Bluetooth

1
Bluetooth WPAN
2
Bluetooth/WPAN

• WPAN (Wireless Personal Area Network) has a
  smaller area of coverage, say, 2.5 mW transmitter
  power, distance lt10m
• Ericsson started the study of such systems in
  1994
• Bluetooth Special Interest Group, or SIG was
  formed in 1998. Members of SIG Ericsson, IBM,
  Intel, Nokia, Toshiba, and later Microsoft,
  3-Com, Motorola

3
Bluetooth

• It is IEEE 802.15 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 (2.400-2.483 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.