Data transmission

Data transmission When dealing with data that can be sent either
asynchronously or synchronously, however, you can use the synchronous
connection oriented (SCO) mechanism mostly for voice communications,
whereas an asynchronous connectionless (ACL) mechanism is meant
mostly for data communications.
When working with a PAN, each pair between the master and the
slave can utilize a different mode of transmission that can be changed on
the fly. For example, time-division duplex (TDD) is employed by both
ACL and SCO. Each of these protocols offers support for 16 types or
packet flavors. Four of these packets represent the same thing in each
type due to the need for an uninterrupted data transmission. In contrast,
SCO packets are sent at periodic times, so that they are transmitted in
groups without permitting any interruptions from other transmissions.
Furthermore, SCO packets are sent without polling from the sending
unit, while ACL links offer support for both asymmetric and symmetric
transmission modes. The master unit actually controls the bandwidth in
an effort to define how much of each slave unit can be used. This is possible
due to the fact that slave units are not able to transmit data until it
has been polled by the master unit. The master unit, however, can unit
the ACL link to send broadcast messages to the slave units.