TAG | Coming soon: Bluetooth devices with 10 year battery life |
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| by Stuart Corner | |
| Tuesday, 15 April 2008 | |
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According to CSR, to connect devices in standard Bluetooth, the master device has to synchronise to a slave device by paging a specific device using up to 32 frequencies, it then issues FHS (frequency hopping spectrum) packets, then it polls the slave before negotiating connections at both the link manager and L2CAP layers – all of this essential connection process takes place before actually sending data. CSR says that, while this overhead is essential for standard Bluetooth carrying more complex data protocols, it does slow down the connection. When ULP Bluetooth is used, in a wireless heart rate monitor for example, the monitor simply 'advertises' itself to the control/reader using just three frequencies. It then connects, sends its very short burst of data and then switches off again. This allows ULP Bluetooth to achieve data transfer 50-times faster than standard Bluetooth; less time spent transferring data means the ULP radio spends less time active and battery life is prolonged. The technology was previously known as Wibree. The Bluetooth Special Interest Group and the Wibree Forum announced in June 2007 that the Wibree technology, then still under development would become a low power version of bluetooth. The move ended a curious phase in Bluetooth's history, in which the unanswered question was why development the functionality provided by Wibree had not been undertaken within Bluetooth in the first place, as several Wibree backers, such a Nokia, had been early players in and continued to be active in Bluetooth developments. The need for a low power version of Bluetooth, suitable for small devices like watches powered by 'button' batteries, had been evident for some time.
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