What is the difference between ACL and SCO Link in Bluetooth?

Question

ACL= Asynchronous Connection-Less. SCO = Synchronous Connection Oriented.

SCO is Point to Point Connection between only one master and only one slave.

ACL is multipoint connection between one master and many slaves.

What are the other differences?

Solution 1

SCO is for real-time narrow band signal which does not require retransmission. Voice data in Bluetooth hands free kit is an example for this. This narrow band audio is called "Bluetooth voice" type. Where as ACL is for all other BT data transfer including High quality audio/video data. Example is music playback through A2DP. This is high bandwidth data and hence called "Advanced Audio". SCO is fixed bandwidth channels and can have maximum 3 channels per device, but throughput of ACL varies with other active connections(SCO and ACL) at that time.

Solution 2

ACL: It is used exclusively to transport data. Retransmission based on ARQ. Available types DMx(Moderate rate), DHx(High data rate). where x=1,3,5

SCO: It is mainly used for Voice Communication (or data and voice combined). No retransmissions.HV1,HV2,HV3 are different types of voice packets possible. each with different encoding scheme.

Solution 3

Check out the following diagram from my favorite conceptual guide to Bluetooth functionality.

Like Abin said, SCO is primarily utilized when a contiguous, real-time signal is required, like during a phone call.

ACL is for everything else, and is the primary mediating protocol for most data-transmission use-cases.