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Title:

Bluetooth

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Bluetooth Introduction Why Bluetooth History The Bluetooth Technology The Bluetooth Stack Bluetooth in ad hoc networks Introduction Why Bluetooth? Cable replacement ... – PowerPoint PPT presentation

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Date added: 15 June 2020
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Title: Bluetooth


1
Bluetooth
  • Introduction
  • Why Bluetooth
  • History
  • The Bluetooth Technology
  • The Bluetooth Stack
  • Bluetooth in ad hoc networks

2
Introduction
  • Why Bluetooth?
  • Cable replacement between devices.
  • Supported by major companies.
  • Open Specification
  • Low power consumption
  • Connection can be initiated without user
    interaction.
  • Devices can be connected to multiple devices at
    the same time.

3
History
  • The technology was born in 1994.
  • The first version was released July 1999.
  • The Bluetooth name comes from the Danish Viking
    Harald Blåtand.

4
The Bluetooth Technology
  • The Bluetooth Stack

5
Radio
  • Bluetooth devices operate on 2.4 GHz Industrial
    Scientific Medical band (ISM band).
  • Unlicensed in most countries.
  • Interferences from
  • Other radio frequency short-range techniques
  • Wireless local area networks (IEEE 802.11)
  • Random noise generators (microwave ovens)
  • Other Bluetooth units

6
Radio (cont.)
  • Techniques to minimize packet loss
  • Frequency Hopping
  • Adaptive power control
  • Short data packets

7
Frequency Hopping
  • Uses FHSS (Frequency Hopping Spread Spectrum)
  • Divides the ISM-band into 79 1-Mhz channels.
  • Communication between devices switches between
    available channels.

8
Frequency Hopping (cont.)
9
Power Control
  • Three power classes defined with max output power
    from 1 mW (Class 1) to 100 mW (Class 3).
  • Devices may be implementet with power control
  • Optimize power consumption
  • Decrease interference

10
Bluetooth Packet Structure
11
Baseband
  • Responsible for channel coding/decoding, timing
    and managing a Bluetooth link.
  • Master/slave
  • Devices in a connection are either master or
    slave.
  • Communication is only possible between a master
    and its slaves.
  • A master and the slaves are named piconets.
  • Scatternet multiple piconets connected together.

12
Piconets and Scatternet
13
The Link Manager
  • Responsible for establishing, supervising and
    tear down connections and logical links.
  • Link controller states introduced to carry out
    these tasks.
  • States
  • Standby
  • Inquiry / Inquiry Scan
  • Page / Page Scan
  • Connection

14
The Link Manager (cont.)
  • Inquiry
  • Used to detect all devcies in an unknown
    environment.
  • Page / Page Scan
  • Describes how connection is established.
  • Have to know the address of the other devices. Is
    usually achieved through inquiry.
  • Connection
  • Master and slaves are synchronized.
  • Connection is established.

15
Inquiry / Inquiry Scan
16
Page / Page Scan
17
Host Controller Interface (HCI)
  • Provided to ease the partition of the Bluetooth
    Stack across two processors.
  • Some systems will implement the baseband and link
    manager on the Bluetooth device and higher levels
    on the host processor.
  • The HCI is provided as an interface between these
    parts.

18
Logical Link Control and Adaption (L2CAP)
  • Deals with
  • multiplexing of different services
  • segmentation
  • reassembling of packets
  • Quality of Service

19
Profiles
  • Provide interoperability between devices from
    different manufacturers for specific services and
    use cases.
  • A profile defines
  • a selection of messages and procedures
  • gives an unambiguous description of
    communication between two devices.

20
Bluetooth in ad hoc networks
  • Bluetooth network infrastructure is of dynamic
    ad-hoc type.
  • It is constantly changing and depending on the
    movement of the devices.

21
Bluetooth in ad hoc networks (cont.)
  • Temporary networks.
  • Connect on-the-fly.
  • Small wireless network called personal area
    network (PAN).
  • Provide voice, data, eliminate cables, bridge
    networks.
  • Supports PDAs, mobile phones, printers, faxes,
    microphones.

22
Bluetooth in ad hoc networks (cont.)
  • The master can support up to 7 devices in its
    network.
  • Devices use the same frequency, but can be in
    multiple networks.

23
Security
  • Bluetooth provides security only over the radio
    link, from each device to all other devices.
  • Three security specifications
  • Confidentiality
  • Authentication
  • Authorization

24
Bluetooth in the future
  • Bluetooth was originally intended to be a cable
    replacement,
  • but, has evolved to become an infrastructure for
    Personal Area Network (PAN)
  • 2001 10 million devices produced
  • 2003 70 million!
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