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Bluetooth

Bluetooth. Introduction Why Bluetooth History The Bluetooth Technology The Bluetooth Stack Bluetooth in ad hoc networks. Introduction. Why Bluetooth? Cable replacement between devices. Supported by major companies. Open Specification Low power consumption

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Bluetooth

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  1. Bluetooth • Introduction • Why Bluetooth • History • The Bluetooth Technology • The Bluetooth Stack • Bluetooth in ad hoc networks

  2. Introduction • Why Bluetooth? • Cable replacement between devices. • Supported by major companies. • Open Specification • Low power consumption • Connection can be initiated without user interaction. • Devices can be connected to multiple devices at the same time.

  3. History • The technology was born in 1994. • The first version was released July 1999. • The Bluetooth name comes from the Danish Viking Harald Blåtand.

  4. The Bluetooth Technology • The Bluetooth Stack:

  5. Radio • Bluetooth devices operate on 2.4 GHz Industrial Scientific Medical band (ISM band). • Unlicensed in most countries. • Interferences from: • Other radio frequency short-range techniques • Wireless local area networks (IEEE 802.11) • Random noise generators (microwave ovens) • Other Bluetooth units

  6. Radio (cont.) • Techniques to minimize packet loss: • Frequency Hopping • Adaptive power control • Short data packets

  7. Frequency Hopping • Uses FHSS (Frequency Hopping Spread Spectrum) • Divides the ISM-band into 79 1-Mhz channels. • Communication between devices switches between available channels.

  8. Frequency Hopping (cont.)

  9. Power Control • Three power classes defined with max output power from 1 mW (Class 1) to 100 mW (Class 3). • Devices may be implementet with power control • Optimize power consumption • Decrease interference

  10. Bluetooth Packet Structure

  11. Baseband • Responsible for channel coding/decoding, timing and managing a Bluetooth link. • Master/slave • Devices in a connection are either master or slave. • Communication is only possible between a master and its slaves. • A master and the slaves are named piconets. • Scatternet; multiple piconets connected together.

  12. Piconets and Scatternet

  13. The Link Manager • Responsible for establishing, supervising and tear down connections and logical links. • Link controller states introduced to carry out these tasks. • States: • Standby • Inquiry / Inquiry Scan • Page / Page Scan • Connection

  14. The Link Manager (cont.) • Inquiry • Used to detect all devcies in an unknown environment. • Page / Page Scan • Describes how connection is established. • Have to know the address of the other devices. Is usually achieved through inquiry. • Connection • Master and slaves are synchronized. • Connection is established.

  15. Inquiry / Inquiry Scan

  16. Page / Page Scan

  17. Host Controller Interface (HCI) • Provided to ease the partition of the Bluetooth Stack across two processors. • Some systems will implement the baseband and link manager on the Bluetooth device and higher levels on the host processor. • The HCI is provided as an interface between these parts.

  18. Logical Link Control and Adaption (L2CAP) • Deals with • multiplexing of different services • segmentation • reassembling of packets • Quality of Service

  19. Profiles • Provide interoperability between devices from different manufacturers for specific services and use cases. • A profile defines • a selection of messages and procedures • gives an unambiguous description of communication between two devices.

  20. Bluetooth in ad hoc networks • Bluetooth network infrastructure is of dynamic ad-hoc type. • It is constantly changing and depending on the movement of the devices.

  21. Bluetooth in ad hoc networks (cont.) • Temporary networks. • Connect ”on-the-fly”. • Small wireless network called ”personal area network” (PAN). • Provide voice, data, eliminate cables, bridge networks. • Supports PDAs, mobile phones, printers, faxes, microphones.

  22. Bluetooth in ad hoc networks (cont.) • The master can support up to 7 devices in its network. • Devices use the same frequency, but can be in multiple networks.

  23. Security • Bluetooth provides security only over the radio link, from each device to all other devices. • Three security specifications: • Confidentiality • Authentication • Authorization

  24. Bluetooth in the future • Bluetooth was originally intended to be a cable replacement, • but, has evolved to become an infrastructure for Personal Area Network (PAN) • 2001: 10 million devices produced • 2003: 70 million!

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