BLE Standard Brings RTLS Functionality to Beacons

By Claire Swedberg

The Bluetooth Special Interest Group's new 5.1 standard comes with angle-of-arrival and angle-of-departure direction finding functionality, so that solutions can be built to locate the position of a tag or mobile phone within centimeters.


The Bluetooth Special Interest Group (SIG) has released a new direction-finding feature for location services as part of its specification update 5.1, making angle-of-departure (AoD) and angle-of-arrival (AoA) standard functions that Bluetooth Low Energy (BLE) beacon technology companies can build into their solutions. That means Bluetooth beacons can comprise a real-time location system (RTLS).

The technology can be used for asset tracking with AoA and wayfinding, or for other smartphone-based systems using AoD. These direction-finding features, built on top of BLE 4.0 and enhanced with proprietary extensions, are already being sold as parts of proprietary solutions, such as those from Quupaa.

The Bluetooth SIG’s Ken Kolderup

With the direction-finding feature in the 5.1 specification, says Ken Kolderup, the Bluetooth SIG’s marketing VP, “We’re adding a new capability that is targeted to up our game in location services.” The 5.1 feature will allow BLE companies to offer solutions by which a Bluetooth device can be trackable down to a location level of a few centimeters. Bluetooth beacons are already being used to identify where individuals or items are located, but not with the granularity afforded by direction-finding.

The AoD and AoA features consist of a beacon (also known as a locator) with multiple antennas rather than the standard single antenna, making it possible for a system to detect the angle at which a signal is sent and received. In the case of AoD, the technology could enable a smartphone to serve as a receiver to identify its own location, based on the angle of the signals transmitted by beacons operating within its vicinity. In another scenario, the phone could employ the antenna array built into it to take samples of beacon transmissions, and thereby understand the exact direction from which the transmission was received. A phone receiving these multiple signals could then utilize both triangulation and trilateration to narrow down the location.

With AoA systems, asset tracking is enabled using tags transmitting via Bluetooth, as well as nodes with a multiple-antenna array built in, serving as locators or receivers. Those receivers measure the angle of transmission from the asset tags and send data to a server.

Traditionally, Kolderup says, most Bluetooth beacon solutions rely on received signal strength indicators (RSSI) to estimate the distance between two devices and thereby calculate the general location of a tag or smartphone. Whether a solution offers wayfinding to help a mobile phone user identify where he or she is, or large-scale, complex asset- and people-tracking capabilities, the technology has based location data on signal strength measurements.

“That’s been great,” Kolderup says. “The basic approach has allowed the location services market to really take off well for Bluetooth.” However, he adds, as technology evolves and as users become more accustomed to a variety of location services, “There has been a market demand for enhanced performance.” While asset tracking now can employ Bluetooth beacons to identify location within about a meter-level accuracy, users are seeking something that can provide centimeter-based granularity.

Quuppa (founded by members of Nokia) has been developing solutions using AoD- and AoA-based technologies since 2004 (see BLE Provides RTLS for Tracking Production at Auto Ceramics Company). In 2010, Quuppa’s team participated in the early phases of the Bluetooth SIG’s standardization process, by contributing the first draft of the specifications and a reference implementation system while they were still at Nokia. Quuppa not only offers direction-finding technology, but is a member of the Bluetooth SIG’s direction-finding working group. What’s more, the company has been helping support the 5.1 standardization for direction-finding, according to Fabio Belloni, Quuppa’s cofounder and chief customer officer.

The standard will allow companies to create both simple and complex solutions, Kolderup predicts. On the simple side of the spectrum, he says, “Imagine a smartphone with this direction-finding capability app that would not only tell me my keys are near, but in what direction.” But it could also be used for much more complex systems, he notes. For instance, a facility could track the real-time locations of such beacon-tagged assets as pallets and vehicles, or employees, in order to identify where they are and trigger alerts when necessary.

Quuppa’s Fabio Belloni

Bluetooth beacon technology use for location services has been growing exponentially, Kolderup reports. ABI Research has forecast the market to grow from 87 million products shipped last year to 402 million in 2022. The direction-finding feature will serve as “another good building block,” he says.

The standardization, initially promoted by Nokia in 2010, has since been embraced by several companies. After Quuppa was established in 2012, it took off from the early-stage prototype systems and developed an angular location platform based on standard BLE radios. “Everything Quuppa has been doing for the past nine years,” Belloni explains, “is to take the base idea of angle-of-arrival and angle-of-departure and build all of the components,” including specification profiles and hardware to enable RTLS solutions, which companies can now leverage to create location services using the 5.1 standard.

“We are excited about the standard,” Belloni states. “We’ve been looking forward to it for many years.” While he says more AoA deployments are likely to take place right away in the form of Internet of Things (IoT) and RTLS solutions, AoD will be a follower since it could require additional hardware—for instance, antenna arrays and new 5.1 BLE-enabled radio chips—built into smartphone handsets. However, he says, his partners who install AoA-based systems are already using AoD to link a laptop or tablet to the hardware during commissioning.

“Now, really, the challenge is to work with anybody who is willing to frog-jump years of development and field testing and trials [by companies like Quuppa],” Belloni says, “and make use of some of the profiles and system components that will allow them to leverage the capability of a Bluetooth AoA system.”

Several technology companies are already developing solutions that are expected to become available during the coming months. In anticipation of these new solutions and products, test and analysis solutions firm Ellisys has released qualification features that support Bluetooth SIG’s version 5.1, as part of its Ellisys Bluetooth Qualifier test system.