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CPET 260

CPET 260. Bluetooth. What is Bluetooth?. Not IEEE802.11 (Wi-Fi) or HomeRF Originally designed to replace wires Short-range, lower-power wireless technology A means to replace cables Keyboard, mouse, printer, etc. What is Bluetooth?.

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CPET 260

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  1. CPET 260 Bluetooth

  2. What is Bluetooth? • Not IEEE802.11 (Wi-Fi) or HomeRF • Originally designed to replace wires • Short-range, lower-power wireless technology • A means to replace cables • Keyboard, mouse, printer, etc.

  3. What is Bluetooth? • A method to allow data communications between diverse devices • I.e. computers, mobile phones, network appliances, handheld devices, digital cameras, etc.

  4. Bluetooth Special Interest Group (SIG) • Originally developed by Swedish Company Ericsson • See http://www.bluetooth.com • A royalty free, open specification to create a wide range of products that can communicate without wires.

  5. SIG • Based on a set of standards • Called profiles • Easy interconnect • Enable exchange of voice, and data

  6. Overview of Bluetooth • Versions 1.0, 1.1 and now 2.0 • Frequency Hopping Spread Spectrum (FHSS) • 1,600 hops per second (HomeRF 50-100) • 79 frequencies separated by 1 MHz • 2.4 GHz band • Asynchronous @ 712 Kbps • Synchronous @ 432.6 Kbps

  7. Overview • Motorola’s Piano • Allows formation of small ad hoc networks – Personal Area Networks (PANs) • Up to 10 meters • Digital Enhanced Cordless Telecommunications (DECT) • Voice and telephony

  8. Overview • Object Exchange Protocol (OBEX) • Borrowed from IrDa (Infrared Data Association) • Allows for data exchanges like synchronizing address books between Bluetooth enabled PDA and a PC

  9. Overview • Each transmission lasts only 625 s • Single master and up to seven slaves • All devices on ‘piconet’ use the same frequency hopping pattern. • Piconets can be in range of one another • When device joins a piconet, a Frequency Hop Synchronization packet is sent by master

  10. Overview • Communications can take place in both directions • 0-227 – 1 time slots • Master starts on even numbered time slot • Slave starts on odd numbered time slots • Up to 5 consecutive time slots can be used.

  11. Piconets • Formed when to or more devices discover each other

  12. Scatternets • Formed when a master of one piconet is a slave of a second piconet.

  13. Modes • Hold – power saving mode for slave • No longer actively exchanges data with other nodes. • Sniff – device in listen • Park – low-power mode no longer has a MAC address • Listens for broadcast messages • Resynchronizes clock w/ master

  14. SCO and ACL links • SCO – a Synchronous Connection Oriented link • Established between Master and a particular slave in the network • Suitable for voice since time slots are reserved

  15. SCO and ACL links • ACL – Asynchronous Connection-less link • Packet switched connections between master and one or more slaves • Can use any time slots not reserved by SCO links. • Only one ACL link can exist at any one time between master and a part. slave

  16. Bluetooth Packets • Access Code – 68 or 72 bits • Used for synchronization • Three different access codes used • CAC – Channel Access Code • Identifies a particular piconet • DAC – Device Access Code • Used during signaling – ie. paging • IAC – Inquiry Access Code • GIAC – General Inquiry Access Code • DIAC – Dedicated Inquiry Access Code

  17. Bluetooth Packets • Header – fixed at 54 bits • AM_ADDR – active Member address • Type – 4 bits = 16 packet types • Flow – 1 bit for flow control • ARQN – 1 bit Acknowledge • SEQN – 1 bit sequence toggle • HEC – Header Error Check 8 bit

  18. Bluetooth Packets • The type field varies, but 5 common types include • ID Packet • Null Packet • Poll Packet • FHS packet • DM1 packet

  19. Bluetooth Packets • Payload 0-2,745 bits • Contains the actual data portion of the packet

  20. Bluetooth profiles • A set of specifications for how end-user functionality should be implemented • The Serial Port Profile Group • Used the RFCOMM for serial port emulation • The Generic Object Exchange Profile Group • The OBEX protocol is used by all profiles in this group • The Telephony Control Protocol Specification Group • For profiles for telephone & intercom functions

  21. General Access Profile • Protocols used to establish and maintain links • LC – Link Controller • LMP – Link Manager Protocol • L2CAP – Logical Link Control and Adaptation Protocol • TCST – Telephony Control Protocol • RFCOMM • SDP – Service Discovery Protocol

  22. Security • Security Mode 1 (non-secure) • Cannot initiate any security mechanisms • Security Mode 2 (service level enforced security) • Initiates after channel-established • Security Mode 3 (link-level …) • Initiates before LMP

  23. Profiles • The Service Discovery Application Profile • The Cordless Telephony Profile • The Intercom Profile • The Serial Port Profile • The Headset Profile • The Dial-up networking profile

  24. Other Bluetooth profiles • Fax • LAN Access • Generic Object Exchange • Object Push • File Transfer • Synchronization

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