actor may vary from frame to frame, a PDSCH transmission with associated DPCH is a special case of multi-code transmission. Thus, when map- ping a DSCH to multiple parallel PDSCHs the spreading factor of all PDSCH codes will be the same. The PDSCH does not carry physical layer info, but all relevant L1 control information. Table 4.26 illustrates PDSCH T bit rates and symbol rates, where spreading factors may vary from 256 to 4. Table 4.26 PDSCH* Fields Channel bit Channel symbol Bits/ Bits/ Ndata format #i rate (kbps) rate (ksps) frame 19200 When open loop transmit diversity is employed for the PDSCH, STTD encoding is used on the data bits. The UTRA Physical Layer Design 4.3.9.6 Acquisition Indicator Channel (AICH) As a physical channel, having the primary CPICH for phase reference, the AICH carries Acquisition Indicators (AI) corresponding to signature S on the PRACH. Figure 4.27 illustrates its structure consisting of a repeated sequence of 15 consecutive Access Slots (AS), each of length 40 bit intervals. In turn, every access slot consists of two parts: an Acquisition-Indicator (AI) part containing 32 real-valued symbols ao,...,A31 and a part of 1024 chips duration without transmission. CDI/CAI part API part AI part 1024 chips a30 a31 Transmission Off AS #14 AS #0 AS #1 AS #i AS #14 AS #0 20 ms Figure 4.27 Structure of the AICH, AP-AICH and CD/CA-ICH. Equation (4.40a) defines the real-valued symbols a0,A1,...,A3 seen in Figure 4.27. Table 20 in [1] provides the acquisition indicator AIS with values +1, -1, and 0 corresponding signature S and the sequence bs.0,...,bs.31. When the AICH has STTD-based open-loop transmit diversity, STTD encoding applies to each sequence separately before these sequences combined into AICH symbols ao,...,A31. (4.40) 4.3.9.7 CPCH Access Preamble Acquisition Indicator Channel (AP-AICH) The physical AP-AICH carries CPCH Access Preamble acquisition Indicators (API). The AP acquisition indicator API corresponds to the AP signature S transmitted by UE. The AP-AICH, with the primary CPIC