Key skills: 3GPP protocol stack, RRC/NAS, log analysis

Protocol Stack Mastery

Protocol test engineers must thoroughly understand the NR protocol stack. The RRC layer manages connection setup, reconfiguration, measurement reporting, and handover. NAS handles registration, authentication, PDU session management, and security. PDCP provides header compression, ciphering, and integrity protection. RLC manages segmentation, retransmission (AM/UM/TM modes), and in-sequence delivery. MAC handles scheduling, multiplexing, HARQ, and random access. Understanding the interaction between layers — such as how an RRC Reconfiguration triggers MAC and RLC entity reconfiguration — is…