Complex industrial networks managed by Operational Technology departments (OT) have traditionally used custom interconnects or modified versions of Ethernet to solve challenges specific to timely and reliable delivery of critical data. With AI penetrating all verticals, including industrial, more high bandwidth cameras acting as visual sensors are getting added to traditional OT networks which creates challenges with legacy proprietary field bus networks. This decades-old infrastructure highlights two main challenges with special-purpose proprietary technology. Firstly, it is more difficult and time consuming to develop new IoT applications, and secondly, it is very expensive to support, maintain and upgrade. It also poses vendor lock-in creating islands of proprietary networks.
To solve these challenges, the IEEE has created a suite of standards called Time Sensitive Networking (TSN). The goal of TSN is to provide time synchronization and minimal bounded latency in a standard Local Area Network (LAN) with seamless redundancy, and centralized configuration and control. With TSN, companies use standard Ethernet to implement a more cost-effective network that enables a converged IT/OT network that shares the same wire for critical time sensitive traffic and regular traffic.
The benefits of enabling deterministic communications over standard ethernet has motivated recent efforts in industry and standards groups to extend TSN capabilities over wireless. An overview of the advances in wireless technologies and extended TSN capabilities for time synchronization and deterministic data delivery over wireless has been provided in [1]. Time synchronization (802.1AS), Time-aware scheduling (802.1Qbv), redundancy (802.1CB), and TSN configuration (802.1Qcc) are the some of the initial features extended to Wi-Fi (802.11) as well as integrated with 5G URLLC Systems.
A sample of the TSN standards that have been receiving most attention and currently being implemented in products are listed the table below.
Area/Performance vector | IEEE 802.1 | Main capability |
Time | 802.1AS | Extends time |
Latency bound | 802.1Qav | Credit-based traffic |
802.1Qbv | Time-Aware scheduling |
|
Reliability | 802.1CB | Frame Replication and |
Resource | 802.1Qcc | TSN configuration and |
Many Industrial IoT (IIoT) applications and endpoints will connect and provide/consume data with timeliness enabled by heterogeneous wired and wireless TSN capable networks as show below.
Fig: 1 TSN over wired (Ethernet) and wireless (Wi-Fi).Key emerging applications include AMR (Autonomous Mobile Robots), AR/VR glasses, and Remote Human Management Interface (HMI) devices, all connected, at scale, to wireless networks that support standards based deterministic communications.
These innovative projects, whereby time-critical devices and applications are connected to an industrial network, are made possible through a unique and differentiated collaboration between Cisco, Intel, Exor International and Keysight Technologies. Cisco and Intel are working together to provide the WTSN enabled network infrastructure and end (client) devices. Cisco provides the ethernet switches, controllers, and Wi-Fi access points, Intel provides the WTSN-enabled Wi-Fi 6 client modules and Exor International provides the client HMI devices. Keysight provides the test and measurement platform, measuring accurate time and latency between network nodes, and demonstrating WTSN optimizes high priority traffic on the network, with minimal delay. Our WTSN testbed setup is shown in Figure 2.
Fig: 2 Wireless TSN testing topology developed by Keysight, Cisco, Exor and Intel.Early results shows that we can achieve close to ~1.5ms deterministic latency over Wi-Fi 6 with TimeSync accuracy close to ~20us. Here is a link to a video of the testbed and demonstration of a time-critical application over Wi-Fi 6 TSN: https://youtu.be/PYoYrc7h-iA. A safety application was implemented that sends periodic time-critical (heartbeat) packets over the wireless link. The Wi-Fi 6 network applies TSN features (time synchronization and time-aware scheduling) to ensure the time-critical packets are delivered with low latency and high reliability, even in the presence of background traffic on the network.
The Cisco/Intel/Keysight/Exor test environment and WTSN capabilities can adapt to support new time sensitive and safety critical use cases, and different application traffic QoS requirements. This pioneering project will create the foundation for innovation and new functionalities enabled by Edge computing and deterministic communications over Ethernet and Wi-Fi TSN-capable networks.
We are very excited to partner with key players in this new and exciting environment!
Cisco, Intel, Exor and Keysight would welcome your comments, thoughts, market insight, and vision for the Industrial IoT networks of tomorrow!
- Avnu Wireless TSN White Paper, https://avnu.org/wireless-tsn-white-paper-download.
- Intel and Cisco: Working Together to Enable Wireless Smart Manufacturing https://community.intel.com/t5/Blogs/Tech-Innovation/Edge-5G/Intel-and-Cisco-Working-Together-to-Enable-Wireless-Smart/post/1332485
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