Architecture Of Bluetooth
Bluetooth operates in the 2.4 GHz ISM band .The following sections explain After presenting the overall architecture of Bluetooth and its specialty, the Pico nets, the following sections explain in detail.
Simple Bluetooth piconet:
- A piconet is a collection of Bluetooth devices which are synchronized to the same hopping sequence.
- Figure shows a collection of devices with different roles.
- One device in the piconet can act as master (M), all other devices connected to the master must act as slaves (S).
- The master determines the hopping pattern in the piconet and the slaves have to synchronize to this pattern.
- parked devices (P) and Devices in stand-by (SB) do not participate in the piconet
- Each piconet has exactly one master and up to seven simultaneous slaves. More than 200 devices can be parked.
The reason for the upper limit of eight active devices is the 3-bit address used in Bluetooth.
Formation of Piconet:
Figure 5.16 shows formation of piconet
- All active devices use the same hopping sequence they must be synchronized.
- A master sends its clock and device ID.
- There is no distinction between terminals and base stations, any two or more devices can form a piconet.
- The unit establishing the piconet automatically becomes the master, all other devices will be slaves.
- The hopping pattern is determined by the device ID, a 48-bit worldwide unique identifier.
- The phase in the hopping pattern is determined by the master’s clock.
After adjusting the internal clock according to the master a device may participate in the piconet. All active devices are assigned a 3-bit active member address (AMA). All parked devices use an 8-bit parked member address (PMA).