PRACH information can be heard in SIB5 during access
1. Based on the given ASC, determine the available RACH access sub-channel set and the next complete A set of available uplink access time slots in the access time slot set, from which an uplink access time slot is randomly selected (equal probability selection).
2. According to the given ASC, randomly select the signature used for access from the signature set (equal probability selection).
3. Send PRACH preamble
This is equivalent to randomly receiving a ticket, and the probability of repetition tends to 0