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 Standalone (SA) operation with NG-RAN connected to the 5G Core Network.

The course starts with a brief introduction to the 5G System, but focuses on the nodes/functions, interfaces, protocols and procedures in the NG-RAN. The course also describes dual connectivity as well as various 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 eg by Apis' 5G System Overview course.

5G System Overview

• 5G System introduction
• E-UTRAN and NG-RAN elements: gNB, eNB, ng-eNB, en-gNB
• Non-Standalone (NSA) vs Standalone (SA) deployment options
• PDU Sessions and QoS flows

C-RAN – Centralized RAN

• Reasons for C-RAN
• gNB Central Unit and gNB 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)
• Virtualization of NG-RAN functions

Standalone NR with 5GC

• Architecture for SA NO
• Basic procedures: Registration and PDU Session Establishment
• NR-NR Dual Connectivity (NR-DC)
• Handling of control plane and user plane connections

NG-RAN Protocol Overview

• Overview of NG-RAN interfaces and protocols
• N2/N3/NG interfaces and NGAP/GTP-U 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

Integrated Access and Backhaul (IAB)

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

Support for 5G Use Cases

• How and in what way does NG-RAN support the main 5G uses cases: eMBB, mMTC and URLLC