Bluetooth

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Bluetooth Technology

• E. Amir Ezzat Amir.ezzat_at_rashpetco.com

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Lecture topics

• Introduction (Name, Program, Description)
• Why Bluetooth?
• Bluetooth network topology
• Physical links
• Connection Establishment States
• Connection Modes
• Protocol Architecture
• Security Modes
• Frame format
• Bluetooth devices classification
• Adv. Dis-adv.
• Summary

3
Whats With the Name?

• King Harald Bluetooth (A.D. 940 to 985)
• 10th century Viking king in Denmark
• Credited for uniting the country (Denmark
  Norway) and established Christianity
• This is one of two Runic stones erected in his
  capital city
• The stones inscription says
• Harald Christianized the Danes
• Harald controlled the Danes

4
Bluetooth program
Bluetooth Special Interest Group (SIG) 5 founding
members
(Ericsson,
Nokia, IBM, Intel Toshiba)
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What is Bluetooth?

• It is a cable-replacement technology
• Technically, is a chip to be plugged into
  computers, printers, mobile phones, etc.
• Designed by taking the information normally
  carried by the cable, and transmitting it
  at a special frequency to a receiver
  Bluetooth chip which will then give
  information received to these mobile devices.

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Why Bluetooth?

• Synchronization
• between mobile and stationary devices
• Data access points
• Connecting mobile users to the internet using
  bluetooth access point
• Dynamic networks
• Piconets
• 8 devices can be actively connected in
  master/slave configuration
• Scatternets
• Piconets can be combined to form providing
  unlimited device connectivity

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General Description

• Standard IEEE 802.15.1
• Frequency 2.4 GHz (Unlicensed ISM band)
• Channel no. 79
• Channel width 1MHz
• Spread Spectrum FHSS (1600 hops/sec)
• Modulation technique GFSK
• Data rate 1 Mb/s
• Range 10 meters
• Key features
• Robustness
• Simplicity
• point-to-point connection

• low power
• low cost
• point-to-multipoint connection

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Bluetooth network topology

• Piconet
• Each piconet has one master and up to 7
  simultaneous slaves
• Master device that initiates a data exchange.
• Slave device that responds to the master.
• Scatternet
• Linking of multiple piconets through the master
  or slave devices
• Bluetooth devices have point-to-multipoint
  capability to engage in Scatternet communication.

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Piconet

• Basic unit of Bluetooth networking
• Master and one to seven slave devices
• Master gives slaves its clock and device ID
• Master determines channel and phase
• All devices in a piconet hop together

MMaster PParked SSlave SBStandby
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Scatternet

• Formed by two or more Piconets
• Master of one piconet can participate as a slave
  in another connected piconet
• No time or frequency synchronization between
  piconets
• Makes efficient use of bandwidth

S
S
P
P
SB
M
S
M
S
SB
SB
S
P
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Physical links

• Between master and slave(s), different types of
  links can be established.
• Two link types have been defined
• Synchronous Connection-Oriented (SCO) link
• Asynchronous Connection-Less (ACL) link

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Physical links

• Synchronous Connection Oriented (SCO)
• Support symmetrical, circuit-switched,
  point-to-point connections
• Typically used for voice traffic.
• Data rate is 64 kbit/s.
• Asynchronous Connection-Less (ACL)
• Support symmetrical and asymmetrical,
  packet-switched, point-to-multipoint connections.
  
• Typically used for data transmission .
• Up to 433.9 kbit/s in symmetrical or 723.2 kbit/s
  in asymmetrical

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Connection Establishment States (i)

• Standby
• State in which Bluetooth device is inactive,
  radio not switched on, enable low power
  operation.
• Page
• Master enters page state and starts transmitting
  paging messages to Slave using earlier gained
  access code and timing information.
• Page Scan
• Device periodically enters page state to allow
  paging devices to establish connections.

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Connection Establishment States (ii)

• Inquiry
• State in which device tries to discover all
  Bluetooth enabled devices in the close vicinity.
• Inquiry scan
• Most devices periodically enter the inquiry scan
  state to make themselves available to inquiring
  devices.

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Connection Modes

• Devices operate in standby mode by default until
  they become connected to a piconet
• 4 Connection Modes
• Active
• Hold
• Park
• Sniff
• Modes allow devices to adjust power consumption,
  performance, and the role of participants in a
  piconet

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Active Mode

• Device operates on high-power
• Limited to 7 Active slaves for each master
• Three bit address (AM_ADDR) given to each active
  slave
• Device participates on channel
• (Can Listens, transmits and receives packets)

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Hold Mode

• Device operates on low-power
• Device keeps active member address
• Device does not support ACL packets on the
  channel but may support SCO packets
• Master and slave agree on a one time hold
  duration after which the slave revives and
  synchronizes with channel traffic

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Sniff Mode

• Very similar to hold mode
• Slave only listens on specified slots
• Master can only communicate during arranged
  sniff time slots

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Park Mode

• Operates in very low-power sleep
• Eight bits address (PM_ADDR) given to each Parked
  slave
• Device stays synchronized to channel
• Master establishes a beacon channel and beacon
  interval when a slave is parked
• Parked slave wakes up at regular beacon interval
  to Maintain synchronization
• Active and Parked slaves can be switched in and
  out to allow many connections to a single piconet

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Protocol Architecture

• Bluetooth is a layered protocol architecture
• Core protocols
• Cable replacement protocol
• Telephony control protocols
• Adopted protocols

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Protocol Architecture

• Core protocols
• Radio
• Baseband
• Link manager protocol (LMP)
• Logical link control and adaptation protocol
  (L2CAP)
• Service discovery protocol (SDP)
• Cable replacement protocol
• RFCOMM

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Protocol Architecture

• Telephony control protocol
• Telephony control specification binary (TCS
  BIN)
• Adopted protocols
• PPP
• TCP/UDP/IP
• OBEX
• WAE/WAP

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Protocol Architecture
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Core protocols

• Radio
• Uses 2.4 GHz ISM band spread spectrum radio (2.4
  2.4835 GHz)
• Modulation GFSK (Gaussian Frequency Shift
  Keying)
• Implements FHSS to mitigate interference
• 1600 hops per second through 79 (1MHz channels)
  (Hops every packet)
• In piconet all slaves follow the master for
  frequency hop sequence
• Packets are pretty short and can be 1, 3, or 5
  slots long (a slot is 625µs)
• Advantages
• Free and Open to everyone worldwide
• Disadvantages
• Can be noisy

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Radio Specification

• Low Cost
• Single chip radio (minimize external
  components)
• Todays technology (Time
  division duplex)
• Low Power
• Low voltage RF (1 mW
  up to 100 mW)
• Robust Operation
• Fast frequency hopping 1600 hops/sec
• Strong interference protection

Applications
IP
SDP
RFCOMM
control
Data
Audio
L2CAP
Link Manager
Baseband
RF
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Core protocols

• Baseband
• Concerned with connection establishment within a
  piconet, addressing, packet format, timing and
  power control.
• Provides in-order delivery of byte streams
• Handles Frequency Hop Sequences for
  Synchronization and Transmission
• Establishes Links
• Synchronous Connection Oriented (SCO)
• Asynchronous Connection-Less (ACL)
• Provides functionality to determine nearby
  Bluetooth devices

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Baseband

• Audio
• Interfaces directly with the baseband.
• it does not go through L2CAP
• Each voice connection is over a 64 Kbps SCO link.
  
• Any two Bluetooth devices can send and receive
  audio data between each other just by opening an
  audio link

Applications
IP
SDP
RFCOMM
control
Data
Audio
L2CAP
Link Manager
Baseband
RF
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Link Manager Protocol

• Responsible for
• Setup and Management of Baseband connections
• Management and control connection states of a
  Bluetooth unit in a piconet
• Handles the control and negotiation of packet
  sizes used when transmitting data
• Controls the power modes and duty cycles of the
  Bluetooth radio device
• Security aspects (Authentication and Encryption )

Applications
IP
SDP
RFCOMM
control
Data
Audio
L2CAP
Link Manager
Baseband
RF
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Logical link Control and Adaptation Protocol
(L2CAP)

• Performs 4 major functions
• Managing the creation and termination of logical
  links for each connection through channel
  structures
• Enforcing and defining QoS requirements
• Adapting Data, for each connection, between
  application (APIs) and Bluetooth Baseband formats
  through Segmentation and Reassembly (SAR)
• Performing Multiplexing to support multiple
  connections over a single common radio interface
  (multiple apps. using link between two devices
  simultaneously)

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Logical link Control and Adaptation Protocol
(L2CAP)

• L2CAP provides requested QoS if possible and
  notifies application if link can not support
  demands
• QoS
• Applications may demand QoS on specific
  parameters as
• Token rate (bytes/second)
• Token bucket size (bytes)
• Peak bandwidth (bytes/second)
• Latency (microseconds)
• Delay variation (microseconds)

Applications
IP
SDP
RFCOMM
control
Data
Audio
L2CAP
Link Manager
Baseband
RF
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Core protocols

• Service discovery protocol (SDP)
• handles device information, services, and queries
  for service characteristics between two or more
  Bluetooth devices.

Applications
IP
SDP
RFCOMM
control
Data
Audio
L2CAP
Link Manager
Baseband
RF
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Cable Replacement Protocol (RFCOMM)

• RFCOMM
• Reliable transport protocol, works with parallel
  data by connecting to the lower layers via L2CAP
• Provides emulation of serial ports control and
  data signals over the L2CAP protocol

Applications
IP
SDP
RFCOMM
control
Data
Audio
L2CAP
Link Manager
Baseband
RF
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Telephony Control Protocol (TCS BIN)

• TCS BIN
• bit-oriented protocol that defines
• the call control signaling for the establishment
  of voice and data calls between Bluetooth
  devices.
• mobility management procedures for handling
  groups of Bluetooth TCS devices

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Adopted Protocols

• PPP
• PPP is designed to run over RFCOMM to accomplish
  point-to-point connections.
• PPP-Networking is the means of taking IP packets
  to/from the PPP layer and placing them onto the
  LAN
• TCP/UDP/IP
• used for communication across the Internet
  (bridge to the Internet).
• most widely used protocol family in the world,
  appeared on numerous devices including printers,
  handheld computers, and mobile handsets.
• Access to these protocols is operating system
  independent

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Adopted Protocols

• OBEX (OBject EXchange)
• Session-layer protocol for the exchange of
  objects, providing a model for object and
  operation representation
• provides the same basic functionality as HTTP but
  in a much lighter fashion, uses a client-server
  model and is independent of the transport
  mechanism.
• defines a folder-listing object, which is used to
  browse the contents of folders on remote device
• WAE/WAP
• Bluetooth incorporates the Wireless Application
  Environment and the Wireless Application Protocol
  into its architecture.
• The goal is to bring Internet content and
  telephony services to digital cellular phones and
  other wireless terminals

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Security Modes

• Bluetooth security is divided into three modes
• Security Mode 1 non-secure
• Security Mode 2 service level enforced security
• Security Mode 3 link level enforced security

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Security Implementation within the Architecture

• Security modes for devices
• Trusted Device
• Such a device would have access to all services
  for which the trust relationship has been set.
• Untrusted Device
• Such a device would have restricted access to
  services.

• Security levels for services
• Authorisation Required
• access granted to trusted devices
• Authentication Required
• the remote device must be authenticated
• Encryption Required
• The link must be changed to encrypted mode,
  before access to the service is possible

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Frame format

• Access code
• Header
• Data

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Frame format

• Access code
• (72 bits) are used for synchronization and
  identification which identifies the master node

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Frame format

• Header
• 54 bits header includes thee repeats of an 18-bit
  
• Address (3-bits) identifies one of the eight
  nodes (slave address)
• TYPE (4 bits) indicates
• Frame type (ACL, SCO)

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Frame format

• FLOW (One bit) is set when the slave buffer is
  full
• ARQN (One bit) Positive or negative
  acknowledgement
• SEQN (One bit) Sequence bit Inverted for each new
  transmitted packet
• HEC (8-bits) error detection code used to protect
  the packet header
• The header repeats three times. If all headers
  are the same, the frame is accepted if differ
  error happened

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Bluetooth devices classification

• Bluetooth Smart Ready devices
• Bluetooth Smart devices

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Bluetooth Smart Ready devices

• Are the most effective way to connect to billions
  of Bluetooth devices in market today.
• Examples include phones, tablets,
  PCs, TVs, even set-top boxes
  and game
  consoles that sit at
  the center of your connected world.
• These devices can efficiently
  receive data from Bluetooth Smart
  devices and let you do
  something with it,
  such as record and chart your morning
  run on your smartphone or let you
  control the
  temperature of your home from your tablet.

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Bluetooth Smart devices

• Are designed to gather a specific piece of
  information Ex. (Are all the windows on my house
  locked? what is my blood glucose level? how
  much do I weigh today?,.) and send it to a
  Bluetooth Smart Ready device.
• Ex. include heart-rate monitors, blood
  glucose meters, smart watches, window and
  door security sensors, key fobs for your car,
  and blood-pressure cuffs, the opportunities are
  endless.
• If you have a Bluetooth Smart device you want to
  connect to a phone, tablet, PC or TV.

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Advantages Disadvantages

• Advantages
• Wireless (No cables)
• No setup needed
• Low power consumption (1 Milli wat)
• Industry wide support
• Disadvantages
• Short range (10 meters)
• Small throughput rates (Data Rate 1 Mbps)
• Mostly for personal use (PANs)
• Fairly Expensive

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Summary

• Introduction (Name, Program, Description)
• Why Bluetooth? (Synchronization, Access point,
  Dynamic networks)
• Bluetooth network topology (Piconet, Scatternet)
• Physical links (SCO, ACL)
• Connection Establishment (States Standby, page,
  page scan, Inquiry, Inquiry scan)
• Connection Modes (Active, Hold, Park, Sniff)
• Protocol Architecture (Core, Cable replacement,
  Telephony control, Adopted)
• Security Modes
• Frame format
• Bluetooth devices classification (Smart Ready,
  Smart devices)
• Adv. Dis-adv.

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Thanks

• E. Amir Ezzat Amir.ezzat_at_rashpetco.com