5G NG-RAN Architecture

CONTENTS

This course provides a thorough overview of the Next-Generation Radio Access Network (NG-RAN) which is part of the 3GPP 5G System. The focus is on Stand-Alone (SA) operation but also Non-Stand Alone (NSA) NR is outlined.

The course starts with a brief introduction to the 5G System, followed by a discussion of aspects of the new radio interface and the nodes, interfaces and procedures in the NG-RAN. The course also describes various RAN – core option and dual connectivity options as well as some NG-RAN implementations such as C-RAN, O-RAN (from O-RAN Alliance) and IAB (Integrated Access and Backhaul).

PREREQUISITES

Knowledge of LTE/4G is required. Basic knowledge of the overall 5G System is recommended. Good 5G background knowledge is provided e.g. by Apis’ 5G System Overview course.

5G System Overview

• 5G System introduction, new Network Functions and Service Based Architecture
• E-UTRAN and NG-RAN elements: gNB, eNB, ng-eNB, en-gNB
• Non-Stand Alone (NSA) and Stand-Alone (SA) deployment options
• PDU Sessions and QoS flows

New Radio (NR) Fundamentals

• NR frequency bands, cell bandwidth, carrier aggregation, millimetre waves
• OFDM NR numerologies, frame and slot structure
• Differences between NR and E-UTRA

Non Stand-Alone NR with EPC

• Architecture for NSA NR
• E-UTRA – NR Dual Connectivity (EN-DC)
• Radio Bearers and CN Connections
• Handling of control plane and user plane
• The Xn interface

Stand-Alone NR with 5GC

• Architecture for SA NR
• NR – NR Dual Connectivity (NR-DC)
• Radio Bearers and CN Connections
• Handling of control plane and user plane

NG-RAN Protocols

• Overview of NG-RAN interfaces and protocols
• N2/N3/NG interfaces and NGAP protocol functions
• Xn interface and XnAP protocol functions
• RRC, SDAP, PDCP, RLC and MAC

NR Uu Channel Architecture

• Overview of the radio interface protocol stack
• Layer 2 protocols: SDAP, PDCP, RLC, MAC
• RLC Channels, Logical Channels, Transport Channels and Physical Channels

RRC and RRC States

• RRC Overview
• RRC States
• Behavior of Network and UE in IDLE, CONNECTED and INACTIVE states
• RAN Notification Areas

C-RAN – Centralized RAN

• Reasons for C-RAN
• Architecture options: gNB Central Unit and Distributed Unit
• gNB-CU Control Plane and User Plane separation
• F1-C, F1-U interfaces
• F1AP – F1 Application Protocol
• E1 interface
• E1AP – E1 Application Protocol

O-RAN Architecture

• Reasons for O-RAN
• Relation to 3GPP specifications
• O-RAN Architecture and Interfaces (A1, E2, O1, O2)
• Non-RT vs Neal-RT RAN Intelligent Controller (RIC)

Integrated Access and Backhaul (IAB)

• IAB Architecture: IAB-donor and IAB-node
• Bandwidth Adaptation Protocol (BAP)

Interworking with LTE/EPS

• Some interworking scenarios and issues between 5G and 4G
• Handover traffic case