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!