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TS 22.104  SA1 ★
Service Requirements for
Cyber-Physical Control Applications
in Vertical Domains

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WI Acronym:  -
Rapporteur:  Dr. Walewski, Joachim  Siemens AG
The present document addresses a challenging class of vertical applications, namely cyber-physical control applications, which require very high levels of communication service availability, and some of them also require very low end-to-end latencies.

full Table of Contents for  TS 22.104  Word version:   17.2.0

Here   Top
1 Scope  2 References  3 Definitions, symbols and abbreviations  4 Overview  5 Performance requirements  6 Ethernet applications  7 ProSe communication for cyber-physical control applications  A Summary of service performance requirements  A.1 About the vertical domains addressed in this Annex  A.2 Factories of the Future  A.4 Electric-power distribution  A.5 Central power generation  A.6 Connected hospitals or medical facilities  B Communication service errors  C Characterising communication services  D 5G in industrial automation: different and multiple time domains for synchronization  E Audio and Video Production  F Change history 

 

1  Scope  Word-p. 7
2  References
[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2] 3GPP TS 22.261: "Service requirements for the 5G system".
[3] IEC 61784-3: "Industrial communication networks - profiles - part 3: functional fieldbuses - general rules and profile definitions".
[4] BZKI, "Aspects of dependability assessment in ZDKI", June 2017.
[5] BZKI, "Requirement Profiles in ZDKI", 2017.
[6] IEC 61158: "Industrial communication networks - fieldbus specification", 2014.
[7] IEC 61907, "Communication network dependability engineering".
[8] Richard C. Dorf and Robert H. Bishop, "Modern Control Systems", Pearson, Harlow, 13th Edition, 2017.
[9] Ernie Hayden, Michael Assante, and Tim Conway, "An Abbreviated History of Automation & Industrial Controls Systems and Cybersecurity", SANS Institute, https://ics.sans.org/media/An-Abbreviated-History-of-Automation-and-ICS-Cybersecurity.pdf {accessed: 2017-05-23}, 2014.
[10] IEC 61512 "Batch control - Part 1: Models and terminology".
[11] RESERVE project, Deliverable D1.3, ICT Requirements, http://www.re-serve.eu/files/reserve/Content/Deliverables/D1.3.pdf, September 2017.
[12] RESERVE project, Deliverable D1.2, Energy System Requirements http://www.re-serve.eu/files/reserve/Content/Deliverables/D1.2.pdf, September 2017.
[13] G. Garner, "Designing Last Mile Communications Infrastructures for Intelligent Utility Networks (Smart Grids)", IBM Australia Limited, 2010.
[14] B. Al-Omar, B., A. R. Al-Ali, R. Ahmed, and T. Landolsi, "Role of Information and Communication Technologies in the Smart Grid", Journal of Emerging Trends in Computing and Information Sciences, Vol. 3, pp. 707-716, 2015.
[15] H. Kagermann, W. Wahlster, and J. Helbig, "Recommendations for implementing the strategic initiative INDUSTRIE 4.0", Final report of the Industrie 4.0 working group, acatech - National Academy of Science and Engineering, Munich, April 2013.
[16] IEC 62443-3-2: "Security for industrial automation and control systems - Part 3-2: Security risk assessment and system design", in progress.
[17] IEC 62657-2: "Industrial communication networks - Wireless communication networks - Part 2: Coexistence management", 2017.
[18] IEC 62657-1: "Industrial communication networks - Wireless communication networks - Part 1: Wireless communication requirements and spectrum considerations".
[19] IEEE Std 802.1Q "Media Access Control (MAC) Bridges and Virtual Bridge Local Area Networks". NOTE: IEEE Std 802.1Qbv-2015 "Enhancements for Scheduled Traffic" has been included into IEEE Std 802.1Q-2018.
[20] IEEE, Use Cases IEC/IEEE 60802, 2018.
[21] "IEEE Standard for Local and metropolitan area networks--Timing and Synchronization for Time-Sensitive Applications in Bridged Local Area Networks--Corrigendum 1: Technical and Editorial Corrections," IEEE Std 802.1AS-2011/Cor 1-2013 (Corrigendum to IEEE Std 802.1AS-2011), pp. 1-128, Sept 2013.
[22] "IEEE Standard for Local and metropolitan area networks--Timing and Synchronization for Time-Sensitive Applications," IEEE Std 802.1AS-Rev/D7.3, pp. 1-502, August 2018.
[23] 3GPP TS 22.289: "Mobile Communication System for Railways".
[24] IEEE P802.1CS: "IEEE Draft Standard for Local and metropolitan area networks - Link-local Registration Protocol"
[25] IEEE P802.1Qdd: "IEEE Draft Standard for Local and Metropolitan Area Networks--Bridges and Bridged Networks -- Amendment: Resource Allocation Protocol (RAP)"
[26] IEC/IEEE 60802: "Time-Sensitive Networking Profile for Industrial Automation".
[27] 3GPP TS 22.263: "Service requirements for Video, Imaging and Audio for Professional Applications (VIAPA)".
3  Definitions, symbols and abbreviations  Word-p. 8
3.1  Definitions
characteristic parameter: numerical value that can be used for characterising the dynamic behaviour of communication functionality from an application point of view.
clock synchronicity: the maximum allowed time offset within a synchronisation domain between the sync master and any sync device.
clock synchronisation service: the service to align otherwise independent user-specific UE clocks.
communication service availability: percentage value of the amount of time the end-to-end communication service is delivered according to an agreed QoS, divided by the amount of time the system is expected to deliver the end-to-end service according to the specification in a specific area.
communication service reliability: ability of the communication service to perform as required for a given time interval, under given conditions.
factory automation: automation application in industrial automation branches typically with discrete characteristics of the application to be automated with specific requirements for determinism, low latency, reliability, redundancy, cyber security, and functional safety.
global clock: a user-specific synchronization clock set to a reference timescale such as the International Atomic Time.
influence quantity: quantity not essential for the performance of an item but affecting its performance.
process automation: automation application in industrial automation branches typically with continuous characteristics of the application to be automated with specific requirements for determinism, reliability, redundancy, cyber security, and functional safety.
service area: geographic region where a 3GPP communication service is accessible.
survival time: the time that an application consuming a communication service may continue without an anticipated message.
sync device: device that synchronizes itself to the master clock of the synchronization domain.
sync master: device serving as the master clock of the synchronization domain.
transfer interval: time difference between two consecutive transfers of application data from an application via the service interface to 3GPP system.
working clock: a user-specific synchronization clock for a localized set of UEs collaborating on a specific task or work function.
3.2  Symbols  Word-p. 10
3.3  Abbreviations
4  Overview
4.1  Introduction
For the purpose of this document, a vertical domain is a particular industry or group of enterprises in which similar products or services are developed, produced, and provided. Automation refers to the control of processes, devices, or systems in vertical domains by automatic means. The main control functions of automated control systems include taking measurements, comparing results, computing any detected or anticipated errors, and correcting the process to avoid future errors. These functions are performed by sensors, transmitters, controllers, and actuators.
In the context of this document, cyber-physical systems are referred to as systems that include engineered, interacting networks of physical and computational components. Cyber-physical control applications are to be understood as applications that control physical processes. Cyber-physical control applications in automation follow certain activity patterns, which are open-loop control, closed-loop control, sequence control, and batch control (see Clause 4.2).
Communication services supporting cyber-physical control applications need to be ultra-reliable, dependable with a high communication service availability, and often require low or (in some cases) very low end-to-end latency.
Communication in automation in vertical domains follows certain communication patterns. The most well-known is periodic deterministic communication, others are aperiodic deterministic communication and non-deterministic communication (see Clause 4.3).
Communication for cyber-physical control applications supports operation in various vertical domains, for instance industrial automation and energy automation. This document addresses service requirements for cyber-physical control applications and supporting communication services from the vertical domains of factories of the future (smart manufacturing), electric power distribution, and central power generation. Service requirements for cyber-physical control applications and supporting communication services for rail-bound mass transit are addressed in TS 22.289.
4.2  Activity patterns in automation  Word-p. 11
Open-loop control: The salient aspect of open-loop control is the lack of feedback from the output to the control; when providing commands to an actuator, it is assumed that the output of the influenced process is predetermined and within an acceptable range. This kind of control loop works if the influences of the environment on process and actuator are negligible. Also, this kind of control is applied in case unwanted output can be tolerated [8].
Closed-loop control: Closed-loop control enables the manipulation of processes even if the environment influences the process or the performance of the actuator changes over time. This type of control is realised by sensing the process output and by feeding these measurements back into a controller [8].
Sequence control: Sequence control may either step through a fixed sequence or employ logic that performs different actions based on various system states and system input [8]. Sequence control can be seen as an extension of both open-loop and closed-loop control, but instead of achieving only one output instance, an entire sequence of output instances can be produced [9].
Batch control: Batch processes lead to the production of finite quantities of material (batches) by subjecting input materials to a defined order of processing actions by use of one or more pieces of equipment [10].
4.3  Communication attributes
Communication in automation can be characterised by two main attributes: periodicity and determinism.
Periodicity means that a transmission interval is repeated. For example, a transmission occurs every 15 ms. Reasons for a periodical transmission can be the periodic update of a position or the repeated monitoring of a characteristic parameter. Most periodic intervals in communication for automation are rather short. The transmission is started once and continuous unless a stop command is provided.
An aperiodic transmission is, for example, a transmission which is triggered instantaneously by an event, i.e., events are the trigger of the transmission. Events are defined by the control system or by the user. Example events are:
  • Process events: events that come from the process when thresholds are exceeded or fallen below, e.g., temperature, pressure, level, etc.
  • Diagnostic events: events that indicate malfunctions of an automation device or module, e.g., power supply defective; short circuit; too high temperature; etc.
  • Maintenance events: events based on information that indicates necessary maintenance work to prevent the failure of an automation device.
Most events, and especially alarms, are confirmed. In this context, alarms are messages that inform a controller or operator that an event has occurred, e.g., an equipment malfunction, process deviation, or other abnormal condition requiring a response. The receipt of the alarm is acknowledged usually within a short time period by the application that received the alarm. If no acknowledgment is received from the target application after a preset time, the so-called monitoring time, the alarm is sent again after a preset time or some failure response action is started.
Determinism refers to whether the delay between transmission of a message and receipt of the message at the destination address is stable (within bounds). Usually, communication is called deterministic if it is bounded by a given threshold for the latency/transmission time. In case of a periodic transmission, the variation of the interval is bounded.
4.4  Control systems and related communication patterns  Word-p. 12
There are preferences in the mapping between the type of control and the communication pattern. Open-loop control is characterised by one or many messages sent to an actuator. These can be sent in a periodic or an aperiodic pattern. However, the communication means used need to be deterministic since typically an activity response from the receiver and/or the receiving application is expected.
Closed-loop control produces both periodic and aperiodic communication patterns. Closed-loop control is often used for the control of continuous processes with tight time-control limits, e.g., the control of a printing press. In this case, one typically relies on periodic communication patterns. Note that in both the aperiodic and periodic case, the communication needs to be deterministic.
Logging of device states, measurements, etc. for maintenance purposes and such typically entails aperiodic communication patterns. In case the transmitted logging information can be time-stamped by the respective function, determinism is often not mandatory.
In practice, vertical communication networks serve a large number of applications exhibiting a wide range of communication requirements. In order to facilitate efficient modelling of the communication network during engineering and for reducing the complexity of network optimisation, traffic classes or communication patterns have been identified [6]. There are three typical traffic classes or communication patterns in industrial environments [6], i.e.,
  • deterministic periodic communication: periodic communication with stringent requirements on timeliness of the transmission.
  • deterministic aperiodic communication: communication without a preset sending time. Typical activity patterns for which this kind of communication is suitable are event-driven actions.
  • non-deterministic communication: subsumes all other types of traffic, including periodic non-real time and aperiodic non-real time traffic. Periodicity is irrelevant in case the communication is not time-critical.
Some communication services exhibit traffic patterns that cannot be assigned to one of the above communication patterns exclusively (mixed traffic).
4.5  Implications for 5G systems
In order to be suitable for automation in vertical domains, 5G systems need to be dependable and flexible to meet specific KPIs to serve specific applications and use cases. They need to come with the system properties of reliability, availability, maintainability, safety, and integrity. What particular requirements each property needs to meet depends on the particularities of the domain and the use case. The requirements in this document provide various sets of performance criteria that need to be met to satisfactorily support different use cases of cyber-physical control applications used by various vertical markets.
5  Performance requirements
5.1  Overview
5.2  Periodic deterministic communication  Word-p. 13
5.3  Aperiodic deterministic communication  Word-p. 19
5.4  Non-deterministic communication  Word-p. 21
5.5  Mixed traffic
5.6  Clock synchronisation requirements  Word-p. 23
5.6.0  Description
5.6.1  Clock synchronisation service level requirements  Up
5.6.2  Clock synchronisation service performance requirements  Word-p. 24
5.7  Positioning performance requirements
5.8  Network operation requirements [R17]  Word-p. 25
6  Ethernet applications
7  ProSe communication for cyber-physical control applications [R17]  Word-p. 26
7.1  Description
7.2  Requirements
7.2.1  General
7.2.2  Network performance
7.2.3  Clock synchronization  Word-p. 27
7.2.4  Service Continuity
7.2.5  Indirect communication
A  Summary of service performance requirements  Word-p. 28
A.1  About the vertical domains addressed in this Annex
A.2  Factories of the Future
A.2.1  Overview
The manufacturing industry is currently subject to a fundamental change, which is often referred to as the "Fourth Industrial Revolution" or simply "Industry 4.0" [15]. The main goals of Industry 4.0 are—among others—the improvement of flexibility, versatility, resource efficiency, cost efficiency, worker support, and quality of industrial production and logistics. These improvements are important for addressing the needs of increasingly volatile and globalised markets. A major enabler for all this are cyber-physical production systems based on a ubiquitous and powerful connectivity, communication, and computing infrastructure. The infrastructure interconnects people, machines, products, and all kinds of other devices in a flexible, secure and consistent manner. Several different application areas can be distinguished:
  1. Factory automation: Factory automation deals with the automated control, monitoring and optimisation of processes and workflows within a factory. This includes aspects like closed-loop control applications (e.g., based on programmable logic or motion controllers) and robotics, as well as aspects of computer-integrated manufacturing. Factory automation generally represents a key enabler for industrial mass production with high quality and cost-efficiency. Corresponding applications are often characterised by highest requirements on the underlying communication infrastructure, especially in terms of communication service availability, determinism, and latency. In the Factories of the Future, static sequential production systems will be more and more replaced by novel modular production systems offering a high flexibility and versatility. This involves many increasingly mobile production assets, for which powerful wireless communication and localisation services are required.
  2. Process automation: Process automation refers to the control of production and handling of substances like chemicals, food & beverage, pulp, etc. Process automation improves the efficiency of production processes, energy consumption, and safety of the facilities. Sensors measuring process values, such as pressures or temperatures, are working in closed loops via centralised and decentralised controllers. In turn, the controllers interact with actuators, e.g., valves, pumps, heaters. Also, monitoring of attributes such as the filling levels of tanks, quality of material, or environmental data are important, as well as safety warnings or plant shut downs. Workers in the plant are supported by mobile devices. A process automation facility may range from a few 100 m2 to several km2, and the facility may be geographically distributed. Depending on the size, a production plant may have several 10 000 measurement points and actuators. Autarkic device power supply for years is needed in order to stay flexible and to keep the total costs of ownership low.
  3. HMIs and production IT: Human-machine interfaces (HMIs) include all sorts of devices for the interaction between people and production facilities, such as panels attached to a machine or production line, but also standard IT devices, such as laptops, tablet PCs, smartphones, etc. In addition, augmented- and virtual-reality applications are expected to play an increasingly important role in future.
  4. Logistics and warehousing: Organisation and control of the flow and storage of materials and goods in the context of industrial production. In this respect, intra-logistics is dealing with logistics within a certain property (e.g., within a factory), for example by ensuring the uninterrupted supply of raw materials on the shop floor level using automated guided vehicles (AGVs), fork lifts, etc. This is to be seen in contrast to logistics between different sites. Warehousing particularly refers to the storage of materials and goods, which is also getting more and more automated, for example based on conveyors, cranes and automated storage and retrieval systems.
  5. Monitoring and maintenance: Monitoring of certain processes and/or assets in the context of industrial production without an immediate impact on the processes themselves (in contrast to a typical closed-loop control system in factory automation, for example). This particularly includes applications such as condition monitoring and predictive maintenance based on sensor data, but also big data analytics for optimising future parameter sets of a certain process, for instance. For these use cases, the data acquisition process is typically not latency-critical.
A.2.2  Factory automation  Word-p. 29
A.2.2.1  Motion control
A.2.2.2  Control-to-control communication  Word-p. 31
A.2.2.3  Mobile robots  Up
A.2.2.4  Wired to wireless link replacement [R17]  Word-p. 34
A.2.2.5  Cooperative carrying [R17]  Word-p. 35
A.2.3  Process automation  Word-p. 37
A.2.3.1  Closed-loop control
A.2.3.2  Process and asset monitoring
A.2.3.3  Plant asset management  Word-p. 38
A.2.4  Human machine interfaces  Word-p. 39
A.2.4.1  Mobile control panels
A.2.4.1A  Mobile operation panels [R17]  Word-p. 41
A.2.4.2  Augmented reality  Word-p. 43
A.2.5  Monitoring and maintenance
A.2.5.1  Remote access and maintenance
A.3  Void
A.4  Electric-power distribution  Word-p. 45
A.4.1  Overview
A.4.2  Primary frequency control
A.4.3  Distributed voltage control  Word-p. 46
A.4.4  Distributed automated switching for isolation and service restoration
A.4.5  Smart grid millisecond-level precise load control  Word-p. 48
A.5  Central power generation  Word-p. 49
A.5.1  Overview  Up
A.5.2  Wind power plant network
A.6  Connected hospitals or medical facilities [R17]
A.6.1  Overview
A.6.2  Robotic Aided Surgery  Word-p. 50
A.6.3  Robotic Aided Diagnosis  Word-p. 52
B  Communication service errors  Word-p. 55
B.1  Introduction
B.2  Corruption
B.3  Unintended repetition
B.4  Incorrect sequence  Up
B.5  Loss  Word-p. 56
B.6  Unacceptable deviation from target end-to-end latency
B.7  Masquerade
B.8  Insertion
B.9  Addressing
C  Characterising communication services  Word-p. 57
C.1  Modelling of communication in automation
C.1.1  Area of consideration
C.1.2  Logical link  Word-p. 58
C.1.2.1  Nature and function  Up
C.1.2.2  Message transformation  Word-p. 59
C.1.2.3  Communication device
C.1.2.4  Communication system
C.2  Communication service description  Word-p. 60
C.2.1  Overview
C.2.2  Characteristic parameters
C.2.3  Influence quantities  Word-p. 62
C.3  Up time and up state vs. down state and down time  Word-p. 63
C.4  Timeliness as an attribute for timing accuracy  Word-p. 64
C.4.1  Overview  Up
C.4.2  Network latency requirement formulated by use of timeliness  Word-p. 65
C.4.3  Timeliness
C.4.4  Deviation
C.4.5  Earliness  Word-p. 66
C.4.6  Lateness  Word-p. 67
C.4.7  Conclusion
C.5  Communication service terminology w.r.t. 5G network and vertical applications
D  5G in industrial automation: different and multiple time domains for synchronization  Word-p. 70
D.1  Description
D.2  Merging of working clock domains  Word-p. 71
D.3  Time synchronization with 5G networks  Word-p. 72
E  Audio and Video Production [R17]  Word-p. 73
E.1  Description
AV production includes television and radio studios, outside and remotely controlled broadcasts, live news-gathering, sports events, music festivals, among others. All of these applications require a high degree of reliability, since they are related to the capturing and transmission of data at the beginning of a production chain. This differs drastically when compared to other multimedia services because the communication errors will be propagated to the entire audience that is consuming that content both live and recorded for later distribution. Furthermore, the transmitted data is often post-processed with nonlinear filters which could actually amplify defects that would be otherwise not noticed by humans. Therefore, these applications call for uncompressed or only slightly compressed data, and very low probability of errors. These devices will also be used alongside existing technologies which have a high level of performance and so any new technologies will need to match or improve upon the existing workflows to drive adoption of the technology.
The performance aspects that are covered by/in TS 22.263 [27] (Service requirements for Video, Imaging and Audio for professional applications) also target the latency that these services experience.
In recent years Production facilities have moved from bespoke unidirectional highly specialised networks to IP based systems and software-based workflows. This migration is expected to continue, and wireless IP connectivity is key to a number of these workflows.
Typical set ups require multiple devices such as cameras, microphones and control surfaces that require extremely close synchronisation to maintain consistency of pictures and audio. Such clock synchronization requirements are captured in clause 5.6. Often devices need to communicate directly to each other for instance a camera to a monitor or a microphone to a PA system.
Video and audio applications also require extremely high quality of service metrics as the loss of a single packet can cause picture or sound breakup in the downstream processing or distribution. Often this is a legal, regulatory or contractual agreement to maintain a high quality, stable and clear video or audio signal.
E.2  Multiple source wireless studio
E.3  Timing use in AV production applications  Word-p. 74
F  Change history  Word-p. 76

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