The Time Sensitive Networking (TSN) family of IEEE 802.1 network standards bring reliability and low latency to applications over Ethernet, Wi-Fi, and 5G.
Timing is everything, whether it’s in delivering a joke, hitting a late-inning home run, transporting a data packet, or sending control signals. As network timing has taken on importance, protocols have evolved from Network Time Protocol to IEEE 1588 Precision Time Protocol to TSN. 5G’s requirement for Ultra-Reliable Low-Latency Communications (URLLC) brings new iterations of the TSN standard.
The rise of 5G networks is poised to accelerate the adoption of TSN technology by dramatically expanding the use cases and extending TSN capabilities to mobile networks. Global Market Insights estimates that the TSN market will grow by 30% annually over the next five years, increasing from $200 million USD in 2019 to over $1 billion USD in 2026. This explosive growth is driven largely by the things in our lives getting smarter – factories, power plants, cars, etc. – and relying more and more on wireless networks.
As described in the Avnu Alliance whitepaper, Wireless TSN – Definitions, Use Cases & Standards Roadmap, the core competencies of time synchronization, bounded latency, reliability, and resource management enhance network performance.
Time Synchronization: The 802.1AS standard defines a profile of the PTP to distribute time across the network. Time synchronization between hosts and network devices can be used by the application and by other TSN capabilities (e.g. Time-Aware 802.1Qbv Scheduling).
Bounded Latency: Providing bounded latency is one of the main features of a TSN-enabled network. Several 802.1 standards have been defined to enable queuing management, gating and traffic shaping (802.1Qav, 802.1Qbv) to ensure time-critical packets receive priority as they are being forwarded through the network. Frame preemption, defined by 802.1Qbu and 802.3br for Ethernet, provide low bounded latency while increasing the efficiency of the network.
Reliability: The bounded latency performance must be delivered with very high reliability. The TSN-enabled network must ensure every packet arrives within a given latency bound with no packet losses and delays due to congestion. In addition, to account for device failure and/or media errors, IEEE 802.1CB also defines packet replication and elimination capabilities to enable redundant links and paths.
Resource Management: Configuring the TSN capabilities and managing the network and device resources is fundamental to assure end-to-end performance for time-critical flow across the network in presence of other traffic flow. By managing the resources in each node, the availability of buffers and timing of transmission can be guaranteed. Thus, TSN latency and reliability goals can be assured. Several network management models and protocols have also been defined (e.g. 802.1Qcc, 802.1Qca, 802.1Qat.
As a subset of the foundational open standards that empower modern networks, TSN is a future-proof technology that enables time-sensitive applications, building on widely adopted LAN connectivity technologies such as Ethernet, Wi-Fi, and now 5G. Here’s how extending TSN capabilities to wireless will change the network landscape over the next five years:
1) TSN over 5G will unleash the robots.
The IIoT is already one of the most promising arenas for TSN adoption. This segment has received significant interest and has motivated the development of the 5G URLLC. Several industrial use cases have been captured in detail by 3GPP, 5G ACIA, and IEEE 802.11 standard groups. Closed loop control is one of the most widely applicable use cases given its generic control loop model (input + compute + actuation), but specific latency and reliability requirements vary significantly depending on the application.
Today’s smart factories are more than just fixed assembly lines, however. Sophisticated industrial robots require mobility, flexibility, and reconfigurability of tasks. Wireless TSN over 5G in IIoT applications will allow the remote control, programming, diagnostics, rerouting, and real-time control of robots without requiring them to be fixed in place. Wireless TSN-capable robots can perform time-critical tasks with precise synchronization across devices, creating a flexible and reliable network of collaborating devices that can also use AI to optimize their operation.
2) TSN over 5G will lead to a smarter, safer grid.
Today’s electrical utilities rely on highly reliable, deterministic wired networks for the transmission, generation, and distribution of power. The IETF DetNet group has described the use case for deterministic networking in power grid applications in detail. Of note within their requirements is the density and variety of sensors that must be controlled in power grid applications; the need for redundant transport pathways for reliability; and the paramount importance of security. The latter concern is pushing utilities toward the adoption of the best practices in packet-based networking and security: an open standards-based network that enables interoperability between vendors, driving down costs and opening options for applying the best security tools in the IT industry to also secure the grid.
Real-time reliable wireless access and control of grid sensors is a huge practical boon to utilities. Although Ethernet and Wi-Fi with TSN capabilities can be used in local substations and indoor deployments, 5G systems are best suited to meet the wide coverage, latency, and density requirements of these large-scale smart grid applications. TSN over 5G will be the nervous system of the modern smart grid that can guarantee precise synchronization between sensors and enable real-time analysis, diagnosis and reconfiguration of the grid.
3) Waves will replace wires in professional live media transmission.
Though the IIoT encompasses some of TSN’s largest use cases, wireless TSN and 5G will be seen and heard in large-scale media experiences as well.
For example, a typical live performance touring production uses miles of Ethernet cabling that connects scores of individual devices that must be set up and torn down over the course of just a few hours, 60 to 100 times per tour. The cables and connectors inevitably get damaged over time, creating issues that are difficult and time consuming to troubleshoot.
As wireless TSN technology matures, cables will be replaced by portable wireless connections, significantly reducing the overall cost of deployment and operation of live audio systems. The adoption of standards-based wireless networks such as Wi-Fi 6 and 5G for media transport in live sound applications will address another problem for live sound applications as well: currently, UHF bands are used in professional wireless audio links with highly specialized RF products. These dedicated spectrum resources are, however, dwindling.
4) TSN will be implemented in consumer technologies.
As a set of tools that enhance wireless performance, TSN has the potential to be a major enabling technology for the next generation of wireless gaming and virtual reality. Interactive real-time video used in these applications requires constrained, predictable latency. As video frame rates climb, latency requirement plummets, per the IEEE’s 802.11 Real Time Applications TIG Report. Past generations of gaming consoles commonly output video at a rate of 60 Hz, resulting in a maximum video transmission latency of around 10 ms to allow for additional signal processing. Current generation consoles such as the PS5 and the Xbox Series X are both capable of outputting interactive video at 120 Hz. The recommended transmission latency for supporting higher video frame rates is in the order of 3 ms per frame.
In VR gaming, such low-latency wireless transmission is an absolute necessity. In order to provide an excellent VR gaming experience, the console must allow freedom of movement (meaning the headset should not be physically tethered to the console), and the video output must also react to the user’s input and head movements in real time. Any noticeable latency can result in “cybersickness,” a nausea caused by the mismatch between physical movement and optical input. A minimum 90 Hz refresh rate is required to avoid cybersickness, meaning that sub 10 ms transmission latency is needed. TSN comes into picture as a solution for guaranteeing the delivery of real-time interactive video data and user control and state information (head movement) with bounded latency even in the presence of other traffic in the network (e.g. other video streaming sections in the home), enabling the next generation of interactive content. In the area of gaming and VR, TSN enhancements in both next generation Wi-Fi 6 and 7, as well as 5G systems are expected to play a key role in enabling the next generation immersive gaming and VR experiences.
5) The full potential for Wireless TSN is yet to come, but will bring major benefits.
Wireless TSN has enormous potential to radically transform networking across industries in an open, standards-based fashion. This technology is, though, still in its youth. Over the next few years, expect a lot of impatience and frustration, especially if TSN certified 5G products are not widely available. Unlike Ethernet and 802.11/Wi-Fi, 5G is not a native 802 LAN technology and thus can’t be directly integrated with Ethernet TSN standards at Layer 2. The 3GPP 5G specifications have, however, defined the required interfaces (called TSN Translators) for both Core Network and User Equipment (UE) to connect a 5G system to a TSN-based network and enable time synchronized communications across both Ethernet and 5G.
The TSN integration approach chosen for 5G will leverage new 5G radio capabilities, such as URLLC to ensure time-critical data are delivered under strict latency bounds with high reliability. In addition, the 5G-ACIA has formed to help coordinate the requirements to 5G standard development that introduce TSN support over 5G focusing on Industrial applications.
TSN networks already see significant use in industrial and professional audio applications. Thus, a common model with clear service requirements and capabilities to integrate wired and wireless TSN domains will also need to be defined to continue leveraging existing TSN standards and ecosystems. The mobility afforded by wireless networks will raise new challenges for TSN as well; current roaming procedures in cellular and Wi-Fi networks can’t meet the stringent latency and high reliability requirements in TSN domains. Future wireless connectivity standards will need to provide TSN-grade latency and packet loss performance during roaming. Dealing with the dynamics of wireless communication channels and new potential security threats due to interference and jamming will require more work to prove the resiliency of wireless systems comparable to wired connectivity.
TSN over wireless faces significant challenges, but the potential applications make the juice more than worth the squeeze. In the near term, the TSN community will be laying the groundwork for this future by developing a deeper understanding of how wireless networks can allocate resources for time-sensitive traffic with determinism as well as new approaches to configure and manage TSN capabilities over dynamic wireless links.
The Avnu Alliance has founded a Wireless TSN Working Group to study the TSN capabilities and performance of Wi-Fi and 5G networks; determine gaps in existing standards for seamless integration, configuration and management of wired and wireless TSN; develop a test plan to ensure the reliability and efficiency of wireless TSN solutions as well as define a certification roadmap for wireless TSN products aligned with ongoing efforts to deploy TSN across multiple market segments . Investment in these cross-market collaborative standards development activities now will position device makers to capitalize on increasing demands for wireless, time-sensitive applications.
For more information on extending TSN to wireless, download the Avnu Wireless TSN Working Group’s whitepaper, which highlights the benefits, challenges, and opportunities associated with wireless TSN.
About Avnu Alliance
Avnu Alliance is a community creating an interoperable ecosystem of low-latency, time-synchronized, highly reliable networked devices using open standards, supporting the foundational technology of IEEE Audio Video Bridging (AVB)/Time Sensitive Network (TSN) base standards. Avnu creates comprehensive certification tests and programs to ensure interoperability of networked devices. The Alliance, in conjunction with other complementary standards bodies and alliances, provides a united network foundation for use in professional AV, automotive, and industrial control.
Dave Cavalcanti received his PhD in computer science and engineering in 2006 from the University of Cincinnati. He is currently Principal Engineer at Intel Corporation where he develops next generation wireless connectivity and networking technologies and their applications in autonomous, time-sensitive systems. He leads a team developing Wireless Time-Sensitive Networking capabilities over next generation 802.11 and 5G networks. He is Senior Member of the IEEE and serves as the chair of the Wireless TSN working group in the Avnu Alliance.