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.

29 interactive0 simulation8 labs5 quizzes

0/42 lessons

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5G Registration

0/10

Master 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.

interactive3 min

Initial Registration — full call flow

Step through the complete initial registration: UE→gNB→AMF→AUSF→UDM→SMF→UPF with every message.

interactive5 min

Authentication: 5G-AKA detailed procedure

Detailed 5G-AKA flow with SUPI/SUCI, key hierarchy (K→CK/IK→KAUSF→KSEAF→KAMF→KNASint/enc→KgNB).

interactive5 min

NAS Security Mode Command

Visualize NAS encryption and integrity protection setup between UE and AMF.

interactive3 min

AS Security Mode Command

Visualize RRC security activation between UE and gNB after NAS security is established.

interactive3 min

Registration Accept and GUTI allocation

Understand Registration Accept contents — 5G-GUTI, allowed NSSAI, TAI list, and registration area.

interactive3 min

Common registration failures and root causes

Troubleshooting decision tree for registration failures — rejected causes, timer expiry, auth failures.

interactive3 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

0/9

Master 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.

interactive3 min

PDU Session Establishment — full call flow

Step through PDU session setup: UE→AMF→SMF→UPF with PFCP rules, QoS flows, and IP allocation.

interactive5 min

PDU Session Modification and Release

Visualize session modification (QoS change, add/remove QoS flow) and session release procedures.

interactive3 min

SSC Modes: SSC1, SSC2, SSC3 explained

Animate session continuity modes — SSC1 (anchor stays), SSC2 (break-before-make), SSC3 (make-before-break).

interactive3 min

Multiple PDU Sessions and multi-homing

Diagram: multiple simultaneous PDU sessions to different DNNs and slices, plus MA-PDU for ATSSS.

interactive3 min

PDU session troubleshooting: Why can't the user get data?

Root cause analysis exercise — step through common data connectivity failures and their fixes.

interactive3 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

0/10

Master 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.

interactive3 min

Connected mode: measurement events (A1-A6, B1-B2)

Interactive: configure measurement event thresholds and see how they trigger handover decisions.

interactive3 min

Xn Handover — full call flow

Animated Xn handover: source gNB→target gNB with preparation, execution, and data forwarding.

interactive5 min

N2 (inter-AMF) Handover — full call flow

Animated N2 handover with AMF relocation — source AMF, target AMF, and path switch.

interactive5 min

Inter-RAT handover: 5G ↔ 4G

Animated handover between 5G NR and 4G LTE — EPS fallback and N26-based handover.

interactive3 min

Conditional Handover (CHO)

Animation: early preparation concept — UE receives multiple target configs, executes when condition is met.

interactive3 min

DAPS (Dual Active Protocol Stack) handover

Animation: make-before-break — UE maintains connection to both source and target gNB during handover.

interactive3 min

Ping-pong handover problem and solutions

Case study: understand ping-pong handovers and optimization techniques — hysteresis, TTT, CIO.

interactive3 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

0/7

Master 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.

interactive3 min

5G Paging procedure

Call flow animation: AMF→gNB paging, paging occasion calculation, and UE response.

interactive3 min

Service Request — UE triggered

Call flow: UE sends Service Request to resume data — RRC setup, context activation, user plane restore.

interactive3 min

Service Request — Network triggered

Call flow: network pages UE for downlink data — paging → service request → data delivery.

interactive3 min

RRC_INACTIVE and RNA (RAN Notification Area)

Animation: RNA update procedure, RRC resume, and benefits of INACTIVE state for IoT devices.

interactive3 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

0/6

Complete 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.

interactive3 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.

interactive3 min

Common failure scenarios and recovery

Decision tree: symptom → root cause → fix for the most common 5G signaling failures.

interactive3 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