User Data Transfer

WCDMA is designed to offer great flexibility in the transmission of user
data across the air interface. For example, data rates can change on a
frame-by-frame basis (every 10 ms). Moreover, it is possible to mix and
match different types of service. For example, a subscriber may be sending
and receiving packet data while also involved in a voice call. When sending
information over the air interface, physical control channels are used in
combination with physical data channels. Although the physical data channels
carry the user information, the physical control channels carry information
to support the correct interpretation of the data carried on the
corresponding DPDCH frame, plus power control commands, and feedback
indicators.