Terminology » Mobile Communication » WCDMA SCCPCH: Secondary Common Control Physical Channel Explained

WCDMA SCCPCH: Secondary Common Control Physical Channel Explained

wcdma umts physical channel sccpch radio communication

This page describes the SCCPCH, or Secondary Common Control Physical Channel, with respect to the WCDMA/UMTS system. It is downlink physical channel which carries essential control information to User Equipment (UE) when no dedicated channel is established. The Secondary CCPCH is used to carry the Forward Access Channel (FACH) and Paging Channel (PCH). It facilitates communication between the network and UEs in idle mode or connected mode.

WCDMA SCCPCH

Functions

Forward Access Channel (FACH): It conveys control information and small amounts of user data to UEs. It is useful to deliver messages to UEs which are in idle mode or have not been assigned a dedicated channel.​

Paging Channel (PCH): It is responsible to alert UEs about incoming calls, messages or system information updates. It ensures that UEs can be notified even when they are not actively engaged in communication.​

Technical characteristics

  • Channel coding: CRC, convolutional code
  • Symbol rate: 15/30/60/120/240/480/960 ksps
  • Modulation: QPSK
  • Spreading: Predefined code broadcast on the BCH
  • Scrambling: Gold sequence - 3.84Mcps, 10 ms periodic
  • Power control: Not supported
  • Pilot symbol: Included
  • TFCI bits: Included/not included

Summary

The SCCPCH plays vital role in WCDMA networks by delivering essential control information to UEs.