Bluetooth Smart is a "ultra" low power, lower cost, and much lower data rate protocol version of Bluetooth. It operates on the same 2.4GHz ISM band as Bluetooth, but is not backwards compatible with classic Bluetooth. Bluetooth Smart is intended to be used in battery operated devices where very little amounts of data needs to be transmitted, for example heart rate belts and motion sensors. It does not support for example audio transmission and is not intended for transferring files.
Two Bluetooth Smart devices can communicate directly with each other, if one is acting as a master and the other is a slave. Bluetooth Smart was originally known as Bluetooth low energy, and devices only supporting Bluetooth Smart are also known as Bluetooth 4.0 single mode devices.
Bluetooth Smart Ready means that the device supports both classic Bluetooth as well as Bluetooth Smart. They can operate with classic Bluetooth devices such as Bluetooth headsets and PCs as well as communicate with Bluetooth Smart sensors. Because of this, the power consumption in Bluetooth Smart Ready is pretty much the same as with normal Bluetooth chips. Bluetooth Smart Ready is also sometimes called Bluetooth 4.0 dual mode.
All Bluetooth 4.0 devices must be either "Bluetooth Smart" or "Bluetooth Smart Ready" devices, but only the Bluetooth Smart Ready devices are backwards compatible with Bluetooth 3.0 and earlier.
The reason why Bluetooth Smart had to be made incompatible with "classic" Bluetooth, was that in in order to lower the power consumption and price of Bluetooth chips, major changes were needed to the Bluetooth protocol. It was not possible to make these changes and remain compatible with existing Bluetooth devices and this is where the confusion began.
Bluetooth High Speed was introduced as a special variant in the Bluetooth 3.0 specification. If a device is a Bluetooth 3.0 device, it does not imply that it has support for Bluetooth High Speed, and if a Bluetooth High Speed device is talking to a non High Speed device, there is practically no difference from having two classical Bluetooth devices communicating.
The only time when Bluetooth High Speed can be faster than classic Bluetooth is when two Bluetooth HS devices are communicating, and using a profile which has been updated to take advantage of it (namely the OBEX file transfer protocol). Then the devices while communicating over Bluetooth, can agree to switch to the High Speed mode. In practice this means that Bluetooth stack will take over the Wi-Fi radio and start using it for the data transfer and communicate directly between each other. Yes, that's right: Using Bluetooth + HS means running a Bluetooth data transfer using Wi-Fi technology.
So in summary:
- Bluetooth Smart:
- Also known as Bluetooth low energy and Bluetooth 4.0 single mode device
- Cannot communicate with devices that are not Bluetooth 4.0
- Examples:
- Bluetooth Smart Ready:
- Also known as Bluetooth 4.0 dual mode
- Can communicate with both Bluetooth Smart as well as classic Bluetooth devices
- Does not imply support for Bluetooth High Speed
- Examples:
- Texas Instruments' CC2567
- CSR's CSR8000 series
- Broadcom's BCM20702
- Bluetooth High Speed:
- Also known as Bluetooth + HS or Bluetooth 3.0 + HS
- A Bluetooth device that supports temporarily using the device's Wi-Fi radio for transferring the data, resulting in a higher data rate than would be possible over classic Bluetooth.
- Most Bluetooth + HS solutions consist of two chips, one for the Wi-Fi and another for the Bluetooth.
- Bluetooth 3.0:
- A classic Bluetooth device that does not support High Speed mode nor Bluetooth Smart.
- Does not actually bring much benefit over Bluetooth 2.1.
- Bluetooth 4.0 + HS:
- High Speed is available, but only when using classic Bluetooth functions
- Also supports Bluetooth Smart sensors
- For example the Broadcom BCM43142 integrates both Bluetooth and Wi-Fi (required for the High Speed) into one chip.
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