Mobile-phone-maker Nokia announced a new short-range wireless technology, Wibree, in October 2006. With several other formats for short-range wireless already on the market or in development, tech pundits questioned what niche Wibree would fill, or even if there was room for it at all. While the long-term success of Wibree remains to be seen, it does have several advantages over the competition, and it has been positioned as a compliment to Bluetooth technology rather than as a competitor.
Both Wibree and Bluetooth allow devices to communicate via short-range radio signals. Bluetooth can be used to perform a variety of tasks, including sharing files between a PC and a PDA , downloading an address book into a cell phone from a PC, and transmitting a signal from a remote control to a television . The Bluetooth radio operates at 2.4 GHz, "hopping" rapidly around different bands close to that frequency to provide security and resistance to interference from other signals (see How Bluetooth Works to learn more). Wibree, it turns out, will use the same radio frequency as Bluetooth, a major advantage over competitors. Using the same basic mechanism for wireless communication will make it much easier for devices to build in both Wibree and Bluetooth compatibility.
Where Wibree came from
Wibree didn't just appear from out of the blue this October. Although the current specification is still confidential a little digging produces a lot of its history and provides a good guide to its content. There is an irony in the fact that the origins of Wibree were the alternative proposal for the radio and Media Access Controller (MAC) for the 802.15.4 standard, which is now the basis of ZigBee and other short range radio networks. Back in 2001 two industry groups put forward proposals for the form of this radio. Nokia headed one of the groups and proposed a development that was handset centric. A major tenet of their design was that "it can be deployed with minor effort into devices already having Bluetooth,
e.g. Cell phones" with the added requirement that a "common RF section with Bluetooth must be possible". Their vision was also broader that that of the competing camp in that it envisaged a world of a trillion wireless, web connected devices. A key slide shows millions of connected laptops, billions of mobile phones and trillions of what could be interpreted as Wibree enabled devices.
What Wibree does
Wibree 's main application is to provide an ultra low power radio within the 2.4GHz band. Low power is always determined in large part by the application - the longer a device is active, and the more data it transmits, the shorter its battery life will be. Wibree is aiming to produce a radio that can transmit a small packet of data approximately every second for a year using a small button cell, such as a CR2430, with a capacity of around 280mAH. If the duty cycle is reduced to one transmission every 15 to 30 seconds, then the battery life effectively becomes the leakage life of the battery. This low power drain is achieved by designing a radio and protocol that lets the radio stay asleep for most of its life.
It can wake up quickly, when it will broadcast its requirement to transfer data on a number of advertising channels across the spectrum. The receiving device, which is likely to contain a larger battery as it will be on for more of the time, will acknowledge the message and tell the first device which channel to send its data on. It will then acknowledge receipt of this data, at which point both can go back to sleep. The whole process will take less than three or four milliseconds.