Common Channels

The downlink (Node B to handset) consists of a number of physical channels. One class
(or group) of physical channels is the Common Control Physical CHannel (CCPCH).
Information carried on the CCPCH is common to all handsets within a cell (or sector)
and is used by handsets to synchronize to the network and assess the link characteristic
when the mobile is in idle mode—that is, when it is not making a call. In dedicated
connection mode—that is, making a call—the handset will still use part of the CCPCH
information to assess cell handover and reselection processes, but will switch to using
more specific handset information from the Dedicated CHannels (DCH) that are created
in call setup.
The CCPCH consists of a Primary CCPCH (P-CCPCH) and a Secondary CCPCH (SCCPCH).
The P-CCPCH is time multiplexed together with the Synchronization CHannel
(SCH) and carries the Broadcast CHannel (BCH).