-Kilometer Bluetooth.”
Michael Koziol is an associate editor at IEEE Spectrum where he covers everything telecommunications. He graduated from Seattle University with bachelor's degrees in English and physics, and earned his master's degree in science journalism from New York University.