meik kottkamp - ernster · finally, as you might expect, we will also discuss the relevant test and...

Meik Kottkamp

Anil Pandey

Daniela Raddino

Andreas Roessler

Reiner Stuhlfauth

5G New Radio

Fundamentals, procedures, testing aspects

Preface

Rohde & Schwarz would like to welcome you to our 5G compendium. As a lead-ing test & measurement equipment manufacturer, we have been directly involved in the field of cellular technologies for over 30 years. As seen in the figure, past generations of these technologies have developed from the very early analog sys-tems into today’s 5G technology.

1980 1990 2000 2010 2020 2030

digital

1G Voice

2G Voice, SMSanalog

3G Voice, SMS, Web

5G Audio, Video, Apps, AR/VR (eMBB)Sensors (mMTC)Sensors/Actuators (URLLC)

4G Voice, Audio, Video, Apps

Evolution of cellular technologies.

The introduction of 2G is what enabled mobile voice services and also as an afterthought the first messaging service, SMS. 3G began the journey towards mobile data services, which were successfully established with 4G (LTE) based only on a packet data network. For the first time in mobile network history, 4G became a globally deployed cellular technology. Is 5G just another generation in this long line of technologies? If so, what is this new generation all about?

The objective of this 5G compendium is to provide a comprehensive answer to this question. Since the authors are employed by a company with unrivaled technical expertise along with the most comprehensive test and measurement (T&M) solutions available for the entire wireless ecosystem, we believe we can provide unique insights into the topic of 5G. Given that a sound grasp of the underlying technology is a prerequisite for building T&M solutions, we believe this work should provide you with all the relevant details of the actual technol-ogy. More importantly, we will take into account the relevant implementation aspects since T&M equipment is required during the realization of products. To the best of our knowledge, we will thus examine the question of “why” in this work. In other words, besides describing “how” the technology was specified, we will elaborate the underlying reasoning behind it.

© Copyright 2019 Rohde&Schwarz GmbH & Co. KG

Mühldorfstraße 1581671 München

www.rohde-schwarz.com

Second, revised edition 2019Printed in Germany

ISBN: 978-3-939837-15-2PW 3642.6376.00

All copyrights are reserved, particularly those of translation, reprinting (pho-tocopying), and reproduction. Also, any further use of this book, particularly recording it digitally, recording it in microform, and distributing it, e.g. via online databases, the filming of it, and the transmission of it are prohibited. However, the use of excerpts for instructional purposes is permitted provided that the source and proprietorship are indicated.

Even though the contents of this book were developed with utmost care, no lia-bility shall be assumed for the correctness and completeness of this information. Neither the authors nor the publisher shall be liable under any circumstances for any direct or indirect damage that may result from the use of the information in this book.

The circuits, equipment, and methods described in this book may also be pro-tected by patents, utility models, or design patterns even if not expressly indi-cated. Any commercial use without the approval of possible licensees represents an infringement of an industrial property right and may result in claims for dam-ages. The same applies to the product names, company names, and logos men-tioned in this book; thus, the absence of the ® or ™ symbol cannot be assumed to indicate that the specified names or logos are free from trademark protection.

Many drawings and tables in this book are derived from 3GPP specifications and reproduced by permission of 3GPP. If this book directly or indirectly refers to laws, regulations, guidelines, and standards (IEEE, IEC, ETSI, etc), or cites infor-mation from them, neither the authors nor the publisher makes any guarantees as to the correctness, completeness, or up-to-dateness of the information. The reader is advised to consult the applicable version of the corresponding docu-mentation if necessary.

Finally, as you might expect, we will also discuss the relevant test and measure-ment aspects. In 1883, William Thomas1) said the following in one of his lec-tures on electrical unit measurements: “I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in num-bers, your knowledge is of a meagre and unsatisfactory kind; it may be the begin-ning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.” This statement has been confirmed in the course of our everyday activities and we could not agree more. Furthermore, along the lines of the Peter Drucker 2) quotation that “what gets measured gets improved”, we truly believe in the value of testing and in particular of quantify-ing the true performance of any developed implementation.

Before you begin to read this work, you should note its structure. There are two basic chapters: “Fundamentals” and “Procedures”. Within “Fundamentals”, we describe what we believe are the core elements of the 5G system. This includes a description of the overall system architecture and how the physical access is real-ized. This chapter also discusses the main differences compared to 4G systems such as inherent support for beamforming and the concept of bandwidth parts. As is our preference, we conclude this chapter with a discussion of the relevant test and measurement aspects.

The chapter on “Overall procedures” takes you on a journey from an end-user device perspective. It explains everything from initially switching on the device through establishing a data connection and maintaining the connection when mobility is involved. Non-standalone (NSA) operation, i.e. when 5G is operated on top of an existing LTE network, is generally of greatest interest for commer-cial deployment. Therefore, we describe this scenario first and then discuss how the standalone (SA) case differs in a separate section later in the same “Overall procedures” chapter.

We hope will you find this compendium useful in your everyday work realizing 5G products.

1) William Thomas, Irish mathematical physicist, 1824–1907.

2) Peter Drucker, Austrian-born American writer, management consultant and university professor, 1909–2005.

1.3 Beamforming fundamentals . . . . . . . . . . . . . . . . . . . . . . . .1691.3.1 Propagation at cm-wave and mm-wave frequencies . . . . . .1701.3.1.1 Channel sounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1721.3.2 Support for beamforming in 5G NR . . . . . . . . . . . . . . . . . . . . . .1731.3.2.1 SS/PBCH block details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1741.3.3 Antenna technology for beamforming . . . . . . . . . . . . . . . . . . . 1771.3.3.1 From analog to digital beamforming . . . . . . . . . . . . . . . . . . . . . . . . . .1791.3.4 Massive MIMO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179

1.4 Bandwidth part fundamentals . . . . . . . . . . . . . . . . . . . . . .1821.4.1 Bandwidth part procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1831.4.2 Bandwidth part configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . .186

1.5 Testing fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1911.5.1 Physical layer testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1921.5.1.1 Over-the-air testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1961.5.1.2 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2041.5.1.3 Near field/far field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2071.5.2 Signaling testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2101.5.2.1 NR protocol testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2111.5.2.2 Dual connectivity testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2141.5.2.3 Mobility testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2151.5.3 Field testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .216

2 Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219

2.1 Overall access procedure for NSA mode . . . . . . . . . .2192.1.1 Gaining access to the LTE network. . . . . . . . . . . . . . . . . . . . . . .2192.1.1.1 LTE cell search, selection and system information acquisition . . . .2192.1.1.2 LTE initial access procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2222.1.1.3 LTE attach procedure and UE capability transfer . . . . . . . . . . . . . . .2292.1.2 5G NR signal quality measurements and reporting . . . . . . . 2372.1.2.1 Other fundamental properties of synchronization

signal blocks (SSBs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2372.1.2.2 Provisioning of the measurement configuration

to the end-user device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2432.1.3 Connecting the 5G RAN and reconfiguration of the

air interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2462.1.4 Random access procedure in 5G NR . . . . . . . . . . . . . . . . . . . . .2502.1.4.1 Transmission of the random access preamble . . . . . . . . . . . . . . . . . .252

Content

1 Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

1.1 Overall system overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101.1.1 Use cases, requirements and services . . . . . . . . . . . . . . . . . . . . 111.1.2 Overall 5G architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121.1.2.1 Connectivity scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131.1.2.2 Timeline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .141.1.2.3 Architecture and interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151.1.2.4 Functional split between 5GC and NG-RAN . . . . . . . . . . . . . . . . . . . . 171.1.2.5 Detailed functions of 5GC components . . . . . . . . . . . . . . . . . . . . . . . .191.1.3 Access stratum protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.1.3.1 Logical, transport and physical channels . . . . . . . . . . . . . . . . . . . . . . . .221.1.3.2 Control plane protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261.1.3.3 User plane protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271.1.3.4 Radio bearers in dual connectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311.1.3.5 UE capabilities transfer and computation . . . . . . . . . . . . . . . . . . . . . . . 331.1.3.6 Fundamental measurements provided by the end-user device . . . . . 371.1.4 Non-access stratum protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . .391.1.5 Quality of service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .401.1.6 Network slicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .421.1.7 Security architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

1.2 Physical access fundamentals . . . . . . . . . . . . . . . . . . . . . . .461.2.1 Flexible numerology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .481.2.1.1 Motivational aspects behind wider subcarrier spacing . . . . . . . . . . . . 531.2.2 Resource grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .561.2.3 Frame structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611.2.4 Duplexing schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .661.2.5 General description of the physical layer . . . . . . . . . . . . . . . . . . 731.2.5.1 Physical layer parameters and services . . . . . . . . . . . . . . . . . . . . . . . . . 731.2.5.2 5G NR baseband signal generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .761.2.5.3 Physical channels in 5G NR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .781.2.5.4 Control resource set CORESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .941.2.5.5 Antenna ports, precoding and quasi co-located antennas . . . . . . . . .981.2.5.6 Physical signals in 5G NR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1101.2.5.7 Transmit power allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1211.2.5.8 Channel coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1321.2.6 Brief digression on OFDMA multiple access schemes . . . .153

2.4.5.2 Actual content of Msg3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4242.4.6 Contention resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4242.4.7 RRC connection establishment . . . . . . . . . . . . . . . . . . . . . . . . . .4242.4.8 Security mode setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4252.4.9 PDU session establishment and

network slicing selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4282.4.9.1 Slice selection procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4292.4.9.2 PDU session establishment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4302.4.9.3 Session and service continuity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4312.4.9.4 SSC mode selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .432

3 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .434

3.1 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .434

3.2 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .445

3.3 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451

2.1.4.2 Reception of the random access response . . . . . . . . . . . . . . . . . . . . . .262

2.2 Overall data transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . .2732.2.1 End to end data session establishment procedure . . . . . . .2802.2.2 End to end quality of service . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2852.2.3 DL resource assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2952.2.4 DL data reception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3072.2.5 Hybrid automatic repeat request (HARQ) operation . . . . . .3182.2.6 Uplink scheduling request and buffer status reporting . . .3262.2.7 UL grant reception or UL assignment . . . . . . . . . . . . . . . . . . . .3292.2.8 UL data transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3352.2.9 Uplink control information (UCI) . . . . . . . . . . . . . . . . . . . . . . . . .3402.2.10 Data flow through 5G NR protocol layers . . . . . . . . . . . . . . . . .3492.2.11 Dynamic, semi-persistent and grant-free scheduling . . . . .3822.2.12 Data security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .384

2.3 Overall Mobility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3862.3.1 Beam mobility procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3872.3.1.1 Beam mobility on the downlink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3892.3.1.2 Beam mobility on the UL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3912.3.1.3 Beam failure detection and recovery . . . . . . . . . . . . . . . . . . . . . . . . . .3922.3.2 RRM mobility procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3952.3.2.1 Intra-RAT mobility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3962.3.2.2 Mobility parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3992.3.2.3 Inter-RAT mobility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4002.3.3 Mobility measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4012.3.3.1 Measurement overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4012.3.3.2 Measurement scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4032.3.4 Mobility security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .405

2.4 Overall access procedure for SA mode . . . . . . . . . . . .4082.4.1 Identifying SSBs in standalone mode . . . . . . . . . . . . . . . . . . . .4082.4.1.1 Cell-defining SSB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4092.4.2 Access system information block type 1 (SIB1) . . . . . . . . . . 4112.4.2.1 Scheduling configuration for SIB1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4112.4.2.2 Scheduling information for SIB1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4132.4.2.3 Content of SIB1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4142.4.3 Random access procedure in standalone mode . . . . . . . . . .4162.4.4 Random access response in standalone mode . . . . . . . . . . . 4172.4.5 Sending Setup request in the uplink . . . . . . . . . . . . . . . . . . . . .4182.4.5.1 RAPID and random access response for standalone mode . . . . . . .418

10 11Fundamentals Overall system overview

1.1.1 Use cases, requirements and services5G intends to focus on the services provided to the users and the technologies required to fulfill the service requirements. The services within the 5G scope can be categorized into three main types: J High data rate services. These services shall be designed to cater to the ever-

growing demand for faster and higher-volume data access. This concept is a direct successor to the high data rate services provided by LTE (enhanced mobile broadband, eMBB)

J Massive Internet of things. Massive IoT shall be an extension of the current IoT services which includes probably almost every machine communicating with other machines. This approach shall open doors to major automation in every area of life (massive machine-type communications = mMTC)

J Ultra reliable low-latency services. These services would involve new use cases in which small data exchanges can be realized to provide reliable and critical communications such as health monitoring (ultra-reliable low-latency communications = URLLC)

For the overall system, the International Telecommunication Union (ITU) already defined in 2015 the requirements in the form of KPI in its IMT Vision for 2020 and Beyond for all upcoming services. These requirements can be categorized by considering the three main services that are the focus in the 5G system as shown in Fig. 1-1. 3GPP has a standardization committee that is seeking to define a tech-nology that fulfills the ITU requirements for submission to the ITU for approval.

Fig. 1-1

URLLCeMBB

mMTC

(enhanced Mobile Broadband)

Massive Internet of Things/Massive Machine-Type

Communications

Ultra Reliable Low-Latency Communications

5G

Extreme mobilityHigh as 500 km/halso the target for eMBB

Ultra reliabilityMinimum reliability of 99.99 % success probability for up to 32 bytes within 1 ms

Extreme capacityHigh as 10 Mbps/m2

Low latencyLow as 1 ms

High data rateUser data as 100 Mbps20 Gbps peak data rate

High spectrum efficiencyPeak as 15 bps/Hz uplink30 bps/Hz for downlink

High connection densityHigh as 106/km2

Low complexity

Energy efficientFactor as great as thetraffic increase

ITU Vision for IMT-2020 and Beyond.

1 Fundamentals

1.1 Overall system overview

Past decades have seen tremendous development of mobile technologies. As the technologies have evolved, it has become customary to indicate them with a gen-eration number, e.g. 2G, 3G, 4G and 5G (the latest generation).

Initially, the new generations referred broadly to significant changes in the under-lying technologies and methods with the aim of providing more reliable and effi-cient communications, e.g. the physical access technologies have changed from TDMA to CDMA to OFDMA. The new 3GPP radio access technology for 5G is designated as “New Radio”, and is based on OFDMA.

In previous mobile technology generations, voice communications have always been the focus even if other services have been made available. Progressively, new services were added, e.g. text messaging in 2G, video calls in 3G and always-on data connectivity in 4G. The upcoming generation, 5G, seeks to make further major changes to services with a wide range of requirements. The networks are capable of providing services ranging from high data rate mobile broadband to ultra-reliable low-latency communications.

As with every technology introduction, 5G also evolved out of the previous gen-eration (LTE). One example involves the concept of WLAN offloading intro-duced in LTE, which was intended to integrate technologies coming from 3GPP and non-3GPP. This concept extends into the 5G core network with a design that is radio access technology (RAT) agnostic so that the core network can work with 3GPP (cellular) and non-3GPP (non-cellular, fixed line etc.) technologies seamlessly.

Similar to LTE, the core network is packet-switched only; however, it has sep-arate control and user plane entities. LTE has a concept of dedicated core net-works in 3GPP Release 13. This concept has evolved into what is known as “net-work slicing”.

Some concepts have reverted to something similar to 3G, e.g. a PDU session is not established by default during registration and is a separate procedure to be performed.


1.1.2.1 Connectivity scenariosThe possibility of the same core network connecting with various access net-works results in several connectivity scenarios (Fig. 1-4). The UE can be con-nected over LTE or over NR to the new 5GC (standalone connectivity options). Moreover, connectivity involving the cellular technologies has further evolved with an option for the connection to pass via more than one access technology at the same time (non-standalone connectivity options).

5G 5G

Option 5 E-UTRA

NG-eNB

Option 2 NR

gNB

Control Data

Standalone

Non standalone

5GCUPFAMF

5GCUPFAMF

Option 3 EN DC: E-UTRA-NR Option 4 NGEN DC: NG-RAN E-UTRA-NR Option 7 NE DC: NR-E-UTRA

EPC

MNeNB

MME

SNgNB

SGW

LTE5G

5GC

SNNG-eNB

AMF

MNgNB

LTE5G

UPF5GC

MNNG-eNB

AMF

SNgNB

LTE5G

UPF

Fig. 1-4 Connectivity options.

The background was prepared with LTE’s introduction of the concept of dual connectivity (DC), which allows the UE to connect simultaneously to two dif-ferent base stations. The two base stations (xNB) are involved in a connec-tion whose signals do not need to be time-synchronized and therefore are not required to be physically collocated.

In 3GPP Release 15, dual connectivity can involve two NR base stations (NR-DC) or one NR and one LTE base station (Multi-Radio-DC or MR-DC). Only LTE is considered for possible multi-radio connectivity with NR. Other technolo-gies such as GSM and WCDMA cannot be combined in DC with NR. Further-more, no interworking between these technologies and NR is defined in 3GPP Release 15.

1.1.2 Overall 5G architecture

The 5G system (5GS, Fig. 1-2) consists of the 5G core and the 5G access network.

5GS

5GC

5G-AN

Fig. 1-2 5G system (5GS).

Unlike previous mobile communication technologies, the core network for 5G is designed to work seamlessly with more than one access technology. The 5G access network (AN) could be built from a 3GPP defined AN (3GPP-AN or NG-RAN) and non-3GPP AN such as WLAN or wired broadband access as depicted in Fig. 1-3. Within the NG-RAN, a new cellular access technology known as “new radio” (NR) is introduced together with E-UTRA, the access technology used for LTE.

5G-ANNon-3GPPAN

NR E-UTRA

NG-RAN

Fig. 1-3 5G access network components.

5GC is defined to be access network agnostic and capable of providing 5G services through any of these access networks. Among cellular technologies (which are collectively designated as the next generation radio access network), the possibility of E-UTRA and NR connecting to 5GC creates several connectiv-ity scenarios (1.1.2.1 Connectivity scenarios, page 13) which have been stud-ied and listed in TR 23.799.


standalone NR option in June 2018 and late drop for further dual connectivity options in March 2019).

In contrast, 3GPP Release 16 targets further improvements to the URLLC use case related in particular to industrial applications. Moreover, several features already available in LTE such as V2X and unlicensed access are first included in 3GPP Release 16 in December 2019, which will then be targeted for inclusion in the ITU 2020 submission.

5GC phase 1 milestones

5GC phase 2milestones

NR phase 1 milestones

NR phase 2 milestones

Requirementsstudies andnormative

Architecturestudies andnormative

Core network protocolstudies and normative

Requirementsstudies andnormative

Architecturestudies andnormative

Core network protocolstudies and normative

L1/L2 NSA option 3 / eMBB

June 2019 / RAN #84IMT-2020 submissionLTE & NR Rel-15/16

L3 specs. (ASN1)

L1/L2 specs.

Focus on NSA/SA deployment scenarios for eMBB/URLLC use cases

3GPP RANworking groups

NG

RAN

3GPP SA andCT working groups

5G

Core

L3 specs. (ASN.1) for option 4 & 7

Release 14

Rel-15 5GC phase 1

L1/L2 specs. for option 4 & 7

L1/L2 for SA option 2 & 5/URLLC

L3 specs. (ASN.1) for option 2 & 5 completed

L3 specs (ASN.1) for option 3 / eMBB

Release 15 Release 16Rel-15 “late drop“

2017 20182016 2019 2020

Further NR use cases (mMTC, V2X, broadcasting, etc.)

Fig. 1-5 5G system 3GPP standardization timeline.

1.1.2.3 Architecture and interfacesAs described above, the 5G system consists of a 5G core network (5GC) and a 5G access network (NG-RAN). In more detailed terms, 5GC consists of the functional components AMF for authentication and mobility functions, UPF for user plane functions and SMF for session management functions.

An NG-RAN node can either be a gNB that provides NR user plane and control plane protocol terminations to the UE or a ng-eNB that provides E-UTRAN user plane protocol and control plane terminations to the UE. Note that the terms NodeB, eNB, gNB and ng-eNB represent a protocol anchor so that the protocol layer perspective is used when describing the related functions, while terms such as base station refer to the hardware and RF resources linked to radio connectiv-ity. 3GPP has introduced the term ng-eNB for the case in which a EUTRA eNB is connected to the 5GC instead of the EPC.

MR-DC connectivity shall allow an easy transition from the currently well-estab-lished LTE radio interface to the new radio interface (NR). In fact, in dual con-nectivity one of the two base stations assumes the master node (MN) function and the other the secondary node (SN) function. The MN is in charge of the sig-naling connection at the air interface (signaling radio bearer, SRB1, SRB2) and in the core network (red lines in Fig. 1-4), while the secondary node is responsi-ble for the additional user data connection at the air interface (data radio bearer, DRB) and with the core network (black line).

In the first phase of deployment, the E-UTRA serves as the MN and handles all of the control signaling to the core network. NR is added to enable a high data rate over the air interface which transports only the user plane data (Option 3, EN-DC) connected to the LTE core network EPC. In a further phase, either NR or LTE will assume the role of the MN and handle both the control and user sig-naling as shown in Fig. 1-4 (Option 4 NGEN-DC or Option 7 NE-DC). In the later options, E-UTRA serves as the SN and completes the user plane connec-tions with additional data bearers.

The different connectivity options over the air interface will also allow migration from the core network EPC to 5GC which was also introduced in 3GPP.

Since each node in dual connectivity can contain several cells, we use the term cell group (CG). The purpose of the cell group is to schedule data over several carriers in order to increase the cell throughput. Within a CG, a primary cell serves as the special cell (SpCell). It is in charge of controlling the overall cell group and optionally one or more secondary cells (SCell) which increase the frequency spectrum of the primary cell, using carrier aggregation. In dual con-nectivity, the MN represents the master cell group (MCG) and the SN repre-sents the secondary cell group (SCG). The following terms are used in dual con-nectivity scenarios: the primary cell (PCell) for the primary cell (SpCell) of the MCG and the primary secondary cell (PSCell) as the primary cell (SpCell) of the SCG.

1.1.2.2 TimelineThe ITU sets the requirements for the next generation telecommunication sys-tems (ITU 2020, Fig. 1-5). The ITU requirements are addressed by standardiza-tion committees such as 3GPP, which will propose the 5G system along with 3GPP Releases 15 and 16. Release 15 is also called phase 1, which addresses the eMBB and URLLC use cases. Phase 1 is also being gradually developed and includes different milestones for the various dual connectivity options (early drop for non-standalone EN-DC option in December 2017, main release for


AMF/UPF (SMF)

5GC

gNB NG-RAN

AMF/UPF (SMF)

gNB

ng-eNB ng-eNB

NG-C/U

Xn

NG-C/U

NG-C/U

NG-C/U

Xn

Xn

NG-C/U

NG-C/

U

NG-

C/U

NG-

C/U

Xn

Fig. 1-6 Overall architecture from 3GPP TS 38.300.

1.1.2.4 Functional split between 5GC and NG-RANAs described above, the main division in the 5G system (5GS) is the split between the radio access network (NG-RAN) and the 5G core network (5GC). More spe-cifically, NG-RAN consists of the components gNB for NR and ng-eNB in case EUTRAN is used. 5GC has the functional components AMF for authentication and mobility, UPF for user plane functions and SMF for PDU session manage-ment. This section is structured to first present the functionality of 5GS com-ponents from a higher-level perspective. In 1.1.2.5 Detailed functions of 5GC components, page 19, more functional details are provided; see also TS 38.300.

From a high-level perspective, gNB and ng-eNB host the following group of functions: J Radio admission control and system information broadcast: This consists

of procedures for access control (i.e. cell barring procedures) and radio access configuration (i.e. broadcasting system information, random access configu-ration)

J Radio connection control: This consists of connection setup and release as well as controlling the UE connection state of idle, connected and inactive

J Radio bearer control: This consists of the procedure for configuration (i.e. security), establishment and maintenance of the radio bearer (RB) both on the uplink and downlink with different quality of service (QoS)

The gNB and ng-eNBs are connected with each other by means of the Xn inter-face, which is a “logical” interface that uses a specific protocol structure. It is up to the operator/manufacturer to decide how the mapping of the logical Xn inter-face to a physical interface such as a fiber-optic cable is implemented. More spe-cifically, the Xn interface can be split into an Xn-U interface for the user plane data exchanged between gNB (or ng-eNB) in the case of, say, handover or dual connectivity scenarios and an Xn-C interface for control information exchange between gNBs. The protocol stack for the user plane Xn-U consists of the proto-col layers PDU, GTP-U, UDP, IP and data link, plus the physical layer, which is up to the manufacturer. The protocol stack for the control plane Xn-C consists of the Xn-AP, SCTP, IP and data link, plus the physical layer which is up to the manufacturer.

In addition, gNB can be divided into a gNB-CU centralized unit and a gNB-DU distributed unit. They are connected to one another via the F1 interface. The specification TS 38.401 provides more details on the relevant architectural aspects.

The gNB and ng-eNB are connected to the 5G core network via the NG interface (Fig. 1-6). More specifically, there is a connection to the AMF via the NG-C inter-face to allow the exchange of control messages. Moreover, there is an interface NG-U to the UPF that contains user plane data. The protocol structure on the NG-U interface is similar to the Xn-U interface and contains the protocol layers, GTP-U, UDP, IP and finally the data link and the physical layer which are up to the manufacturer. The protocol structure on the NG-C interface is similar to the Xn-C and consists of the protocol layers NG-AP, SCTP, IP and data link, plus the physical layer, which is up to the manufacturer.


an “association between the UE and a data network that provides a PDU con-nectivity service”

J UE IP address allocation: This ensures not only the possibility to route data packets within the 5G NR system but also supports data reception and for-warding to outside networks and provides interconnectivity to external packet data networks (PDNs). As discussed below, 5G NR supports IPv4 and IPv6 addressing

These functions are summarized in Fig. 1-7 which depicts both the logical nodes and their main functionality (see TS 38.300). A more detailed presentation of the additional functions of the 5G NR components can be found in the follow-ing section.

Radio connection control

RB control

Dynamic resourceallocation (scheduler)

Measurementconfiguration & provisioning

Connection mobility control

NG-RAN

Internet

UPF

5GC

Inter-cell RRM PDU handling

Mobility anchoring

Connection mobility

Idle mode mobility

Security

Radio admission control NAS signaling

AMF

SMF

UE IP address allocation

PDU session control

gNB or ng-eNB

Fig. 1-7 Functional split between NG-RAN and 5GC.

1.1.2.5 Detailed functions of 5GC componentsIn this section, we will examine additional detailed functions of the main 5GC components. First, we should summarize the functions for gNB and ng-eNB as explained in TS 38.300: J Scheduling and transmission of system broadcast information and paging:

Originated by the AMF or operating and maintenance center O&M (the latter is used e.g. for unexpected SIB broadcasts such as PWS or ETWS)

J Security: IP header compression, encryption and integrity protection of data based on the NAS security keys derived during the registration and authenti-cation procedure

J Dynamic resource allocation and scheduling: This consists of scheduling RF resources according to their availability on the uplink and downlink for multiple UEs according to the QoS profiles of a radio bearer

J Measurement configuration: This consists of provisioning the configuration of the UE for radio resource management procedures such as cell selection and re-selection and for requesting measurement reports to improve scheduling

J Inter-cell radio resource management: This allows the UE to detect neigh-bor cells, query about the “best serving cell” and support the network during handover decisions by providing measurement feedback

J Connection mobility: This supports idle mode and connected mode intra cell handover situations

The authentication and mobility function (AMF) is responsible for these high-level functions (TS 23.501): J Network signaling: Anchor point for NAS signaling for accessing the network

and paging the UE J Security: NAS security functions such as authentication, authorization, cipher-

ing and control of AS security J Idle mobility handling: Relevant functions covering aspects such as legacy

home and visitor location registers to know the whereabouts of subscribers for mobile terminated connections, identifiers for UEs and subscribers for pag-ing and registration aspects, location and tracking areas for mobility scenarios and of course, functionality to support international or inter-PLMN roaming

J Connection mobility: Intra-system and inter-system mobility

The user plane function (UPF) supports the following high-level functions related to user data transfer: J PDU handling: Since 5G NR is a packet-switched network concept, all user

data is encapsulated into data packets (PDUs). This function thus enables packet routing, forwarding and QoS handling for the user plane

J Mobility anchoring function: In contrast to the gNB mobility function which enables a seamless radio connection transfer (“handover”), the UPF must ensure that during such handover procedure, no data loss occurs. The need for such a function becomes obvious if we consider procedures such as inter-PLMN handover and inter-system handover.

The session management function (SMF) is responsible for the setup, release and maintenance of a session for user data transfer with the following high-level functions: J PDU session control: In cooperation with the UPF, the SMF must establish,

maintain and release a PDU session for user data transfer, which is defined as


J Selection and control of user plane function J Configuration of traffic steering at UPF to route traffic to proper destination J Control part of policy enforcement and QoS J Downlink data notification

1.1.3 Access stratum protocol5G uses a similar access stratum (i.e. air interface protocol structure and func-tions) to LTE. There are two protocol stacks: the user plane (UP) and the control plane (CP). They contain several protocols but still adopt the well-known OSI reference model. In this section, only the protocol layers specific to the air inter-face will be described in brief.

The begin is a general introduction to the two terms used in the protocol descrip-tion: SDU and PDU. The OSI model describes seven communication layers and introduces the interaction between the lower and higher layers via service access points (SAP). Each protocol sublayer or layer typically adds additional informa-tion such as the packet header, checksum and so on. The full content including the data and the protocol header information is known as the protocol data unit (PDU). A lower layer that receives a PDU will treat it as “data” to be transferred, i.e. it is a transport service offered to a higher layer. Thus, the protocol data unit received by a lower layer will be referred to as a service data unit (SDU) since it is still lacking a protocol header for the corresponding layer [Ref. 2], [Ref. 4]. Com-munication between two protocol layers on the same layer is known as peer-to-peer communication (Fig. 1-8).

Layer N PDUSAP

Layer N+1 PDU

Layer N SDULayer N header

Layer N+1

Layer N

Layer N–1

SAP

SAP

Radio interface

Peer to peerLayer N+1

Layer N

Layer N–1

SAP

SAP

Fig. 1-8 Layer concept in the OSI model.

Between the different protocol layers, channels are used to exchange data to sup-port various QoS classes of services. Each channel is associated with a service access point (SAP) between different layers (Fig. 1-9).

J Interface to 5GC: Selection of an AMF at UE attachment, routing of control plane information to the AMF, support for network slicing. Additionally, rout-ing of user plane data to UPF(s) based on a QoS flow, QoS flow management and mapping to data radio bearers

J Radio access network sharing J Dual connectivity and tight interworking between NR and EUTRA

The authentication and mobility function (AMF) has the following additional functionality in accordance with TS 23.501: J NAS signaling termination J NAS signaling security J AS security control J Idle mode UE reachability (including control and execution of paging retrans-

mission) J Registration area management J Support for intra-system and inter-system mobility J Access authentication J Access authorization including checking roaming rights J Mobility management control (subscription and policies) J Support for network slicing J SMF selection

The AMF performs similar functions as the mobility management entity (MME) in the LTE core network. The Mobility Management Entity (MME) is the con-trol unit that processes the signaling between the user equipment (UE) and the evolved packet core network (EPC) regarding bearer and connection manage-ment; see TS 23.002, TS 24.301, TS 36.300 and TS 36.401.

The user plane function (UPF) has the following additional functionalities in accordance with TS 23.501: J External PDU session point of interconnect to data network J Packet inspection and user plane part of policy rule enforcement, e.g. by lawful

interception rules J Traffic usage reporting J Uplink classifier to support routing traffic flows to a data network J Branching point to support multi-homed PDU session J Uplink traffic verification (SDF to QoS flow mapping) J Downlink packet buffering and downlink data notification triggering

The session management function (SMF) has the following additional func-tionalities in accordance with TS 23.501:


identical physical transmission. In this section, the purpose of these channels and their hierarchical structure is described.

The term logical channel refers to what type of information is transferred. Log-ical channels are classified into two groups: control channels and traffic chan-nels. Control channels are used for the transfer of control plane information only, while traffic channels are used for the transfer of user plane information only. The following channels are defined (see also Fig. 1-10):

Broadcast control channel (BCCH): Downlink channel for broadcasting sys-tem control information. The system information is divided into different sys-tem information blocks (SIB) and one master information block (MIB). Only the MIB is mapped onto the transport channel BCH and then to the physical channel PBCH; the other SIB will be mapped onto the DL-SCH transport chan-nel and physical channel PDSCH. This is because the MIB must have specific transmission characteristics and adhere to a specific frequency and periodicity as described in 1.2 Physical access fundamentals, page 46.

Paging control channel (PCCH): Downlink channel that transfers paging infor-mation, system information change notifications and indications of ongoing PWS broadcasts. PCCH is mapped to a PCH transport channel and PDSCH physical channels.

CCCH

PDCCH

CCCH

PUCCH

UL logical channels

UL transport channels

UL physical channels

DL logical channels

DL transport channels

DL physical channels

DCCH

DL-SCH

PDSCH

DCCH

UL-SCH

PUSCH

DTCH

DTCH

PCCH

PCH

BCCH

BCH

PBCH

RACH

PRACH

Fig. 1-10 NR logical, transport and physical channel mapping for the uplink and downlink.

Qos flow

Radio bearer

RLC channel

Logical channel

Transport channel

5GC

SDAP

PDCP

RLC

MAC

PHY

Physical channel

Fig. 1-9 NR Access Stratum Protocol channels.

The description of the specific channel types is as follows: J QoS flow: Represents the finest granularity for routing and forwarding in the

5G system. QoS policy profiles containing QoS parameters and identifiers are attached to each data packet to enable the corresponding flow routing.

J Radio bearer: Represents a connection for transporting user and signaling data over the 5G radio interface. Multiple QoS flows can be combined in one radio bearer. There is the data radio bearer (DRB) for user data and the signal-ing radio bearer (SRB) for signaling data.

J RLC channel: One-to-one mapping to radio bearer and supporting proto-col, to enable specific transmission modes (transparent, unacknowledged or acknowledged). RLC channels represent the data exchange point between the RLC and PDCP protocol layer

J Logical channel: Collection of the type of data in order to answer the question “What type of information is being transferred?” (e.g. paging or broadcasting)

J Transport channel: Represents the multiplexing of logical data to be trans-ported by the physical layer over the radio interface with similar physical char-acteristics

J Physical channel: Mapping to a specific data transmission characteristic such as modulation, reference signal multiplexing, transmit power, RF resources, etc.

1.1.3.1 Logical, transport and physical channelsIn NR protocol stacks, logical, transport and physical channels also follow a hier-archical structure, i.e. separate channels which transport data between proto-col layers are conveyed to one channel on another lower layer if they require


Uplink shared channel (UL-SCH): Transmits information from several logi-cal channels, i.e. user and control plane data. Like the downlink DL-SCH, the uplink UL-SCH also supports HARQ and AMC as well as dynamic and semi-static scheduling. Uplink beamforming is possible, but optional for the UE and likely to occur in FR2 only.

Random access channel (RACH): Carries the random access preamble for ini-tial network access. Collisions can occur from multiple UEs access this channel simultaneously.

Physical channels are used to carry information over the radio interface. There are physical channels to transfer data obtained via transport channels as well as physical channels that are located in the physical layer only. 1.2.5.3 Physical channels in 5G NR, page 78 provides a detailed introduction to these physi-cal channels.

Common control channel (CCCH): Channel for transmitting control informa-tion between UEs and the network. This channel is used for UEs that do not have an RRC connection with the network, i.e. for initial cell access as described in 2.1.1.2 LTE initial access procedure, page 222.

Dedicated control channel (DCCH): Point-to-point bi-directional channel that transmits dedicated control information between a UE and the network. This channel is used by UE and network after an RRC connection is established (see 2.1.1.2 LTE initial access procedure, page 222).

Dedicated traffic channel (DTCH): Point-to-point bi-directional channel that is dedicated to one UE and used for the transfer of user information. A DTCH can exist on both the uplink and downlink.

Logical channels are combined in transport channels, referring to how the infor-mation is transferred. Each transport channel conveys services which will be transferred with the same characteristics over the physical radio interface. The following transport channels are defined (see also Fig. 1-10):

Broadcast channel (BCH): Used to partially transport the BCCH system infor-mation. The BCH uses a fixed, pre-defined transport format. There is a require-ment for broadcasting in the entire coverage area of the cell, either as a single message or by beamforming of different BCH instances.

Downlink shared channel (DL-SCH): Used to transport different logical chan-nel data such as the DTCH, BCCH, DCCH and CCCH. DL-SCH supports error correction via HARQ and uses AMC for dynamic link adaptation by varying the modulation, coding and transmit power. It is possible to broadcast shared data to the entire cell are or to transmit data UE-specifically in a certain direction based on beamforming. The radio resources linked to the DL-SCH can be allo-cated based on either dynamic or semi-static resource allocation. Furthermore, this transport channel supports UE discontinuous reception (DRX) to enable UE power saving.

Paging channel (PCH): Used to transmit paging information from the PCCH. It can be dynamically mapped onto physical resources which can be used by other traffic/control channels as well. Supports DRX mode for power saving. Regard-ing the coverage requirement, the PCH must be broadcast in the entire cover-age area of the cell, either as a single message or by beamforming different PCH instances.


– Addition, modification and release of dual connectivity in NR or between EUTRA and NR

J Security functions including key management for authentication, ciphering and authorization aspects

J Establishment, configuration, maintenance and release of signaling radio bearers (SRBs) and data radio bearers (DRBs)

J Mobility functions including: – Handover and context transfer – UE cell selection and reselection and control of cell selection and reselection – Inter-RAT mobility

J QoS management functions J UE measurement reporting and control of the reporting J Detection of and recovery from radio link failure J NAS message transfer to/from core network, from/to UE

The UE can be in three possible RRC states: J In RRC_IDLE where no RRC connection is established, the UE selects the

PLMN and re-selects the cell based on its cell selection and reselection config-uration, acquires system information and paging for mobile terminated data, and may use the random access resource when triggered to establish a con-nection.

J The RRC_CONNECTED indicates the situation where an RRC connection is established, transfer of bidirectional user data is possible, and the mobility is controlled by the network, e.g. as described in 2.3.2 RRM mobility procedure, page 395.

J The RRC_INACTIVE state is an interim state between both of these possibili-ties, indicating that an RRC connection is established, but no user data is trans-ferred. The UE and NG-RAN store the AS context, mobility is based on cell re-selection, and connection can be re-established via random access or paging.

1.1.3.3 User plane protocolThe user plane represents the protocol structure between the UE and gNB that is intended for user data transfer (Fig. 1-12). It is based on protocol sublayers SDAP, PDCP, RLC, MAC and PHY interworking with one other to guarantee success-ful data transfer over the radio interface. The following section briefly introduces these protocol sublayers.

1.1.3.2 Control plane protocolThe control plane protocol (C-plane) represents the protocol structure between the UE and network to transport control information (Fig. 1-11). We distinguish between the control protocol between the UE and 5G RAN (access stratum pro-tocol AS) and the control protocol between the UE and 5GC (non-access stra-tum protocol NAS). The C-plane protocol structure consists of the protocol sub-layers NAS, RRC, PDCP, RLC, MAC and PHY. The following sections briefly describe the main sublayer RRC. The sublayers below the RRC have the same functions as in the user plane protocol and are described under user plane pro-tocol. The NAS is described under non-access stratum protocol.

UE gNB

NAS

AMF

NAS

PDCP

RLC

MAC

PHY

RRC

PDCP

MAC

PHY

RRC

RLC

Fig. 1-11 Control plane protocol structure from TS 38.300.

Radio resource controlThe radio resource control protocol handles the bidirectional exchange of con-trol messages over the radio interface between the UE and gNB and is defined in TS 38.331. An established RRC connection uses signaling radio bearers (SRB) to exchange control information. The main services and functions of the RRC sub-layer include: J Broadcasting of system information related to AS and NAS J Paging initiated by 5GC or NG-RAN and triggering of the transmission of

paging control information over the radio interface J Establishment, maintenance and release of an RRC connection between the

UE and NG-RAN, including: – Addition, modification and release of carrier aggregation


A single SDAP protocol entity is configured for each individual PDU session. A PDU session is a point-to-point connection between the UE and application and consists of one or more QoS flows.

In the uplink direction, the mapping of QoS flow IDs to over the air data radio bearer (DRB) can be handled in two different ways. In reflective mapping, the UE monitors the QoS flow ID(s) of the downlink packets for each DRB and applies the same mapping in the uplink.

Alternatively, the 5GC may configure mapping by RRC IE “QoS flow to DRB mapping” in the SDAP configuration, which corresponds to an explicit config-uration. For further details, see 2.2.2 End to end quality of service, page 285.

Packet data convergence protocol (PDCP)The PDCP layer provides data radio bearers to the upper layer SDAP. As in LTE, the PDCP layer plays an important role in mobility situations by avoiding packet losses due to handovers. It also controls the proper functioning of certain con-nection scenarios such as dual connectivity. In addition, the PDCP performs header compression and decompression of higher layer protocol (i.e. TCP/IP header).

The main services and functions of the PDCP sublayer for the user plane include: J Transfer of user data J Sequence numbering in order to guarantee in-sequence delivery and avoid

packet loss, especially in case of handover situations or dual connectivity. More-over reordering and duplicate detection in order to guarantee in-sequence delivery

J Higher layer protocol header compression and decompression (i.e. TCP/IP header)

J Ciphering, deciphering and integrity protection J PDCP SDU discards J PDCP re-establishment and data recovery for RLC AM J PDCP PDU routing in case of split bearers while dual connectivity is activated J Duplication of PDCP PDUs; especially in dual connectivity scenarios to main-

tain low latency, the PDCP layer may send a duplicate packet on a different RLC channel

Radio link control (RLC)As was already introduced in WCDMA and LTE, the NR protocol stack supports an RLC layer. The RLC layer provides RLC channels to the upper layer PDCP.

UE gNB

SDAP

PDCP

RLC

MAC

PHY

SDAP

PDCP

RLC

MAC

PHY

Fig. 1-12 User plane protocol stack from TS 38.300.

Service data adaptation protocol (SDAP)The SDAP is a new protocol sublayer compared to LTE. Its main function involves transmission of service data identified by the network in the form of QoS flows (Fig. 1-13). 5GC relies on the SDAP layer to perform mapping of the QoS flow to a specific over the air data radio bearer. Data bearers are then han-dled in the air interface protocol with a specific priority.

5GPackets

fromapplications

Markingwith QoSflow IDs

UPF

QoS flow 2

QoS flow 1

PDUsession

5G-RAN

Data radio bearer

SDAP protocol:Mapping to

data radio bearers

Fig. 1-13 Role of SDAP and QoS flow ID within 5G PDU session.

The SDAP introduces the term QoS flow ID (QFI), which can be understood as a sort of label for each of the DL or UL data packets. This label guarantees trans-mission of the data packet with a correctly allocated QoS profile in the lower lay-ers over the entire transmission path.


Medium access protocol (MAC)The MAC layer maps logical channels from RLC to the transport channels. Thus, if the logical channels answer the question “What will be transferred?” (i.e. logi-cal channel for broadcasting or user data), the transport channels stand for “How will the transfer be performed?” (i.e. fixed transport block size or adaptive mod-ulation). The main services and functions of the MAC sublayer include: J Multiplexing/demultiplexing of MAC SDUs belonging to one or more logical

channels into/from transport blocks (TB) delivered to/from the physical layer on transport channels

J Scheduling information reporting, i.e. triggering scheduling requests for data transfer

J Error correction through HARQ; in case of carrier aggregation or DC, there is one HARQ entity per cell

J Priority handling between UEs by means of dynamic scheduling J Priority handling between logical channels of one UE by means of logical

channel prioritization J Padding bit attachment to fit the required packet sizes

A single MAC entity can support multiple numerologies, transmission timings and cells. Mapping restrictions within logical channel prioritization are used to control which numerologies, cells and transmission timings a logical channel may use.

Physical layer (PHY)The physical layer provides data transfer services to MAC and higher layers. The physical layer takes the characteristics of transport channel and maps them to the radio interface through mechanisms such as channel coding, modulation and rate matching. For a detailed description of the physical layer in 5G NR, see 1.2 Physical access fundamentals, page 46.

1.1.3.4 Radio bearers in dual connectivityThe concept of dual connectivity was introduced in 1.1.2.1 Connectivity scenarios, page 13. Dual connectivity allows data transmission to be split among differ-ent radio networks based on routing of PDCP data bearers on different radio networks. Radio bearers are data channels on the air interface that are used to transmit data with specific network parameters (i.e. quality of service).

The UE has both data radio bearers (DRB) and signaling radio bearers (SRB). An SRB transmits control messages, which in case of dual connectivity are trans-mitted over the MCG. Optionally, a UE can also have a signaling connection

Depending on the reliability and latency required for data transported in logical channels, the RLC channel may be configured with three transmission modes: J Transparent mode (TM): In this mode, the RLC protocol layer forwards the

data packet from PDCP without attaching any header. Therefore, the packet size must be known a priori and there is also no need for packet segmenta-tion or reassembly. Moreover, no error recovery mechanism for lost packets is introduced such as retransmission or in-sequence delivery

J Unacknowledged mode (UM): In this mode, the RLC header is attached, allowing the transmission of variable packet sizes. Thus, this mode introduces a segmentation mechanism to adapt the packet sizes, for example to the trans-mission channels. RLC performs buffering at both the TX and RX ends, but no mechanism for acknowledgment is introduced. Thus, there is no checking for lost packets

J Acknowledged mode (AM): This mode provides automatic repeat request (ARQ) feedback: lost packets are retransmitted. Moreover, duplication detec-tion is introduced. An RLC header is attached, allowing sequence number identification and the adaptation of packet sizes with segmentation and reas-sembly. Buffering is implemented at both the TX and RX ends

Each of these modes can both transmit and receive data. In TM and UM, a sepa-rate entity is used for transmission and reception, but in AM a single RLC entity performs both transmission and reception.

Certain logical channels will use a specific RLC mode, e.g. for SRB0, paging and broadcast system information, TM mode is used. For other SRBs, AM mode is used. For DRBs, either UM or AM mode is used.

The main services and functions of the RLC sublayer depend on the transmis-sion mode and include: J Transfer of upper layer PDUs from logical channel to RLC channel J Sequence numbering independent of the PDCP (UM and AM) J Error correction through ARQ (AM only) J Segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs,

needed to match the size of the MAC PDU J Reassembly of SDU (AM and UM) J Duplicate detection (AM only) J RLC SDU discard (AM and UM) J RLC re-establishment in case the lower layer indicates radio link out-of-sync J Protocol error detection (AM only)


The UE does not need to know if the bearer anchor point is on the MCG or SCG; the UE sees several air interface channels (MCG, SCG bearers and split bearer) in the direction of the core network.

1.1.3.5 UE capabilities transfer and computationIn previous generations of cellular networks, namely GSM, UMTS/HSPA and LTE, UE categories were defined as a way to indicate a basic UE capability to the network.

For example, the first set of 3GPP specifications for LTE included five main UE categories. Those categories only distinguished the maximum number of transport blocks received within a TTI, i.e. a maximum data rate, and the num-ber of spatial streams supported by that UE category. In the UL direction, the optional support for 64QAM modulation was also indicated per UE category. The data rate of these categories comprises a range from 10 Mbps to 300 Mbps in the downlink direction and 5 Mbps to 75 Mbps in the uplink direction. The first commercial end-user devices arriving on the market were mostly UE category 3, supporting up to 100 Mbps on the downlink and up to 50 Mbps on the uplink. Therefore, the UE category indication was mainly used to describe a maximum supported data rate capability of an end-user device. The categories were also used for marketing purposes, i.e. advertising a new category arriving on the mar-ket (supporting an even higher maximum data rate). Over the years, the UE cat-egories were extended and also defined separately in the downlink and uplink directions. In 3GPP Release 15, there are 12 common (DL/UL) UE categories defined. Additionally, 26 separate UE DL and UL categories are specified in total. The high number of UE categories is determined by various carrier aggregation and spatial multiplexing (MIMO) combinations and also indicates support for enhanced modulation schemes up to 256QAM. Note that even more specific UE categories are defined which indicate support for dedicated features such as side-link for V2X applications and NB-IoT. During the specification of LTE and its enhancements, the UE category became quite cumbersome. On top of the basic UE categories, there are many more UE capabilities for which support is signaled to the network. They are specified in TS 36.306 section 4.3 (“Parameters inde-pendent of the field ue-Category and ue-CategoryDL / ue-CategoryUL”).

In 5G NR, it was decided not to maintain the concept of UE categories as in exist-ing cellular technologies. Therefore, a basic category number is not available to provide the maximum data rate capability of a UE, which is generally consid-ered an important performance indicator. In contrast, TS 38.306 provides a for-mula to calculate the maximum date rate mainly depending on the number of spatial layers and the number of carriers that an end-user device supports. The

with the SN for all control information where involvement of the MN is not required, e.g. SN reconfiguration (SRB3).

From a network perspective, the connection can be distinguished between the transmission bearer starting at the core network and terminating at the master cell group (MCG bearer) or the transmission bearer starting at the core network and terminating at the secondary cell group (SCG bearer).

This is illustrated in Fig. 1-14 for the case of EN-DC. For operators, this can involve a load balancing decision on whether to use a bearer terminating in either cell group.

MCG bearer MCG split bearer SCG split bearer SCG bearerXn

E-UTRA/NR PDCP NR PDCP

E-UTRA MAC/PHY

eNB (MN)

E-UTRARLC

E-UTRARLC

E-UTRARLC

NR PDCP

NR MAC/PHY

gNB (SN)

NR RLC NR RLC NR RLC

NR PDCP

Fig. 1-14 Radio bearer types in LTE/NR dual connectivity (EN-DC).

An additional option is that the bearer can be split over both connections and data can be distributed or duplicated between the two nodes (split bearer). Split bearers allow additional load balancing between the two connections. The deci-sion is made dynamically depending on the amount of data on the main connec-tion leg as well as a network-defined threshold. Split bearers are specific to dual connectivity and can have an anchor point (PDCP layer) on MN (MCG split bearer) or SN (SCG split bearer).

In general, the advantage of dual connectivity is that it diversifies transmission over separate frequency links without a constraint for linked time synchroniza-tion between the two NodeBs. In fact, the two nodes can be collocated or non-collocated, and no high-performance backhaul is required. Some operators see the split bearer as an ideal solution for minimizing control signaling while still dynamically branching out the data on both frequencies. In the URLLC case, for example, a split bearer is also required for duplication of data on both links since it increases the reliability by reducing the packet error rate and decreases the latency due to fewer retransmissions. Lost packets on one link can be recovered from the corresponding duplicate packet on the other link.


5G

gNB

AMF UPF

NGC

UE capability enquiry

UE capability information

Fig. 1-17 UE capability transfer procedure.

In general, the UE jointly indicates its support for both TDD and FDD modes with a single value in case the functionality is supported for both modes. If the capabilities differ, the corresponding values are signaled in dedicated informa-tion fields with a corresponding prefix, i.e. as part of the fdd-UE-NR-Capability and tdd-UE-NR-Capability fields.

TS 38.306 specifies a long list of different UE capability parameters. If applicable, the parameter is classified as mandatory. For each parameter, the list also defines whether the value is common or different to FDD and TDD modes. We have selected a few examples for illustration in this section.

General parameters include the mandatory inactiveState parameter, which indi-cates whether the UE supports RRC_INACTIVE state as specified in TS 38.331, and the optional voiceOverMCGBearer parameter, which indicates whether the UE supports IMS voice over the NR PDCP for MCG bearer in 5G NR.

Two examples of PDCP parameters are pdcp-DuplicationSplitDRB, which indi-cates whether the UE supports PDCP duplication over split DRB, and the supportedROHC-Profiles parameter, which defines which robust header com-pression profiles are supported.

There are only three RLC parameters and they are all mandatory. am-WithShortSN, um-WithLongSN and um-WithShortSN indicate support for acknowledged and unacknowledged modes with different bit length of RLC sequence numbers.

Related to the MAC layer, one example of a mandatory parameter is longDRX-Cycle, which indicates support for long DRX cycles. An optional MAC parameter is multipleSR-Configurations, which indicates whether the UE supports eight scheduling request configurations per cell group.

The most comprehensive list of parameters is in the physical layer parameter section of TS 38.306. On the physical layer, the UE indicates which band com-binations related to carrier aggregation (within EUTRA = LTE, within 5G NR

formula is given in Fig. 1-15: For a more detailed explanation of the formula, see Downlink data rate, page 308.

=10−3

14 ⋅ 2

10−6 ⋅ ( ) ⋅ ( ) ⋅ ( ) ⋅ ⋅( ), ⋅ 12

⋅ 1 − ( )

=1

��

Data rate = 10–6 · 1 · 1 · 8 ·1 · (948/1024) · (270 · 12) · (14 · 20)/10–3 · (1 – 0.14)

(Mbps)

= 288.9 Mbps

Data rate =

Adjustment to Mbps

Number oflayers v

Sub carrier per RB

Numerology μ

Number ofcarriers J

Scalingfactor f

Max. code rate Rmax

Overhead OHMax. number of RBs N

Average OFDM symbol duration Ts

Bits per symbol frommodulation scheme Qm

Fig. 1-15 Formula for data rate calculation with sample calculation for FR1, assuming 15 kHz SCS and 256QAM (maximum data rate is 288.9 Mbps in this example).

Based on this information, the maximum supported data rate can be deter-mined. Fig. 1-16 provides sample calculations for FR1 and FR2 applying differ-ent subcarrier spacings and bandwidth allocations in FR1 and FR2. FR1 and FR2 are the two frequency ranges defined for 5G NR, further details are given in Fig. 1-50, page 74.

Frequency range SCS Bandwidth DL ULFR1 15 kHz 50 MHz 288.9 Mbps 309.1 MbpsFR1 30 kHz 100 MHz 584.3 Mbps 625 MbpsFR1 60 kHz 100 MHz 577.8 Mbps 618.1 MbpsFR2 60 kHz 200 MHz 1.08 Gbps 1.18 GbpsFR2 120 kHz 400 MHz 2.15 Gbps 2.37 Mbps

Fig. 1-16 Examples of maximum data rate calculations for one spatial layer and for one component carrier for 5G.

As previously mentioned, there is no UE category indication to the net-work. Instead, 5G NR defines a UE capability transfer procedure as specified in TS 38.331 (see Fig. 1-17). The network initiates the procedure to the UE in RRC_CONNECTED mode if it needs UE radio access capability information. The procedure is always required after initial access to the network. However, it may also be executed if the network requires updated information.


calculated from a well-defined formula. However, the relevant parameters are provided via signaling of detailed UE capability parameters.

1.1.3.6 Fundamental measurements provided by the end-user device

In all cellular technologies, there is the essential network (base station scheduler) task to schedule resources in the most efficient way. Moreover, varying propaga-tion conditions need to be taken into account in order to support UE mobility and connection handover between cells.

FDD systems operate the downlink transmission link from the base station to the end-user device in a different frequency spectrum than the uplink from the end-user device to the base station. Since propagation conditions can be differ-ent in the downlink and uplink directions, a feedback mechanism from the UE is required. This allows the base station to allocate resources appropriately as well as to prepare handover scenarios.

TDD systems use the same frequency for the downlink and uplink, which enables the base station to deduce downlink propagation conditions from uplink mea-surements executed in its own receiver. However, this is only possible in the fre-quency range actually in use by the UE. In order to gain knowledge for addi-tional carrier frequencies, e.g. to prepare for an inter-frequency handover, specific resources need to be scheduled. Furthermore, with 5G NR there is specific empha-sis on the implementation of beamforming, which adds another dimension.

In this section, we provide a basic overview of the measurements executed by a UE to support the scheduling mechanism in the base station throughout mul-tiple relevant phases, i.e. during initial access, during establishment and main-tenance of a connection as well as to support mobility. Details are provided in other sections of this 5G compendium and are referenced where relevant.

In previous cellular technologies, the basic end-user device measurement relied on the always-on reference signal transmitted within a cell. For LTE networks, power measurements are executed and feedback is provided based on the cell-specific reference symbols. Additionally, the UE can be tasked to provide mea-surement reports based on the channel state information (CSI) reference sym-bols (RS). The CSI-RS are temporarily scheduled and the position in frequency and time is signaled to the UE.

and for dual connectivity = EUTRA/NR) are supported. The BandNR parame-ters include many capabilities such as the absolute NR frequency band, but also very detailed capabilities like the beamReportTiming parameter. This parameter indicates the number of OFDM symbols between the last symbol of SSB/CSI-RS and the first symbol of the transmission channel containing a beam report. The UE includes this field for each supported subcarrier spacing. The sections CA-ParametersEUTRA and CA-ParametersNR describe a few parameters such as the multipleTimingAdvances parameter for NR, i.e. whether multiple timing advances are supported. Many parameters relevant to calculation of the maxi-mum data rate are included in the so-called FeatureSet parameter sections, spec-ified for both the DL and UL and also detailed per component carrier (CC), e.g. the scalingFactor or maxNumberMIMO-LayersPDSCH parameters. The latter specifies the maximum number of spatial multiplexing layer(s) supported by the UE for DL reception. For single carrier standalone NR, it is mandatory with capa-bility signaling to support at least four MIMO layers in the bands where 4 RX is specified as mandatory for the given UE and at least two MIMO layers in FR2. Some relaxations to this requirement may be applicable in the future (includ-ing in Rel-15). Mandatory in all cases means mandatory with capability signal-ing. The physical layer parameter section also lists multi-RAT dual connectivity (MR-DC) parameters. One example is dynamicPowerSharing, a parameter that indicates whether the UE supports dynamic EN-DC power sharing or not. Many more parameters are included in the Phy-Parameters and other PHY parameter subsections in TS 38.306.

Many measurement and mobility capability parameters can be indicated to the net-work. They relate to UE capabilities to perform measurements and report results to the network. For example, the parameter csi-RSRP-AndRSRQ-MeasWithSSB indicates whether the UE can perform CSI-RSRP and CSI-RSRQ measurements as specified in TS 38.215, where the CSI-RS resource is configured with an asso-ciated SS/PBCH. Note that this parameter requires FR1 and FR2 differentiation.

Finally, the inter-RAT parameter section list two single capabilities: support for EUTRA FDD and EUTRA TDD.

In conclusion, 5G NR provides a very granular way of indicating UE capabilities to the network. This must be taken into account when scheduling resources to a specific UE or when tasking the UE to provide measurement reports. In pre-vious cellular network technologies, the UE category concept provided a very coarse indication of basic capabilities, mostly to reflect a certain maximum data rate. This concept is not maintained in 5G NR. The maximum data rate can be


information (UCI), page 340. The measurements to be executed are defined in TS 38.215.

As mentioned before, even in TDD systems the base station cannot necessarily rely on its own receiver measurements for evaluation of propagation conditions. The network may schedule sounding reference signals (SRS) to gain propagation information in time and frequency ranges for potential use. The concept is the same as in LTE. For a more detailed description, see 1.2.5.6 Physical signals in 5G NR, page 110. Therefore, the base station can take these measurements into account for resource allocation.

The measurements discussed above play a key role during initial access, while setting up a connection and when maintaining the connection if mobility is involved. The procedure for measuring and evaluating suitable cells and beams during initial access in the NSA case is described in detail in 2.1.2 5G NR signal quality measurements and reporting, page 237. Measurements in case of mobil-ity are described in 2.3.3 Mobility measurement, page 401.

1.1.4 Non-access stratum protocolThe non-access stratum (NAS) describes the protocol layers for 5G mobility management (5G-MM) between the UE and the AMF as well as for 5G session management (5G-SM) between the UE and the SMF.

5G mobility management describes procedures for the control of mobility when the UE is using NG-RAN and/or a non-3GPP access network. Typical proce-dures for 5G-MM include: J Registration procedure: 5GMM distinguishes between the two major states

5GMM-REGISTERED and 5GMM-DEREGISTERED (additional states are defined in TS 24.501). The main purpose of the registration procedure is to update the network with the UE’s whereabouts, to negotiate the services and update the UE about its allowed services. It is triggered by the NAS control message REGISTRATION REQUEST and completed by the network response REGISTRATION ACCEPT in the successful case.

J Deregistration procedure: This procedure can be initiated by either the UE or the network to perform de-registration from the 5G services.

J Primary authentication and key agreement procedure: The purpose of the primary authentication and key agreement procedure is to enable mutual authentication between the UE and the network by using NAS control mes-sages for authentication and to exchange security keys that can be used between the UE and network in subsequent security procedures such as integrity pro-tection and/or ciphering

This mechanism enables the network to receive feedback on additional frequen-cies to prepare for inter-frequency handovers. It also enables the application of UE-specific beamforming in LTE.

In 5G NR, there are no cell-specific reference symbols that could serve as the basis for measurements. Therefore, it was decided to perform UE measurements based on the secondary synchronization (SS) signals. Only the SS-RS receive power (SS-RSRP) must be measured among the reference signals correspond-ing to SS/PBCH blocks with the same SS/PBCH block index and the same phys-ical layer cell identity. This means that all beams applied within a cell and their individual beam power measurements correspond to the cell-specific measure-ments used in previous cellular technologies. Fig. 1-18 illustrates the difference. The left side shows a three-sector cell in LTE with cell-specific reference symbols in each sector, which would allow power measurements per sector. The right shows a 5G NR example that implements SSB beams to cover the whole cell area, whereas power measurements are possible on a per beam basis. All SSB beams belong to the same cell.

eNB gNB

Fig. 1-18 Differences between sectorized eNB and SSB-beamformed sectorized gNB cells.

The UE measurements to execute and report are defined in TS 38.215. For SS/PBCH blocks, there are essentially three measurements: synchronization sig-nal reference signal received power (SS-RSRP), synchronization signal signal to interference and noise ratio (SS-SINR) and synchronization signal refer-ence signal received quality (SS-RSRQ). Note that these are based on resource elements carrying secondary synchronization signals only. The definition fol-lows the same principle as for cell-specific power, SINR and quality measure-ments in existing cellular networks such as LTE.

CSI-RS are scheduled by the network to serve a specific purpose. One purpose is enabling measurement on multiple carrier frequencies of neighbor cells. Sec-ondly, CSI-RS can be scheduled to enable UE-specific beamforming. Both mech-anisms are used in the same way as in LTE networks. A detailed description is provided in 1.2.5.6 Physical signals in 5G NR, page 110 and 2.2.9 Uplink control


(known as a PDU session) conveys multiple QoS flows where each flow is accom-panied by mechanisms such as packet labeling and bearer mapping.

A QoS flow of this type can be considered as granularity for QoS forward-ing treatment in the overall 5G system. All traffic that is mapped to the same QoS flow will receive the same forwarding treatment, e.g. the scheduling pol-icy, queue management, prioritization, rate allocation policy and protocol layer configuration such as the RLC transmission mode selection or transport chan-nel mapping, etc. In case different QoS treatments are required, this results in a need for separate QoS flows.

The QoS architecture in NG-RAN, both for NR connected to 5GC and for EUTRA connected to 5GC, is depicted in Fig. 1-19. For each UE, 5GC estab-lishes one or more PDU sessions; a PDU session should be understood as the connectivity service that facilitates the exchange of protocol data units (PDU) between a UE and a data network. An example of a PDU session is an IP PDU session supporting both IPv4 and IPv6.

UE UPF

NG-RAN

Radio N3

NodeB

5GC

PDU session

Radio bearer

Radio bearer

NG-U tunnel

QoS flow

QoS flow

QoS flow

Fig. 1-19 QoS flow architecture from 3GPP TS 38.300.

At the NAS level (N3), the QoS flow is thus the finest granularity for QoS differ-entiation in a PDU session. A QoS flow is identified within a PDU session by a QoS flow ID (QFI) that is carried in an encapsulation header over the NG-U inter-face, i.e. the interface between the gNB and the UPF. At the NAS level, packet fil-ters in the UE and the 5GC associate UL and DL packets with QoS flows; this is

J Identification procedures: These procedures are initiated by the AMF by sending the IDENTITY REQUEST message to request UE identification val-ues such as SUCI or IMEI.

J Service request procedure: The main purpose is to change the 5GMM mode from 5GMM-IDLE to 5GMM-CONNECTED and establish user plane resources.

J Mobility procedures: These procedures support both 3GPP access as well as non-3GPP access and are essential for UE mobility. A registration area is defined as a set of tracking areas that a UE is registered to. Each tracking area corresponds to a non-overlapping set of cells covering a geographical area.

J Notification procedure: This is used to ask the UE to re-establish the user plane resources for the PDU session.

J Paging procedure: This is triggered by the AMF to establish a mobile termi-nated connection. The paging procedure in cooperation with the access stra-tum establishes a NAS signaling connection between the AMF and the UE.

5G mobility management provides security control for the NAS protocols. Aspects related to security in 5G include procedures for authentication, integ-rity protection and ciphering. Authentication is based on a key-exchange proce-dure between the UE and AMF and thus realizes a method to avoid user identity fraud. Integrity protection requires an initially established security context and protects the NAS control message. It is activated by the network to protect NAS message transfer with a key procedure and prevent “man-in-the-middle” attacks that could take control of the connection.

Ciphering is applied to both user data as well as control messages and is based on a security context exchange of keys between the UE and the AMF. The goal is to avoid eavesdropping of ongoing connections (and especially the radio connec-tions since they are susceptible to interception).

5G session management provides procedures for handling of PDU sessions such as IP address allocation, domain name resolution and proxy server allocations. In conjunction with the access stratum and UPF, it controls the radio bearer QoS. Typically, 5G session management messages are piggybacked on specific 5G mobility management messages. In terms of the preferences, the UE usage settings can be either “voice centric” or “data centric”.

1.1.5 Quality of serviceThe 5G QoS model is based on QoS flows and thus involves a minor differ-ence compared to LTE where the QoS parameters are negotiated by means of a so-called traffic flow template. The main idea is that an E2E data connection


CP NFs for slice A

UP NFs for slice A

CP NFs for slice B

UP NFs for slice B

CommonCP NFs

RAN

CommonCP NFs

CP NFs for slice C

UP NFs for slice C

Slice selectionfunction (SSF)

Subscriberrepository

Network slice A

CP: Control planeUP: User planeNF: Network function

Network slice B

Network slice C

Fig. 1-20 Control plane interfaces for network slicing (from TR 23.799).

There are three types of standard slices that are defined according to the fol-lowing Fig. 1-21. Each slice could possibly be connected to service providers via APIs to allow the implementation of various commercial services.

Slice / Service type (SST) SST value CharacteristicseMBB (enhanced mobile broadband)

1 Slice suitable for the handling of 5G enhanced Mobile broadband, but not limited to the general consumer space mobile broadband applications including streaming of high quality video, fast large file transfers etc. It is expected this SST will aim at supporting High data rates and high traffic densities as outlined in Table 7.1-1 “Perfor-mance requirements for high data rate and traffic density scenarios” in TS 22.261 [2].

URLLC (ultra-reliable low latency communications)

2 Supporting ultra-reliable low latency communications for applica-tions including industrial automation, (remote) control systems.This SST is expected to aim at supporting the requirements in Table 7.2.2-1 “Performance requirements for low-latency and high-reli-ability services.” in TS 22.261 [2] related to high reliability and low latency scenarios.

MIoT (massive IoT) 3 Allowing the support of a large number and high density of IoT devices efficiently and cost effectively.

Fig. 1-21 Standardized slice/service types (from TS 23.501, Table 5.15.2.2-1).

considered as a labeling procedure to ensure proper PDU transport through the overall protocol layers and interfaces.

The NG-RAN establishes for each UE at least one data radio bearer (DRB) (default bearer) and additional DRB(s) depending on the QoS flow(s) estab-lished on the network and the scheduling decisions by the network. For trans-port over the air interface, there is an AS-level mapping rule in the UE and in the NG-RAN which associates UL and DL QoS flows with DRBs. Via the SDAP pro-tocol layer on the xNB, the NG-RAN maps a QoS flow belonging to same PDU sessions to the same or different DRBs (TS 23.501).

5G NR supports both QoS flows that require a guaranteed flow bit rate (GBR QoS flows) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flows). In addition, there is support for reflective QoS, meaning that the UE will use the same QoS parameters on the uplink as obtained from the downlink QoS flow.

1.1.6 Network slicingIn 5G, the core network has gone through a transformation. It is designed to cater to various services such as mobile broadband, vehicle to vehicle, machine-type communications, smart home/city and Internet of things (IoT). Designing a network that provides services with highly variable requirements leads to an architecture that can provide different logical networks by reusing the available hardware.

The concept of having different logical networks using shared hardware is known as network slicing and each logical network is known as a network slice. An end user can register with one or more network slices depending upon the particular requirements and subscription options.

A network slice is defined within a PLMN and includes the control plane and user plane network functions (CP and UP NF) and in the serving PLMN, at least one of the following: J NG radio access network J Non-3GPP interworking functions (N3IWF) to the non-3GPP access network

(e.g. for WLAN access, which is not shown in Fig. 1-20)

A logical representation of a network slice is shown in Fig. 1-20.


AMF

UE

UP encryption

UP integrity

CP integrity

EP encryption

AS security

Authentication

CP encryption

CP integrity

NAS security

SEAF AUSF ARPF/UDM

gNB UPF

AUSF: authenticaton server functionARPF: authentication credential respository and processing functionSEAF: security anchor functionUDM: unified data management

Fig. 1-23 5GC security functions.

There are security associations on the access stratum (AS) layer between the UE and the gNB that are intended to secure both the user data (UP) and control data (CP) with integrity and encryption. Another security association is on the non-access stratum (NAS) level where the integrity and ciphering algorithms are applied to control plane (CP) data and the authentication process occurs.

The security anchor function (SEAF) provides an interface to the authentica-tion functionality within the 5G System. SEAF is collocated inside the AMF. The authentication server function (AUSF) must handle authentication requests for both 3GPP access and non-3GPP access and has an interface to the AMF via SEAF.

The unified data management (UDM) and authentication credential repository and processing function (ARPF) contain the set of values (like in the UE/USIM) consisting of at least the long-term key(s) and the subscription permanent iden-tifier (SUPI), used to uniquely identify a subscription and to mutually authenti-cate the UE and 5G core network (generation of authentication credentials).

The long-term keys used for authentication and security association setup pur-poses must be protected against physical attacks and must never leave the secure environment of the ARPF/UDM.

1.1.7 Security architectureSecurity is an important topic in 5G due to the increasing number of laws on pri-vate data protection as well as new and critical applications and verticals, such as industrial automation and autonomous driving.

Service

Security Security

Security

User equipment 5G system

Fig. 1-22 5G security for the user, service and network.

Security is also relevant in mobility scenarios with the refreshing of security parameters and during long data transmissions where the security keys must not be reused.

In 5G, security is achieved using two mechanisms: mutual authentication and data ciphering/integrity. Mutual authentication means that the network and UE can each verify the identity of the counterpart. With ciphering, transmitted data is encrypted using a shared key between the user and network. With integrity, a checksum is added to the data message to guarantee the accuracy and valid-ity of the data.

Moreover, 5G implements the concept of key separation in which each connec-tion (i.e. user plane or control plane) always uses distinct keys derived from one master key.

Data security is based on a shared key (K) which is agreed between a UE/USIM and 5GC. Several keys are generated from the shared keys depending on the security algorithm and association. The 5G integrity and encryption mech-anism supports different algorithms with a 128-bit key length as specified in Annex D of TS 33.501. The keys used for NAS and AS as well as for CP and UP depend on the algorithm with which they are used.

The 5G system includes several components that are interconnected to increase the security encapsulation as shown in Fig. 1-23.

434 435Appendix Abbreviations

3 Appendix

3.1 Abbreviations

3GPP 3rd generation partnership program5G-GUTI 5G globally unique temporary identity5G-AN 5G access network5GC 5G core network5GMM 5G mobility management5GSM 5G session management5GTF 5G technical Forum5QI 5G QoS identifier

AAAA Authentication, authorization and acountingACK AcknowledgementAKA Authentication and key agreementAM Acknowledged modeAMBR Aggregate maximum bit rateAMC Adaptive modulation and codingAMD Acknowledge mode dataAMF Access and mobility management functionAN Access networkAPN Access point nameARFCN Absolute radio frequency channel numberARP Address resolution protocol,

Allocation and retention priority as QoS parameterARPF Authentication credential respository and processing

functionARQ Automatic repeat requestAS Access stratumASN.1 Abstract syntax notation oneAUSF: Authenticaton server functionAUTN Authentication tokenAWGN Additive white gaussian noise

BBA Bandwidth adaptationBBU Baseband unitBCCH Broadcast control channel (logical channel)

BCH Broadcast channel (transport channel)BLER Block error rateBPSK Binary phase shift keyingBS Base stationBSD Bucket size durationBSMC Binary-input symmetric memoryless channelBSR Buffer status reportBWP Bandwidth part

CC-RNTI Cell RNTICA Carrier aggregationCATR Compact antenna test rangeCBG Code block groupCBRA Contention based random accessCCCH Common control channelCCE Control channel elementCD-SSB Cell defining SSBCDM Code division multiplexCDMA Code division multiple accessCE Control elementCFO Carrier-frequency offsetCFRA Contention free random accessCID Context identifierCK Ciphering keyCMAS Commercial mobile alert serviceCoMP Coordinated multipointCORESET Control-resource setCP Cyclic prefix – or – control planeCP-OFDM Cyclic prefix OFDMCP-OFDMA Cyclic prefix OFDMACPE Customer premises equipmentCQI Channel quality indicatorCRB Common resource blockCRC Cyclic redundancy checkCRI CSI-RS resource indicatorCRS Cell specific reference signals (LTE)CS Configured schedulingCS-RNTI Configured scheduling RNTICSI Channel-state informationCSI-IM CSI interference measurement


CSI-RS Channel-state information reference signalCSI-RSRP CSI reference signal received powerCSI-RSRQ CSI reference signal received qualityCSI-SINR CSI reference signal to noise and interference ratioCSS Common search spaceCW Continuous wave

DD2D Device to deviceDC Dual connectivity or direct currentDCCH Dedicated control channelDCI Downlink control informationDFF Direct far fieldDFT Discrete fourier transformationDFT-s-OFDM Discrete fourier transform-spread-orthogonal frequency

division multiplexingDL DownlinkDL-SCH Downlink shared channelDMRS Demodulation reference symbolsDN-AAA Data network authentication, authorisation and

accountingDNN Data network nameDRB Data radio bearer DRX Discontinuous receptionDTCH Dedicated traffic channelDUT Device under test

EE-RAB EUTRAN radio access bearerEAP Extensible authentication protocolEARFCN EUTRA ARFCNECGI EUTRAN cell global identityECM EPS connection managementEHPLMN Equivalent home public land mobile networkeMBB Enhanced mobile broadbandEMM EPS mobility managementeMTC Enhanced machine type communicationEN-DC EUTRA NR dual connectivityeNB EUTRAN NodeBEPC Evolved packet coreEPRE Energy per resource element

EPS Evolved packet systemESM EPS session managementETWS Earthquake and tsunami warning systemEUTRA Evolved universal terrestrial radio accessEUTRAN Evolved universal terrestrial radio access networkEVM Error vector magnitude

FFDD Frequency division duplexFDL Frequency downlinkFDMA Frequency division multiple accessFEC Forward error correctionFFS For further studyFGI Feature group indicatorFMC First missing count – used in PDCP status reportFR1 Frequency range 1FR2 Frequency range 2FUL Frequency uplinkFWA Fixed wireless access

GGBR Guaranteed bit rateGCF Global certification forumGERAN GSM/EDGE radio access networkGF Grant-freeGFBR Guaranteed flow bit rateGMSK Gaussian minimum shift keyinggNB NR NodeBGNSS Global navigation satellite systemGPRS General packet radio servicesGSCN Global synchronization channel numberGSM Global system for mobile communicationsGTP GPRS tunneling protocolGUTI Globally unique temporary UE identityGW Gateway

HHARQ Hybrid automatic repeat requestHFN Hyper frame numberHSDPA High speed downlink packet access – 3GPP Rel. 5


HSPA High speed packet access – using HSDPA in downlink and HSUPA in uplink

HSS Home subsciber serverHSUPA High speed uplink packet access – 3GPP Rel. 6

IICI Inter-carrier interferenceIE Information elementIEI Information element identifierIETF Internet engineering task forceIFF Indirect far fieldIFFT Inverse fast fourier transformationIK Integrity keyIMEI International mobile equipment identityIMSI International mobile subscriber identityINT-RNTI Interruption RNTIIP Internet protocolISI Inter-symbol interferenceITU International telecommunication union

KkB Kilobyte (1000 bytes)KDF Key derivation functionKPI Key performance indicator

LL2 Layer 2 (data link layer)L3 Layer 3 (network layer)LAN Local area networkLCG Logical channel groupLCID Logical channel ID – MAC header parameterLCP Logical channel prioritizationLDPC Low density parity checkLI Layer indicatorLOS Line of sightLSB Least significant bitsLTE Long term evolution

MMAC Medium access controlMAC-I Message authentication code for integrity

MBMS Multimedia broadcast and messaging servicesMCC Mobile country codeMCG Master cell groupMCS Modulation and coding schemeMCS-C-RNTI Modulation and coding scheme C-RNTIMEC Mobile edge computingMFBR Maximum flow bit rateMIB Master information blockMICO Mobile initiated connection onlyMIMO Multiple input multiple outputmIoT Massive internet of thingsMME Mobility management entity mMTC Massive machine type communicationsMN Master nodeMNC Mobile network codeMPA Message passing algorithmMPP Multipath propagationMR-DC Multi-radio dual connectivityMSB Most significant bitsMSI Minimum system informationMTC Machine type communication,

Measurement timing configurationMU-MIMO Multi-user MIMO

NN3IWF Non-3GPP interworking functionsNAI Network access identifierNAS Non-access stratumNCC Next hop chaining counter or network color codeNCGI NR cell global identifierNCR Neighbour cell relationNDI New data indicatorNF network functionNG-RAN NG radio access networkNGAP NG application protocolng-eNB next generation evolved NodeBNH Next hopNLOS Non line of sightNR New radioNSA Non-standaloneNSSAI Network slice selection assistance information


NW NetworkNZP CSI-RS Non zero power CSI-RS

OOFDM Orthogonal frequency division multiplexingOFDMA Orthogonal frequency division multiple accessOSI Open system interconnection,

Other system information

PP-GW Packet gatewayP-RNTI Paging RNTIPAPR Peak-to-average power ratioPBCH Physical broadcast channelPBR Prioritised bit ratePCCH Paging control channelPCell Primary cell PCF Policy control functionPCH Paging channelPCI Physical cell identityPCRF Policy control and routing functionPDB Packet delay budgetPDCCH Physical downlink control channelPDCP Packet data convergence protocolPDSCH Physical downlink shared channelPDU Protocol data unitPER Packet error ratePH Power headroomPHICH Physical hybrid indicator channelPHR Power headroom reportPL Path lossPLL Phase locked loopPLMN Public land mobile networkPMI Precoding matrix indicationPRACH Physical random access channelPRB Physical resource blockPRG Precoding resource block groupPSS Primary synchronisation signalPTRS Phase tracking reference signalPTAG Primary timing advance groupPTRS Phase tracking reference signal

PUCCH Physical uplink control channelPUSCH Physical uplink shared channelPWC Plane wave converterPWS Public warning system

QQAM Quadrature amplitude modulationQCI QoS class identifierQCL Quasi co-locationQFI QoS flow IDQoS Quality of serviceQPSK Quadrature phase shift keyingQZ Quite zone

RRA-RNTI Random access radio network temporary identifierRACH Random access channelRAN Radio access networkRAPID Random access preamble identifierRAR Random access response (Msg2)RAT Radio access technologyRB Radio bearer or resource block RBG Resource block groupRDI Reflective QoS flow to DRB mapping indicationREG Resource element groupRF Radio frequencyRFC Request for commentsRI Rank indicatorRIV Resource indicator valueRLC Radio link controlRMSI Remaining minimum system informationRNA RAN-based notification areaRNAU RAN-based notification area updateRNTI Radio network temporary identifierROHC Robust header compressionRQA Reflective QoS attributeRQI Reflective QoS indicationRQoS Reflective quality of serviceRRC Radio resource controlRRH Remote radio headRRU Remote radio unit


RSRP Reference signal received powerRSSI Received signal strength indicatorRTP Real time protocolRTT Round trip timeRU Radio unitRV Redundancy version

SS-GW Serving gatewayS-NSSAI Single network slice selection assistance informationSA StandaloneSAE Service architecture evolutionSAP Service access pointSC-FDMA Single carrier FDMASCell Secondary cellSCG Secondary cell groupSCH Shared channelSCS Subcarrier spacingSCTP Stream control transmission protocol

(defined in RFC 4960)SD Slice differentiatorSDAP Service data adaptation protocolSDF Service data flowSDL Supplementary downlinkSDU Service data unitSEAF Security anchor functionSFI-RNTI Slot format indicator RNTISFN System frame numberSI System informationSI-RNTI System information radio network temporary identifierSIB System information blockSIM Subscriber identity moduleSINR Signal-to-interference-plus-noise ratioSISO Single input single outputSLA Service level agreementSLIV Start and length valueSMF Session management functionSN Sequence number

Secondary nodeSNR Signal to noise ratioSpCell Special cell

SPS Semi-persistent schedulingSQN Sequence number (ciphering)SR Scheduling requestSRB Signalling radio bearerSRS Sounding reference signalSS Synchronization signalSSB Synchronization signal blockSSBRI SS/PBCH block resource indicatorSSC Session and service continuitySSF Slice selection functionSSS Secondary synchronisation signalSST Slice/service typeSTAG Secondary timing advance groupSU-MIMO Single user MIMO, also referred to as

spatial multiplexingSUL Supplementary uplinkSUPI Subscription permanent identifier

TT&M Test & measurementTA Timing advance or tracking areaTAG Timing advance groupTB Transport blockTBS Transport block sizeTCI Transmission configuration indicatorTCP Transmission control protocolTC-RNTI Temporary cellular radio network temporary identifierTDD Time division duplexTDMA Time division multiplex accessTM Transparent modeTNL Transport network layerTPC Transmit power controlTPC-CS-RNTI TPC configured scheduling-RNTITPC-PUCCH-RNTI TPC physical uplink control channel-RNTITPC-PUSCH-RNTI TPC physical uplink shared channel-RNTITPC-SRS-RNTI TPC sounding reference symbols-RNTITPMI Transmit precoding matrix indicatorTRP Transmission and reception pointTRS Tracking reference signalTTCN-3 Testing and test control notation version 3TTI Transmission time interval

444 445Appendix References

UUCI Uplink control informationUDM Unified data management UDP User datagram protocolUE User equipmentUICC Universal integrated circuit cardUL UplinkUL-SCH Uplink shared channelUM Unacknowledged modeUMTS Universal mobile telecommunication systemUP User planeUPF User plane functionURLLC Ultra-reliable and low latency communicationsUSIM UMTS subscriber identity module

VV2X Vehicle to x communicationVCO Voltage controlled oscillatorVNA Vector network analyzerVRB Virtual resource block

WWLAN Wireless LAN

XX2 The interface between the eNBsX-MAC Computed MAC-IxNB Either NR NodeB or EUTRA NodeBXn The interface between the gNBsXn-C Xn-Control planeXn-U Xn-User planeXnAP Xn application protocolXRES Expected response

ZZF Zero forcing equalizationZP CSI-RS Zero power CSI-RS

3.2 References

Ref. 1 Digital Communications, John G. Proakis, Mcgraw-Hill Publ. Comp, Jan 2008

Ref. 2 Nachrichtenuebertragung, Prof. Dr. K.-D. Kammeyer, University of Bremen, ISBN 978-3-8351-0179-1, Teubner Verlag, March 2008

Ref. 3 Near Shannon Limit Error-Correction Coding and Decoding: Turbo Codes, C. Berrou, A. Glavieux and P. Thitimajshima, IEEE Interna-tional Communication Conference ICC, Geneva, May 1993, pp. 1064–1070

Ref. 4 Digital Communications, B. Sklar, 2nd Edition, Prentice-Hall, Upper Saddle River, NJ, 2001

Ref. 5 R. G. Gallager, Low-Density Parity-Check Codes. Cambridge, MA:MIT Press, 1963

Ref. 6 Sarah S. Johnson, Introducing Low-Density Parity-Check Codes, Newcastle university

Ref. 7 T. Strutz, LDPC codes – eine EinfuehrungRef. 8 R. M. Tanner, A recursive approach to low complexity codes, IEEE

Trans. Inform. Theory, vol. IT-27, no. 5, pp. 533–547, September 1981Ref. 9 E. Arıkan. Channel polarization: A method for constructing capacity-

achieving codes. In Proceedings IEEE International Symposium on Infor- mation Theory (ISIT), pages 1173–1177, July 2008

Ref. 10 M. Seidl, Polar Coding: Finite-Length Aspects Friedrich-Alexander Universität Erlangen-Nürnberg

Ref. 11 H. Vangala, Y. Hong, and E. Viterbo, Efficient Algorithms for System-atic Polar Encoding, IEEE

Ref. 12 E. Sasoglu, Polarization and Polar Codes. Now publishers, 2012Ref. 13 T. Richardson, S. Kudekar, Design of LDPC codes for 5G New Radio,

IEEE March 2018Ref. 14 S. Park, Y. Wu, H. Kim, N. Hur, J. Kim, Raptor-like rate compatible

LDPC codes and their puncturing performance for the cload transmis-sion system, IEEE June 2014

Ref. 15 http://www.3gpp.org/news-events/3gpp-news/1931-industry_pr_5g Press release from 3GPP meeting, Lisbon Dec 2017 about 5G NR com-pletion status

Ref. 16 3GPP R1-165177, see www.3gpp.org, NTTDoCoMo, View on 5G NR numerologies, 3GPP meeting #85, May 2016

Ref. 17 mmMAGIC, Deliverable D2.2 – Measurement Results and Final mmMAGIC Channel Models (download link from an external web site: https://bscw.5g-mmmagic.eu/pub/bscw.cgi/d202656/mmMAGIC_D2-2.pdf)

http://www.3gpp.org/news-events/3gpp-news/1931-industry_pr_5g

https://bscw.5g-mmmagic.eu/pub/bscw.cgi/d202656/mmMAGIC_D2-2.pdf

https://bscw.5g-mmmagic.eu/pub/bscw.cgi/d202656/mmMAGIC_D2-2.pdf

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