Bluetooth Justin Paupore (jpaupore) Russ Bielawski (jbielaws)
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Transcript of Bluetooth Justin Paupore (jpaupore) Russ Bielawski (jbielaws)
BluetoothJustin Paupore (jpaupore)Russ Bielawski (jbielaws)
What is Bluetooth?
What, exactly, is Bluetooth?
What is the purpose of Bluetooth?
What is Bluetooth?Protocol Goals
• Cable replacement technology (initially)
• Short-range wireless communication technology (unlicensed 2.4GHz band)
• Wireless Personal Area Networks (WPANs)
• Standardization of Solution to Common Problem
• Simple
• Standardized (highly interoperable)
• Low Powero Most common "class 2" radio consumes 2.5mW
• Robusto Frequency Hopping Spread Spectrum (FHSS)o Profiles
• Simultaneous Connection Service Classeso Voice - Circuit-Switchedo Data - Best Effort
• QoS
What is Bluetooth?Advantages By Design
What is Bluetooth?History
• 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
• 2010: Bluetooth 4.0
What is Bluetooth?Aside: The Bluetooth SIG
• Bluetooth was initially conceived by Ericsson
• The Bluetooth SIG was founded in 1998 by Ericsson, IBM, Intel, Toshiba and Nokia
• Promoter Memberso Ericsson, Intel, Lenovo, Microsoft, Motorola, Nokia,
Toshiba, Apple, Nordic Semiconductor
• Associate Members
• Adopter Members
Outline
• What is Bluetooth?
• Licensing, Patents and Certification
• Bluetooth "Variants"
• Profiles
• The Bluetooth Protocol Stack
Licensing, Patents and Certification
• 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 re-qualification
• There are some fees for qualificationo Not publicly availableo Based upon membership status
Outline
• What is Bluetooth?
• Licensing, Patents and Certification
• Bluetooth "Variants"
• Profiles
• The Bluetooth Protocol Stack
Bluetooth "Variants"History (Again)
• 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
• 2010: Bluetooth 4.0
Bluetooth "Variants"EDR - Enhanced Data Rate
• 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
• 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
• Bluetooth Low Energy (BLE) is the main feature of Bluetooth 4.0
• Re-imagining of Bluetooth for 4.0o Bluetooth Classico Bluetooth HSo Bluetooth LE
• Competes with low power WPAN protocolso ANTo 802.15.4 (MAC and PHY of ZigBee)o Nike+
• No Mesh Networking Support
Bluetooth "Variants"BLE and the Future of Bluetooth
• Adoption of BLE enables new technology arenaso Home Automationo Medical Deviceso Wearable Electronics
• New product branding
Outline
• What is Bluetooth?
• Licensing, Patents and Certification
• Bluetooth "Variants"
• Profiles
• The Bluetooth Protocol Stack
Profiles
Profile Examples
• Advanced Audio Distribution Profile (A2DP)o 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)o e.g. Bluetooth Keyboard
• Serial Port Profile (SPP)
Profiles
• 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
Profiles
Profile Examples
• Advanced Audio Distribution Profile (A2DP)o 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)o e.g. Bluetooth Keyboard
• Serial Port Profile (SPP)
Outline
• 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
• Runs in unlicensed 2.4 GHz (ISM) band
• 79 frequency bands, separated by 1 MHz
• Transmit power classeso Class 1: 100mW, ~100m rangeo Class 2: 2.5mW, ~10m rangeo Class 3: 1mW, ~1m range
• Modulation: Gaussian frequency-shift keyingo Positive frequency offset -> 1o Negative frequency offset -> 0o 2.0 EDR adds phase-shift keying
Baseband Layer
Baseband Layer
• Master/slave setup
• Piconet: 1 master + up to 8 slaves
• Pseudorandom frequency hopping based on device address of master
• Time-division duplexing - 625µs slotso Master transmits in even-numbered slotso Slave transmits in odd-numbered slotso One packet transmitted in each slot
Baseband Layer
• Data is transmitted in packets
• Connections come in two types:o SCO (Synchronous Connection-Oriented)
Reserved bandwidth Master to single slave Typically carries voice data
o 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
• Error Correctiono 1/3-rate FEC
Transmit each bit 3 times - majority winso 2/3-rate FEC
Error-correcting code turns 10 bits into 15o ARQ
Retransmit until acknowledgedo Type used depends on packet type - see spec
swedetrack.com/images/bluet08.htm
Link Manager Protocol (LMP)
Link Manager Protocol (LMP)
• Establishes, manages, and tears down links
• Functions include:o Pairingo Authenticationo Encryptiono Connection establishmento Device discovery
Host Controller Interface (HCI)
Host Controller Interface (HCI)
• Standard interface between Bluetooth chipsets and host devices
• Communication protocol to chipset
http://www.palowireless.com/infotooth/tutorial/hci.asp
Host Controller Interface (HCI)
• Chipset manages radio, baseband, LMP
• Exports commands such as:o Send ACL/SCO datao Create piconetso Encrypt a linko Get status information
• Allows reusing drivers and interchanging chipsets
Logical Link Control and Adaptation Protocol (L2CAP)
Logical Link Control and Adaptation Protocol (L2CAP)
• Provides abstracted data-carrying capability over ACL links
• Work around limitations of ACL
• Controllable reliabilityo Guaranteed delivery (using ARQ)o Best-effort delivery
• Important functions:o Multiplexingo Segmentation/reassemblyo Quality-of-Service
RFCOMM Protocol
RFCOMM Protocol
• Serial port emulation over L2CAP
• Carries data + flow control signals
• Can emulate multiple serial ports
Service Discovery Protocol (SDP)
Service Discovery Protocol (SDP)
• Ask devices what profiles they supporto Search for a specific profileo Get a list of all profiles
• Get necessary information for connection
Putting it All Together: SPP
Putting it All Together: SPP
• Connect with LMP
• Find info with SDP
• Start L2CAP
• Start RFCOMM
• Send data!
Conclusion
• What is Bluetooth?
• Licensing, Patents and Certification
• Bluetooth "Variants"
• Profiles
• The Bluetooth Protocol Stack
References
• http://www.bluetooth.com/
• http://www.bluetooth.org/
• http://ieee802.org/15/Bluetooth/
• http://www.palowireless.com/infotooth/
• http://www.radio-electronics.com/info/wireless/bluetooth/radio-interface-modulation.php
• http://www.eetimes.com/design/automotive-design/4009313/Testing-and-Qualifying-a-Bluetooth-Design
• www.hp.com/rnd/library/pdf/understandingBluetooth.pdf
• http://grouper.ieee.org/groups/802/15/Bluetooth/core_10_b.pdf
• https://support.apple.com/kb/HT3647