BLUETOOTH HEADS IN A NEW DIRECTION Steven Keeping*
Bluetooth wireless’s constant evolution is impressive; originally designed as a method to transfer information between handsets without cables, the technology — particularly since the 2010 launch of the Low Energy (LE) version as a ‘hallmark element’ of Bluetooth 4.0 — has expanded dramatically.
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luetooth LE extended the technology’s reach to devices with modest battery resources and, at a stroke, opened up wireless connectivity to thousands of previously ‘dumb’ products. In the early years, the growth of Bluetooth LE was primarily driven by the market for ‘appcessories’ — wireless products such as wearables, toys, bike lights and coffee machines — that could be controlled directly from a smartphone. Fortuitously, the key attributes of the technology also ideally suited the demands of the wireless sensors that form the foundation of the Internet of Things (IoT). More recently, the introduction of Bluetooth 5 — which added enhanced throughput, increased range and improved coexistence — cemented Bluetooth technology’s position as a major technology driving the ‘smart’ future. Bluetooth 4.0 and 5 were launched with the degree of hype that marketing folk do so well, and to be fair, those revisions to the standard did bring significant techni-
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cal enhancements. In contrast, the latest upgrade, Bluetooth 5.1, received a little less marketing pizzazz yet promises a solution to a problem that no other wireless technology has addressed.
Where am I? Global navigation satellite services such as Galileo, global positioning systems (GPS) and global navigation satellite systems (GLONASS) form the backbone of many guidance and tracking applications. But without ‘line of sight’ to the satellites, the systems fail. Engineers have implemented alternative solutions such as determining a location based on the known position of a Wi-Fi router, but such solutions are limited to an accuracy of around 10 m. For its part, Bluetooth has employed a received signal strength indicator (RSSI) methodology for estimating the position of a Bluetooth transceiver (embedded, for example, in a consumer’s smartphone). As the name suggests, the technique works
by estimating the distance from the transceiver to a known fixed point (for example, a beacon) based on the Bluetooth signal strength. Such a system is generally unable to determine the exact location of the target transceiver being limited to an estimate of position on the circumference of a circle of known radius around the beacon (for a Bluetooth transceiver restricted to a horizontal plane such as a floor). Precision is further undermined by the (typically unknown) attenuation of signal strength by walls and other obstacles. Both Wi-Fi and Bluetooth technology’s proximity systems have found favour in retail applications whereby consumers can be fed contextual information based on their approximate location, but the lack of precision of each means neither is up to the task of indoor navigation or asset tracking.
Working the angles According to John Leonard, a Senior Product Marketing Manager with Bluetooth chip
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