Random Access Channel

RACH Random Access Channel

5G RACH is an essential procedure in 5G NR that enables a UE to obtain uplink synchronization with the gNodeB, request radio resources, and establish a connection when idle or moving between Cells.

• Consists of transmitting a preamble by the UE on PRACH, followed by a sequence of message exchanges with the network.
• Two main types of RACH procedures exist in 5G: Contention-based and Contention-free. The contention-based procedure is common for initial access, while contention-free is typically used for scenarios like handovers.
• RACH parameters like RACH configuration, preamble formats, preamble groups, root sequence, cyclic shift, subcarrier spacing, and timing are broadcasted to the UE via SIBs.