Baseband in Bluetooth

Manages physical channels and logical lines.

  • Controls device addressing, channel control, power-saving operations, and flow control and synchronization among devices.

  • Implements TDD aspects: master and slave switch in communications.

Works closely with Link controller:

  • Manages link (a)synchronism.

  • Controls paging and inquiries.

  • Controls power save modes.

Polling-based (TDD) frame transmissions.

  • 1 slot: 0.625msec (max 1600 slots/sec).

  • master/slave slots (even-/odd-numbered slots).

  • polling: master always “polls” slaves.

Synchronous connection-oriented (SCO) link.

  • “circuit-switched”.

    • periodic single-slot frame assignment.

  • symmetric 64Kbps full-duplex.

Asynchronous connection-less (ACL) link.

  • Frame switching.

  • asymmetric bandwidth.

    • variable frame size (1-5 slots).

      • max. 721 kbps (57.6 kbps return channel).

      • 108.8 - 432.6 kbps (symmetric).

Packet

Frame

Access Code: time synchronization, offset, paging, inquiry.

  • Channel Access Code (CAC), piconet identification, synchronization, DC offset.

  • Device Access Code (DAC), paging and replies.

  • Inquiry Access Code (IAC), inquiries (GIAC, general; DIAC, dedicated).

Header: packet acknowledgment and numbering, flow control, slave address, error checking.

Payload: voice, data or both (DV packets).

  • When data, the payload has additional internal header.

Role of Fields

  • ACCESS CODE - based on identity and system clock of Master.

  • Provides means for synchronization; Unique for the channel.

  • Used by all frames on the channel.

Packets

Last updated