Level 5
5G Signaling & Procedures
Deep dive into 5G signaling procedures — Registration, PDU Session Management, Mobility & Handover, Paging & Service Request, De-registration, NAS error codes, and real-world troubleshooting with protocol log analysis.
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5G Registration
0/10Master the complete 5G registration procedure — registration types, initial registration call flow, 5G-AKA authentication, NAS/AS security, GUTI allocation, and troubleshoot common registration failures.
Registration types: initial, mobility, periodic, emergency
Compare all four registration types — when each is triggered and what information is exchanged.
lesson3 min
Initial Registration — full call flow
Step through the complete initial registration: UE→gNB→AMF→AUSF→UDM→SMF→UPF with every message.
animation5 min
Authentication: 5G-AKA detailed procedure
Detailed 5G-AKA flow with SUPI/SUCI, key hierarchy (K→CK/IK→KAUSF→KSEAF→KAMF→KNASint/enc→KgNB).
animation5 min
NAS Security Mode Command
Visualize NAS encryption and integrity protection setup between UE and AMF.
animation3 min
AS Security Mode Command
Visualize RRC security activation between UE and gNB after NAS security is established.
animation3 min
Registration Accept and GUTI allocation
Understand Registration Accept contents — 5G-GUTI, allowed NSSAI, TAI list, and registration area.
lesson3 min
Common registration failures and root causes
Troubleshooting decision tree for registration failures — rejected causes, timer expiry, auth failures.
lesson3 min
Lab: Step through a full registration trace
Interactive log walker — identify each NAS and NGAP message in a real registration trace.
lab5 min
Lab: Fix a failed registration
Debug exercise — find the error in a failed registration using 5GMM cause codes.
lab5 min
Quiz: Registration
Test your knowledge of 5G registration procedures — 10 questions covering all registration topics.
quiz5 min
PDU Session Management
0/9Master PDU session lifecycle — session types, establishment/modification/release call flows, SSC modes, multi-homing, and troubleshoot data connectivity issues.
PDU Session types: IPv4, IPv6, IPv4v6, Ethernet, Unstructured
Compare all five PDU session types — when each is used and how they affect IP allocation.
lesson3 min
PDU Session Establishment — full call flow
Step through PDU session setup: UE→AMF→SMF→UPF with PFCP rules, QoS flows, and IP allocation.
animation5 min
PDU Session Modification and Release
Visualize session modification (QoS change, add/remove QoS flow) and session release procedures.
animation3 min
SSC Modes: SSC1, SSC2, SSC3 explained
Animate session continuity modes — SSC1 (anchor stays), SSC2 (break-before-make), SSC3 (make-before-break).
animation3 min
Multiple PDU Sessions and multi-homing
Diagram: multiple simultaneous PDU sessions to different DNNs and slices, plus MA-PDU for ATSSS.
lesson3 min
PDU session troubleshooting: Why can't the user get data?
Root cause analysis exercise — step through common data connectivity failures and their fixes.
lesson3 min
Lab: Trace PDU session establishment in protocol logs
Log analysis exercise — identify NAS, NGAP, and PFCP messages in a PDU session trace.
lab5 min
Lab: PDU session failure diagnosis
Given symptoms (no data, slow data, intermittent), diagnose the PDU session failure cause.
lab5 min
Quiz: PDU Sessions
Test your knowledge of PDU session types, call flows, SSC modes, and troubleshooting.
quiz3 min
Mobility & Handover
0/10Master 5G mobility — cell reselection, measurement events (A1-A6), Xn handover, N2 handover, inter-RAT handover, CHO, DAPS, and optimize handover KPIs.
Idle mode mobility: cell reselection
Animate UE moving between cells — SIB-based cell ranking, S-criteria, R-criteria, and intra/inter-frequency reselection.
lesson3 min
Connected mode: measurement events (A1-A6, B1-B2)
Interactive: configure measurement event thresholds and see how they trigger handover decisions.
lesson3 min
Xn Handover — full call flow
Animated Xn handover: source gNB→target gNB with preparation, execution, and data forwarding.
animation5 min
N2 (inter-AMF) Handover — full call flow
Animated N2 handover with AMF relocation — source AMF, target AMF, and path switch.
animation5 min
Inter-RAT handover: 5G ↔ 4G
Animated handover between 5G NR and 4G LTE — EPS fallback and N26-based handover.
animation3 min
Conditional Handover (CHO)
Animation: early preparation concept — UE receives multiple target configs, executes when condition is met.
lesson3 min
DAPS (Dual Active Protocol Stack) handover
Animation: make-before-break — UE maintains connection to both source and target gNB during handover.
lesson3 min
Ping-pong handover problem and solutions
Case study: understand ping-pong handovers and optimization techniques — hysteresis, TTT, CIO.
lesson3 min
Lab: Analyze handover KPIs and identify failure cause
KPI dashboard exercise — analyze HOSR, HO prep/exec failure rates, and identify root causes.
lab5 min
Quiz: Mobility & Handover
Test your knowledge of cell reselection, measurement events, handover types, and KPI optimization.
quiz5 min
Paging & Service Request
0/7Master UE state management — RRC states (CONNECTED/IDLE/INACTIVE), paging procedures, UE-triggered and network-triggered service requests, and RAN notification areas.
UE states: RRC_CONNECTED, RRC_IDLE, RRC_INACTIVE
State diagram animation showing all three RRC states and transitions between them.
lesson3 min
5G Paging procedure
Call flow animation: AMF→gNB paging, paging occasion calculation, and UE response.
animation3 min
Service Request — UE triggered
Call flow: UE sends Service Request to resume data — RRC setup, context activation, user plane restore.
animation3 min
Service Request — Network triggered
Call flow: network pages UE for downlink data — paging → service request → data delivery.
animation3 min
RRC_INACTIVE and RNA (RAN Notification Area)
Animation: RNA update procedure, RRC resume, and benefits of INACTIVE state for IoT devices.
lesson3 min
Lab: Paging failure analysis
Identify why paging failed from protocol logs — wrong TAI, paging timer expiry, DRX misconfiguration.
lab5 min
Quiz: Paging & Service Request
Test your knowledge of RRC states, paging, service request, and RNA concepts.
quiz3 min
De-registration & Error Handling
0/6Complete the signaling lifecycle — UE and network de-registration, 5G NAS error codes (5GMM/5GSM cause values), common failure scenarios, and systematic troubleshooting approaches.
UE-initiated and network-initiated deregistration
Side-by-side call flows: UE power-off deregistration vs network-initiated implicit/explicit deregistration.
animation3 min
5G NAS error codes and cause values
Searchable reference for 5GMM and 5GSM cause values — what each code means and when it is sent.
lesson3 min
Common failure scenarios and recovery
Decision tree: symptom → root cause → fix for the most common 5G signaling failures.
lesson3 min
Lab: Match error codes to root causes
Matching exercise: given an error code, identify the cause and recommended action.
lab5 min
Lab: End-to-end troubleshooting challenge
Multi-step troubleshooting: given user complaint, trace through logs to find and fix the issue.
lab5 min
Quiz: De-registration & Error Handling
Test your knowledge of deregistration procedures, NAS error codes, and troubleshooting approaches.
quiz3 min