Downlink CPICH Frame Structure

The CPICH is a fixed rate (30 kbps, SF=256) downlink physical channel that carries a pre-defined bit sequence.

In the case that transmit diversity (open or closed loop) is used on any downlink channel in the cell, the CPICH shall be transmitted from both antennas using the same channelization and scrambling code. In this case, the pre-defined bit sequence of the CPICH is different for Antenna 1 and Antenna 2, see the figure below. In the case that no transmit diversity is used, the bit sequence of Antenna 1 in the figure below is used.