Bluetooth & WPAN

2 Bluetooth/WPAN WPAN (Wireless Personal Area Network) has a smaller area of coverage, say, 2.5 mW transmitter power, distance <10m Ericsson started the study of such systems in 1994 Bluetooth Special Interest Group, or SIG was formed in Members of SIG: Ericsson, IBM, Intel, Nokia, Toshiba, and later Microsoft, 3- Com, Motorola

3 Bluetooth It is IEEE standard Named after the Danish King Harald Bluetooth who ruled approximately from A.D. 940 to 985, and who is reported to have united Denmark and Norway. The Bluetooth logo was inspired by the initials H and B. Works in the same frequency band as Wi-Fi devices in ISM band ( GHz) Uses FHSS (1600 hop/s over 79 channels spaced 1 MHz apart) Transmitting rate: less than 1Mbps

4 Features of Bluetooth Used anywhere in the world: operates within a chosen frequency spectrum that is unlicensed throughout the world Ad hoc only topology Plug and play architecture Support of voice and data devices Low-power consumption, good for portable devices using batteries

5 Applications Wire replacement to connect a PC or laptop to its keyboard, mouse, microphone, printer, and notepad: Electronic equipment uses cables which connect to a multitude of devices using a wide variety of connectors with many combinations of shapes, sizes and number of pins; this plethora of cables can become quite burdensome to users. With Bluetooth technology, these devices can communicate without wires over a single air-interface, using radio waves to transmit and receive data. Bluetooth handles both voice and data, and is an ideal technology for unifying these worlds by enabling all sorts of devices to communicate using either or both voice and data. Ad hoc networking of several users at short range, e.g., in a conference room Enough speed for file transfer, printing, etc., but not enough for live video

6 Architecture A small cell is called a piconet M: master, S: slave, SB: stand by, and P: Parked/hold

7 Master and Slaves The specification permits any Bluetooth radio to assume either master or slave role, and a device may act as a master for one communication link and as a slave for another link. The role of master does not imply special privileges or authority; instead it governs the synchronization of the FHSS communications between the devices. The master device determines the frequency hopping pattern. All slaves hop together in unison with the master. The master role generally is assumed by the device that initiates the communication.

8 How does Bluetooth work A master can handle seven active slaves. And many more (255) slaves in parked, sniff, and hold modes. The above three modes are low-power modes to save energy of the slaves and to allow a great number of stations to be connected. Better than IR, which requires line-of-sight links If not connected, the station is in the standby mode.