cording to Table 4.27, respectively, and indicate the signature number S in Table 20 [1]. The sequence bs,0 ,bs,31 given in Table 20 [1]. CDI, with values +1/0 or -1/0, is the CD indicator corresponding to the CD preamble i transmitted by the UE, and CAI, with values +1/0 or -1/0, is the CA indicator corresponding to the assigned channel index k as given in Table 4.27. Table 4.27 Generation of CDI/CAIk UE transmitted CD Signature Channel assign- preamble i ment index k Signature The UTRA Physical Layer Design 4.3.9.9 Paging Indicator Channel (PICH) As a physical channel the PICH has a fixed rate (SF = 256) and carries the Paging Indi- cators (PI). It is always associated with a S-CCPCH to which a PCH transport channel is mapped. Figure 4.28 illustrates PICH frame structure, where one PICH radio frame of 10 ms length consists of 300 bits (b0,b1,...,b299). Of these, 288 bits (bo,b1 ,b287) are used to carry paging indicators. The remaining 12 bits (b288,b289 ,b299) are undefined. Each PICH frame transmits N paging indicators {PI,...,PIN-1}, where N = 18, 36, 72, or 144. 288 bits for paging indication 12 bits (undefined) bo b1 One radio frame (10 ms) Figure 4.28 Structure of Paging Indicator Channel (PICH). Higher layers calculate the PI mapped to the paging indicator PI, where p is computed as a function of the PI, the SFN of the P-CCPCH radio frame during which the start of the PICH radio frame occurs, and the number of paging indicators per frame (N) see Equation (4.3). Table 4.28 shows the mapping from {PI,...,PIN-1} to the PICH bits {b0,...,b287}. (4.42) Table 4.28 Mapping of Paging Indicators (PI) to PICH Bits Number of PI per frame (N) N = 18 {b16p>....b16p+15}= N = 36 N = 72 N = 144 {b2p,b2p+1} = {1,1} {b2p,b2p+1} {0,0} If a paging indicator in a certain frame has the value '1', it indicates that UEs associated with this paging indicator should read the corresponding frame of the associated S-CCPCH. In the event of transmit diversity for the PICH, STTD encoding applies on the PICH bits. The UMTS Network and R