eginning of an uplink access slot. Figure 4.32 illustrates the PRACH/AICH timing relation, where the preamble-to- preamble distance Tp-p shall be larger than or equal to the minimum preamble-to- preamble distance Tp-p,min i.e. Tp-p > Tp-p,min One access slot AICH access slots RX at UE amble amble Message part PRACH access slots TX at UE Figure 4.32 Timing relation between PRACH and AICH as seen at the UE. In addition to T p-p,min' [1] defines the preamble-to-AI distance Tp-a and preamble-to- message distance Tp-m as follows: The UMTS Network and Radio Access Technology when AICH_transmission_timing = 0, then when * *AICH_transmission_timing = 1, then Tp-p,min = 15 360 chips (3 access slots) Tp-p,min = 20 480 chips (4 access slots) Tp-a = 7680 chips Tp-a 12 800 chips p-m = 15 360 chips (3 access slots) Tp-m = 0480 chips (4 access slots) * Higher layers signal the parameter AICH_Transmission_Timing 4.3.11.3 PCPCH/AICH Timing Relation AICH, the message and the PRACH/AICH have an identical timing relationship be- tween preambles, where the collision resolution preambles follow the access preambles of the latter. The RACH preamble and AICH have the same timing relationship of the CD preamble and CD-ICH. Likewise, AICH to message in RACH and CD-ICH power control preamble in CPCH, have identical timing relationships. Finally, the PRACH/ AICH transmission timing parameter and the Tcpch timing parameter are identical. See that a corresponds to AP-AICH and a2 corresponds to CD-ICH. When Tooch = O or =1,the following PCPCH/AICH timing values apply: T p-p Time to next available access slot, between access preambles Minimum time = 15 360 chips + 5120 chips X Tepch Maximum time = 5120 chips X 12 = 61 440 chips Actual time = time to next slot (which meets minimum time criterion) in allo- cated access slot sub-channel group Time between access preamble and AP-AICH has two alternative values: 7680 chips or 12 800 chips depending on Tepch al-cdp Time between receipt of AP-AICH and CD preamble T al-cdp transmission has a minimum va