Asynchronous Connection-Less


Asynchronous Connection-Less is a communications protocol. It is used as a transmission link used for data communication in the Bluetooth system or as a definition with access code + packet header + payload + CRC.
Asynchronous Connection-Less Link is used when data integrity is more important than avoiding latency. In this type of link, if a payload encapsulated in the frame is corrupted, it is retransmitted. A secondary returns an ACL frame in the available odd-numbered slot if and only if the previous slot has been addressed to it. ACL can use one, three or more slots and can achieve a maximum data rate of 721 kbit/s.

Packet Types

DM1, DH1, DM3, DH3, DM5, DH5, AUX1
D
M : rate 2/3 FEC used
H : no FEC used
1 : 1 slot used for one frame
3 : 3 slots used for one frame
5 : 5 slots used for one frame