Bluetooth goes low-power for small devices

Bluetooth is being extended to include the WiBree specification, a low-power radio communications standard designed for small devices. Integrating the technology into future Bluetooth chips will enable smartphones to link with new types of peripheral for little or no additional cost, according to the Bluetooth special interest group (SIG).

Nokia, which developed the standard, said that the WiBree forum will merge with the Bluetooth SIG and the technology will now be called ultra low power (ULP) Bluetooth. Chipmaker CSR has already said it will have sample Bluetooth chips with ULP later this year, and devices using it are expected in the second half of 2008. 

Robin Haydon, standards architect at CSR, said that ULP will drive new applications for small devices powered by button-cell batteries. It could be used to link your phone with your digital watch, for example, so the watch shows the caller ID and lets you accept or reject incoming calls at the touch of a button.

"Nokia came up with this as a way of getting people to use smartphones in more interesting ways," he said.

As another example, Haydon cited the small remote that Apple ships with its MacBooks, used to control presentations. "Wouldn't it be good if there was an open standard for this, and it could be included for free in every laptop?" he said.

ULP operates at the same radio frequency and modulation as Bluetooth and so can use the same transceiver circuitry. All it requires is some additional logic inside the Bluetooth chip itself to support ULP packet formats, according to Haydon.

Such dual-mode chips will feature in laptops and smartphones, while ULP-only chips will be used in peripherals and other low-power devices. These devices typically require a battery life of several years, hence the need for a new low-power communications technology.

"Bluetooth's standby current when a device is in 'discoverable' mode is actually quite high, while ULP is less than a tenth of that," explained Haydon.

The Bluetooth SIG itself said that the work of integrating ULP into Bluetooth has begun and the first version of its revised specification is expected during the first half of 2008.