Network Working Group Y. Zha
Internet Draft Huawei Technologies
Intended status: Informational
Expires: January 2016
July 1, 2015
Deterministic Networking Use Case in Mobile Network
draft-zha-detnet-use-case-00
Abstract
This document describes some high level use cases and scenarios
with requirements on delay sensitive and deterministic networking.
Not only the telecom industry but also vertical industries have
been investigated. In addition to the 5G networking, industrial
automation, automotive industry, media and gaming industry are
typical related industries believed to be representative for the
technical requirements on ultra-fast and ultra-reliability
communications.
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Table of Contents
1. Introduction .................................................2
2. Conventions used in this document ............................3
3. Critical Delay Requirements ..................................4
4. Coordinated multipoint processing (CoMP) .....................5
4.1. CoMP Architecture .......................................5
4.2. Delay Sensitivity in CoMP ...............................6
5. Industrial Automation ........................................6
6. Vehicle to Vehicle ...........................................7
7. Gaming, Media and Virtual Reality ............................7
8. Security Considerations ......................................8
9. IANA Considerations ..........................................8
10. Acknowledgments .............................................8
11. References ..................................................8
11.1. Normative References ...................................8
11.2. Informative References .................................8
1. Introduction
The rapid growth of the today's communication system and its
access into almost all aspects of daily life has led to great
dependency on services it provides. The communication network, as
it is today, has applications such as multimedia and peer-to-peer
file sharing distribution that require Quality of Service (QoS)
guarantees in terms of delay and jitter to maintain a certain
level of performance. Meanwhile, mobile wireless communications
has become an important part to support modern sociality with
increasing importance over the last years. A communication network
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of hard real-time and high reliability is essential for the next
concurrent and next generation mobile wireless networks as well as
its bearer network for E-2-E performance requirements.
Conventional transport network is IP-based because of the
bandwidth and cost requirements. However the delay and jitter
guarantee becomes a challenge in case of contention since the
service here is not deterministic but best effort. With more and
more rigid demand in latency control in the future network [METIS],
deterministic networking [I-D.finn-detnet-architecture] is a
promising solution to meet the ultra low delay applications and
use cases. There are already typical issues for delay sensitive
networking requirements in midhaul and backhaul network to support
LTE and future 5G network [5G]. And not only in the telecom
industry but also other vertical industry has increasing demand on
delay sensitive communications as the automation becomes critical
recently.
More specifically, CoMP techniques, D-2-D, industrial automation
and gaming/media service all have great dependency on the low
delay communications as well as high reliability to guarantee the
service performance. Note that the deterministic networking is not
equal to low latency as it is more focused on the worst case delay
bound of the duration of certain application or service. It can be
argued that without high certainty and absolute delay guarantee,
low delay provisioning is just relative [RFC3393], which is not
sufficient to some delay critical service since delay violation in
an instance cannot be tolerated. Overall, the requirements from
vertical industries seem to be well aligned with the expected low
latency and high determinist performance of future networks
This document describes several use cases and scenarios with
requirements on deterministic delay guarantee within the scope of
the deterministic network [I-D.finn-detnet-problem-statement].
2. Conventions used in this document
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 [RFC2119]. In
this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to
be interpreted as carrying [RFC2119] significance.
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3. Critical Delay Requirements
Delay and jitter requirement has been take into account as a major
component in QoS provisioning since the birth of Internet. The
delay sensitive networking with increasing importance become the
root of mobile wireless communications as well as the applicable
areas which are all greatly relied on low delay communications.
Due to the best effort feature of the IP networking, mitigate
contention and buffering is the main solution to serve the delay
sensitive service. More bandwidth is assigned to keep the link low
loaded or in another word, reduce the probability of congestion.
However, not only lack of determinist but also has limitation to
serve the applications in the future communication system, keeping
low loaded cannot provide deterministic delay guarantee.
Take the [METIS] that documents the fundamental challenges as well
as overall technical goal of the 5G mobile and wireless system as
the starting point. It should supports:
-1000 times higher mobile data volume per area,
-10 times to 100 times higher typical user data rate,
-10 times to 100 times higher number of connected devices,
-10 times longer battery life for low power devices, and
-5 times reduced End-to-End (E2E) latency,
at similar cost and energy consumption levels as today's system.
Taking part of these requirements related to latency, current LTE
networking system has E2E latency less than 20ms [LTE-Latency]
which leads to around 5ms E2E latency for 5G networks. It has been
argued that fulfill such rigid latency demand with similar cost
will be most challenging as the system also requires 100 times
bandwidth as well as 100 times of connected devices. As a result
to that, simply adding redundant bandwidth provisioning can be no
longer an efficient solution due to the high bandwidth
requirements more than ever before. In addition to the bandwidth
provisioning, the critical flow within its reserved resource
should not be affected by other flows no matter the pressure of
the network. Robust defense of critical flow is also not depended
on redundant bandwidth allocation.
Deterministic networking techniques in both layer-2 and layer-3
using IETF protocol solutions can be promising to serve these
scenarios.
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4. Coordinated multipoint processing (CoMP)
In the wireless communication system, Coordinated multipoint
processing (CoMP) is considered as an effective technique to solve
the inter-cell interference problem to improve the cell-edge user
throughput [CoMP].
4.1. CoMP Architecture
+--------------------------+
| CoMP |
+--+--------------------+--+
| |
+----------+ +------------+
| Uplink | | Downlink |
+-----+----+ +--------+---+
| |
------------------- -----------------------
| | | | | |
+---------+ +----+ +-----+ +------------+ +-----+ +-----+
| Joint | | CS | | DPS | | Joint | | CS/ | | DPS |
|Reception| | | | | |Transmission| | CB | | |
+---------+ +----+ +-----+ +------------+ +-----+ +-----+
| |
|----------- |-------------
| | | |
+------------+ +---------+ +----------+ +------------+
| Joint | | Soft | | Coherent | | Non- |
|Equalization| |Combining| | JT | | Coherent JT|
+------------+ +---------+ +----------+ +------------+
Figure 1: Framework of CoMP Technology
As shown in figure 1, CoMP reception and transmission is a
framework that multiple geographically distributed antenna nodes
cooperate to improve the performance of the users served in the
common cooperation area. The design principal of CoMP is to extend
the current single-cell to multi-UEs transmission to a multi-cell-
to-multi-UEs transmission by base station cooperation. In contrast
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to single-cell scenario, CoMP has critical issues such as:
Backhaul latency, CSI (Channel State Information) reporting and
accuracy and Network complexity. Clearly the first two
requirements are very much delay sensitive and will be discussed
in next section.
4.2. Delay Sensitivity in CoMP
As the essential feature of CoMP, signaling is exchanged between
eNBs, the backhaul latency is the dominating limitation of the
CoMP performance. Generally, JT and JP may benefit from
coordinating the scheduling (distributed or centralized) of
different cells in case that the signaling exchanging between eNBs
is limited to 4-10ms. For C-RAN the backhaul latency requirement
is 250us while for D-RAN it is 4-15ms. And this delay requirement
is not only rigid but also absolute since any uncertainty in delay
will down the performance significantly. Note that, some
operator's transport network is not build to support Layer-3
transfer in aggregation layer. In such case, the signaling is
exchanged through EPC which means delay is supposed to be larger.
CoMP has high requirement on delay and reliability which is lack
by current mobile network systems and may impact the architecture
of the mobile network.
5. Industrial Automation
Traditional "industrial automation" terminology usually refers to
automation of manufacturing, quality control and material
processing. "Industrial internet" and "industrial 4.0" [EA12] is
becoming a hot topic based on the Internet of Things. This high
flexible and dynamic engineering and manufacturing will result in
a lot of so-called smart approaches such as Smart Factory, Smart
Products, Smart Mobility, and Smart Home/Buildings. No doubt that
ultra high reliability and robustness is a must in data
transmission, especially in the closed loop automation control
application where delay requirement is below 1ms and packet loss
less than 10E-9. All these critical requirements on both latency
and loss cannot be fulfilled by current 4G communication networks.
Moreover, the collaboration of the industrial automation from
remote campus with cellular and fixed network has to be built on
an integrated, cloud-based platform. In this way, the
deterministic flows should be guaranteed regardless of the amount
of other flows in the network. The lack of this mechanism becomes
the main obstacle in deployment on of industrial automation.
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6. Vehicle to Vehicle
V2V communication has gained more and more attention in the last
few years and will be increasingly growth in the future. Not only
equipped with direct communication system which is short ranged,
V2V communication also requires wireless cellular networks to
cover wide range and more sophisticated services. V2V application
in the area autonomous driving has very stringent requirements of
latency and reliability. It is critical that the timely arrival of
information for safety issues. In addition, due to the limitation
of processing of individual vehicle, passing information to the
cloud can provide more functions such as video processing, audio
recognition or navigation systems. All of those requirements lead
to a highly reliable connectivity to the cloud. On the other hand,
it is natural that the provisioning of low latency communication
is one of the main challenges to be overcome as a result of the
high mobility, the high penetration losses caused by the vehicle
itself. As result of that, the data transmission with latency
below 5ms and a high reliability of PER below 10E-6 are demanded.
It can benefit from the deployment of deterministic networking
with high reliability.
7. Gaming, Media and Virtual Reality
Online gaming and cloud gaming is dominating the gaming market
since it allow multiple players to play together with more
challenging and competing. Connected via current internet, the
latency can be a big issue to degrade the end users' experience.
There different types of games and FPS (First Person Shooting)
gaming has been considered to be the most latency sensitive online
gaming due to the high requirements of timing precision and
computing of moving target. Virtual reality is also receiving more
interests than ever before as a novel gaming experience. The delay
here can be very critical to the interacting in the virtual world.
Disagreement between what is seeing and what is feeling can cause
motion sickness and affect what happens in the game. Supporting
fast, real-time and reliable communications in both PHY/MAC layer,
network layer and application layer is main bottleneck for such
use case.
The media content delivery has been and will become even more
important use of Internet. Not only high bandwidth demand but also
critical delay and jitter requirements have to be taken into
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account to meet the user demand. To make the smoothness of the
video and audio, delay and jitter has to be guaranteed to avoid
possible interruption which is the killer of all online media on
demand service. Now with 4K and 8K video in the near future, the
delay guarantee become one of the most challenging issue than ever
before. 4K/8K UHD video service requires 6Gbps-100Gbps for
uncompressed video and compressed video starting from 60Mbps. The
delay requirement is 100ms while some specific interactive
applications may require 10ms delay [UHD-video].
8. Security Considerations
TBD
9. IANA Considerations
This document has no actions for IANA.
10. Acknowledgments
This document has benefited from reviews, suggestions, comments
and proposed text provided by the following members, listed in
alphabetical order: Jing Huang, Junru Lin, Lehong Niu and Oilver
Huang.
11. References
11.1. Normative References
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3393] C. Demichelis, "IP Packet Delay Variation Metric for IP
Performance Metrics (IPPM) ", RFC 3393, Novermber 2002.
11.2. Informative References
[I-D.finn-detnet-problem-statement]
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Finn, N. and P. Thubert, "Deterministic Networking Problem
Statement", draft-finn-detnet-problem-statement-01 (work in
progress), October 2014.
[I-D.finn-detnet-architecture]
Finn, N., Thubert, P., and M. Teener, "Deterministic Networking
Architecture", draft-finn-detnet-architecture-01 (work in
progress), March 2015.
[METIS] METIS Document Number: ICT-317669-METIS/D1.1, Scenarios,
requirements and KPIs for 5G mobile and wireless system, April 29,
2013. Available on line at: <https://www.metis2020.com/wp-
content/uploads/deliverables/METIS_D1.1_v1.pdf>
[5G] Ericsson white paper, "5G Radio Access, Challenges for 2020
and Beyond." June 2013. Available at:
<http://www.ericsson.com/res/docs/whitepapers/wp-5g.pdf>
[CoMP] NGMN Alliance, "RAN EVOLUTION PROJECT COMP EVALUATION AND
ENHANCEMENT ", MARCH 2015,
<https://www.ngmn.org/uploads/media/NGMN_RANEV_D3_CoMP_Evaluation_
and_Enhancement_v2.0.pdf>
[LTE-Latency]Samuel Johnston, "LTE Latency: How does it compare to
other technologies?" report of OpenSignal March 10, 2014.
<http://opensignal.com/blog/2014/03/10/lte-latency-how-does-it-
compare-to-other-technologies/>
[EA12] P. C. Evans, M. Annunziata, "Industrial Internet: Pushing the
Boundaries of Minds and Machines", General Electric White paper,
November 2012.
[UHD-video] Petr Holub, "Ultra-High Definition Videos and Their
Applications over the Network", The 7th International Symposium on
VICTORIES Project, OCTOBER 8, 2014. <http://www.aist-
victories.org/jp/7th_sympo_ws/PetrHolub_presentation.pdf>
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Authors' Addresses
Yiyong Zha
Huawei Technologies
Email: zhayiyong@huawei.com
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