Bluetooth low energy – two years on a coin-cell battery

Bluetooth low energy (BLE) is part of the Bluetooth 4 standard and enables new devices such as watches and sensors that consume very little power while being able to communicate with general-purpose computing devices such as cell phones and notebooks. Quoting Wikipedia:
Devices using Bluetooth low energy wireless technology are expected to consume a fraction of the power of classic Bluetooth enabled products. In many cases, products will be able to operate more than a year on a button cell battery without recharging. It will be possible to have sensors such as thermometers operating continuously, communicating with other devices like a mobile phone.
Compare [source: Wikipedia]:
Classic BluetoothBluetooth low energy
Setup time< 6s< 3ms
Range~30 m (class 2)~50 m
Bit rate1-3 Mbit/s~200 kbit/s
Thus: BLE is not very fast, but starts up quickly. Applications [Wikipedia]:
The respective chips may be integrated into products such as tokens, watches, manual controls, wireless keyboards, gaming pads and body sensors, which may then connect to host devices such as mobile phones, smartphones, personal digital assistants (PDAs), tablet PCs, notebook PCs, laptop PCs and other grades of and personal computers (PCs).
I can see it working especially well in input devices, which currently consume a lot of energy. Watches also are appealing – they currently have to be recharged once a day which is unacceptably often. Casio has presented a G-Shock watch that supports the standard. Quoting Wired:
... the watch will run for two years on a coin-cell, just like any other wristwatch.

... The main schtick is that the watch will sync its clock with your cellphone. [which might be interesting for travelers]

You’ll also get notifications of incoming calls, SMS and email, and if you lose your phone you can use the watch to activate an alarm or make it vibrate. [However,] ... the maximum range of low-energy Bluetooth is just 5 meters ...

MacRumors quotes EETimes on a BLE application:
One key application could be indoor location (where there is no GPS signal) whereby sensors around a large public building (such as an airport or rail station) constantly broadcast information about their location. A Bluetooth low energy equipped cell phone passing within range could then display that information to its owner. Sensors could transmit other information such as flight times and gates, location of amenities, or special offers from nearby shops.
Currently the only general purpose computing devices that support BLE (as far as I am aware) are MacBook Airs and the Mac mini. BLE competes with Near Field Communication when it comes to paying with your mobile phone. NFC has a shorter range than BLE, but that is not a disadvantage for this application. Google already supports NFC for this purpose [1], Apple might instead use BLE in the next iPhone.

Related reading:

  1. Google Wallet: pay with your Android phone (a summary)