AAAAAAAA AAAAAAAAA AAAAA Antenna 2 -A-AAA-A-AAA-AA-A-AAA-AAAA-AAAA-AA slot #14 slot #0 slot #1 Frame#i Frame#i+1 Frame Boundary Figure 4.21 Common pilot channel (with 1A=1+j) modulation pattern. Antenna 1 and Antenna 2 do have different CPICH pre-defined symbol sequences. In the absence of transmit diversity, the symbol sequence of Antenna 1 applies. In the sequel we describe the two types of common pilot channels, i.e. primary and sec- ondary CPICHs, which differ in their use and the limitations placed on their physical features. 4.3.9.1.1 Primary and Secondary Common Pilot Channels (P-CPICH) Table 4.21 illustrates the main characteristics of the P-CPICHs. The coding and spread- ing section present more details on scrambling issues. Table 4.21 Characteristics of Primary and Secondary P-CPICHs Primary P-CPICH characteristics Secondary P-CPICH characteristics The P-CPICH uses always the same chan- The S-CPICH uses an arbitrary channeliza- nelization code tion code of SF=256 The primary scrambling code scrambles the Either the primary or a secondary scrambling P-CPICH code scrambles a S-CPICH Each cell has only one P-CPICH A cell may contain zero, one, or several S- CPICHsl The P-CPICH is broadcast over the entire cell A S-CPICH may be transmitted over the entire cell or only over a part of the cell P-CPICH serves as phase reference for DL: A secondary CPICH may be the reference for SCH, primary CCPCH, AICH, and PICH secondary CCPCH and DL- DPCH. It is also the default phase reference for all Upper layers inform the UE when a secon- other downlink physical channels dary CPICH is used as reference 4.3.9.2 Primary Common Control Physical Channel (P-CCPCH) The primary CCPCH, as a downlink physical channel with a fixed rate (30 kbps, SF = 256), carries the BCH transport channel. Figure 4.22 shows the frame structure of the primary CCPCH, which differs from the downlink DPCH in that it does not transmit TPC commands, or TFCI, or pilot bits. In addition, it is not transmitted during the first 256 chips of each slot. The 