Bluetooth defines five types of logical data channels designed to carry different types of payload traffic. They are:

• Link control (LC): Used to manage the flow of packets over the link interface. The LC channel is mapped onto the packet header. This channel carries low level link control information like ARQ, flow control, and payload characterization. The LC channel is carried in every packet except in the ID packet, which has no packet header.

• Link manager (LM): Transports link management information between par- ticipating stations. This logical channel supports LMP traffic and can be carried over either an SCO or ACL link.

• User asynchronous (UA): Carries asynchronous user data. This channel is normally carried over the ACL link but may be carried in a DV packet on the SCO link.

• User isochronous (UI): Carries isochronous user data. This channel is normally carried over the ACL link but may be carried in a DV packet on the sca link. At the baseband level, the VI channel is treated the same way as a VA channel. Timing to provide isochronous properties is provided at a higher layer.

• User synchronous (US): Carries synchronous user data. This channel is carried over the SCO link.