Internet DRAFT - draft-peng-rtgwg-apn-for-media-service
draft-peng-rtgwg-apn-for-media-service
Network Working Group S. Peng
Internet-Draft X. Geng
Intended status: Standards Track Huawei Technologies
Expires: 25 April 2024 23 October 2023
Application-aware Networking (APN) for Performance Enhancement of Media
Service
draft-peng-rtgwg-apn-for-media-service-00
Abstract
This draft explores the requirements and benefits of carrying media
metadata in the network layer (i.e. IP packets) by following the
Application-aware Networking (APN) framework with extension for the
application side, and defines the specific carrying information and
format.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 25 April 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Typical Use Cases of Media Service . . . . . . . . . . . . . 3
3.1. Cloud Extended reality (XR) . . . . . . . . . . . . . . . 3
3.2. Cloud Gaming . . . . . . . . . . . . . . . . . . . . . . 4
3.3. Metaverse . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Media Service and 5G network . . . . . . . . . . . . . . . . 4
4.1. Architecture of 5G network . . . . . . . . . . . . . . . 4
4.2. Media Delivery in 5G Network . . . . . . . . . . . . . . 5
4.3. Challenges on Media Delivery . . . . . . . . . . . . . . 6
5. APN for Media Delivery . . . . . . . . . . . . . . . . . . . 7
5.1. Use Case 1 and Requirements . . . . . . . . . . . . . . . 7
5.2. Use Case 2 and Requirements . . . . . . . . . . . . . . . 8
5.3. Use Case 3 and Requirements . . . . . . . . . . . . . . . 8
6. Media Metadata . . . . . . . . . . . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
8. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
10. Normative References . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Media services are highly demanding but have very wide applications,
especially in the new era, such as extended reality (XR) and cloud
gaming. Metaverse has been in various ways referring to broader
implication of extended reality. For providing more immersing
experience, some advanced XR may include more modalities besides
video and audio stream, such as haptic data or sensor data. The
rapid development of extended reality technology and computer
graphics has created the technical basis for the development of
various media services.
To facilitate the media service performance, necessary metadata is
desired to be exchanged among media applications and network devices.
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The Application-aware Networking (APN) framework
[I-D.li-apn-framework] defines that application-aware information
(i.e. APN attribute) including APN identification (ID) and/or APN
parameters (e.g. network performance requirements) is encapsulated at
network edge devices and carried in packets traversing an APN domain
in order to facilitate service provisioning, perform fine-granularity
traffic steering and network resource adjustment.
[I-D.li-rtgwg-apn-app-side-framework] defines the extension of the
APN framework for the application side. In this extension, the APN
resources of an APN domain is allocated to applications which compose
and encapsulate the APN attribute in packets.
This draft explores the requirements and benefits of carrying media
metadata in the network layer (i.e. IP packets), and defines the
specific carrying information and format.
2. Requirements
Necessary metadata is desired to be exchanged among media
applications and network devices.
The corresponding mechanisms for exchanging the necessary metadata
are desired.
This metadata needs to be designed following the principles as
specified in RFC 9419 [RFC9419]. The metadata being carried needs to
be minimal, compact and has low processing overhead per-packet for
encoding and retrieval.
3. Typical Use Cases of Media Service
3.1. Cloud Extended reality (XR)
Extended reality (XR) refers to all real-and-virtual combined
environments and human-machine interactions generated by computer
technology and wearables. It includes representative forms such as
AR, MR and VR and the areas interpolated among them. For providing
more immersing experience, some advanced XR may include more
modalities besides video and audio stream, such as haptic data or
sensor data.
Cloud XR migrates the computing resource-intensive tasks, such as
video rendering, computing acceleration and other tasks with high
requirements for hardware, from terminals to the data center for
processing. In this way, client act only as a video player, which
improves the mobility and flexibility of XR, and greatly reduces
terminal costs.
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3.2. Cloud Gaming
Cloud gaming is to deploy the game application in the data center,
and realize the functions includes the logical process of game
command control, as well as the tasks of game acceleration, video
rendering and other tasks with high requirements for chips. In this
way, the terminal is a video player. Users can get a good game
experience without the support of high-end system and chips.
Compared with the traditional game mode, there are several advantages
of cloud game, such as no installation, no upgrade, no repair, quick
to play and reduce the terminal cost, so it will have stronger
promotion.
3.3. Metaverse
The term, metaverse, refer to a persistent, shared, perceived set of
interactive perceived spaces, which is facilitated by integrating
various new technologies, such as extended reality, digital twin, and
blockchain. Users can be allowed to produce and edit content in the
metaverse which combines the virtual world with the real world in
economic systems, social systems, and identity systems. Metaverse
has been in various ways to refer to the broader implications of
extended reality, and it in diverse sectors evokes a number of
possible new experiences, products and services that may emerge once
metaverse-related technologies become commonly available and find
application in our work, leisure and other activities.
The rapid development of extended reality technology and computer
graphics created the technical basis for the development of the
Metaverse. At the primary level, metaverse is still in its infancy
and its business model is immature.
4. Media Service and 5G network
4.1. Architecture of 5G network
The high level architecture of 5G network is depicted as the
following figure.
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+----+ +-----+ +-----+ +----+
| AMF|-NG11-| SMF |- NG7-| PCF |-NG6-| AF |
+----+ +-----+ +-----+ +----+
| | |
+-----+ | |
NG1 NG2 NG4
| | |
+--+-+/ +-----+/ +---+-+ +-----+
| UE |----| RAN |-NG3-| UPF |--NG6--| DN |
|----+ +- --+ +-----+ +-----+
Overview of 5G Network Architecture
The 5G network includes Radio access network (RAN) and Core network
(CN). The RAN provides network access capability for the client with
wireless interface, i.e., the 5G NR interface.
The CN includes user plane function (UPF) and control plane function
(CPF). The UPF provides service delivery related function, e.g. IP
packet routing & forwarding. The CPF provide signaling control
related function, e.g. session establishment, mobility management.
The CPFs include many control plane elements, e.g. Access and
Mobility Management Function (AMF), Policy Control Function (PCF),
Session Management Function (SMF) and Network Exposure Function
(NEF).
4.2. Media Delivery in 5G Network
The media delivery may benefit from the 5G architectural functions,
e.g. quality of service (QoS) and edge computing.
The 5G QoS model is based on QoS Flows. The 5G QoS model supports
both QoS Flows that require guaranteed flow bit rate (GBR QoS Flows)
and QoS Flows that do not require guaranteed flow bit rate (Non-GBR
QoS Flows). A QoS Flow ID (QFI) is used to identify a QoS Flow in
the 5G System. User Plane traffic with the same QFI receives the
same traffic forwarding treatment (e.g. scheduling, admission
threshold). For real time media service, e.g. the cloud VR, the 5G
network may provide the necessary QoS handling with appropriate bit
rate and delay.
Edge computing enables operator and 3rd party services to be hosted
close to the UE's access point of attachment, so as to achieve an
efficient service delivery through the reduced end-to-end latency and
load on the transport network. Edge computing can be supported by
one or a combination of the following enablers:
- User plane (re)selection: the 5G Core Network (re)selects UPF to
route the user traffic to the local Data Network.
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- Local Routing and Traffic Steering: the 5G Core Network selects the
traffic to be routed to the applications in the local Data Network.
- Session and service continuity to enable UE and application
mobility.
- The application may influence UPF (re)selection and traffic routing
via PCF or NEF.
- Network capability exposure: 5G Core Network and application to
provide information to each other via NEF or directly.
- QoS and Charging: PCF provides rules for QoS Control and Charging
for the traffic routed to the local Data Network.
- Support of Local Area Data Network: 5G Core Network provides
support to connect to the LADN in a certain area where the
applications are deployed.
4.3. Challenges on Media Delivery
The media traffic, e.g. cloud XR and cloud gaming, has the
characteristics of high throughput, low latency, and high reliability
requirement.
Considering the user experience, cloud XR usually needs a high
bandwidth, e.g. 100Mbps, due to the downlink video/haptic feedback
data, and a low end-to-end latency less than 20ms. With introducing
the cloud server, the transmission distance and downlink traffic load
are extended compared with the traditional XR mode. Therefore, cloud
XR imposes strict requirements on the latency, network bandwidth, and
reliability of the entire communication process.
Currently, it can only support limited XR capacity in 5G network due
to high requirement on data rate, reliability and latency. As
evaluated in 3GPP, one cell with 100MHz bandwidth could just support
5 XR users. It is a big challenge how to improve the system capacity
to support more XR users.
To provide good service experience for users, the XR services with
real-time interaction typically require very low motion-to-photon
(MTP) latency. Poor MTP latency performance leads to spatial
disorientation, motion sickness and dizziness. It is a big challenge
how to meet the very low RTT latency requirement in variable wireless
networks.
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5. APN for Media Delivery
All media traffic, in spite of which codec was used, have some common
characteristics. These characteristics can be very useful for better
transmission control and efficiency. However, currently 5GS uses
common QoS mechanisms to handle media services together with other
data services without taking full advantage of these information.
In order to cope with the challenges of media delivery, it is a
possible way to make the network learn more information of media
service to enhance the experience of these media services.
[I-D.li-apn-framework] proposes the framework of Application-aware
Networking (APN), where application-aware information (APN attribute)
including application-aware identification (APN ID) and application-
aware parameters (APN Parameters), is encapsulated at network edge
devices and carried along with the encapsulation of the tunnel used
by the packet when traversing the APN domain. By APN domain we
intend the operator infrastructure where APN is used from edge to
edge (ingress to egress) and where the packet is encapsulated using
an outer header incorporating the APN information. The APN attribute
will facilitate service provisioning and provide fine-granularity
services in the APN domain.
[I-D.li-apn-framework] defines the extension of the APN framework for
the application side. APN framework can be adopted to provide more
application-aware information of media services to the network. Then
the network can take use of these application-aware information to
provide enhanced network services to improve the experience of media
services.
5.1. Use Case 1 and Requirements
APN Attribute can carry the packet dependency information for the
media service. Packets within a frame have dependency with each
other since the application needs all of these packets for decoding
the frame. Hence one packet loss will make other correlative packets
useless even if they are successfully transmitted.
[REQ11] APN SHOULD be extended to carry the packet dependency
information.
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5.2. Use Case 2 and Requirements
Media packets have different importance. Packets of the same video
stream but different frame types (I/P frame) or even different
positions in the GoP (Group of Picture) are of different
contributions to user experience, so a layered QoS handling within
the video stream can potentially relax the requirement thus lead to
higher efficiency. APN Attribute can be adopted to carry information
about the frame types and positions in the GoP.
[REQ21] APN SHOULD be extended to carry information about frame types
and positions in the GoP.
5.3. Use Case 3 and Requirements
The XR/media traffic has natural interval between periodic video/
audio frames. It would be possible to enhance power saving
mechanisms (e.g. CDRX) considering the XR/media traffic pattern.
APN Attribute can be used to carry such information.
[REQ31] APN SHOULD be extended to carry informaton about XR/media
traffic pattern.
6. Media Metadata
This Media Metadata parameter indicates the media application-aware
information requested by the APN traffic to satisfy the potential
requirements raised above, e.g. packet dependency, frame types, and
so on. A format example of this parameter is shown in the following
diagram:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Media Metadata |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The detailed design of this metadata parameter proposed by use cases
of APN for media services as well as its encapsulation will be
defined in the future version of the draft.
7. IANA Considerations
TBD.
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8. Security Considerations
TBD.
9. Acknowledgements
10. Normative References
[I-D.li-apn-framework]
Li, Z., Peng, S., Voyer, D., Li, C., Liu, P., Cao, C., and
G. S. Mishra, "Application-aware Networking (APN)
Framework", Work in Progress, Internet-Draft, draft-li-
apn-framework-07, 3 April 2023,
<https://datatracker.ietf.org/doc/html/draft-li-apn-
framework-07>.
[I-D.li-rtgwg-apn-app-side-framework]
Li, Z. and S. Peng, "Extension of Application-aware
Networking (APN) Framework for Application Side", Work in
Progress, Internet-Draft, draft-li-rtgwg-apn-app-side-
framework-00, 22 October 2023,
<https://datatracker.ietf.org/doc/html/draft-li-rtgwg-apn-
app-side-framework-00>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC9419] Arkko, J., Hardie, T., Pauly, T., and M. Kühlewind,
"Considerations on Application - Network Collaboration
Using Path Signals", RFC 9419, DOI 10.17487/RFC9419, July
2023, <https://www.rfc-editor.org/info/rfc9419>.
Authors' Addresses
Shuping Peng
Huawei Technologies
China
Email: pengshuping@huawei.com
Xuesong Geng
Huawei Technologies
China
Email: gengxuesong@huawei.com
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