Introduction to RACH Procedure in 5G
Channel: Wireless Explained
Date: 2023-03-14

This video explains how a UE establishes its initial connection using RACH procedure in 5G.

▬ Contents of this video  ▬▬▬▬▬▬▬▬▬▬

0:00 - Introduction
0:39 -SSB Burst
2:21 - RACH Transmission (Message 1)
2:41 - Zadoff Chu Sequences
5:05 - Timing Advance Command (Message 2)
5:26 - RRC Connection Request (Message 3)
5:40 - Contention Resolution (Message 4)
7:53 - Contention Free RACH procedure

Correction: 6:18 - UE sends *ue-identiy* in "RR Connection Request" (Msg3), not TC-RNTI. *ue-identiy* is typically a random number, hence it will be different for UE 1 and UE 2. Base Station selects one of the *ue-identity* and sends it over "Contention Resolution" (Msg4). UE matches received *ue-identity* with its own *ue-identity* to check if its RACH attempt is a Success or Failure.

References:
1. ETSI TS 138 211
2. ETSI TS 138 321
3. Textbook “5G New Radio in Bullets” by Chris Johnson
4. ShareTechNote: https://www.sharetechnote.com/html/5G/5G_RACH.html
5. TechPlayOn: https://www.techplayon.com/5g-nr-rach-procedure-overview-cbra-cfra/

Music: Erik SATIE - Gymnopedies 1

#5G, #RACH, #Wireless, #WirelessCommunication, #CellularCommunication