Network Architecture
Communications between Bluetooth devices are normally peer-to-peer with each device being equal.Two connectivity topologies are defined in Bluetooth: the piconet and scatternet. when two or more devices link into a small ad hoc network called a piconet, one device acts as the master and the others are slaves for the duration of the piconet connection. A piconet is a WPAN formed by a Bluetooth device serving as a master in the piconet and one or more Bluetooth devices serving as slaves. A frequency-hopping channel based on the address of the master defines each piconet. All devices participating in communications in a given piconet are synchronize using the clock of the master. Slaves communicate only with their master in a point-to-point fashion under the control of the master. The master’s transmissions may be either point-to-point or point-to multipoint. Also, besides in an active mode, a slave device can be in the parked or standby modes so as to reduce power consumptions. A scatternet is a collection of operational Bluetooth piconets overlapping in time and space. Two piconets can be connected to form a scatternet. A Bluetooth device may participate in several piconets at the same time, thus allowing for the possibility that information could flow beyond the coverage area of the single piconet. A device in a scatternet could be a slave in several piconets, but master in only one of them [3]