Dual Mode

In addition to defining a ULP mode, the Bluetooth SIG will also port the Wibree dual-mode specification into its body of documentation. In terms of silicon, this means three kinds of chips: standard Bluetooth (which could be Bluetooth EDR) devices; a stand-alone ULP devices; and, dual-mode devices.

A dual-mode chipset will reuse the Bluetooth RF section with no changes; there will be some additional functions in the Bluetooth baseband section, and a separate protocol stack. The RF link will be at 2.4 GHz, just as it is for Bluetooth. It will also have the Bluetooth RF power level of 0 dBm, and a similar range of around 10m. Modulation will be GMSK (Gaussian minimum shift keying—a small change from the Bluetooth case).

Dual-mode devices will undoubtedly attract a lot of interest because they will be capable of operating in either standard Bluetooth mode or ULP mode. Interestingly, however, the power consumption of a dual mode chip is expected to be about 80% of that of standard Bluetooth.

The dual-mode chip's power performance is lacking mostly because of Bluetooth's complicated but robust modulation scheme, which requires it to hop around in the spectrum. This makes it difficult for the device to go to sleep because it could not follow the hopping. It needs to remain in a semi-aware state at all times.


http://www.eetimes.com/design/microwave-rf-design/4012680/Introduction-to-Bluetooth-ULP — Good

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