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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