Market Expectations, Capabilities & Certification

This document describes the market requirements and expectations for Wireless TSN that may be supported by Wi-Fi and 5G systems. This document also captures the main assumptions and functionalities required to enable integration and interoperability between wireless with wired TSN.

As TSN specifications evolve and wired/Ethernet- based products are certified, interest in Wireless TSN is growing, mainly motivated by recent advances in Wi-Fi and 5G technologies towards supporting TSN-grade performance. Initial work has been done to define Wireless TSN (WTSN) concepts, use cases, and candidate wireless technologies, which were described in the WTSN white paper [1]. To move from the initial exploration toward enabling the necessary WTSN capabilities along with interoperability testing and certification, it is important to understand priority use cases, performance requirements, and capabilities expected from WTSN systems and end stations.

This paper provides an overview of the market requirements and expectations for WTSN that may be supported by Wi-Fi and 5G systems. The document also captures the main assumptions and functionalities required to enable integration and management of wireless and wired TSN systems. The requirements and capabilities discussed in this document are guiding Avnu testing and certification activities towards enabling an ecosystem of interoperable wired and wireless TSN products.

Wireless Use Cases

It is important to identify high priority use cases and requirements that can drive the development and deployment of WTSN products. This section is not intended to be a comprehensive list of all possible wireless use cases, especially given the variety of applications and usages in different markets. The goal is to describe select use cases that are representative of the broad set of requirements and market expectations for WTSN.

Key Performance Indicators

The technical requirements across the various use cases are described in terms of KPIs (Key Performance Indicators). The following TSN-related KPI are considered:

• Time Synchronization: Capability to synchronize to a primary clock across the network. In a TSN capable network, the time synchronization should follow the IEEE 802.1AS-2020 standard.
• Bounded latency: Worst case latency for time-sensitive data packets over a given link. In some applications, jitter, measured as the variation in the latency of received data packets, is also an important metric in addition to bounded latency.
• Reliability: This is usually associated with the probability of delivering packets within a given worst latency over a given link. Reliability can also be described as a Packet Delivery Ratio (PDR = percentage of packets delivered within a given latency). Device and link redundancy are typical mechanisms used to meet high reliability requirements.
• Security: Security requirements include authentication, integrity, confidentiality, availability, and resiliency to potential interference/attacks from (malicious or misbehaving) devices. TSN applications and systems are expected to implement industry recommended security best practices.
• Capacity: It is important to maximize the overall capacity of the network while meeting all the other KPIs. The capacity requirements can be described as the number of end stations and time-sensitive traffic streams that can be supported under a given network configuration and load.

Priority Use Cases and KPIs

There are many use cases for wireless technologies across different markets. Industrial automation, control systems, robotics, professional Audio and Video (ProAV), automotive networking, and Augmented and Virtual Reality (AR/ VR) can all benefit from determinism in data delivery provided by TSN over wireless. The industrial segment has generated significant interest in wireless, and industrial use cases have been driving the developments in standards and early trials of WTSN technologies. Table 1 summarizes the KPIs for high priority wireless use cases.

Table 1. Wireless Use Cases and KPIs (Key Performance Indicators). (Avnu Alliance)

Mobile robot use cases typically involve communication between robots and a control system including guidance control, process data exchange, video/image, and emergency stop. A mobile robot can be an autonomous mobile robot (AMR), automated guided vehicle (AGV), or any other type of robot that is typically mobile and can be controlled over wireless connectivity.

Synchronous communications between sensors, controllers (e.g., Programmable Logic Controllers), and actuators is the fundamental building block for most industrial processes and machines. The generic closed loop control described in Table 1 is representative of various applications. The specific requirements vary widely with the application/process and industry, but the range of requirements described here should capture most of the usages.

ProAV use cases will most likely require a combination of a Wired and Wireless TSN. Wireless TSN can enable flexibility and mobility of instruments, wearable devices, speakers, and other supporting equipment. Wireless TSN can also enable distribution of live streaming content and new services to audiences in events.

Wireless connectivity is a key requirement to enable the usability of AR/VR solutions, which also have bandwidth, latency, jitter, and reliability requirements that can benefit from TSN capabilities. AV/VR applications have been considered within industrial environments, enterprises, and consumer spaces. For instance, remote maintenance and operation of industrial equipment and robots can enhance efficiency and safety aspects for workers. AR/VR applications in education and remote collaboration can bring benefits to enterprises and consumers.

As shown in Table 1, time synchronization with accuracy around 1 μs is a common requirement for most use cases. Latency requirements are in the order of single to double digit millisecond for this initial set of use cases. Reliability requirements also vary per use case, but are typically higher than today’s general consumer and enterprise applications (e.g., voice, video, teleconference).

While TSN builds on standard security features and best practices, the strict time synchronization, latency, and reliability performance must be resilient to potential attacks or device failures. Redundancy in time and data transmission, as discussed next, are key in improving resiliency, especially for wireless links that are subject to interference and other stochastic propagation effects.

1. Market Expectations, Capabilities & Certification
2. Wireless TSN Capabilities
3. Network Management Considerations