 i.e. TS-CCPCH,k = Tkx256 chip, Tk E {0,1,...,149}. The UMTS Network and Radio Access Technology The PICH timing is TPICH = 7680 chips prior to its corresponding S-CCPCH frame timing, i.e. the timing of the S-CCPCH carrying the PCH transport channel with the corresponding paging information. AICH access slots #0 starts the same time as P-CCPCH frames with (SFN modulo 2) = 0. Any DPCH frame is associated to one PDSCH frame through the relation 46 080 chips TPDSCH - TDPCH < 84 480 chips. The DPCH timing may be different for different DPCHs, but the offset from the P- CCPCH frame timing is a multiple of 256 chips, i.e. TDPCH,n = Tn X 256 chips, Tn E {0,1,...,149} Primary Secondary Any CPICH P-CCPCH, (SFN modulo 2) = 0 P-CCPCH, (SFN modulo 2) = 1 TS-CCPCH,k k:th S-CCPCH TPICH PICH for k:th S-CCPCH AICH access slots Any PDSCH TDPCH,n n:th DPCH 10 ms Figure 4.30 Frame timing and access slot timing of downlink physical channels. 4.3.11.1 PICH/S-CCPCH Timing Relation Figure 4.31 illustrates the timing between a PICH frame and its associated S-CCPCH frame, i.e. the S-CCPCH frame carrying paging information related to the paging indi- The UTRA Physical Layer Design cators in the PICH frame. A paging indicator set in a PICH frame means that the paging message is transmitted on the PCH in the S-CCPCH frame starting TPICH chips after the transmitted PICH frame. PICH frame containing paging indicator Associated S-CCPCH frame TPICH Figure 4.31 Timing relation between PICH frame and associated S-CCPCH frame. 4.3.11.2 PRACH/AICH Timing Relation The downlink AICH has two downlink access slots, each with 5120 chips length and time aligned with the P-CCPCH. The uplink PRACH has uplink access slots, each with 5120 chips length. The UE transmits Uplink access slot number n, Tp-a chips prior to the reception of downlink access slot number n, n = 0,1 14. Downlink acquisition indicators may only start at the beginning of a downlink access slot. Likewise, transmission of uplink RACH preambles and RACH message parts may only start at the b