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.
Link types
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
