What is work of Primary Common Control Physical Channel PCCPCH in 3G
Main work of Primary Common Control Physical Channel PCCPCH in 3G wcdma as below.
- Carrying BCH transport channel
- Fixed rate, fixed OVSF code (30kbps，Cch, 256, 1)
- The PCCPCH is not transmitted during the first 256 chips of each time slot
The Primary Common Control Physical Channel (P-CCPCH) is a fixed rate (SF=256) downlink physical channel used to carry the BCH transport channel. It is broadcasted continuously over the entire cell like the P-CPICH.
The figure above shows the frame structure of the P-CCPCH. The frame structure is special because it does not contain any layer 1 control bits. The P-CCPCH only has one fix predefined transport format combination, and the only bits transmitted are data bits from the BCH transport channel. It is important to note that the P-CCPCH is not transmitted during the first 256 chips of the slot. In fact, another physical channel (SCH) is transmitted during that period of time. Thus, the SCH and the P-CCPCH are time multiplexed on every time slot.
Channelization code Cch, 256, 1 is always used to spread the P-CCPCH.