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Bluetooth

Bluetooth. Overview. Bluetooth is a low power short-range wireless standard for a wide range of devices Uses 2.4 GHz unlicensed band Two Bluetooth devices within 10m of each other can share up to 720 kbps of capacity

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Bluetooth

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  1. Bluetooth

  2. Overview • Bluetooth is a low power short-range wireless standard for a wide range of devices • Uses 2.4 GHz unlicensed band • Two Bluetooth devices within 10m of each other can share up to 720 kbps of capacity • Designed to operate with up to 8 devices communicating in a small network called piconet • Tens of piconets can coexist in the same coverage range of Bluetooth radio • Each link is encoded and protected against eavesdropping and interface

  3. Applications • Data and voice access points • Facilitates real-time voice and data transmission between portable and stationary communication devices • Cable replacement • Eliminates the need for cable in communicating devices • Ad hoc networks • A device equipped with Bluetooth radio can communicate directly with another Bluetooth radio

  4. Protocol Architecture • Core protocols • Cable replacement protocols • Telephony control protocols • Adopted protocols

  5. Core Protocols • Radio • Specifies air interface, frequency, use of frequency hopping, modulation scheme and transmission power • Baseband • Concerned with connection establishment within a piconet, addressing, packet format, timing and power control • Link manager protocol (LMP) • Responsible for link setup between Bluetooth devices and ongoing link management • Logical link control and adaptation protocol (L2CAP) • Adapts upper-layer protocols to the baseband layer • Service Discovery Protocol (SDP) • Device information, services and their characteristics can be queried to establish a connection

  6. Cable Replacement Protocols • RFCOMM • Virtual serial port that is designed to make replacement of cable techniques transparent • Provides binary data transport and emulates EIA-232 control signals over the Bluetooth baseband layer

  7. Telephony Control Protocol • TCS BIN (telephony control specification – binary) • Bit-oriented protocol that defines the call control signaling for the establishment of speech and data calls between Bluetooth devices • Defines mobility management procedures

  8. Adopted Protocols • PPP: point-to-point protocol (IP) • TCP/UDP/IP • OBEX: Object exchange protocol is a session-level protocol developed by Infrared Data Association for the exchange of objects • WAE/WAP: Wireless application environment and wireless application protocols are incorporated

  9. Piconets and Scatternets • Piconets are basic units of networking: one master and up to seven active slave devices • The master radio determines the channel and phase that shall be used by all devices • A slave can only communicate with the master and only when granted permission • A device in one piconet may also exist as part of another piconet and may function as either a slave or a master in each piconet. This form of overlapping is called scatternet • Piconet/Scatternet allows many devices to share the same physical area and make effective use of bandwidth

  10. Frequency Hopping • Bluetooth uses a frequency hopping (FH) scheme where the total bandwidth is divided up to 80 physical channels, each with a bandwidth of 1 MHz • Same hopping sequence is shared by all devices on a single piconet (called as FH channel) • Hop rate = 1600 hops per second. • The same hopping sequence is shared by all the devices in a piconet • Bluetooth radios communicate using TDD discipline • Multiple devices use TDMA for channel access • Piconet acesss: (FH-TDD-TDMA)

  11. Physical Links • Types: • Synchronous connection oriented (SCO) • Allocates a fixed bandwidth between master and single slave • Reserved slots at regular intervals • Used to exchange time-bounded data requiring guaranteed rate • Asynchronous connectionless (ACL) • Facilitates point-to-point link between master and all slaves in the piconet • Provides for packet-switched style of connection

  12. Channel Control • Handout

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