What is TSN, and why industrial 5G won’t work without it? (Talking 5G-TSC with 5G-ACIA)
Time sensitive networking (TSN), designed to manage latency between industrial devices in Ethernet networks, is essential if a new industrial-grade version of cellular-based 5G is to find its mark in smart factories. TSN is key for industrial applications such as process and machine control where low latency and jitter are critical to closed loop control requirements in communications networks.
Integration with 5G, extending critical orchestration techniques into industrial wireless networks, is in-process with 3GPP, but far from finished – and far from straightforward. The 5G Alliance for Connected Industries and Automation (5G-ACIA) has just published a paper about integration of TSN and 5G, coming with Releases 16 and 17 of the standard, which says 5G has all “essential capabilities” to interwork with TSN for industrial automation.
This interview was scheduled to go into a new Enterprise IoT Insights report on the subject. The report has been postponed, but the conversation is timely, given the latest 5G-ACIA whitepaper (plus another on industrial 5G use cases), the group’s recent work with the OPC Foundation to also bring OPC UA (the key open protocol standard to connect industrial machines) over 5G, and the continuing work to develop 5G as a platform for industrial change.
The interview below is with Kun Wang, system manager for digital services at Ericsson. Wang works with both 3GPP and 5G-ACIA, focusing on 5G solutions for vertical industries, industrial IoT and ‘time sensitive communication’ (TSC) – which a number of interviewees for the abandoned Enterprise IoT Insights report have noted is the formal term (rather than TSN) being attached with 5G, as 5G-TSC. All the answers are from Wang.
Note this is the first of a number of Q&A sessions Enterprise IoT Insights will publish in the next weeks on the subject of 5G-TSN/TSC. The subject of TSN integration with OPC-UA has been explored separately, and at length, in these pages also, with major input from Cisco. For further reading, an excellent commentary on how wireless TSN will be designed, deployed, managed in industrial 5G and Wi-Fi networks is provided here. Now, we turn it over to Wang.
What is the role of TSN in industry?
“Time sensitive networking (TSN) is a set of novel open standards specified by IEEE that provide deterministic, reliable, high-bandwidth, and low-latency communication. In a modern factory, many processes have to be controlled and regulated. They often consist of many individual steps that have to be coordinated with each other. In addition, such applications are becoming faster and more demanding with increasing digitization.
“TSN has been introduced to guarantee high availability, high throughput, real-time transmission, low latency, and low jitter. Behind the term are various standards for the transmission of data in Ethernet networks. TSN is therefore not a communication protocol, but a technology that can facilitate the critical requirements of higher-level industrial applications. In this respect, TSN is the key to wired industrial communication, just as 5G is for wireless connectivity.”
Why is TSN important for Industry 4.0?
“TSN is the Industry 4.0 enabler. In fact, TSN enables more robust and reliable Ethernet communication between machines and plants, even under high network loads. Since network resources can be reserved for time-sensitive traffic in the TSN network, data transmission is guaranteed and it is precisely predictable regardless of the load. Today a large variety of fieldbuses – real-time Ethernet protocols on factory shop floors – make the interconnectivity needed for Industry 4.0 difficult to achieve.
“To overcome this issue, the IEEE 802.1 TSN Ethernet standard family was introduced for real-time deterministic, enterprise-wide, low-latency industrial communication. In contrast to existing industrial Ethernet protocols, TSN is not only compatible with standard IEEE 802.3 Ethernet on the physical layer but also higher layers, such as the data link layer. As part of the IEEE 802 standards that specify Ethernet-bridged networks, TSN bridges are interoperable with all standard Ethernet bridges in the entire enterprise network.”
Why is TSN important for industrial 5G in Industry 4.0?
“A communication network for Industry 4.0 must also support wireless communication for mobile, rotating, and flexible objects. Furthermore, wireless communication systems entail lower installation costs and enable upgrades and modernization of production facilities on a larger scale. The general usage of wireless communication was limited in the past to open-loop control and manufacturing execution system (MES) applications due to the lack of ultra-high availability, reliability and real-time capability.
“The new 5G communication standard with increased throughput, reliability, availability and low latency performance will enable large-scale industrial usage including field-level applications. There are significant benefits that can be achieved for industrial use cases with the introduction of TSN and 5G wireless communication – for example, due to increased flexibility in the deployment of industrial equipment and the network. This requires 5G to provide robust support for Ethernet-TSN communication services and interworking with wired TSN networks.”
What are the key Industry 4.0 applications for 5G-TSN?
“A recent 5G-ACIA whitepaper (from May 2020) [presents] typical industrial use cases [for industrial 5G with TSN] – crucially for controller-to-controller, controller-to-device and device-to-compute communications. The paper shows that 5G, as specified in Release 16 and 17, provides all functionality needed for integration with TSN for industrial automation. A very realistic application is shuttles in a packaging plant.
“With many state-of-the-art packaging machines, one or more track-based shuttles convey materials inside a single machine or between multiple machines. These shuttles have local on-board controllers that can communicate their position or other control data via 5G. As shuttle controllers interact with other devices, such as robots or machines that require the exact position of the shuttles in real time, failed or delayed transmission of the corresponding data could lead to the cessation of machine operation and therefore downtime.”
How does OPC UA fit with TSN and with 5G-TSN?
“With TSN, applications become more robust in the face of high network loads and synchronous clock operations – even without having to use special hardware components. However, TSN not only plays out its advantages at the field level, but also for the control and operator level. Here, the open, manufacturer- and platform-independent standard OPC UA has become widely accepted.
“TSN is ideal for time-critical communication from machine to machine and from machines to MES and ERP level [systems]. This means connectivity is manufacturer-independent and several protocols, including those with real-time capability, can be transmitted simultaneously. Large amounts of data can be transmitted in this way, and high-performance machine communications, with the possibility of dynamic ad hoc networking relationships, take place at the control and operator level.
“The main advantages come with the combination of 5G-TSN and OPC UA, enabling enterprises to use one network infrastructure for different applications – like automation, maintenance, or analytics. Additionally, the combination of 5G-TSN and OPC UA provides a guaranteed but differentiated quality-of-service, low transmission latency, and high-quality real-time communications.”
What are the challenges / obstacles – in terms of technological development?
“5G-ACIA is also looking at how industrial private 5G networks can be integrated with existing and emerging Industry 4.0 operations systems. We recently published another whitepaper, on use of digital twins to integrate 5G into production networks, which provides an overview. A key aspect is the integration of 5G into Industry 4.0 by defining a 5G Asset Administration Shell (AAS).
“The AAS concept has emerged as an important building block for the ‘factory of the future’, and is about to be standardized by the International Electrotechnical Commission (IEC). A new organization, the Industrial Digital Twin Association, is being formed by the German Electrical and Electronic Manufacturers Association (ZVEI) and Mechanical Engineering Industry Association (VDMA) to drive the commercial implementation of AAS.
“On the hardware side, things are looking good in terms of industrial 5G devices, as well. Chip manufacturers have already been on the market with Release 15 chipsets for some time, and manufacturers have announced they will also offer chips that meet Release 16 requirements by the end of 2021.”
What are the challenges / obstacles – in terms of the standardization process?
“First of all, there’s a lot of work [to do – and also to answer the question]! 3GPP has worked out 5G-based industrial communication with TSN. Starting from Release 15, ultra-reliable low-latency communication (URLLC) capabilities have been gradually introduced. 3GPP was able to launch the next round of evolution as early as mid-2020 – three months late due to the Covid 19 pandemic. Development always follows the same principles: add new features, improve existing ones, simplify implementation, and make operations more efficient.
“This was true for the latest 5G spec, too. Support for TSN was added in Release 16, and extended in the Release 17 work item on industrial IoT. The standardization work covers new 5G capabilities to support TSC, and 5G integration with TSN networks – a 5G system has been specified, for example, to appear to an external TSN network as a set of virtual TSN-enabled 5G bridges. At the same time, IEEE TSN standardization is evolving, too, and specification of a TSN profile for industrial automation IEC/IEEE 60802 is currently under development. It is important that the 5G standard remains aligned with this evolution of TSN.”
What is the roadmap for these technologies?
“Further improvements are to be made in ongoing 3GPP Release 17 work. Here, too, there are already some interesting technologies that create further application possibilities for 5G. These include the extension of the radio spectrum up to 71 GHz, enhancements for private 5G networks, positioning enhancement, a ‘5G Light’ (or ‘Reduced Capability NR’) with an energy efficient mode for industrial sensors running on batteries, and – also of interest to industrial users – new functions for the optimized use of augmented or virtual reality.
“In addition, users should not lose sight of their own roadmap. The use of wireless technologies can bring many advantages to enterprises. But there is always an impact on how products are designed, and how production workflows and processes are organized. In this context, enterprises find answers to certain concrete questions right away, like where to put the antennas and who to work with. The learning curve rises steeply, from there. But ultimately, those who use the technology will be rewarded.”