A few short years ago, Bluetooth was just a nifty way to make phone calls through chintzy headsets—but oh, how things change. Wednesday the Bluetooth Special Interest Group (SIG) announced the latest update to the Bluetooth specification, with a focus on preparing the protocol for future use cases while improving the experience for users today.
One of the most user-facing changes is extending the interval a Bluetooth device will seek a lost connection. If you've ever walked too far from your wireless speakers and had to manually reconnect your device to resume playback, you understand the issue. Under the new Bluetooth 4.1 spec, devices that lose a connection will have up to three minutes to rediscover their paired devices again before a manual reconnection will be required.
Developers get much of the attention in this update. Improvements to bulk data transfers decrease the overhead necessary for such actions. That feature will come in handy as wearables become more complex and laden with sensors. After a run, for instance, your fitness tracker can transmit motion, heart rate, and other sensor data logged during the activity to your phone for analysis and upload to the cloud.
Devices can now also act as both hubs and endpoints for Bluetooth data. Previously, early adopters might have needed to pair their heart rate monitor, wireless headphones, and movement tracker directly with their phones. In Bluetooth 4.1, devices like smartwatches or fitness monitors can be configured to pair with these accessories and then transmit the combined data to the paired phone.
Interference with LTE radios is another focus of the update, particularly for European and Chinese users. Bluetooth devices transmit in the 2.45GHz band, an unlicensed space. Several LTE bands operate near these frequencies, and when Bluetooth is used on the same device, there's the potential for interference. The new Bluetooth specification adds signaling coordination with LTE radios to minimize interference concerns.
The last update is the most forward looking. Within the whole Bluetooth protocol, the major tool used to transmit data between devices is the logical link control and adaptation protocol (L2CAP). As Bluetooth radios find homes in more and more devices, it will be necessary to isolate devices to specific chunks of spectrum (channels) so that two devices don't try to transmit on the same channel at once. Bluetooth 4.1 introduced dedicated channels for this purpose and lays the groundwork for implementing IPv6 within the Bluetooth stack. That's still some ways off, as is the networked toaster of my dreams, but it's encouraging to see the necessary steps taken now.
The spec update is meant to offer a seamless improvement to the user experience. Users also don't need to worry about compatibility if their devices are already Bluetooth Smart or Smart Ready compliant. Bluetooth 4.1 will be fully backward compatible with existing hardware, and Bluetooth silicon vendors and device manufacturers that want to update their existing 4.0 hardware can have their products requalified by Bluetooth SIG and updated through software patches. The window to get devices requalified opens next week, so we just might see some Bluetooth 4.1 devices introduced or updated from 4.0 just in time for CES next month.
