SPAWN                                                    G. Papadopoulos
Internet-Draft                                            IMT Atlantique
Intended status: Standards Track                              P. Thubert
Expires: September 26, 2019                                        Cisco
                                                            F. Theoleyre
                                                           CJ. Bernardos
                                                          March 25, 2019

                            SPAWN 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 some of these use-cases.

Status of This Memo

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   This Internet-Draft will expire on September 26, 2019.

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   publication of this document.  Please review these documents

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   carefully, as they describe your rights and restrictions with respect
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Amusement Parks . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Use Case Description  . . . . . . . . . . . . . . . . . .   4
     2.2.  Specificities . . . . . . . . . . . . . . . . . . . . . .   5
     2.3.  The Need for Wireless . . . . . . . . . . . . . . . . . .   5
     2.4.  Asks for SPAWN  . . . . . . . . . . . . . . . . . . . . .   6
   3.  Wireless for Industrial Applications  . . . . . . . . . . . .   6
     3.1.  Use Case Description  . . . . . . . . . . . . . . . . . .   6
     3.2.  Specificities . . . . . . . . . . . . . . . . . . . . . .   6
       3.2.1.  Control Loops . . . . . . . . . . . . . . . . . . . .   6
       3.2.2.  Unmeasured Data . . . . . . . . . . . . . . . . . . .   7
     3.3.  The Need for Wireless . . . . . . . . . . . . . . . . . .   7
     3.4.  Asks for SPAWN  . . . . . . . . . . . . . . . . . . . . .   8
   4.  Pro Audio and Video . . . . . . . . . . . . . . . . . . . . .   8
     4.1.  Use Case Description  . . . . . . . . . . . . . . . . . .   8
     4.2.  Specificities . . . . . . . . . . . . . . . . . . . . . .   9
     4.3.  The Need for Wireless . . . . . . . . . . . . . . . . . .   9
     4.4.  Asks for SPAWN  . . . . . . . . . . . . . . . . . . . . .   9
   5.  UAV control . . . . . . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Use Case Description  . . . . . . . . . . . . . . . . . .   9
     5.2.  Specificities . . . . . . . . . . . . . . . . . . . . . .   9
     5.3.  The Need for Wireless . . . . . . . . . . . . . . . . . .  10
     5.4.  Asks for SPAWN  . . . . . . . . . . . . . . . . . . . . .  10
   6.  Edge Robotics control . . . . . . . . . . . . . . . . . . . .  10
     6.1.  Use Case Description  . . . . . . . . . . . . . . . . . .  10
     6.2.  Specificities . . . . . . . . . . . . . . . . . . . . . .  11
     6.3.  The Need for Wireless . . . . . . . . . . . . . . . . . .  11
     6.4.  Asks for SPAWN  . . . . . . . . . . . . . . . . . . . . .  11
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   9.  Informative References  . . . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

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,

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   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, and

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

   Wireless operates on a shared medium, and transmissions cannot be
   fully deterministic due to uncontrolled interferences, including
   self-induced multipath fading.  Scheduling transmissions enables to
   alleviate those effects by leveraging diversity in the spatial, time
   and frequency domains, enabling Scheduled Predictable and Available
   Wireless Networks (SPAWN).

   The wireless and wired media are fundamentally different at the
   physical level, and while the generic Problem Statement
   [I-D.ietf-detnet-problem-statement] for DetNet applies to the wired
   as well as the wireless medium, the methods to achieve SPAWN
   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
   [I-D.ietf-detnet-architecture] 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 developed and deployed to cope for the lack

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   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:

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

   o  IEEE 802.11 is integrating real-time applications in the charter
      of the Extreme High Throughput (EHT) Task Group (to be formed at
      the time of this writing), and

   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 Scheduled Predictable
      and Available Wireless Networks (SPAWN) on a shared MAC.

   This draft extends the "Deterministic Networking Use Cases"
   [I-D.ietf-detnet-use-cases] and describes a number of additional use
   cases which require deterministic flows over wireless links and
   possibly complex multi-hop paths called Tracks.

2.  Amusement Parks

2.1.  Use Case Description

   The digitalization of Amusement Parks is expected to decrease
   significantly the cost for maintaining the attractions.  By
   monitoring in real-time the machines, predictive maintenance will
   help to reduce the repairing cost as well as the downtime.  Besides,
   the attractions may use wireless transmissions to interconnect
   sensors and actuators, to privileged reconfigurability, and

   Attractions may comprise a large set of sensors and actuators, which
   react in real time.  Typical applications (ordered by criticality in
   descending order) are:

   o  emergency: safety has to be preserved.  An attraction has to be
      stopped if a failure is detected;

   o  real-time control: real-time applications embedded in the
      attraction need to trigger an action when an event is detected.
      For instance, a photograph can be taken when a car crosses an
      actuator, combined with a wireless ID that the tourists wear;

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   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.

2.2.  Specificities

   Amusement parks comprise a variable number of attractions, mostly
   outdoor.  Thus,

   The tourists are free to move from an attraction to another, covering
   a large geographical area.  Wearable devices are expected for a user
   experience personalisation.  Thus, some devices may be mobile, while
   the rest of the infrastructure remains static.

   The infrastrcuture is typically multi-scale:

   o  local area: the sensors and actuators controlling the attractions
      are co-located.  Real-time flows are localized, a set of sensors
      triggering actuators.  Maintenance flows are mostly lrage-range,
      interconnected with the information system;

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

   o  global information system manages the whole park, and exchange
      commands or information with the different parts.

2.3.  The Need for Wireless

   Amusement parks cover large areas and a global interconnection would
   require a huge length of cables.  Wireless also optimizes the
   reconfigurability, enabling to plug novel services easily to increase
   e.g. the interactivity.

   Attractions comprise mobile components (e.g. robots, wagons), which
   require wireless connections since cables are particulalry
   inconvenient and source of failures in such conditions.

   Wearable devices have to support by nature wireless transmissions.
   They aim to enable novel high-value services.  VIP tickets are
   nowadays more and more popular.  Wireless wearable devices may help
   to reduce the operating costs [disney-VIP] and increasing the number
   of charged services provided to the audience (VIP tickets,
   interactivity, etc.)

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2.4.  Asks for SPAWN

   The networ infrastructure has to support heterogenous traffic, with
   very different criticalities.  Thus, flow isolation has to be
   provided, where best effort traffic only

   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, 6TiSCH focused on best-
   effort IPv6 flows.  SPAWN expects to schedule appropriately the
   transmissions, across heterogeneous technologies, with strict SLA

   Nowadays, long-range wireless transmissions are used for best-effort
   traffic, and [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 layer to maximize the

3.  Wireless for Industrial Applications

3.1.  Use Case Description

   A major use case for networking in Industrial 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 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.

3.2.  Specificities

3.2.1.  Control Loops

   Process Control designates continous 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.

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   In all those cases, a packet must flow deterministically 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.

3.2.2.  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.

3.3.  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.

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   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 3.2.1).  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.

3.4.  Asks for SPAWN

   As stated by the "Deterministic Networking Problem Statement"
   [I-D.ietf-detnet-problem-statement], 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.  SPAWN 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.  SPAWN 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.

4.  Pro Audio and Video

4.1.  Use Case Description

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

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

   Today the ProAV applications are moving towards packet-based
   technology to introduce routing features and to reduce costs.

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4.2.  Specificities

   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.

4.3.  The Need for Wireless

4.4.  Asks for SPAWN


5.  UAV control

5.1.  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
      manuevering as well as monitoring of the drone;

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

5.2.  Specificities

   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 cases, however, there are situations that need very
   low latencies and deterministic behavior of the connectivity.

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   Examples involve platooning of drones or sharing of computing
   resources among drones (e.g., a drone offload some function to a
   neighboring drone).

5.3.  The Need for Wireless

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

5.4.  Asks for SPAWN

   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, bandwith and
   jitter) that have to be met.

6.  Edge Robotics control

6.1.  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:

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   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.

6.2.  Specificities

   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).

6.3.  The Need for Wireless

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

6.4.  Asks for SPAWN

   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, bandwith and
   jitter) that have to be met.

7.  IANA Considerations


8.  Security Considerations


9.  Informative References

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

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   [EIP], "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.",

              Thubert, P., "An Architecture for IPv6 over the TSCH mode
              of IEEE 802.15.4", draft-ietf-6tisch-architecture-20 (work
              in progress), March 2019.

              Finn, N., Thubert, P., Varga, B., and J. Farkas,
              "Deterministic Networking Architecture", draft-ietf-
              detnet-architecture-12 (work in progress), March 2019.

              Finn, N. and P. Thubert, "Deterministic Networking Problem
              Statement", draft-ietf-detnet-problem-statement-09 (work
              in progress), December 2018.

              Grossman, E., "Deterministic Networking Use Cases", draft-
              ietf-detnet-use-cases-20 (work in progress), December

              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".

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

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

    , "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,

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

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

   Phone: +33 497 23 26 34

   Fabrice Theoleyre
   Office B-270
   Boulevard Sebastien Brant
   Illkirch  67400

   Phone: +33 368 85 45 33

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

   Phone: +34 91624 6236

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