E60, E61, E63, E64, E87, E90: Bluetooth Radio Standard
Bluetooth radio standard
Bluetooth is a new short-range radio standard with which several units with bluetooth interface are able to communicate with each other at once. Bluetooth allows up to 8 bluetooth-compatible transmission/reception devices within the space of up to 10 m to be networked together. 4 bluetooth mobile phones can be signed on to the ULF control unit. However, only one of the bluetooth mobile phones signed on can be used for communication.
The bluetooth connection in the vehicle can be temporarily deactivated. This is necessary:
- If bluetooth is not permitted in a country due to legal stipulations
- To continue a call in privacy mode, i.e. only using the mobile phone
Transmission frequency
| Key | Explanation | Key | Explanation |
|---|---|---|---|
| f [GHz] | Frequency in gigahertz | t [s] | Time in seconds |
Bluetooth uses the licence-free, global ISM frequency band at 2.45 GHz. The frequency range from 2.402 GHz to 2.480 GHz is divided into 79 channels, each with a band-width of 1 MHz. To prevent disturbance in other electrical equipment and to increase security against calls being monitored, channels are changed 1600 times every second.
The ISM frequency band is freely available to everybody. The ISM frequency band is used for medical research, for microwave ovens and for radio remote controls for garage doors systems.
Transmission quality
The transmission quality of the hands-free system deteriorates if there are objects between the mobile phone and the bluetooth aerial in the vehicle.
Data and speech
Voice information and data are transmitted using bluetooth: audio data, telephone directory and current operating status of mobile phone. A band-width of approx. 1 MBit/s is available for transmission.
Call-monitoring security
Call-monitoring security is characterized by the following measures:
- Frequency change (1600 times per second).
- Applied encryption procedure
- Every bluetooth-compatible unit has its own 48-bit address.
- All data transmitted can be encrypted and deciphered with a key up to 128 bit long.
This makes it possible to distinguish up to 281 trillion different units.
- The relatively short range of approx.10 m makes it more difficult to manipulate the flow of data. Manipulation of the data flow is only possible in the immediate vicinity of the ULF.