My favorite aspect of being a wireless solution architect is how incredibly dynamic this space remains. My second favorite part about working in wireless is the direct touch these technologies have with end users. The only similar technology would be voice, but everyone already takes voice services for granted. Luckily, for me, we’re not quite there yet for wireless services.
One topic starting to get a lot of attention – with thanks to that dominant Cupertino fruit known as Apple – is Bluetooth Low Energy (BLE). As the name implies, this is derived from the same technology as the Bluetooth you’re likely already familiar with in your portable speakers or vehicle hands-free system. However, the applications that BLE enables are very different.
Known commercially as Bluetooth Smart, BLE provides – among other things – a way to employ low-cost radio beacons in an environment. (Think: retail store, museum gallery or office.) These beacons enable a mobile application to estimate the proximity of the mobile device on which the application is running relative to the known location of the beacon.
This brings us to a critical aspect of BLE technology which differentiates it from location services delivered over Wi-Fi. Location services delivered over the WLAN are driven by the network. The network determines the location of the device based on how many access points see it and at what power levels. With BLE-based beacons, the mobile application determines its own location based on the beacon(s) it sees and a lookup table embedded in the app or in a back-end system.
Another key difference is accuracy. While locating from the WLAN can routinely provide less than 5 meter accuracy, there is no established mechanism for providing this level of accuracy with BLE. It’s up to the app to noodle this out on its own and, thus, the app developer (or SDK provider) to implement algorithms such as time difference of arrival or TDoA-based multilateration. While at least one beacon manufacturer is working on providing these types of location services in software libraries, it’s really not what this architecture is able to provide today.
So, what is BLE good for? First, to finish our accuracy discussion, understand that Apple’s iBeacon implementation, for instance, divides location into four distinct regions: Immediate, Near, Far and Unknown. And this range is based on the signal strength (RSSI) of a single beacon.
Therefore, the type of location resolution we get from this solution is what we typically refer to as “presence detect.” In other words, we can accurately detect our proximity to a single beacon at a single moment in time, but not provide real-time location over time as required for something like a wayfinding application.
Remember, I said one of my favorite aspects of wireless is how dynamic this technology is today. I’m sure attempts will be made to provide higher accuracy location using beacons, but it’s not the original intent of this technology. It is great for enabling a mobile app to alert a user/guest to when they’ve approached something of interest – or to push content towards them when they are in a particular area. These alerts and content can be anything from curator’s notes about a museum gallery to a coupon for use within a food court.
For these rough accuracy applications, look at BLE in your WLAN infrastructure as it’s now available from multiple vendors. It will simplify deployment and management. For increased proximity resolution look at stand-alone beacon solutions for a low-cost, battery-powered radio that can be stuck almost anywhere.
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