BLUETHOOTH ARCHITECTURE

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BLUETHOOTH ARCHITECTURE

• Olena Hunsicker
• CS 555

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WHAT IS BLUETOOTH WIRELESS TECHNOLOGY?

• Bluetooth wireless technology is a short-range
  communications technology intended to replace the
  cables connecting portable and/or fixed devices
  while maintaining high security level.
• The key features of Bluetooth technology are
• Robustness
• low power
• low cost

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BLUETOOTH IS GLOBAL

• One version for the world
• Bluetooth technology operates in the unlicensed
  industrial, scientific and medical (ISM) band at
  2.4 to 2.485 GHz.
• The 2.4 GHz ISM band is available and unlicensed
  in most countries.

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BLUETOOTH TECHNOLOGY USE
Landline
Cable Replacement
Data/Voice Access Points
Personal Ad-hoc Networks
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BLUETOOTH PROTOCOL ARCHITECTURE
Application Framework and Support
Host Controller Interface
Link Manager and L2CAP
Radio Baseband
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BLUETOOTH STRUCTURE
Link Control Hardware
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Link Control Hardware Duties

• radio transmission and reception
• digital signal processing
• establishing connection
• support for asynchronous (data) synchronous
  (voice) links
• error correction
• authentication
• provide Host Controller Interface as a standard
  interface for software

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Radio Layer (RF)

• Operates in the unlicensed ISM (industrial,
  scientific, medical) band at 2.4 GHz
• Responsible for transmitting and receiving
  packets of information on the physical channel
• Transforms a stream of data to and from the
  physical channel into required formats.
• Support data rate 1Mbps (Basic Rate) / 3 Mbps
  (Enhanced Data Rate)
• Bluetooth hops 1600 times/sec (uses frequency
  only for 625 microsecond) in order to avoid
  interference with other devices
  (frequency-hopping spread spectrum (FHSS)).

Baseband
RF
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Network Topology

• Piconet
• Master can connect to 7 simultaneous active
  slaves per piconet
• Scatternet
• High capacity system
• Minimal impact with up to 10 piconets within
  range

S
P
M
M
sb
P
S
sb
P
S
S
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The scatternet
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Baseband Layer

• Provide transmission channels for voice and data
• Synchronous connection-oriented (SCO) links -
  used for voice transmission.
• Slave device is always allowed to respond during
  the time-slot immediately following a SCO
  transmission from the master
• No retransmission allowed
• Asynchronous connectionless (ACL) links -used for
  data transmission.
• After an ACL transmission from the master, only
  the addressed slave device may respond during the
  next time-slot, or if no device is addressed, the
  packet is considered a broadcast message.
• Packet retransmission allowed.

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Basic Baseband Protocol

• Spread spectrum frequency hopping radio
• 79 or 23 one MHz channels (country dependent)
• Hops every packet
• Packets are 1, 3, or 5 slots long
• Frame consists of two packets
• Transmit followed by receive
• Nominally hops at 1600 times a second (1 slot
  packets)

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Baseband Layer

• Single-slave communication (one slave in
  piconet)
• Time divided into slots 625 msec
• Master uses even-numbered slots, slave
  odd-numbered
• Multiple-slave communication (more than one slave
  in the piconet)
• Master uses even-numbered slots
• Slaves use odd-numbered slots if they have packet
  to send, or stay silent if none.
• All slaves listen on even-numbered slots

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Link Manager

• Link Manager duties
• Controls baseband state
• Authentication and security services
• QoS monitoring
• Change slaves modes
• Handling changes in master/slave roles
• Communicate with each other using link management
  protocol (LMP)

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L2CAP

• Logical link control and Adoption Protocol (LL2L)

• The lowest layer of software protocols
• Provide service for upper level protocols
  transmitting data over L2CAP channels
• The L2CAP Specification is defined for only ACL
  links and no support for SCO links.

Applications
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HOW TO ESTABLISH CONNECTION

• The inquiry procedure enables a device to
  discover which devices are in range, and
  determine the addresses and clocks for the
  devices. (baseband layer).
• Send out inquiry packets and then receiving the
  inquiry reply.

inquiry packets
inquiry reply
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HOW TO ESTABLISH CONNECTION (cont)

• 2. Paging Paging procedure synchronize the
  device with access point (baseband layer).
• 3. Establish a link LMP establish a link with
  access point
• 4. Discover services LMP uses Service Discovery
  Protocol (SDP) to find which services are
  available.
• 5. Create L2CAP channel LMP create L2CAP channel
  to access point/or can use RFCOMM (Radio
  Frequency protocol) to simulate serial line.
• 6. Authentication input from the user.
  Authentication request -gt PIN -gt encryption -gt
  Authentication reply.
• 7. Log in if use PPP over RFCOMM serial port
  is emulated, then log in
• 8. Send and Receive use TSP/IP

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References

• R. Spaker, Bluetooth Basics http//www.embedded
  .com/2000/0007/0007ia1.htm
• Joe Decuir Bluetooth Wireless System
• http//www.bluetooth.com/Bluetooth/

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• THANK YOU!