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5G engineering reference

5G NR and 5G Core tutorials, PHY references, procedures, protocol pages, troubleshooting paths, and calculators for engineers and testers.

Use this section as the entry point for 5G PHY, registration, PDU session management, mobility, security, RRC behavior, VoNR, and supporting engineering tools.

5G Architecture Start with NG-RAN, 5GC, interfaces, SBA, and the main 5G architecture reading paths. 5G NR PHY Physical layer overview, numerology, frame structure, channels, signals, and troubleshooting. 5G NR MAC Scheduling, random access, HARQ, buffer reporting, and MAC control elements. 5G NR RRC States, procedures, messages, IEs, call flows, and troubleshooting for NR RRC. 3GPP Messages Searchable 5G message references for RRC, NAS, NGAP, and related protocols. 5G Call Flows Move from high-level procedures into registration, security, session, mobility, and VoNR signaling. 5G Tools Open ARFCN, throughput, GSCN, decoder, and radio-planning tools used in 5G workflows.

Architecture and interfaces

Use these pages to navigate 5G from NG-RAN, 5GC, and interface structure before diving into procedures or protocol detail.

5G Network Architecture Parent hub for NG-RAN, 5GC, interfaces, protocol stack, and VoNR architecture. 5G Architecture Overview Fast conceptual map of UE, NG-RAN, 5GC, SBA, and the main interfaces. 5G RAN (NG-RAN) Architecture Read gNB, CU-DU split, radio bearers, mobility, and NG-RAN structure. 5G Core Network (5GC) Read AMF, SMF, UPF, policy, subscriber, and SBA-oriented core functions. 5G Interfaces Open N1, N2, N3, N4, N6, N9, F1, E1, Xn, and SBA interface explanations.

Core procedures

High-value 5G procedures grouped around the main engineering workflows.

RACH / Initial Access Cell discovery, PBCH, PRACH, and the first access path into RRC setup. Initial Registration Baseline registration flow from access to AMF handling. PDU Session Establishment Establishment path across N1, N2, and user plane setup. Connected-Mode Handover Core mobility flow for active radio connection transfer. Security Mode Command Security progression and AS protection flow. Mobility Registration Update Registration update during movement or area change.

PHY and radio engineering

5G NR physical-layer and radio-planning references for access, coverage, and performance work.

5G NR Physical Layer PHY hub with channels, signals, procedures, and troubleshooting paths. 5G NR MAC MAC hub for scheduling, random access, HARQ, and control elements. Numerology and Subcarrier Spacing SCS, slot timing, and numerology behavior. Frame Structure Radio frame, slot, symbol, and timing structure. 5G NR ARFCN Frequency mapping, channel numbering, and planning context inside the PHY cluster. NR Link Budget Calculator Coverage and margin estimation.

VoNR and voice over 5G

Voice-related IMS and VoNR flows that belong inside the 5G workflow rather than as a separate product area.

VoNR Registration IMS registration over the 5G access path. VoNR Mobile Originated Call MO voice setup and SIP progression. VoNR Mobile Terminated Call MT voice procedure and session establishment. VoNR Emergency Call Emergency voice call flow over IMS and 5G.