Common control physical channel
CCPCH stands for Common Control Physical CHannel in UMTS and some other CDMA communications systems. It is a broadcast radio channel by which a mobile phone or user equipment can decode and determine important system parameters before establishing a dedicated communications link. In a FDD UMTS system, there are two CCPCH- Primary and Secondary. Exactly one Primary-CCPCH, which has a data rate of 27kbit/s and is always broadcast using Channelisation Code Cch,256,1. This channel can be detected by mobiles due to its fixed channelisation code, slot format and TTI, as well as being time aligned to the Synchronisation Channel which replaces the first 2 bits of P-CCPCH in every slot. The Broadcast Control Channel (BCH) transport channel is mapped onto the P-CCPCH, allowing mobiles to decode important system parameters prior to establishing a dedicated connection. One or more Secondary-CCPCHs are also provided to broadcast paging blocks and FACH messages. The P-CCPCH in a TDD-mode UMTS system also carries pilot bits in (in contrast to FDD-mode, which provides a distinct pilot channel named CPICH). The pilot bits on the CCPCH can be used for measurements of the signal quality (e.g. RSCP, Ec/Io, etc.) and for synchronisation and timing reference when decoding