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BLUETOOTH WIRELESS TECHNOLOGY

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BLUETOOTH WIRELESS TECHNOLOGY Maureen Stella B. Lim – PowerPoint PPT presentation

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Date added: 18 August 2020
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Title: BLUETOOTH WIRELESS TECHNOLOGY


1
BLUETOOTH WIRELESS TECHNOLOGY
  • Maureen Stella B. Lim

2
What is Bluetooth?
  • A way to form connections between electronic
    devices in close proximity
  • Cable-replacement technology
  • It is a radio-frequency technology that uses the
    2.4 GHz Industrial-Scientific-Medical (ISM) band
  • To be Bluetooth certified, a device must pass
    interoperability testing by the Bluetooth Special
    Interest Group (SIG), thus assuring that products
    meeting the specification will be able to
    interact with all other Bluetooth-certified
    products.

3
Bluetooth
  • ideal for small devices, short range, and low
    power radio links
  • fit for connecting PCs and laptop computers,
    phones, printers, and
    cameras.
  • Low power Bluetooth devices have a range of about
    30 feet.

4
Bluetooth Features
  • Wireless and automatic
  • Inexpensive
  • The ISM band that Bluetooth uses is regulated,
    but unlicensed.
  • Handles both voice and data
  • Signals are omni-directional
  • Uses frequency hopping

5
Network Topology
Piconet
Scatternet
6
Packets
  • All data on the piconet channel are conveyed in
    packets
  • Each packet consists of three entities
  • Acces Code used for timing synchronization,
    offset compensation, paging and inquiry
  • Header information for packet acknowledgment,
    numbering, flow control, slave address, error
    check
  • Payload voice field or data field

7
Radio Frequency and Spectrum Hopping
  • Uses fast acknowledgment and frequency-hopping
  • Bluetooth divides the 2.4 GHz frequency band into
    79 channels (from 2.402 to 2.480 GHz)
  • Jumps to a new frequency after every packet

8
Physical Channel
  • Piconets are formed by two or more Bluetooth
    devices using the same channel
  • The channel is represented by a pseudo-random
    hopping sequence
  • Hopping sequence - unique for each piconet and
    determined by the Bluetooth device address of the
    master
  • Phase - determined by the Bluetooth clock of the
    master

Master Slave
9
Physical Channel
  • The channel is divided into time slots, each 625
    microseconds long
  • Time-division multiplexing (TDM) scheme a
    master device always uses an even-numbered slot
    when it transmits, and a slave uses an
    odd-numbered slot.

10
Physical Links
  • 1. Synchronous Connection Oriented (SCO)
  • Symmetric point-to-point link
  • Carries voice information
  • Reserved time slots to guarantee timely
    transmission
  • Works at 64 Kb/s

11
Physical Links
  • 2. Asynchronous Connection Less (ACL)
  • Primarily for data
  • Established on a per-slot basis
  • Support point-to-multipoint transmissions
  • A slave can only transmit only after receiving a
    packet from a master
  • For this purpose, the master can send a polling
    packet
  • Can transmit as much as 721 Kb/s in one direction

12
Physical Links
13
Connection Set-up
  • Step 1 Inquiry procedure
  • Source inquiry state sends out inquiry packets
  • Destination inquiry scan state
  • Destination inquiry response state sends an
    inquiry reply to the source

14
Connection Set-up
  • Step 2 Paging Procedure
  • Source pages another device
  • Destination receives page
  • Destination replies
  • Source sends an FHS packet to the destination
  • Destination sends second reply
  • Destination and source then switch to the source
    channel parameters

15
Error Checking
  • 1/3 Forward Error Checking (FEC)
  • Implemented by repeating three bits at a time
  • 2/3 FEC
  • Generator polynomial is used to encode 10 bit
    code to 15 bit code
  • Automatic Repeat Request
  • requires that the header error and cyclic
    redundancy checks are okay

16
Whose teeth are blue?
  • 10th century Scandinavian king, Harald Bluetooth
    managed to unite several unruly kingdoms. Thus,
    Bluetooth is a reference to the taming of a
    myriad of unruly competing standards by defining
    one world-wide specification.
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