RAW Use-Cases
Universidad Carlos III de Madrid
Av. Universidad, 30Leganes, Madrid28911Spain+34 91624 6236cjbc@it.uc3m.eshttp://www.it.uc3m.es/cjbc/IMT AtlantiqueOffice B00 - 114A2 Rue de la ChataigneraieCesson-Sevigne - Rennes35510FRANCE+33 299 12 70 04georgios.papadopoulos@imt-atlantique.frCisco Systems, IncBuilding D45 Allee des Ormes - BP1200 MOUGINS - Sophia Antipolis06254FRANCE+33 497 23 26 34pthubert@cisco.comCNRSICube Lab, Pole API300 boulevard Sebastien Brant - CS 10413Illkirch67400FRANCE+33 368 85 45 33fabrice.theoleyre@cnrs.frhttps://fabrice.theoleyre.cnrs.fr/RAW
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 (such as aeronautical
communications, amusement parks, industrial applications, pro audio and video,
gaming, UAV and V2V control, edge robotics and emergency vehicles) demanding
reliable and available behavior.
Based on time, resource reservation, and policy enforcement by distributed
shapers, deterministic networking (DetNet) 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 aims at eliminating packet loss
for a committed bandwidth while ensuring a worst case end-to-end latency,
regardless of the network conditions and across technologies. By leveraging
lower layer (Layer 2 and below) capabilities, L3 can exploit the use of a service layer,
steering over multiple technologies, and using media independent signaling to
provide high reliability, precise time delivery, and rate enforcement.
Deterministic networking 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., using time-shared resources (bandwidth and buffers)
per circuit, and/or by shaping and/or scheduling the packets at every hop.
Key attributes of Deterministic networking include:
time synchronization on all the nodes,multi-technology path with co-channel interference minimization,frame preemption and guard time mechanisms to ensure a worst-case delay, andnew traffic shapers within and at the edge to protect the network.
Wireless operates on a shared medium, and transmissions cannot be guaranteed to
be fully deterministic due to uncontrolled interferences, including self-induced
multipath fading. The term RAW stands for Reliable and Available Wireless, and refers to the mechanisms aimed for providing high reliability and availability for IP connectivity over a wireless medium. 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 resources.
The wireless and wired media are fundamentally different at the physical level,
and while the generic Problem Statement 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, e.g., due to the wireless radio channel specifics.
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 at the IETF. But wires cannot be used in
several 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 , which
incorporates IPv6, were developed and deployed to cope with 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 :
IMT-2020 has recognized Ultra-Reliable Low-Latency Communication (URLLC) as a
key functionality for the upcoming 5G.
IEEE 802.11 has identified a set of real-applications which may use the IEEE802.11 standards. They
typically emphasize strict end-to-end delay requirements.
The IETF has produced an IPv6 stack for IEEE Std. 802.15.4 TimeSlotted Channel
Hopping (TSCH) and an architecture
that enables RAW on a shared MAC.
Experiments have already been conducted with IEEE802.1 TSN over IEEE802.11be .
This mode enables time synchronization, and time-aware scheduling
(trigger based access mode) to support TSN flows.
This document extends the "Deterministic Networking use-cases" document and describes several additional use-cases which require
"reliable/predictable and available" flows over wireless links and possibly
complex multi-hop paths called Tracks. This is covered mainly by the "Wireless
for Industrial Applications" use-case, as the "Cellular Radio" is mostly
dedicated to the (wired) link 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.
Aircraft are currently connected to ATC (Air-Traffic Control) and AOC (Airline
Operational Control) via voice and data communication systems through all
phases of a flight. Within the airport terminal, connectivity is focused on high
bandwidth communications while en-route high reliability, robustness and
range are the focus.
Up to 2020, civil air traffic has been growing constantly at a compound rate of
5.8% per year and despite the severe impact of the
COVID-19 pandemic, air traffic growth is expected to resume very quickly in
post-pandemic times . 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
calling for suitable new digital approaches such as AeroMACS for airport
communications, SatCOM for remote domains, and LDACS as long-range terrestrial
aeronautical communication system. Making the frequency spectrum's usage more
efficient a transition from analog voice to digital data communication 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 Communication System (LDACS) .
During the creation process of new communication system, analog voice is
replaced by digital data communication. This sets a paradigm shift from analog
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
:
This paradigm change brings a lot of new challenges:
Efficiency: It is necessary to keep latency, time and data overhead of new aeronautical datalinks at a minimum.
Modularity: Systems in avionics usually operate up to 30 years, thus solutions
must be modular, easily adaptable and updatable.
Interoperability: All 192 members of the international Civil Aviation
Organization (ICAO) must be able to use these solutions.
Dynamicity: the communication infrastructure needs to accommodate mobile devices (airplanes)
that move extremely fast.
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. Wireless technologies have to be used to tackle this enormous need for a worldwide digital aeronautical datalink infrastructure.
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 on 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 track a packet takes to
reach its end destination. This would minimize the amount of routing information
that must 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.
Achieving low latency is a requirement for aeronautics communications, though
the expected latency is not extremely low and what is important is to keep
the overall latency bounded under a certain threshold. This use-case is not
latency-critical from that view point. On the other hand, given the controlled
environment, end-to-end mechanisms can be applied to guarantee bounded latency
where needed.
The digitalization of Amusement Parks is expected to decrease significantly the
cost for maintaining the attractions.
Such deployment is a mix between multimedia (e.g., Virtual and Augmented Reality,
interactive video environments) and non-multimedia applications (e.g, industrial
automation for a roller-coaster, access control).
Attractions may rely on a large set of sensors and actuators, which react in
real time. Typical applications comprise:
Emergency: the safety of the operators / visitors has to be preserved and the
attraction must be stopped appropriately when a failure is detected.
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.
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) .
Geolocation: visitors are tracked with a personal wireless tag so that their user
experience is improved. This requires special care to ensure that visitors' privacy is not breached, and users are anonymously tracked.
Predictive maintenance: statistics are collected to predict the future failures,
or to compute later more complex statistics about the attraction's usage, the
downtime, etc.
Marketing: to improve the customer experience, owners may collect a large amount
of data to understand the behavior, and the choice of their clients.
Amusement parks comprise a variable number of attractions, mostly outdoor, over
a large geographical area. The IT infrastructure is typically multi-scale:
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 less than 10 ms, like classical industrial systems .
Wearable mobile devices are free to move in the park. They exchange traffic locally
(identification, personalization, multimedia) or globally (billing, child
tracking).
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).
Removing cables helps to change easily the configuration of the attractions, or to
upgrade parts of them at a lower cost. The attraction can be designed modularly,
upgrade or insert novel modules later in the lifecycle of the attraction. Novelty
of attractions tends to increase the attractiveness of an amusement park,
encouraging previous visitors to visit regularly the park.
Some parts of the attraction are mobile, like trucks of a roller-coaster or
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 and to increase the number
of charged services provided to the audience (e.g., VIP tickets or
interactivity). Some applications rely on more sophisticated wearable devices
such as digital glasses or Virtual Reality (VR) headsets for an immersive
experience.
The network infrastructure must support heterogeneous traffic, with very
different critical requirements. Thus, flow isolation must be provided.
The transmissions must be scheduled appropriately even in presence of mobile
devices. While the already proposes an architecture for
synchronized, IEEE Std. 802.15.4 Time-Slotted Channel Hopping (TSCH) networks,
the industry requires a multi-technology solution, 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, 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.
It is expected that several different technologies (long vs. short range) are
deployed, which have to cohabit in the same area. Thus, we need to provide
layer-3 mechanisms able to exploit multiple co-interfering technologies (i.e., different radio technologies using overlapping spectrum, and therefore, potentially interfering to each other).
It is worth noting that low-priority flows (e.g., predictive maintenance,
marketing) are delay tolerant: a few minutes or even hours would be acceptable.
While classical unscheduled wireless networks already accomodate best-effort
traffic, this would force several colocated and subefficient deployments. Unused
resources could rather be used for low-priority flows. Indeed, allocated resources
are consuming energy in most scheduled networks, even if no traffic is transmitted.
While some of the applications in this use-case involve control loops (e.g.,
sensors and actuators) that require bounded latencies below 10 ms, that can
therefore be considered latency critical, there are other applications as well
that mostly demand reliability (e.g., safety related, or maintenance).
A major use-case for networking in Industrial environments is the control
networks where periodic control loops operate between a collection of sensors
that measure 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 actuators that perform the required action, such as the injection of
power in a resistor.
Process Control designates continuous processing operations, like heating oil
in a refinery or mixing drinking soda. Control loops in the Process Control
industry operate at a very low rate, typically four times per second. Factory
Automation, on the other hand, deals with discrete goods such as individual
automobile parts, and requires faster loops, on the order of milliseconds.
Motion control that monitors dynamic activities may require even faster rates on
the order of and below the millisecond.
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 a loss of multiple packets in a row will cause an emergency halt
of the production and incur a high cost for the manufacturer.
Additional details and use-cases related to Industrial applications and their
RAW requirements can be found in
.
A secondary use-case deals with monitoring and diagnostics. This data is essential to improve the performance 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. One of the goals 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 monitoring and diagnostics data are not welcome in that network for several
reasons. On the one hand it is rich and asynchronous, meaning that it may
influence the deterministic nature of the control operations and impact the
production. On the other hand, this information must be reported to the operators 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.
Wires used on a robot arm are prone to breakage after a few thousands
flexions, a lot faster than a power cable that is wider in 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, like in the case of an existing control network,
asynchronous IP packets such as diagnostics may not be welcome for operational
and security reasons. For those packets, the option to create a parallel
wireless network offers a credible solution that can scale with the many sensors
and actuators that equip every robot, every valve and fan that are deployed on
the factory floor. It may also help detect and prevent a failure that could
impact the production, like the degradation (vibration) of a cooling fan on the
ceiling. IEEE Std. 802.15.4 Time-Slotted Channel Hopping (TSCH) 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.
As stated by the "Deterministic Networking 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 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 (i.e., scheduled cells ) for use by a centralized scheduler, and
leverage time and spatial diversity over a graph of end-to-end paths called a
Track that is based on those cells.
Over the course of the recent years, major Industrial Protocols (e.g., with EtherNet/IP and ) 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 and a wired or wireless backbone to report
both sensor data and critical monitoring within a bounded latency and maintain
the high reliability of the flows over time. It is also important to ensure that
RAW solutions are interoperable with existing wireless solutions in place, and
with legacy equipment whose capabilities can be extended using retrofitting.
Maintainability, as a broader concept than reliability is also important in
industrial scenarios .
Monitoring and diagnostics applications do not require latency critical
communications, but demand reliable and scalable communications. On the other
hand, process control applications involve control loops that require a bounded
latency, thus are latency critical, but can be managed end-to-end, and therefore
DetNet mechanisms can be applied in conjunction with RAW mechanisms.
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 plays in real
time - meaning live for public addresses in train stations or in theme parks.
The professional audio and video industry ("ProAV") includes:
Virtual Reality / Augmented Reality (VR/AR)
Production and post-production systems such as CD and Blu-ray disk mastering.
Public address, media and emergency systems at large venues (e.g., airports,
train stations, stadiums, and theme parks).
Considering the uninterrupted audio or video stream, a potential packet loss
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
viable in application where delays are not acceptable.
In the context of ProAV over packet networks, 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.
The devices need the wireless communication to support video streaming via IEEE
802.11 wireless LAN for instance. Wireless communications provide huge
advantages in terms of simpler deployments in many scenarios, where the use of a
wired alternative would not be feasible. Similarly, in live events, mobility
support makes wireless communications the only viable approach.
Deployed announcement speakers, for instance
along the platforms of the train stations, need the wireless communication to
forward the audio traffic in real time. Most train stations are already built, and
deploying novel cables for each novel service seems expensive.
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 (tracks) through the
network to support redundancy.
For synchronized streaming, latency must be bounded, and therefore, depending on
the actual requirements, this can be considered as latency critical. However,
the most critical requirement of this use-case is reliability, by the network
providing redundancy. Note that in many cases, wireless is only present in the
access, where RAW mechanisms could be applied, but other wired segments are also
involved (like the Internet), and therefore latency cannot be guaranteed.
The gaming industry includes real-time mobile
gaming, wireless console gaming, wireless gaming controllers and cloud gaming. Note that they are not mutually exclusive (e.g., a console can connect wirelessly to the Internet to play a cloud game). For RAW, wireless console gaming is the most relevant one. We next summarize the four:
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 (E2E) latency plus game servers processing time must be the same for
all players and should not be noticeable as the game is played. RAW technologies might help in keeping latencies low on the wireless segments of the communication.
Wireless Console Gaming: while gamers may use a physical console, interactions with
a remote server may be required for online games. Most of the gaming consoles today
support Wi-Fi 5, but may benefit from a scheduled access with Wi-Fi 6 in the
future. Previous Wi-Fi versions have an especially bad reputation among the gaming
community. The main reasons are high latency, lag spikes, and jitter.
Wireless Gaming controllers: most controllers are now wireless for a freedom of
movement.Controllers may interact with consoles or directly with gaming server in
the cloud. A low and stable end-to-end latency is here of predominant importance.
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.
While a lot of details can be found on , we next
summarize the main requirements in terms of latency, jitter and packet loss:
Intra Basic Service Set (BSS) latency is less than 5 ms.
Jitter variance is less than 2 ms.
Packet loss is less than 0.1 percent.
Gaming is evolving towards wireless, as players demand being
able to play anywhere, and the game requires a more immersive experience
including body movements. Besides, the industry is changing towards playing from
mobile phones, which are inherently connected via wireless technologies.
Wireless controllers are the rule in modern gaming, with increasingly sophisticated
interactions (e.g., haptic feedback, augmented reality).
Time sensitive networking extensions: extensions, such as time-aware shaping and
redundancy can be explored to address congestion and reliability problems
present in wireless networks. As an example, in haptics it is very important to minimize latency failures.
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 (like best-effort) traffic.
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. Note though, that while this requirement
needs to be signalled by RAW mechanisms, it would be actually served by the
lower layer.
Dual/multiple link: due to the fact that competitions and interference are common and
hardly in control under wireless network, to improve the latency stability,
dual/multiple link proposal is brought up to address this issue.
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 may be acceptable for many applications today,
however emerging time-sensitive applications are highly susceptible to increased
latency and jitter. To better control QoS, it is important to control
access to the network resources.
Depending on the actual scenario, and on use of Internet to interconnect
different users, the communication requirements of this use-case might be
considered as latency critical due to the need of bounded latency. But note that
in most of these scenarios, part of the communication path is not wireless and
DetNet mechanisms cannot be applied easily (e.g., when the public Internet is
involved), and therefore in these cases, reliability is the critical
requirement.
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
(i.e., the 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 (e.g., medicine in rural
areas). Note that the surveillance and monitoring application would have to comply with local regulations regarding location privacy of users. Different considerations have to be applied when surveillance is performed for traffic rules enforcement (e.g., generating fines) as compared to when traffic load is being monitored.
Many types of vehicles, including UAVs but also others, such as cars, can travel
in platoons, driving together with shorter distances between vehicles to
increase efficiency. Platooning imposes certain vehicle-to-vehicle
considerations, most of these are applicable to both UAVs and other vehicle
types.
UAVs/vehicles typically have various forms of wireless connectivity:
Cellular: for communication with the control center, for remote
maneuvering as well as monitoring of the drone;
IEEE 802.11: for inter-drone communications (i.e., platooning)
and providing connectivity to other devices (i.e., acting as Access Point).
Note that autonomous cars share many of the characteristics of the aforemention
UAV case, and therefore it is of interest for RAW.
Some of the use-cases/tasks involving UAVs require coordination among UAVs.
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 UAVs.
Remote maneuvering of a drone might be performed over a cellular network in some
cases, however, there are situations that need very low latency and
deterministic behavior of the connectivity. Examples involve platooning of
drones or sharing of computing resources among drones (like, a drone offload some
function to a neighboring drone).
UAVs cannot be connected through any type of wired media, so it is obvious that
wireless is needed.
The network infrastructure is 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 UAVs --
chained, each link connecting two given functions would have a well-defined set
of requirements (e.g., latency, bandwidth and jitter) that must be met.
Today's solutions keep the processing operations that are critical local (i.e.,
they are not offloaded). Therefore, in this use-case, the critical requirement
is reliability, and only for some platooning and inter-drone communications
latency is critical.
The Edge Robotics scenario consists of several robots, deployed in a given area
(like a shopping mall), inter-connected via an access network to a
network 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).
Simple examples of the use of multiple robots are cleaning, video surveillance (note that this have to comply with local regulations regarding user's privacy at the application level),
search and rescue operations, and delivering of goods from warehouses to shops.
Multiple robots are simultaneously instructed to perform individual tasks by
moving the robotic intelligence from the robots to the network's edge. That
enables easy synchronization, scalable solution, and on-demand option to create
flexible fleet of robots.
Robots would have various forms of wireless connectivity:
IEEE 802.11: for connection to the edge and also inter-robot communications
(i.e., for coordinated actions).
Cellular: as an additional communication link to the edge, though primarily as
backup, since ultra-low latency is needed.
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 latency (0.5-20 ms ) between the robot and the location where the control intelligence resides (which might be the edge or another robot).
Deploying robots in scenarios such as shopping malls for the applications
mentioned cannot be done via wired connectivity.
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 must be met.
This use-case might combine multiple communication flows, with some of them
being latency critical (like those related to robot control tasks). Note that
there are still many communication flows (like some offloading tasks) that only
demand reliability and availability.
An instrumented ambulance would be one that one or multiple network segments to which are connected
these end systems such as:
vital signs sensors attached to the casualty in the ambulance. Relay medical
data to hospital emergency room,
radio-navigation sensor to relay position data to various destinations including
dispatcher,
voice communication for ambulance attendant (like to consult with ER doctor), and
voice communication between driver and dispatcher.
The LAN needs to be routed through radio-WANs (a radio network in the interior of a network, i.e., it is terminated by routers) to complete the network linkage.
What we have today is multiple communication systems to reach the vehicle via:
A dispatching system,
a cellphone for the attendant,
a special purpose telemetering system for medical data,
etc.
This redundancy of systems does not contribute to availability.
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. Special care (at application level) have to be paid to ensuring that sensitive data is not disclosed to unauthorized parties, by properly securing traffic and authenticating the communication ends.
Local traffic between the first responders/ambulance staff and the ambulance
equipment cannot be done via wired connectivity as the responders perform
initial treatment outside of the ambulance. The communications from the
ambulance to external services must be wireless as well.
We can derive some pertinent requirements from this scenario:
High availability of the inter-network is required. The exact level of availability depends on the specific deployment scenario, as not all emergency agencies share the same type of instrumented emergency vehicles.
The inter-network needs to operate in damaged state (e.g. during an earthquake
aftermath, heavy weather, wildfire, etc.). In addition to continuity of
operations, rapid restore is a needed characteristic.
The radio-WAN has characteristics similar to cellphone -- the vehicle will
travel from one radio coverage area to another, thus requiring some hand-off approach.
In this case, all applications identified do not require latency critical
communication, but do need high reliability and availability.
This document enumerates several use-cases and applications that need RAW
technologies, focusing on the requirements from reliability, availability and
latency. Whereas some use-cases are latency-critical, there are also several
applications that are non-latency critical, but that do pose strict reliability
and availability requirements.
This document has no IANA actions.
This document covers several 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.
provides a comprehensive discussion of security considerations in the context of
deterministic networking, which are generally applicable also to RAW.
Nils Mäurer, Thomas Gräupl and Corinna Schmitt have contributed
significantly to this document, providing input for the Aeronautical
communication 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, Rute
Sofia, Corinna Schmitt, Victoria Pritchard, John Scudder, Joerg Ott and
Stewart Bryant for their valuable comments on previous versions of this document.
The work of Carlos J. Bernardos in this document has been partially supported by
the Horizon Europe PREDICT-6G (Grant 101095890) and UNICO I+D 6G-DATADRIVEN-04 project.
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