An interesting aspect of the technology is the instant formation of networks once the bluetooth devices come in range to each other. A piconet is a collection of devices connected via Bluetooth technology in an ad hoc fashion. A Piconet can be a simple connection between two devices or more than two devices. Multiple independent and non-synchronized piconets can form a scatternet. Any of the devices in a piconet can also be a member of another by means of time multiplexing. i.e a device can be a part of more than one piconet by suitably sharing the time. The Bluetooth system supports both point-to-point and point-to-multi-point connections. When a device is connected to another device it is a point to point connection. If it is connected to more that one (upto 7 ) it is a point to multipoint connection. Several piconets can be established and linked together ad hoc, where each piconet is identified by a different frequency hopping sequence. All users participating on the same piconet are synchronized to this hopping sequence. If a device is connected to more than one piconet it communicates in each piconet using a different hopping sequence. A piconet starts with two connected devices, such as a portable PC and cellular phone, and may grow to eight connected devices. All Bluetooth devices are peer units and have identical implementations. However, when establishing a piconet, one unit will act as a master and the other(s) as slave(s) for the duration of the piconet connection. In a piconet there is a master unit whose clock and hopping sequence are used to synchronize all other devices in the piconet. All the other devices in a piconet that are not the master are slave units. A 3-bit MAC address is used to distinguish between units participating in the piconet. Devices synchronized to a piconet can enter power-saving modes called Sniff and hold mode, in which device activity is lowered. Also there can be parked units which are synchronized but do not have a MAC addresses. These parked units have a 8 bit address, therefore there can be a maximum of 256 parked devices.
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