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Versions: 00 01

RAW                                                      G. Papadopoulos
Internet-Draft                                            IMT Atlantique
Intended status: Standards Track                              P. Thubert
Expires: August 26, 2021                                           Cisco
                                                            F. Theoleyre
                                                           CJ. Bernardos
                                                       February 22, 2021

                             RAW use cases


   The wireless medium presents significant specific challenges to
   achieve properties similar to those of wired deterministic networks.
   At the same time, a number of use cases cannot be solved with wires
   and justify the extra effort of going wireless.  This document
   presents wireless use cases demanding reliable and available

Status of This Memo

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   This Internet-Draft will expire on August 26, 2021.

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   publication of this document.  Please review these documents
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Aeronautical Communications . . . . . . . . . . . . . . . . .   5
     2.1.  Problem Statement . . . . . . . . . . . . . . . . . . . .   5
     2.2.  Specifics . . . . . . . . . . . . . . . . . . . . . . . .   5
     2.3.  Challenges  . . . . . . . . . . . . . . . . . . . . . . .   6
     2.4.  The Need for Wireless . . . . . . . . . . . . . . . . . .   7
     2.5.  Requirements for RAW  . . . . . . . . . . . . . . . . . .   7
   3.  Amusement Parks . . . . . . . . . . . . . . . . . . . . . . .   7
     3.1.  Use Case Description  . . . . . . . . . . . . . . . . . .   7
     3.2.  Specifics . . . . . . . . . . . . . . . . . . . . . . . .   8
     3.3.  The Need for Wireless . . . . . . . . . . . . . . . . . .   8
     3.4.  Requirements for RAW  . . . . . . . . . . . . . . . . . .   9
   4.  Wireless for Industrial Applications  . . . . . . . . . . . .   9
     4.1.  Use Case Description  . . . . . . . . . . . . . . . . . .   9
     4.2.  Specifics . . . . . . . . . . . . . . . . . . . . . . . .  10
       4.2.1.  Control Loops . . . . . . . . . . . . . . . . . . . .  10
       4.2.2.  Unmeasured Data . . . . . . . . . . . . . . . . . . .  10
     4.3.  The Need for Wireless . . . . . . . . . . . . . . . . . .  11
     4.4.  Requirements for RAW  . . . . . . . . . . . . . . . . . .  11
   5.  Pro Audio and Video . . . . . . . . . . . . . . . . . . . . .  12
     5.1.  Use Case Description  . . . . . . . . . . . . . . . . . .  12
     5.2.  Specifics . . . . . . . . . . . . . . . . . . . . . . . .  12
       5.2.1.  Uninterrupted Stream Playback . . . . . . . . . . . .  12
       5.2.2.  Synchronized Stream Playback  . . . . . . . . . . . .  12
     5.3.  The Need for Wireless . . . . . . . . . . . . . . . . . .  12
     5.4.  Requirements for RAW  . . . . . . . . . . . . . . . . . .  13
   6.  Wireless Gaming . . . . . . . . . . . . . . . . . . . . . . .  13
     6.1.  Use Case Description  . . . . . . . . . . . . . . . . . .  13
     6.2.  Specifics . . . . . . . . . . . . . . . . . . . . . . . .  14
     6.3.  The Need for Wireless . . . . . . . . . . . . . . . . . .  14
     6.4.  Requirements for RAW  . . . . . . . . . . . . . . . . . .  14
   7.  UAV platooning and control  . . . . . . . . . . . . . . . . .  15
     7.1.  Use Case Description  . . . . . . . . . . . . . . . . . .  15
     7.2.  Specifics . . . . . . . . . . . . . . . . . . . . . . . .  15
     7.3.  The Need for Wireless . . . . . . . . . . . . . . . . . .  15
     7.4.  Requirements for RAW  . . . . . . . . . . . . . . . . . .  16
   8.  Edge Robotics control . . . . . . . . . . . . . . . . . . . .  16
     8.1.  Use Case Description  . . . . . . . . . . . . . . . . . .  16
     8.2.  Specifics . . . . . . . . . . . . . . . . . . . . . . . .  17

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     8.3.  The Need for Wireless . . . . . . . . . . . . . . . . . .  17
     8.4.  Requirements for RAW  . . . . . . . . . . . . . . . . . .  17
   9.  Emergencies: Instrumented emergency vehicle . . . . . . . . .  17
     9.1.  Use Case Description  . . . . . . . . . . . . . . . . . .  17
     9.2.  Specifics . . . . . . . . . . . . . . . . . . . . . . . .  18
     9.3.  The Need for Wireless . . . . . . . . . . . . . . . . . .  18
     9.4.  Requirements for RAW  . . . . . . . . . . . . . . . . . .  18
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  19
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  19
   12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  19
   13. Informative References  . . . . . . . . . . . . . . . . . . .  19
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  22

1.  Introduction

   Based on time, resource reservation, and policy enforcement by
   distributed shapers, Deterministic Networking provides the capability
   to carry specified unicast or multicast data streams for real-time
   applications with extremely low data loss rates and bounded latency,
   so as to support time-sensitive and mission-critical applications on
   a converged enterprise infrastructure.

   Deterministic Networking in the IP world is an attempt to eliminate
   packet loss for a committed bandwidth while ensuring a worst case
   end-to-end latency, regardless of the network conditions and across
   technologies.  It can be seen as a set of new Quality of Service
   (QoS) guarantees of worst-case delivery.  IP networks become more
   deterministic when the effects of statistical multiplexing (jitter
   and collision loss) are mostly eliminated.  This requires a tight
   control of the physical resources to maintain the amount of traffic
   within the physical capabilities of the underlying technology, e.g.,
   by the use of time-shared resources (bandwidth and buffers) per
   circuit, and/or by shaping and/or scheduling the packets at every

   Key attributes of Deterministic Networking include:

   o  time synchronization on all the nodes,

   o  centralized computation of network-wide deterministic paths,

   o  multi-technology path with co-channel interference minimization,

   o  frame preemption and guard time mechanisms to ensure a worst-case
      delay, and

   o  new traffic shapers within and at the edge to protect the network.

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   Wireless operates on a shared medium, and transmissions cannot be
   fully deterministic due to uncontrolled interferences, including
   self-induced multipath fading.  RAW (Reliable and Available Wireless)
   is an effort to provide Deterministic Networking Mechanisms on across
   a path that include a wireless physical layer.  Making Wireless
   Reliable and Available is even more challenging than it is with
   wires, due to the numerous causes of loss in transmission that add up
   to the congestion losses and the delays caused by overbooked shared

   The wireless and wired media are fundamentally different at the
   physical level, and while the generic Problem Statement [RFC8557] for
   DetNet applies to the wired as well as the wireless medium, the
   methods to achieve RAW necessarily differ from those used to support
   Time-Sensitive Networking over wires.

   So far, Open Standards for Deterministic Networking have prevalently
   been focused on wired media, with Audio/Video Bridging (AVB) and Time
   Sensitive Networking (TSN) at the IEEE and DetNet [RFC8655] at the
   IETF.  But wires cannot be used in a number of cases, including
   mobile or rotating devices, rehabilitated industrial buildings,
   wearable or in-body sensory devices, vehicle automation and
   multiplayer gaming.

   Purpose-built wireless technologies such as [ISA100], which
   incorporates IPv6, were developped and deployed to cope for the lack
   of open standards, but they yield a high cost in OPEX and CAPEX and
   are limited to very few industries, e.g., process control, concert
   instruments or racing.

   This is now changing [I-D.thubert-raw-technologies]:

   o  IMT-2020 has recognized Ultra-Reliable Low-Latency Communication
      (URLLC) as a key functionality for the upcoming 5G.

   o  IEEE 802.11 has identified a set of real-applications
      [ieee80211-rt-tig] which may use the IEEE802.11 standards.  They
      typically emphasize strict end-to-end delay requirements.

   o  The IETF has produced an IPv6 stack for IEEE Std. 802.15.4
      TimeSlotted Channel Hopping (TSCH) and an architecture
      [I-D.ietf-6tisch-architecture] that enables Reliable and Available
      Wireless (RAW) on a shared MAC.

   This draft extends the "Deterministic Networking Use Cases" document
   [RFC8578] and describes a number of additional use cases which
   require "reliable/predictable and available" flows over wireless
   links and possibly complex multi-hop paths called Tracks.  This is

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   covered mainly by the "Wireless for Industrial Applications" use
   case, as the "Cellular Radio" is mostly dedicated to the (wired)
   transport part of a Radio Access Network (RAN).  Whereas the
   "Wireless for Industrial Applications" use case certainly covers an
   area of interest for RAW, it is limited to 6TiSCH, and thus its scope
   is narrower than the use cases described next in this document.

2.  Aeronautical Communications

   Aircraft are currently connected to ATC (Air-Traffic Control) and AOC
   (Airline Operational Control) via voice and data communications
   systems through all phases of a flight.  Within the airport terminal,
   connectivity is focused on high bandwidth communications while during
   en-route high reliability, robustness and range is the main focus.

2.1.  Problem Statement

   Up to 2020 civil air traffic has been growing constantly at a
   compound rate of 5.8% per year [ACI19] and despite the severe impact
   of the COVID-19 pandemic, air traffic growth is expected to resume
   very quickly in post-pandemic times [IAT20] [IAC20].  Thus, legacy
   systems in air traffic management (ATM) are likely to reach their
   capacity limits and the need for new aeronautical communication
   technologies becomes apparent.  Especially problematic is the
   saturation of VHF band in high density areas in Europe, the US, and
   Asia [KEAV20] [FAA20] calling for suitable new digital approaches
   such as AeroMACS for airport communications, SatCOM for remote
   domains, and LDACS as long-range terrestrial aeronautical
   communications system.  Making the frequency spectrum's usage more
   efficient a transition from analogue voice to digital data
   communication [PLA14] is necessary to cope with the expected growth
   of civil aviation and its supporting infrastructure.  A promising
   candidate for long range terrestrial communications, already in the
   process of being standardized in the International Civil Aviation
   Organization (ICAO), is the L-band Digital Aeronautical
   Communications System (LDACS) [ICAO18] [I-D.ietf-raw-ldacs].

2.2.  Specifics

   During the creation process of new communications system, analogue
   voice is replaced by digital data communication.  This sets a
   paradigm shift from analogue to digital wireless communications and
   supports the related trend towards increased autonomous data
   processing that the Future Communications Infrastructure (FCI) in
   civil aviation must provide.  The FCI is depicted in Figure 1:

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   #         #
   #          # #
   #            #   #
   #             #      #
   #               #        #
   #                #          #
   #                  #            #
   # Satellite-based   #              #
   #   Communications   #                 #
   #      SatCOM (#)     #                   #
   #                      #                    Aircraft
   #                       #                 %         %
   #                        #              %             %
   #                         #           %     Air-Air     %
   #                          #        %     Communications   %
   #                           #     %         LDACS A/A (%)    %
   #                           #   %                              %
   #                            Aircraft  % % % % % % % % % %  Aircraft
   #                                 |           Air-Ground           |
   #                                 |         Communications         |
   #                                 |           LDACS A/G (|)        |
   #      Communications in          |                                |
   #    and around airports          |                                |
   #         AeroMACS (-)            |                                |
   #                                 |                                |
   #         Aircraft-------------+  |                                |
   #                              |  |                                |
   #                              |  |                                |
   #         Ground network       |  |         Ground network         |
   SatCOM <---------------------> Airport <----------------------> LDACS
   transceiver                     based                             GS

   Figure 1: The Future Communication Infrastructure (FCI): AeroMACS for
    APT/TMA domain, LDACS A/G for TMA/ENR domain, LDACS A/G for ENR/ORP
               domain, SatCOM for ORP domain communications

2.3.  Challenges

   This paradigm change brings a lot of new challenges:

   o  Efficiency: It is necessary to keep latency, time and data
      overhead (routing, security) of new aeronautical datalinks at a

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   o  Modularity: Systems in avionics usually operate up to 30 years,
      thus solutions must be modular, easily adaptable and updatable.

   o  Interoperability: All 192 members of the international Civil
      Aviation Organization (ICAO) must be able to use these solutions.

2.4.  The Need for Wireless

   In a high mobility environment such as aviation, the envisioned
   solutions to provide worldwide coverage of data connections with in-
   flight aircraft require a multi-system, multi-link, multi-hop
   approach.  Thus air, ground and space-based datalink providing
   technologies will have to operate seamlessly together to cope with
   the increasing needs of data exchange between aircraft, air traffic
   controller, airport infrastructure, airlines, air network service
   providers (ANSPs) and so forth.  Thus, making use of wireless
   technologies is a MUST in tackling this enormous need for a worldwide
   digital aeronautical datalink infrastructure.

2.5.  Requirements for RAW

   Different safety levels need to be supported, from extremely safety
   critical ones requiring low latency, such as a WAKE warning - a
   warning that two aircraft come dangerously close to each other - and
   high resiliency, to less safety critical ones requiring low-medium
   latency for services such as WXGRAPH - graphical weather data.

   Overhead needs to be kept at a minimum since aeronautical data links
   provide comparatively small data rates in the order of kbit/s.

   Policy needs to be supported when selecting data links.  The focus of
   RAW here should be on the selectors, responsible for the routing path
   a packet takes to reach its end destination.  This would minimize the
   amount of routing information that has to travel inside the network
   because of precomputed routing tables with the selector being
   responsible for choosing the most appropriate option according to
   policy and safety.

3.  Amusement Parks

3.1.  Use Case Description

   The digitalization of Amusement Parks is expected to decrease
   significantly the cost for maintaining the attractions.  Such
   deployment is a mix between industrial automation (aka.  Smart
   Factories) and multimedia entertainment applications.

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   Attractions may rely on a large set of sensors and actuators, which
   react in real time.  Typical applications comprise:

   o  Emergency: safety has to be preserved, and must stop the
      attraction when a failure is detected.

   o  Video: augmented and virtual realities are integrated in the
      attraction.  Wearable mobile devices (e.g., glasses, virtual
      reality headset) need to offload one part of the processing tasks.

   o  Real-time interactions: visitors may interact with an attraction,
      like in a real-time video game.  The visitors may virtually
      interact with their environment, triggering actions in the real
      world (through actuators) [robots].

   o  Geolocation: visitors are tracked with a personal wireless tag so
      that their user experience is improved.

   o  Predictive maintenance: statistics are collected to predict the
      future failures, or to compute later more complex statistics about
      the attraction's usage, the downtime, its popularity, etc.

3.2.  Specifics

   Amusement parks comprise a variable number of attractions, mostly
   outdoor, over a large geographical area.  The IT infrastructure is
   typically multi-scale:

   o  Local area: the sensors and actuators controlling the attractions
      are co-located.  Control loops trigger only local traffic, with a
      small end-to-end delay, typically inferior than 10 milliseconds,
      like classical industrial systems [ieee80211-rt-tig].

   o  Wearable mobile devices are free to move in the park.  They
      exchange traffic locally (identification, personalization,
      multimedia) or globally (billing, child tracking).

   o  Computationally intensive applications offload some tasks.  Edge
      computing seems an efficient way to implement real-time
      applications with offloading.  Some non time-critical tasks may
      rather use the cloud (predictive maintenance, marketing).

3.3.  The Need for Wireless

   Amusement parks cover large areas and a global interconnection would
   require a huge length of cables.  Wireless also increases the
   reconfigurability, enabling to update cheaply the attractions.  The
   frequent renewal helps to increase customer loyalty.

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   Some parts of the attraction are mobile, e.g., trucks of a roller-
   coaster, robots.  Since cables are prone to frequent failures in this
   situation, wireless transmissions are recommended.

   Wearable devices are extensively used for a user experience
   personalization.  They typically need to support wireless
   transmissions.  Personal tags may help to reduce the operating costs
   [disney-VIP] and to increase the number of charged services provided
   to the audience (VIP tickets, interactivity, etc.)  Some applications
   rely on more sophisticated wearable devices such as digital glasses
   or Virtual Reality (VR) headsets for an immersive experience.

3.4.  Requirements for RAW

   The network infrastructure has to support heterogeneous traffic, with
   very different critical requirements.  Thus, flow isolation has to be

   We have to schedule appropriately the transmissions, even in presence
   of mobile devices.  While the [I-D.ietf-6tisch-architecture] already
   proposes an architecture for synchronized, IEEE Std. 802.15.4 Time-
   Slotted Channel Hopping (TSCH) networks, we still need multi-
   technology solutions, able to guarantee end-to-end requirements
   across heterogeneous technologies, with strict SLA requirements.

   Nowadays, long-range wireless transmissions are used mostly for best-
   effort traffic.  On the contrary, [IEEE802.1TSN] is used for critical
   flows using Ethernet devices.  However, we need an IP enabled
   technology to interconnect large areas, independent of the PHY and
   MAC layers.

   We expect to deploy several different technologies (long vs. short
   range) which have to cohabit in the same area.  Thus, we need to
   provide layer-3 mechanisms able to exploit multiple co-interfering

4.  Wireless for Industrial Applications

4.1.  Use Case Description

   A major use case for networking in Industrial environments is the
   control networks where periodic control loops operate between a
   sensor that measures a physical property such as the temperature of a
   fluid, a Programmable Logic Controller (PLC) that decides an action
   such as warm up the mix, and an actuator that performs the required
   action, e.g., inject power in a resistor.

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4.2.  Specifics

4.2.1.  Control Loops

   Process Control designates continuous processing operations, e.g.,
   heating Oil in a refinery or mixing drinking soda.  Control loops in
   the Process Control industry operate at a very low rate, typically 4
   times per second.  Factory Automation, on the other hand, deal with
   discrete goods such as individual automobile parts, and requires
   faster loops, in the order of 10ms.  Motion control that monitors
   dynamic activities may require even faster rates in the order of a
   few ms.  Finally, some industries exhibit hybrid behaviors, like
   canned soup that will start as a process industry while mixing the
   food and then operate as a discrete manufacturing when putting the
   final product in cans and shipping them.

   In all those cases, a packet must flow reliably between the sensor
   and the PLC, be processed by the PLC, and sent to the actuator within
   the control loop period.  In some particular use cases that inherit
   from analog operations, jitter might also alter the operation of the
   control loop.  A rare packet loss is usually admissible, but
   typically 4 losses in a row will cause an emergency halt of the
   production and incur a high cost for the manufacturer.

4.2.2.  Unmeasured Data

   A secondary use case deals with monitoring and diagnostics.  This so-
   called unmeasured data is essential to improve the performances of a
   production line, e.g., by optimizing real-time processing or
   maintenance windows using Machine Learning predictions.  For the lack
   of wireless technologies, some specific industries such as Oil and
   Gas have been using serial cables, literally by the millions, to
   perform their process optimization over the previous decades.  But
   few industries would afford the associated cost and the Holy Grail of
   the Industrial Internet of Things is to provide the same benefits to
   all industries, including SmartGrid, Transportation, Building,
   Commercial and Medical.  This requires a cheap, available and
   scalable IP-based access technology.

   Inside the factory, wires may already be available to operate the
   Control Network.  But unmeasured data are not welcome in that network
   for a number of reasons.  On the one hand it is rich and
   asynchronous, meaning that using they may influence the deterministic
   nature of the control operations and impact the production.  On the
   other hand, this information must be reported to the carpeted floor
   over IP, which means the potential for a security breach via the
   interconnection of the Operational Technology (OT) network with the
   Internet technology (IT) network and possibly enable a rogue access.

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4.3.  The Need for Wireless

   Ethernet cables used on a robot arm are prone to breakage after a few
   thousands flexions, a lot faster than a power cable that is wider inn
   diameter, and more resilient.  In general, wired networking and
   mobile parts are not a good match, mostly in the case of fast and
   recurrent activities, as well as rotation.

   When refurbishing older premises that were built before the Internet
   age, power is usually available everywhere, but data is not.  It is
   often impractical, time consuming and expensive to deploy an Ethernet
   fabric across walls and between buildings.  Deploying a wire may take
   months and cost tens of thousands of US Dollars.

   Even when wiring exists, e.g., in an existing control network,
   asynchronous IP packets such as diagnostics may not be welcome for
   operational and security reasons (see Section 4.2.1).  An alternate
   network that can scale with the many sensors and actuators that equip
   every robot, every valve and fan that are deployed on the factory
   floor and may help detect and prevent a failure that could impact the
   production.  IEEE Std. 802.15.4 Time-Slotted Channel Hopping (TSCH)
   [RFC7554] is a promising technology for that purpose, mostly if the
   scheduled operations enable to use the same network by asynchronous
   and deterministic flows in parallel.

4.4.  Requirements for RAW

   As stated by the "Deterministic Networking Problem Statement"
   [RFC8557], a Deterministic Network is backwards compatible with
   (capable of transporting) statistically multiplexed traffic while
   preserving the properties of the accepted deterministic flows.  While
   the [I-D.ietf-6tisch-architecture] serves that requirement, the work
   at 6TiSCH was focused on best-effort IPv6 packet flows.  RAW should
   be able to lock so-called hard cells for use by a centralized
   scheduler, and program so-called end-to-end Tracks over those cells.

   Over the course of the recent years, major Industrial Protocols,
   e.g., [ODVA] with EtherNet/IP [EIP] and [Profinet], have been
   migrating towards Ethernet and IP.  In order to unleash the full
   power of the IP hourglass model, it should be possible to deploy any
   application over any network that has the physical capacity to
   transport the industrial flow, regardless of the MAC/PHY technology,
   wired or wireless, and across technologies.  RAW mechanisms should be
   able to setup a Track over a wireless access segment such as TSCH and
   a backbone segment such as Ethernet or WI-Fi, to report a sensor data
   or a critical monitoring within a bounded latency.  It is also
   important to ensure that RAW solutions are interoperable with
   existing wireless solutions in place, and with legacy equipment which

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   capabilities can be extended using retrofitting.  Maintanability, as
   a broader concept than reliability is also important in industrial
   scenarios [square-peg].

5.  Pro Audio and Video

5.1.  Use Case Description

   Many devices support audio and video streaming by employing 802.11
   wireless LAN.  Some of these applications require low latency
   capability.  For instance, when the application provides interactive
   play, or when the audio takes plays in real time (i.e. live) for
   public addresses in train stations or in theme parks.

   The professional audio and video industry ("ProAV") includes:

   o  Virtual Reality / Augmented Reality (VR/AR)

   o  Public address, media and emergency systems at large venues
      (airports, train stations, stadiums, theme parks).

5.2.  Specifics

5.2.1.  Uninterrupted Stream Playback

   Considering the uninterrupted audio or video stream, a potential
   packet losses during the transmission of audio or video flows cannot
   be tackled by re-trying the transmission, as it is done with file
   transfer, because by the time the packet lost has been identified it
   is too late to proceed with packet re-transmission.  Buffering might
   be employed to provide a certain delay which will allow for one or
   more re-transmissions, however such approach is not efficient in
   application where delays are not acceptable.

5.2.2.  Synchronized Stream Playback

   In the context of ProAV, latency is the time between the transmitted
   signal over a stream and its reception.  Thus, for sound to remain
   synchronized to the movement in the video, the latency of both the
   audio and video streams must be bounded and consistent.

5.3.  The Need for Wireless

   The devices need the wireless communication to support video
   streaming via 802.11 wireless LAN for instance.

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   During the public address, the deployed announcement speakers, for
   instance along the platforms of the train stations, need the wireless
   communication to forward the audio traffic in real time.

5.4.  Requirements for RAW

   The network infrastructure needs to support heterogeneous types of
   traffic (including QoS).

   Content delivery with bounded (lowest possible) latency.

   The deployed network topology should allow for multipath.  This will
   enable for multiple streams to have different (and multiple) paths
   through the network to support redundancy.

6.  Wireless Gaming

6.1.  Use Case Description

   The gaming industry includes [IEEE80211RTA] real-time mobile gaming,
   wireless console gaming and cloud gaming.  For RAW, wireless console
   gaming is the most relevant one.  We next summarize the three:

   o  Real-time Mobile Gaming: Different from traditional games, real
      time mobile gaming is very sensitive to network latency and
      stability.  The mobile game can connect multiple players together
      in a single game session and exchange data messages between game
      server and connected players.  Real-time means the feedback should
      present on screen as users operate in game.  For good game
      experience, the end to end latency plus game servers processing
      time should not be noticed by users as they play the game.

   o  Wireless Console Gaming: Playing online on a console has 2 types
      of internet connectivity, which is either wired or Wi-Fi.  Most of
      the gaming consoles today support Wi-Fi 5.  But Wi-Fi has an
      especially bad reputation among the gaming community.  The main
      reasons are high latency, lag spikes and jitter.

   o  Cloud Gaming: The cloud gaming requires low latency capability as
      the user commands in a game session need to be sent back to the
      cloud server, the cloud server would update game context depending
      on the received commands, and the cloud server would render the
      picture/video to be displayed at user devices and stream the
      picture/video content to the user devices.  User devices might
      very likely be connected wirelessly.

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6.2.  Specifics

   While a lot of details can be found on [IEEE80211RTA], we next
   summarize the main requirements in terms of latency, jitter and
   packet loss:

   o  Intra BSS latency: less than 5 ms.

   o  Jitter variance: less than 2 ms.

   o  Packet loss: less than 0.1 percent.

6.3.  The Need for Wireless

   It is clear that gaming is evolving towards wireless, as players
   demand being able to play anywhere.  Besides, the industry is
   changing towards playing from mobile phones, which are inherently
   connected via wireless technologies.

6.4.  Requirements for RAW

   o  Time sensitive networking extensions.  Extensions, such as time-
      aware shaping and redundancy (FRE) can be explored to address
      congestion and reliability problems present in wireless networks.

   o  Priority tagging (Stream identification).  One basic requirement
      to provide better QoS for time-sensitive traffic is the capability
      to identify and differentiate time-sensitive packets from other
      (e.g. best-effort) traffic.

   o  Time-aware shaping.  This capability (defined in IEEE 802.1Qbv)
      consists of gates to control the opening/closing of queues that
      share a common egress port within an Ethernet switch.  A scheduler
      defines the times when each queue opens or close, therefore
      eliminating congestion and ensuring that frames are delivered
      within the expected latency bounds.

   o  Dual/multiple link.  Due to the competitions and interference are
      common and hardly in control under wireless network, in order to
      improve the latency stability, dual/multiple link proposal is
      brought up to address this issue.  Two modes are defined:
      duplicate and joint.

   o  Admission Control.  Congestion is a major cause of high/variable
      latency and it is well known that if the traffic load exceeds the
      capability of the link, QoS will be degraded.  QoS degradation
      maybe acceptable for many applications today, however emerging
      time-sensitive applications are highly susceptible to increased

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      latency and jitter.  In order to better control QoS, it is
      important to control access to the network resources.

7.  UAV platooning and control

7.1.  Use Case Description

   Unmanned Aerial Vehicles (UAVs) are becoming very popular for many
   different applications, including military and civil use cases.  The
   term drone is commonly used to refer to a UAV.

   UAVs can be used to perform aerial surveillance activities, traffic
   monitoring (e.g., Spanish traffic control has recently introduced a
   fleet of drones for quicker reactions upon traffic congestion related
   events), support of emergency situations, and even transportation of
   small goods.

   UAVs typically have various forms of wireless connectivity:

   o  cellular: for communication with the control center, for remote
      maneuvering as well as monitoring of the drone;

   o  IEEE 802.11: for inter-drone communications (e.g., platooning) and
      providing connectivity to other devices (e.g., acting as Access

7.2.  Specifics

   Some of the use cases/tasks involving drones require coordination
   among drones.  Others involve complex compute tasks that might not be
   performed using the limited computing resources that a drone
   typically has.  These two aspects require continuous connectivity
   with the control center and among drones.

   Remote maneuvering of a drone might be performed over a cellular
   network in some cased, however, there are situations that need very
   low latencies and deterministic behavior of the connectivity.
   Examples involve platooning of drones or share of computing resources
   among drones (e.g., a drone offload some function to a neighboring

7.3.  The Need for Wireless

   UAVs cannot be connected through any type of wired media, so it is
   obvious that wireless is needed.

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7.4.  Requirements for RAW

   The network infrastructure is actually composed by the UAVs
   themselves, requiring self-configuration capabilities.

   Heterogeneous types of traffic need to be supported, from extremely
   critical ones requiring ultra low latency and high resiliency, to
   traffic requiring low-medium latency.

   When a given service is decomposed into functions -- hosted at
   different drones -- chained, each link connecting two given functions
   would have a well-defined set of requirements (latency, bandwidth and
   jitter) that have to be met.

8.  Edge Robotics control

8.1.  Use Case Description

   The Edge Robotics scenario consists of several robots, deployed in a
   given area (for example a shopping mall), inter-connected via an
   access network to a network's edge device or a data center.  The
   robots are connected to the edge so complex computational activities
   are not executed locally at the robots, but offloaded to the edge.
   This brings additional flexibility in the type of tasks that the
   robots do, as well as reducing the costs of robot manufacturing (due
   to their lower complexity), and enabling complex tasks involving
   coordination among robots (that can be more easily performed if
   robots are centrally controlled).

   A simple example of the use of multiples robots is cleaning,
   delivering of goods from warehouses to shops or video surveillance.
   Multiple robots are simultaneously instructed to perform individual
   tasks by moving the robotic intelligence from the robots to the
   network's edge (e.g., data center).  That enables easy
   synchronization, scalable solution and on-demand option to create
   flexible fleet of robots.

   Robots would have various forms of wireless connectivity:

   o  IEEE 802.11: for connection to the edge and also inter-robot
      communications (e.g., for coordinated actions).

   o  Cellular: as an additional communication link to the edge, though
      primarily as backup, since ultra low latencies are needed.

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8.2.  Specifics

   Some of the use cases/tasks involving robots might benefit from
   decomposition of a service in small functions that are distributed
   and chained among robots and the edge.  These require continuous
   connectivity with the control center and among drones.

   Robot control is an activity requiring very low latencies between the
   robot and the location where the control intelligence resides (which
   might be the edge or another robot).

8.3.  The Need for Wireless

   Deploying robots in scenarios such as shopping malls for the
   aforementioned applications cannot be done via wired connectivity.

8.4.  Requirements for RAW

   The network infrastructure needs to support heterogeneous types of
   traffic, from robot control to video streaming.

   When a given service is decomposed into functions -- hosted at
   different robots -- chained, each link connecting two given functions
   would have a well-defined set of requirements (latency, bandwidth and
   jitter) that have to be met.

9.  Emergencies: Instrumented emergency vehicle

9.1.  Use Case Description

   An instrumented ambulance would be one that has a LAN to which are
   connected these end systems:

   o  vital signs sensors attached to the casualty in the ambulance.
      Relay medical data to hospital emergency room,

   o  radionavigation sensor to relay position data to various
      destinations including dispatcher,

   o  voice communication for ambulance attendant (e.g. consult with ER

   o  voice communication between driver and dispatcher,

   o  etc.

   The LAN needs to be routed through radio-WANs to complete the
   internetwork linkage.

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9.2.  Specifics

   What we have today is multiple communications systems to reach the

   o  A dispatching system,

   o  a cellphone for the attendant,

   o  a special purpose telemetering system for medical data,

   o  etc.

   This redundancy of systems, because of its stovepiping, does not
   contribute to availability as a whole.

   Most of the scenarios involving the use of an instrumented ambulance
   are composed of many different flows, each of them with slightly
   different requirements in terms of reliability and latency.
   Destinations might be either at the ambulance itself (local traffic),
   at a near edge cloud or at the general Internet/cloud.

9.3.  The Need for Wireless

   Local traffic between the first responders/ambulance staff and the
   ambulance equipment cannot be doine via wireled connectivity as the
   responders perform initial treatment outside of the ambulance.  The
   communications from the ambulance to external services has to be
   wireless as well.

9.4.  Requirements for RAW

   We can derive some pertinent requirements from this scenario:

   o  High availability of the internetwork is required.

   o  The internetwork needs to operate in damaged state (e.g. during an
      earthquake aftermath, heavy weather, wildfire, etc.).  In addition
      to continuity of operations, rapid restoral is a needed

   o  End-to-end security, both authenticity and confidentiality, is
      required of traffic.  All data needs to be authenticated; some
      (such as medical) needs to be confidential.

   o  The radio-WAN has characteristics similar to cellphone -- the
      vehicle will travel from one radio footprint to another.

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10.  IANA Considerations

   This document has no IANA actions.

11.  Security Considerations

   This document covers a number of representative applications and
   network scenarios that are expected to make use of RAW technologies.
   Each of the potential RAW use cases will have security considerations
   from both the use-specific perspective and the RAW technology
   perspective.  [I-D.ietf-detnet-security] provides a comprehensive
   discussion of security considerations in the context of Deterministic
   Networking, which are generally applicable also to RAW.

12.  Acknowledgments

   Nils Maeurer, Thomas Graeupl and Corinna Schmitt have contributed
   significantly to this document, providing input for the Aeronautical
   communications section.  Rex Buddenberg has also contributed to the
   document, providing input to the Emergency: instrumented emergency
   vehicle section.

   The authors would like to thank Toerless Eckert, Xavi Vilajosana
   Guillen and Rute Sofia for their valuable comments on previous
   versions of this document.

   The work of Carlos J.  Bernardos in this draft has been partially
   supported by the H2020 5Growth (Grant 856709) and 5G-DIVE projects
   (Grant 859881).

13.  Informative References

   [ACI19]    Airports Council International (ACI), "Annual World
              Aitport Traffic Report 2019", November 2019,

              Wired, "Disney's $1 Billion Bet on a Magical Wristband",
              March 2015,

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   [EIP]      http://www.odva.org/, "EtherNet/IP provides users with the
              network tools to deploy standard Ethernet technology (IEEE
              802.3 combined with the TCP/IP Suite) for industrial
              automation applications while enabling Internet and
              enterprise connectivity data anytime, anywhere.",

   [FAA20]    U.S. Department of Transportation Federal Aviation
              Administration (FAA), "Next Generation Air Transportation
              System", 2019, <https://www.faa.gov/nextgen/ >.

              Thubert, P., "An Architecture for IPv6 over the TSCH mode
              of IEEE 802.15.4", draft-ietf-6tisch-architecture-30 (work
              in progress), November 2020.

              Grossman, E., Mizrahi, T., and A. Hacker, "Deterministic
              Networking (DetNet) Security Considerations", draft-ietf-
              detnet-security-13 (work in progress), December 2020.

              Maeurer, N., Graeupl, T., and C. Schmitt, "L-band Digital
              Aeronautical Communications System (LDACS)", draft-ietf-
              raw-ldacs-06 (work in progress), January 2021.

              Thubert, P., Cavalcanti, D., Vilajosana, X., Schmitt, C.,
              and J. Farkas, "Reliable and Available Wireless
              Technologies", draft-thubert-raw-technologies-05 (work in
              progress), May 2020.

   [IAC20]    Iacus, S., Natale, F., Santamaria, C., Spyratos, S., and
              V. Michele, "Estimating and projecting air passenger
              traffic during the COVID-19 coronavirus outbreak and its
              socio- economic impact", Safety Science 129 (2020)
              104791 , 2020.

   [IAT20]    International Air Transport Association (IATA), "Economic
              Performance of the Airline Industry", November 2020,

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   [ICAO18]   International Civil Aviation Organization (ICAO), "L-Band
              Digital Aeronautical Communication System (LDACS)",
              International Standards and Recommended Practices Annex 10
              - Aeronautical Telecommunications, Vol. III -
              Communication Systems , 2018.

              IEEE standard for Information Technology, "IEEE
              802.1AS-2011 - IEEE Standard for Local and Metropolitan
              Area Networks - Timing and Synchronization for Time-
              Sensitive Applications in Bridged Local Area Networks".

              IEEE, "IEEE 802.11 Real Time Applications TIG Report",
              Nov. 2018,

              IEEE standard for Information Technology, "IEEE 802.11
              Real Time Applications TIG Report", Nov 2018.

   [ISA100]   ISA/ANSI, "ISA100, Wireless Systems for Automation",

   [KEAV20]   T. Keaveney and C. Stewart, "Single European Sky ATM
              Research Joint Undertaking", 2019,

   [ODVA]     http://www.odva.org/, "The organization that supports
              network technologies built on the Common Industrial
              Protocol (CIP) including EtherNet/IP.".

   [PLA14]    Plass, S., Hermenier, R., Luecke, O., Gomez Depoorter, D.,
              Tordjman, T., Chatterton, M., Amirfeiz, M., Scotti, S.,
              Cheng, Y., Pillai, P., Graeupl, T., Durand, F., Murphy,
              K., Marriott, A., and A. Zaytsev, "Flight Trial
              Demonstration of Seamless Aeronautical Networking", IEEE
              Communications Magazine, vol. 52, no. 5 , May 2014.

              http://us.profinet.com/technology/profinet/, "PROFINET is
              a standard for industrial networking in automation.",

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   [RFC7554]  Watteyne, T., Ed., Palattella, M., and L. Grieco, "Using
              IEEE 802.15.4e Time-Slotted Channel Hopping (TSCH) in the
              Internet of Things (IoT): Problem Statement", RFC 7554,
              DOI 10.17487/RFC7554, May 2015,

   [RFC8557]  Finn, N. and P. Thubert, "Deterministic Networking Problem
              Statement", RFC 8557, DOI 10.17487/RFC8557, May 2019,

   [RFC8578]  Grossman, E., Ed., "Deterministic Networking Use Cases",
              RFC 8578, DOI 10.17487/RFC8578, May 2019,

   [RFC8655]  Finn, N., Thubert, P., Varga, B., and J. Farkas,
              "Deterministic Networking Architecture", RFC 8655,
              DOI 10.17487/RFC8655, October 2019,

   [robots]   Kober, J., Glisson, M., and M. Mistry, "Playing catch and
              juggling with a humanoid robot.", 2012,

              Martinez, B., Cano, C., and X. Vilajosana, "A Square Peg
              in a Round Hole: The Complex Path for Wireless in the
              Manufacturing Industry", 2019,

Authors' Addresses

   Georgios Z. Papadopoulos
   IMT Atlantique
   Office B00 - 114A
   2 Rue de la Chataigneraie
   Cesson-Sevigne - Rennes  35510

   Phone: +33 299 12 70 04
   Email: georgios.papadopoulos@imt-atlantique.fr

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   Pascal Thubert
   Cisco Systems, Inc
   Building D
   45 Allee des Ormes - BP1200
   MOUGINS - Sophia Antipolis  06254

   Phone: +33 497 23 26 34
   Email: pthubert@cisco.com

   Fabrice Theoleyre
   ICube Lab, Pole API
   300 boulevard Sebastien Brant - CS 10413
   Illkirch  67400

   Phone: +33 368 85 45 33
   Email: theoleyre@unistra.fr
   URI:   http://www.theoleyre.eu

   Carlos J. Bernardos
   Universidad Carlos III de Madrid
   Av. Universidad, 30
   Leganes, Madrid  28911

   Phone: +34 91624 6236
   Email: cjbc@it.uc3m.es
   URI:   http://www.it.uc3m.es/cjbc/

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