Bluetooth

1
Bluetooth ??

• Bluetooth in Wireless Communication
• K. V. S. S. S. S. Sairam, University of Madras,
  Dr. M. G. R. Engineering College
• N. Gunasekaran, Anna University
• S. Rama Reddy, Jerusalam College of Engineering,
  Dr. M. G. R. Engineering College
• IEEE Communication Magazine, June 2002
• Bluetooth A New Era of Connectivity
• W.-S. Wang, a former RD intern at Agilent
  Technologies, is a Norlin scholar pursuing a
  B.S.in electrical engineering from the University
  of Colorado in Boulder, Colorado, USA.
• IEEE microwave magazine, September 2002

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Outline

• Introduction
• Network Topology
• Bluetooth Architecture Overview
• Logical Link Control Adaptation Protocol
• Service Discovery Protocol

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Bluetooth History

• Bluetooth was invented in 1994 by L. M. Ericsson
  of Sweden. The standard is named after Harald
  Blaatand Bluetooth II, king of
  Denmark940981A.D.
• The Bluetooth Special Interest Group (SIG) was
  founded by Ericsson, IBM, Intel, Nokia, and
  Toshiba in February 1998 to develop an open
  specification for short-range wireless
  connectivity.

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Bluetooth Background Information

• Short-range, low-power radio link (10-100 m)
• Radio frequency (RF) technology utilizing the
  unlicensed 2.4 GHz ISM band
• Support only 780 kb/s .(but in fact23KB/s)
• Market for data and voice transfer
• Vs. IrDA (hidden computing)

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Network Topology

• Groups of two to eight devices called piconets
• consist of a single master device, one or more
  slave devices.
• Multiple piconets gt scatternet.

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Communication

• To help Bluetooth devices coexist and operate
  reliably alongside other ISM devices, each
  Bluetooth piconet is synchronized to a specific
  frequency hopping pattern. This pattern, moving
  through 1600 different frequencies per second, is
  unique to the particular piconet. Each frequency
  hop is a time slot during which data packets are
  transferred.
• Types of Link SCO, ACL
• Synchronous Connection-Oriented link
• for voice applications
• point-to-point
• Asynchronous ConnectionLess Link
• transfer data
• point-to-multipoint

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Device Access Code (DAC)

• The access code is used primarily for piconet
  identification and synchronization.
• The access code identifies the piconet to which
  each data packet belongs
• all data packets sent within the same piconet
  will have the same access code

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Establishing a Connection

• Inquiry -gt Page command -gt connected state -gt
  synchronize
• Inquiry
• send out an inquiry access code packet to search
  and locate these devices, when a device receive
  an inquiry, it will response with frequency hop
  synchronization (FHS) packet.
• Paging
• 1. The paging device transmits the DAC on
  several different hop frequencies that it thinks
  the target device is receiving (as calculated
  using the FHS packet) and continues to do so
  until a connection is made.
• 2. Once the paging device receives a page
  response from the target device, information
  vital for a connection is exchanged between the
  two devices.

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Architecture of Bluetooth
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Host Controller Interface Layer
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Lower Layer of Architecture

• Baseband link SCO, ACL.
• Link Manager (firmware)
• Handle link setup, security, and control.
• communicate with each other using Link Management
  Protocol (LMP).
• HCI (firmware)
• Isolate baseband and link manager from a
  transport protocol such as USB or RS-232
• a Bluetooth application can access Bluetooth
  hardware without knowledge of the transport layer
  or other hardware implementation details

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Software Protocol

• L2CAP (Logical Link Control And Adaptation
  Protocol)
• SDP (Service Discovery Protocol)
• RFCOMM
• TCS (Telephony Control Protocol Specification)
• OBEX (Object Exchange Protocol)
• IrOBEX (IrDA Object Exchange Protocol)

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Logical Link Control And Adaptation Protocol
(L2CAP)

• provides connection-oriented and connectionless
  data services to the upper-layer protocols with
  protocol multiplexing capability, segmentation
  and reassembly, and group abstractions.
• Three channel
• Bidirectional signaling channels
• Connection-oriented channels for bidirectional
  point-to-point connections
• Unidirectional Connectionless channels for
  point-to-multipoint connections

• Logical Channel Identifier (CID)
• Each CID may represent a channel endpoint for a
  connection-oriented channel, a connectionless
  channel, or a signaling channel.

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L2CAP (cont.)
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L2CAP (cont.)

• Bidirectional signaling channels
• before communication
• every L2CAP entity will have one signaling
  channel endpoint with a reserved CID of 0x0001
• Connection-oriented channel
• before data transfer can take place
• local CID is dynamically allocated
• Connectionless channel
• outgoing CIDs are dynamically allocated, incoming
  connectionless CID is fixed at 0x0002
• only one incoming connectionless CID is provided
  on each L2CAP entity

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Service Discovery Protocol (SDP)

• provides a means to determine which Bluetooth
  services are available on a particular device
• Each service is represented by a single service
  record with a dynamically allocated service
  record handle that is unique within the server.
• Service attributes within a service record
  describe and define the supported service
  including the service type, a service ID, the
  protocols supported, the service name, a service
  description, and so on.
• Date type Universally Unique Identifier (UUID)

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SDP (cont.)

• The purpose of SDP is to discover, not access,
  services. Two processes are supported searching
  and browsing
• A service record is returned by a search only if
  all of the UUIDs in the service search pattern
  are found within service record attribute values.

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Bluetooth Network World