Bluetooth
Justin Paupore (jpaupore)
Russ Bielawski (jbielaws)
What is Bluetooth?
What, exactly, is Bluetooth?
What is the purpose of Bluetooth?
What is Bluetooth?
Protocol Goals
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Cable replacement technology (initially)
Short-range wireless communication
technology (unlicensed 2.4GHz band)
Wireless Personal Area Networks (WPANs)
Standardization of Solution to Common
Problem
What is Bluetooth?
Advantages By Design
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Simple
Standardized (highly interoperable)
Low Power
o Most common "class 2" radio consumes 2.5mW
Robust
o Frequency Hopping Spread Spectrum (FHSS)
o Profiles
Simultaneous Connection Service Classes
o Voice - Circuit-Switched
o Data - Best Effort
What is Bluetooth?
History
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1998: Special Interest Group (SIG) formed
1999: Bluetooth 1.0
2000: mobile phone
2001: printer, laptop, hands-free in-car
2002: keyboard and mouse, GPS
2002: Bluetooth 1.1 - IEEE 802.15.1-2002
2004: Bluetooth 2.0 + EDR
2007: Bluetooth 2.1 + EDR
2009: Bluetooth 3.0 + HS
What is Bluetooth?
Aside: The Bluetooth SIG
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Bluetooth was initially conceived by Ericsson
The Bluetooth SIG was founded in 1998 by
Ericsson, IBM, Intel, Toshiba and Nokia
Promoter Members
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Ericsson, Intel, Lenovo, Microsoft, Motorola, Nokia,
Toshiba, Apple, Nordic Semiconductor
Associate Members
Adopter Members
Outline
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What is Bluetooth?
Licensing, Patents and Certification
Bluetooth "Variants"
Profiles
The Bluetooth Protocol Stack
Licensing, Patents and Certification
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Bluetooth Qualification is required to use
Bluetooth trademarks
Patents are FRAND, subject to qualification
Embedding a qualified Bluetooth module
WITH an antenna does not required requalification
There are some fees for qualification
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Not publicly available
Based upon membership status
Outline
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What is Bluetooth?
Licensing, Patents and Certification
Bluetooth "Variants"
Profiles
The Bluetooth Protocol Stack
Bluetooth "Variants"
History (Again)
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1998: Special Interest Group (SIG) formed
1999: Bluetooth 1.0
2000: mobile phone
2001: printer, laptop, hands-free in-car
2002: keyboard and mouse, GPS
2002: Bluetooth 1.1 - IEEE 802.15.1-2002
2004: Bluetooth 2.0 + EDR
2007: Bluetooth 2.1 + EDR
2009: Bluetooth 3.0 + HS
Bluetooth "Variants"
EDR - Enhanced Data Rate
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Added in Bluetooth 2.0
Allows speeds up to 3.0 Mbps theoretically,
2.1 Mbps in practice
Adds new modulation schemes improve data
rate
Bluetooth 2.0 devices may not actually
support EDR!
Bluetooth "Variants"
HS - High Speed
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Added in Bluetooth 3.0
Allows speeds up to 24.0 Mbps via Alternate
MAC/PHY (AMP)
Uses 802.11 to actually perform data
transfer
Bluetooth 3.0 devices may not actually
support HS!
Bluetooth "Variants"
BLE - Bluetooth Low Enegry
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Bluetooth Low Energy (BLE) is the main
feature of Bluetooth 4.0
Re-imagining of Bluetooth for 4.0
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Competes with low power WPAN protocols
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Bluetooth Classic
Bluetooth HS
Bluetooth LE
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ANT
802.15.4 (MAC and PHY of ZigBee)
Nike+
No Mesh Networking Support
Bluetooth "Variants"
BLE and the Future of Bluetooth
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Adoption of BLE enables new technology
arenas
Home Automation
o Medical Devices
o Wearable Electronics
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New product branding
Outline
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What is Bluetooth?
Licensing, Patents and Certification
Bluetooth "Variants"
Profiles
The Bluetooth Protocol Stack
Profiles
Profile Examples
Advanced Audio Distribution Profile (A2DP)
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e.g. Bluetooth Headphones
A/V Remote Control Profile (AVRCP)
Basic Printing Profile (BPP)
File Transfer Profile (FTP)
Hands-Free Profile (HFP)
Human Interface Device Profile (HID)
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e.g. Bluetooth Keyboard
Serial Port Profile (SPP)
Profiles
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Profiles reduce the risk of poor or partial
interoperability between devices
Endpoints can and usually do support
multiple profiles
What's in a profile?
Dependencies
Suggested user interface
Bluetooth protocols required
Dependencies on other profiles
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Profiles
Profile Examples
Advanced Audio Distribution Profile (A2DP)
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e.g. Bluetooth Headphones
A/V Remote Control Profile (AVRCP)
Basic Printing Profile (BPP)
File Transfer Profile (FTP)
Hands-Free Profile (HFP)
Human Interface Device Profile (HID)
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e.g. Bluetooth Keyboard
Serial Port Profile (SPP)
Outline
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What is Bluetooth?
Licensing, Patents and Certification
Bluetooth "Variants"
Profiles
The Bluetooth Protocol Stack
The Bluetooth Protocol Stack
Bluetooth Protocol Example
Radio Layer
Radio Layer
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Runs in unlicensed 2.4 GHz (ISM) band
79 frequency bands, separated by 1 MHz
Transmit power classes
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Class 1: 100mW, ~100m range
Class 2: 2.5mW, ~10m range
Class 3: 1mW, ~1m range
Modulation: Gaussian frequency-shift keying
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Positive frequency offset -> 1
Negative frequency offset -> 0
2.0 EDR adds phase-shift keying
Baseband Layer
Baseband Layer
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Master/slave setup
Piconet: 1 master + up to 8 slaves
Pseudorandom frequency hopping based on
device address of master
Time-division duplexing - 625µs slots
Master transmits in even-numbered slots
o Slave transmits in odd-numbered slots
o One packet transmitted in each slot
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Baseband Layer
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Data is transmitted in packets
Connections come in two types:
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SCO (Synchronous Connection-Oriented)
 Reserved bandwidth
 Master to single slave
 Typically carries voice data
ACL (Asynchronous Connectionless)
 Uses slots not used for SCO links
 Master to all slaves in piconet
 Carries non-voice data (L2CAP)
 Only one ACL connection for the piconet
Baseband Layer
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Error Correction
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1/3-rate FEC
 Transmit each bit 3 times - majority wins
2/3-rate FEC
 Error-correcting code turns 10 bits into 15
ARQ
 Retransmit until acknowledged
Type used depends on packet type - see spec
swedetrack.com/images/bluet08.
htm
Link Manager Protocol (LMP)
Link Manager Protocol (LMP)
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Establishes, manages, and tears down links
Functions include:
Pairing
o Authentication
o Encryption
o Connection establishment
o Device discovery
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Host Controller Interface (HCI)
Host Controller Interface (HCI)
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Standard interface between Bluetooth
chipsets and host devices
Communication protocol to chipset
http://www.palowireless.com/infotooth/tutorial/hci.asp
Host Controller Interface (HCI)
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Chipset manages radio, baseband, LMP
Exports commands such as:
Send ACL/SCO data
o Create piconets
o Encrypt a link
o Get status information
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Allows reusing drivers and interchanging
chipsets
Logical Link Control and
Adaptation Protocol (L2CAP)
Logical Link Control and
Adaptation Protocol (L2CAP)
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Provides abstracted data-carrying capability
over ACL links
Work around limitations of ACL
Controllable reliability
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Guaranteed delivery (using ARQ)
Best-effort delivery
Important functions:
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Multiplexing
Segmentation/reassembly
Quality-of-Service
RFCOMM Protocol
RFCOMM Protocol
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Serial port emulation over L2CAP
Carries data + flow control signals
Can emulate multiple serial ports
Service Discovery Protocol (SDP)
Service Discovery Protocol (SDP)
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Ask devices what profiles they support
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Search for a specific profile
Get a list of all profiles
Get necessary information for connection
Putting it All Together: SPP
Putting it All Together: SPP
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Connect with LMP
Find info with SDP
Start L2CAP
Start RFCOMM
Send data!
Conclusion
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What is Bluetooth?
Licensing, Patents and Certification
Bluetooth "Variants"
Profiles
The Bluetooth Protocol Stack
References
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http://www.bluetooth.com/
http://www.bluetooth.org/
http://ieee802.org/15/Bluetooth/
http://www.palowireless.com/infotooth/
http://www.radioelectronics.com/info/wireless/bluetooth/radio-interfacemodulation.php
http://www.eetimes.com/design/automotivedesign/4009313/Testing-and-Qualifying-a-BluetoothDesign
www.hp.com/rnd/library/pdf/understandingBluetooth.pdf
http://grouper.ieee.org/groups/802/15/Bluetooth/core_1