ETSI TR 121 915 V15.0.0 (2019-10)

Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); LTE; 5G; Release description; Release 15 (3GPP TR 21.915 version 15.0.0 Release 15)

DTR/TSGS-0021915vf00

General Information

• Status: Published
• Publication Date: 15-Oct-2019
• Technical Committee: 3GPP SA - Technical Specification Group Services and System Aspects
• Current Stage: 12 - Completion
• Completion Date: 16-Oct-2019

Standards Content (Sample)

TECHNICAL REPORT
Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS);
LTE;
5G;
Release description;
Release 15
(3GPP TR 21.915 version 15.0.0 Release 15)

3GPP TR 21.915 version 15.0.0 Release 15 1 ETSI TR 121 915 V15.0.0 (2019-10)

Reference
DTR/TSGS-0021915vf00
Keywords
5G,GSM,LTE,UMTS
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Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 7
Introduction . 7
1 Scope . 8
2 References . 8
3 Definitions of terms, symbols and abbreviations . 8
3.1 Terms . 8
3.2 Symbols . 8
3.3 Abbreviations . 8
4 Rel-15 Executive Summary . 9
5 The 5G System (5GS) - Phase 1 . 9
5.1 Work organisation for 5GS . 9
5.2 The 5GS service aspects . 9
5.3 Overview of the 5GS architecture . 10
5.3.1 Introduction. 11
5.3.2 The NSA versus SA architecture . 11
5.3.3 Overview of the Core Network . 12
5.3.4 Overview of the Access Network . 13
5.3.5 References for 5GS Stage 2 . 13
5.5 One step deeper into the 5GS . 14
5.5.1 Functional split between Radio and Core . 14
5.5.2 The 5G Core Network. 15
5.5.2.1 Main NFs . 15
5.5.2.2 Specificities of the 5G Core Network and associated NFs . 16
5.5.2.2.1 Local hosting of services and Edge Computing . 16
5.5.2.2.2 Network slicing . 16
5.5.2.2.3 Unified access control . 17
5.5.2.2.4 Support of 3GPP and non-3GPP access . 17
5.5.2.2.5 Policy framework and QoS support . 17
5.5.2.2.6 Network capability exposure . 18
5.5.2.2.7 Other specific services . 18
5.5.2.2.8 Other 5G specificities . 18
5.5.2.3 CN protocols . 18
5.5.3 The 5G Access Network . 20
5.5.3.1 Introduction . 20
5.5.3.2 Overview of the AN Control Plane . 21
5.5.3.3 Overview of the AN User Plane . 22
5.5.3.4 The higher layers of the AN . 22
5.5.3.4.1 Layer 2 related aspects: MAC, RLC, PDCP user plane, PCP control plane, and SDAP . 22
5.5.3.4.2 RRC related aspects . 23
5.5.3.5 The Access Network interfaces . 23
5.5.3.5.1 Overview . 23
5.5.3.5.2 The Xn and X2 interfaces . 23
5.5.3.5.3 The NG and S1 interfaces . 24
5.5.3.5.4 The F1 interface . 25
5.5.4 Radio Physical layer aspects . 25
5.5.4.1 Numerologies, waveform and frame structure . 25
5.5.4.2 Physical Channels and Signals in NR . 26
5.5.4.3 Initial access and mobility . 27
5.5.4.4 MIMO aspects . 29
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5.5.4.5 PDCCH and PDSCH . 30
5.5.4.6 PUCCH and PUSCH . 31
5.5.4.7 Scheduling/HARQ . 32
5.5.4.8 Carrier Aggregation, Bandwidth Parts, and LTE/NR dual connectivity . 33
5.5.4.9 NR-LTE co-existence. 33
5.5.4.10 Supplementary Downlink . 33
5.5.4.11 Supplementary Uplink . 33
5.5.4.12 UL TPC . 34
5.5.5 Frequency aspects . 34
5.6 Other 5G aspects . 36
5.6.1 5G AN connected to 4G AN: NSA and EDCE5 . 36
5.6.1.1 Overview . 36
5.6.1.2 CN impacts: EPC enhancements to support 5G New Radio via Dual Connectivity (EDCE5) . 36
5.6.1.3 AN impacts: NSA radio protocol architecture . 38
5.6.1.3.1 Control Plane . 38
5.6.1.3.2 User Plane . 38
5.6.2 LTE connectivity to 5G-CN (4G AN with 5G CN) . 39
5.6.3 Security aspects of the 5G System - Phase 1 . 40
5.6.4 Charging and OAM aspects of 5G System - Phase 1 . 43
5.6.4.1 Data Charging in 5G System Architecture Phase 1 . 43
5.6.4.2 Other 5G System Charging aspects . 44
6 Critical Communications . 45
6.1 EPC support for E-UTRAN Ultra Reliable Low Latency Communication . 45
6.2 Highly Reliable Low Latency Communication for LTE . 45
7 Machine-Type of Communications (MTC) and Internet of T hings (IoT ) . 49
7.1 Improvements of Machine-Type of Communications (MTC) and Internet of Things (IoT) . 49
7.2 Further enhancements for Extended Coverage GSM for support of Cellular Internet of Things . 51
7.2.1 Introduction. 51
7.2.2 Energy Efficient Paging Reception with EC Paging Indication channel . 51
7.2.3 Deferred System Information Acquisition in EC operation and for PEO . 52
7.3 Even further enhanced MTC for LTE . 53
7.3.1 Support for new use cases . 53
7.3.2 Reduced latency . 53
7.3.3 Reduced UE power consumption . 54
7.3.4 Increased spectral efficiency . 54
7.3.5 Improved access control . 55
7.4 Other MTC related work . 55
74.1 AT Commands for CIoT-Ext . 55
74.2 Battery Efficient Security for very low Throughput MTC Devices . 55
8 Vehicle-to-Everything Communications (V2X) Improvements . 57
8.1 Enhancement of 3GPP support for V2X scenarios . 57
8.2 Enhancements on LTE-based V2X Services . 57
9 Improvements of Mission Critical (MC) . 59
9.1 Enhancements to MCPTT . 59
9.2 Enhancements to MC Data . 60
9.3 Enhancements to MC Video . 62
9.4 Other Mission Critical Enhancements . 62
9.4.1 MC Security Enhancements . 62
9.4.2 MBMS usage for MC communication services . 63
10 Features related to WLAN and unlicensed spectrum . 64
10.1 WLAN direct discovery . 64
10.2 Voice services over WLAN. 65
10.3 Unlicensed Spectrum Offloading System . 65
10.4 Enhancements to LTE operation in unlicensed spectrum . 66
10.5 Other functionalities related to WLAN and unlicensed spectrum . 67
11 Other new features. 68
11.1 Mobile Communication System for Railways . 68
11.2 Northbound APIs related features . 69
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11.2.1 Common API Framework for 3GPP Northbound APIs . 69
11.2.2 Northbound APIs for SCEF – SCS/AS Interworking . 71
12 System enhancements. 72
12.1 Control plane - user plane separation . 72
12.1.1 Separation of CP and UP for Split Option 2 of NR . 72
12.1.2 Management Enhancement for EPC Control and User Plane Separation (CUPS) . 73
12.2 Quality of Experience (QoE) related Features. 74
12.3 Security-related improvements . 75
12.4 Virtual Reality (VR), TV, Codec and multimedia-related improvements . 75
12.4.1 Test Methodologies for the Evaluation of Perceived Listening Quality in Immersive Audio Systems . 75
12.4.2 Addition of HDR to TV Video Profiles . 76
12.4.3 Virtual Reality Profiles for Streaming Media . 76
12.4.4 FEC and ROHC Activation for GCSE over MBMS . 78
12.4.5 Media Handling Aspects of 5G Conversational Services . 78
12.5 Codec and multimedia-related improvements . 79
12.5.1 Receive acoustic output test in the presence of background noise . 79
12.5.2 Server and Network Assisted DASH for 3GPP Multimedia Services . 79
12.5.3 SAND for MBMS . 80
12.5.4 Framework for Live Uplink Streaming . 81
12.5.5 Further video enhancements for LTE . 82
12.5.6 Speech quality with ambient noise . 82
12.6 Active Antenna System (AAS) . 83
12.6.1 Architecture and interfaces . 83
12.6.2 OTA requirements . 84
12.7 OAM improvements . 85
12.8 Other enhancements . 87
12.8.1 Simplified HS-SCCH for UMTS . 87
12.8.2 Increased number of E-UTRAN data bearers . 89
12.8.3 Increasing the number of EPS bearers . 90
12.8.4 Enhancement of background data transfer . 90
12.8.5 Enhanced VoLTE performance . 90
12.8.6 DL interference mitigation for UMTS . 91
12.8.7 Enhanced Calling Name Service . 92
12.8.8 PS Data Off Phase 2. 93
13 LTE improvements . 94
13.1 Further enhancements to Coordinated Multi-Point (CoMP) Operation for LTE . 94
13.2 Enhancements for high capacity stationary wireless link and introduction of 1024 QAM for LTE DL . 95
13.3 UE requirements for network-based CRS interference mitigation for LTE . 96
13.4 Bluetooth®/WLAN measurement collection in LTE Minimization of Drive Tests (MDT) . 97
13.5 UL data compression in LTE . 98
13.6 UE Positioning Accuracy Enhancements for LTE . 98
13.7 UE requirements for LTE DL 8Rx antenna ports . 99
13.8 Shortened TTI and processing time for LTE . 100
13.8.1 Short processing time for 1 ms TTI . 100
13.8.2 Short TTI . 101
13.9 Enhanced LTE Support for Aerial Vehicles . 105
13.10 Enhancing LTE CA Utilization . 106
14 OAM improvements . 106
14.1 Other 5G System Charging aspects . 106
14.1.1 Service Based Interface for 5G Charging . 106
14.1.2 Charging for IMS over 5G System Architecture Phase 1 . 107
14.1.3 SMS Charging in 5G System Architecture Phase 1 . 107
14.2 Management and virtualization aspects of 5G networks and network slicing . 108
15 Work Items for which no summary is needed . 110
Annex A: Structure of 5GS Rel-15 3GPP work. 112
Annex B: Process to get further information . 114
B.1 General . 114
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B.2 Direct method . 115
B.3 Step by step method . 115
Annex C: Change history . 118
History . 119

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Foreword
This Technical Report has been produced by the 3rd Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
Introduction
The present document provides a summary of each and every 3GPP Release 15 Feature, and more generally of all Work
Items for which a summary has been agreed to be provided.
These summaries are based on the inputs issued by the Work Item Rapporteurs, slightly rewritten by the TR Rapporteur
to ensure overall consistency. The original Work Item Rapporteur inputs can be retrieved as temporary document
(tdoc), as stated in the first sentence of each clause.
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1 Scope
The present document provides a summary of each Release 15 Feature or, whenever needed, of each significant Work
Item.
The information provided in the present document is limited to an overview of each Feature, explaining briefly its
purpose and the main lines of the system's behaviour to execute the Feature.
More information is available by consulting the 3GPP Ultimate web site, as explained in "Annex C: Process to get
further information".
The present document presents the "initial state" of the Features introduced in Release 15, i.e. as they are by the time of
publication of the present document. Each Feature is subject to be later modified or enhanced, over several years, by the
means of Change Requests (CRs). It is therefore recommended to retrieve all the CRs which relate to the given Feature,
as explained in Annex C, to further outline a feature at a given time.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including
a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same
Release as the present document.
[1] TR 21.905: "Vocabulary for 3GPP Specifications".
NOTE: Due to the specificity of the present document, consisting in a collection of independent summaries, the
references are given at the end of each clause rather than in this clause.
3 Definitions of terms, symbols and abbreviations
3.1 Terms
For the purposes of the present document, the terms given in TR 21.905 [1] and the following apply. A term defined in
the present document takes precedence over the definition of the same term, if any, in TR 21.905 [1].
3.2 Symbols
Void.
3.3 Abbreviations
For the purposes of the present document, the abbreviations given in TR 21.905 [1] and the following apply.
An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any,
in TR 21.905 [1]. Abbreviations specific to a given clause are provided in the clause they appear.
KPI Key Performance Indicator
Rel 3GPP Release
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4 Rel-15 Executive Summary
3GPP main area of work in Release 15 is the definition of the initial phase of 5G, the Fifth Generation of Mobile
Communications, also referred to as "5GS" ("the 5G System").
5G is to be defined in at least 2 phases, the phase 1 being specified in Release 15, as summarised in the present
document. Subsequent phase(s) will be specified in future Release(s).
Beside 5G Phase 1, Release 15 also specifies, among other Features: further enhancements on Critical Communications
(including Ultra Reliable Low Latency Communication and Highly Reliable Low Latency Communication), Machine-
Type of Communications (MTC) and Internet of Things (IoT), Vehicle-related Communications (V2X), Mission
Critical (MC), and features related to WLAN and unlicensed spectrum.
The continuation of the present document provides an exhaustive view of all the items specified in Release 15 by 3GPP.
5 The 5G System (5GS) - Phase 1
5.1 Work organisation for 5GS
The 5G System is the main topic of 3GPP Release 15. Release 15 defines the 5G system Phase 1, while the 5G system
Phase 2 is to be defined in Release 16.
The specification of Phase 1 has involved all the 3GPP Working Groups and TSG, defining all the (many) necessary
aspects.
The table in Annex A provides the overall view of all the 5G-related work items in Rel-15, including their hierarchical
structure.
Next clauses provide a summary of 5G System service aspects, its architecture, the protocols, the radio aspects and
several specific aspects such as security, charging, etc.
5.2 The 5GS service aspects
Unique_ID Name Acronym WG WID WI Rapporteur
720005 (Stage 1 of 5G) New Services and Markets SMARTER S1 SP-160364 Vodafone , Li, Alice
Technology Enablers
Summary based on the input provided by Vodafone in SP-180883.
The 5G requirements have been defined in terms of new services and markets by SA1, under the "SMARTER" work
item. These are defined mostly in TS 22.261 [1], which describes different types of requirements for different 5G usage:
- Enhanced Mobile Broadband (eMBB): the new requirements -higher than for 4G- are specified for data-rates,
traffic/connection density, user mobility, etc. Various deployment and coverage scenarios are considered,
addressing different service areas (e.g., indoor/outdoor, urban and rural areas, office and home, local and wide
areas connectivity), and special deployments (e.g., massive gatherings, broadcast, residential, and high-speed
vehicles). The scenarios and their performance requirements can be found in table 7.1-1 of TS 22.261 [1]. For
instance, for the downlink, data rate of up to 50 Mbps are expected when outdoor and 1 Gbps when indoor
(5GLAN), and half of these values for the uplink. For services to an airplane, a bitrate of 1,2 Gbps is expected
per plane.
- Critical Communications (CC) and Ultra Reliable and Low Latency Communications (URLLC): Several
scenarios require the support of very low latency and very high communications service availability. These are
driven by the new services such as industrial automation. The overall service latency depends on the delay on the
radio interface, transmission within the 5G system, transmission to a server which may be outside the 5G system,
and data processing. Some of these factors depend directly on the 5G system itself, whereas for others the impact
can be reduced by suitable interconnections between the 5G system and services or servers outside of the 5G
system, for example, to allow local hosting of the services. The scenarios and their performance requirements
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can be found in table 7.2.2-1 of TS 22.261 [1]. For instance, in the context of remote control for process
automation, a reliability of 99,9999% is expected, with a user experienced data rate up to 100 Mbps and an end-
to-end latency of 50 ms. This is provided in particular through the Edge Computing capability described below.
- Massive Internet of Things (mIoT). Several scenarios require the 5G system to support very high traffic
densities of devices. The Massive Internet of Things requirements include the operational aspects that apply to
the wide range of IoT devices and services anticipated in the 5G timeframe.
- Flexible network operations. These are a set of specificities offered by the 5G system, as detailed in the
following sections. It covers aspects such as network slicing, network capability exposure, scalability, and
diverse mobility, security, efficient content delivery, and migration and interworking.
This diversity of requirements, associated to the different categories of usage described above, enables the use of the
5GS by different sectors of the industry, referred to as "verticals". Some of these verticals are mentioned in the annexes
of TS 22.261 [1]:
- Automotive and other transport (trains, maritime communications),
- Transport, logistics, IoT,
- Discrete automation,
- Electricity distribution,
- Public Safety,
- Health and wellness,
- Smart cities,
- Media and entertainment.
Some of these aspects are further described in corresponding clauses of this document: e.g. Railways, eV2X and its
associated requirements as defined in TS 22.186 [10], etc.
As for the migration path, the 5G system supports, in addition to the new 5G-specific services, all the former EPS (4G)
capabilities that were defined in TS 22.278 [2] and in TSs 22.011 [3], 22.101 [4], 22.185 [5], 22.071 [6], 22.115 [7],
22.153 [8], 22.173 [9]. There are some exceptions, i.e. some 4G services are not supported in 5G: they relate to the
interworking with legacy systems, as specified in clause 5.1.2.2 of TS 22.261. Finally, mobility between a 5G core
network and an EPC (4G) is supported, with minimum impact to the user experience.
NOTE: In this document, EPS and all the other concepts related to LTE, such as "LTE Advanced Pro", will be
referred to as "4G", although this is not an official 3GPP terminology.
References
[1] TS 22.261, "Service requirements for the 5G system".
[2] TS 22.278, "Service requirements for the Evolved Packet System (EPS)".
[3] TS 22.011, "Service accessibility".
[4] TS 22.101, "Service aspects; Service principles".
[5] TS 22.185, "Service requirements for V2X services".
[6] TS 22.071, "Location Services (LCS); Service description".
[7] TS 22.115, "Service aspects; Charging and billing".
[8] TS 22.153, "Multimedia priority service".
[9] TS 22.173, "IP Multimedia Core Network Subsystem (IMS) Multimedia Telephony Service and
supplementary services".
[10] TS 22.186, "Service requirements for enhanced V2X scenarios".

5.3 Overview of the 5GS architecture
Unique_ID Name Acronym WG WID WI Rapporteur
740061 Stage 2 of 5G System - Phase 1 5GS_Ph1 S2 SP-160958 China Mobile, Tao
Sun
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Summary based on the inputs provided by China Mobile, Nokia, Ericsson, Huawei in SP-180595, by Vodafone in SP-
180883 and by NTT DOCOMO, INC. in RP-181724.
5.3.1 Introduction
As seen above, 5G is designed to support diverse services with different data traffic profiles (e.g., high throughput, low
latency and massive connections) and models (e.g., IP data traffic, non-IP data traffic, short data bursts and high
throughput data transmissions). Various PDU session types are supported including IPv4, IPv6, IPv4v6, Ethernet and
Unstructured.
The 5G's main characteristic is the introduction of a new radio interface, the New Radio (NR), which offers the
flexibility needed to support these very different types of services.
Another key characteristic of 5G is that the 5G Access Network can connect not only to a new 5G Core Network but
also to the 4G (LTE) Core Network. This is known as the NSA architecture, while the 5G AN connected to a 5G CN is
called the SA architecture.
On the Core Network side, the 5G System offers also a wide array of new characteristics, such as a deeper use of
Network Slicing, Mobile Edge Computing or Network Capability Exposure. All these concepts are presented below.
5.3.2 The NSA versus SA architecture
Two deployment options are defined for 5G:
- the "Non-Stand Alone" (NSA) architecture, where the 5G Radio Access Network (AN) and its New Radio (NR)
interface is used in conjunction with the existing LTE and EPC infrastructure Core Network (respectively 4G Radio and
4G Core), thus making the NR technology available without network replacement. In this configuration, only the 4G
services are supported, but enjoying the capacities offered by the 5G New Radio (lower latency, etc). The NSA is also
known as "E-UTRA-NR Dual Connectivity (EN-DC)" or "Architecture Option 3". See also the clause on EDCE5.
- the "Stand-Alone" (SA) architecture, where the NR is connected to the 5G CN. Only in this configuration, the full
set of 5G Phase 1 services are supported.
The NSA architecture is illustrated in the following figure.

Figure 5.3.2-1: The NSA Architecture
The NSA architecture can be seen as a temporary step towards "full 5G" deployment, where the 5G Access Network is
connected to the 4G Core Network. In the NSA architecture, the (5G) NR base station (logical node "en-gNB")
connects to the (4G) LTE base station (logical node "eNB") via the X2 interface. The X2 interface was introduced prior
to Release 15 to connect two eNBs. In Release 15, it also supports connecting an eNB and en-gNB as to provide NSA.
The NSA offers dual connectivity, via both the 4G AN (E-
...