Content for TR 38.838 Word version: 17.0.0

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1 Scope p. 11

The present document captures the results and findings from the study item "Study on XR Evaluation for NR"[2].

The purpose of this TR is

to document the evaluation methodology for XR evaluation including XR applications, simulation scenarios, traffic models, KPIs, simulation parameters, etc,
to document the performance evaluation results of XR applications in NR for both FR1 and FR2 considering the scenarios and services of interest,
to document the identified problems/challenges in supporting XR applications of interest in various scenarios.

This activity involves the Radio Access work area of the 3GPP studies and has potential impacts both on the Mobile Equipment and Access Network of the 3GPP systems.

2 References p. 11

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".

[2]

3GPP RP-201145: "Revised SI on XR Evaluations for XR".

[3]

3GPP R1-2104023: "LS on Status Update on XR Traffic".

[4]

3GPP S4-210614: "FS_XRTRaffic: Permanent document, v0.6.0".

[5]

TS 23.501: "System architecture for the 5G System (5GS) ".

[6]

TR 38.840: "Study on User Equipment (UE) power saving in NR".

[7]

3GPP R1-2101765: "LS on XR-Traffic Models".

3 Definitions of terms, symbols and abbreviations p. 11

3.1 Terms p. 11

For the purposes of the present document, the terms and definitions given in TR 21.905 apply.

For the purposes of the present document, the abbreviations given in TR 21.905 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.

ACK

Acknowledgement

Augmented Reality

BWP

Bandwidth Part

CDRX

Connected mode Discontinuous Reception

Cloud Gaming

CSI

Channel State Information

Downlink

DMRS

Dedicated Demodulation Reference Signals

Dense Urban

FDD

Frequency Division Duplex

gNB

NR Node B

fps

Frames per second

FR1

Frequency Range 1

FR2

Frequency Range 2

HARQ

Hybrid Automatic Repeat reQuest

iBLER

initial BLock Error Rate

InH

Indoor Hotspot

MCS

Modulation and Coding Scheme

Multi-User (MIMO)

MU-MIMO

Multi-User Multiple-Input Multiple-Output

Mixed Reality

MIMO

Multiple-Input Multiple-Output

NACK

Negative Acknowledgement

PDCCH

Physical Downlink Control Channel

PDB

Packet Delay Budget

PDCCH

Physical Downlink Control Channel

PDSCH

Physical Downlink Shared Channel

PSG

Power Saving Gain

PSR

Packet Success Rate

PUCCH

Physical Uplink Control Channel

PUSCH

Physical Uplink Shared Channel

Scheduling Request

Single-User (MIMO)

SU-MIMO

Single-User Multiple-Input Multiple-Output

STD

STandard Deviation

TDD

Time Division Duplex

User Equipment

UMa

Urban Macro

Uplink

Virtual Reality

Extended Reality

4 Introduction p. 12

XR Applications

eXtended Reality(XR) is a term for different types of realities and refers to all real-and-virtual combined environments and human-machine interactions generated by computer technology and wearables. It includes following representative forms and the areas interpolated among them.

Augmented Reality (AR)
Mixed Reality (MR)
Virtual Reality (VR)

XR and Cloud Gaming (CG) are currently one of the most important 5G media applications under consideration in the industry [2].

System Architecture

One specific aspect to be considered is the role of Edge Computing as a network architecture to enable XR and Cloud Gaming. Edge Computing is a concept that enables cloud computing capabilities and service environments to be deployed close to the cellular network. It promises several benefits such as lower latency, higher bandwidth, reduced backhaul traffic and prospects for several new services as indicated in the SA6 Study on application architecture for enabling Edge Applications (TR 23.758). Edge Applications are expected to take advantage of the low latencies enabled by 5G and the Edge network architecture to reduce the end-to-end Application-level latencies. Edge Computing is a valuable enabler which should be considered to help 5G systems achieve the required performance to enable XR and Cloud Gaming [2].

Traffic Characteristics

5G NR is designed to support applications demanding high throughput and low latency in line with the requirements posed by the support of XR and Edge Computing applications in NR networks. XR and Edge Computing are services enabled by Rel-15 NR networks [2].

Objectives

The objectives of this study are as follows.

Confirm XR and Cloud Gaming applications of interest
Identify the traffic model for each application of interest taking outcome of SA WG4 work as input, including considering different upper layer assumptions, e.g. rendering latency, codec compression capability etc.
Identify evaluation methodology to assess XR and CG performance along with identification of KPIs of interest for relevant deployment scenarios
Once traffic model and evaluation methodologies are agreed, carry out performance evaluations towards characterization of identified KPIs