Bluetooth is a wireless method by which devices can communicate without a physical connection such as a cable.This technology is based on radio waves, there can be objects or even walls placed between the communicating devices and the connection wont be disrupted.

Multiple devices connected in a network using bluetooth forms a piconet. Piconets can include anywhere from two to eight devices. Bluetooth communication always designates one of the Bluetooth devices as a main controlling unit i.e. master unit. While all other devices that follow master device are known as slave units. This makes Bluetooth system to be non colliding network. This means that after a Bluetooth device has been added to the the Piconet, each device is assigned a specific time period to transmit and they do not collapse or overlap with each other units operating within the same Piconet. The master device acts as the hub i.e. all slave devices must have to communicate through the master device in order to communicate with each other. In most piconets, the computer serves as the master device.

The master unit is responsible for synchronising all other devices. Clock and hopping sequences of master are used to perform synchronisation. The master also assigns numbers to the communication channels. The master unit sends a train of 16 identical page messages on 16 different hop frequencies defined for the device to be paged (slave unit). If there is no response, the master transmits a train on the remaining 16 hop frequencies in the wake-up sequence. The maximum delay before the master reaches the slave is twice the wakeup period is 2.56 seconds while the average delay is half the wakeup period is 0.64 seconds.

Bluetooth uses a technique known as spread-spectrum frequency hopping that makes it rare for more than one device to be transmitting on the same frequency at the same moment. In this technique, the Bluetooth system hops over 79 channels, the probability of interfering (overlapping) with another Bluetooth system is less than 1.5%.. Transmitters change frequencies up to 1,600 times every second in this case.
There are two types of message “page” & “inquiry” responsible for the building of piconet: The connection procedure of piconet is initiated by any one of the device and this device later becomes the master for the network. Page message is used to form piconet only if the address is already known. While INQUIRY message is followed by a subsequent PAGE message only if the address is unknown.

A slave device on a Bluetooth network or piconet can be in either active state or park state. As discussed before, active slave devices can be up to sseven but there can be up to two fifty five (255) parked slave devices. Parked devices retain time synchronization with the piconet but are otherwise disconnected and consume the lowest power (power consuming depend upon the protocol used).

Author's Bio: 

The writer is doing graduation in computer Engineering. The only reason for writing is to explore my inner-soul. As writing create rooms in unexplored regions.