ayer control command such as emergency stop command. The exact num- ber of bits of DL DPCCH fields (Npilot NTFCI, Nccc and NTPC) is determined in Table 4.20. Table 4.17 defines the pilot bit pattern for Npilot=4 used for DPCCH for CPCH. Table 4.20 DPCCH Fields for CPCH Message Transmission Channel bit Channel sym- Bits/ DPCCH Transmitted format rate (kbps) bol rate (ksps) bits/slot slots/frame NTFCI The UMTS Network and Radio Access Technology DPCCH for CPCH Pilot NTPC bits NTFCI bits Nccc bits Npilot bits lot=2560 chips, 10 bits Slot #0 Slot #1 Slot #i Slot #14 One radio frame, Tf = 10 ms Figure 4.19 Frame structure for downlink DPCCH for CPCH. The transmission of the CPCH control command uses the CCC field in Figure 4.19 upon request from higher layers, where a given pattern is mapped onto the CCC field. If no requests exist, nothing is transmitted in the CCC field; thus, there is one to one map- ping between the CPCH control command and the pattern. 'CPCH emergency stop transmission' maps the [1111] pattern onto the CCC field. This stop command cannot be transmitted during the first NStart_Message frames of DL DPCCH after power control preamble. The CCC field gets the [1010] pattern for the start of message indicator dur- ing the first NStart_Message frames of DL DPCCH after power control preamble. 4.3.9 Common Downlink Physical Channels 4.3.9.1 Common Pilot Channel (CPICH) Figure 4.20 illustrates the frame structure of the CPICH, which is a fixed rate (30 kbps, SF = 256) downlink physical channel that carries a pre-defined bit/symbol sequence. Pre-defined symbol sequence Tslot =2560 chips 20 bits = 10 symbols Slot #0 Slot # Slot #i Slot #14 1 radio frame: Tf=10ms Figure 4.20 Frame structure for the common pilot channel. During transmit diversity on any downlink cell channel, either with open or closed loop power control, the CPICH shall be transmitted from both antennas using the same chan- nelization and scrambling code (in this case, as illustrated in Figure 4.21). The UTRA Physical Layer Design Antenna 1 A