Time-Sensitive Networking Networks Research Articles

A conflict-free CAN-to-TSN scheduler for CAN-TSN gateway

The automotive Electrical/Electronic (E/E) architecture with Time-Sensitive Networking (TSN) as the backbone network and Controller Area Network (CAN) as the intra-domain network has attracted extensive research attention. In this architecture, the CAN-TSN gateway serves as a vital hub for communication between the CAN and TSN networks. However, with frequent information exchange between domains, multiple real-time applications inevitably compete for the same network resources. The limited availability of schedule table entries and bandwidth allocation pose challenges in scheduling design. To mitigate the transmission conflicts at the CAN-TSN gateway, this paper proposes a CAN-to-TSN scheduler consisting of two primary stages. The first stage introduces the Message Aggregation Optimization (MAO) algorithm to aggregate multiple CAN messages into a single TSN message, ultimately decreasing the communication overhead and the schedule table entries number. The second stage proposes the Exploratory Message Scheduling Optimization (EMSO) algorithm based on MAO. EMSO disaggregates and reassembles the CAN messages with small deadlines within the currently un-scheduled TSN message to improve the acceptance ratio of CAN messages. Experimental results demonstrate that EMSO achieves an average acceptance ratio of CAN messages 4.3% higher in preemptive mode and 8.2% higher in non-preemptive mode in TSN than state-of-the-art algorithms.

Autonomous integration of TSN-unaware applications with QoS requirements in TSN networks

Modern industrial networks transport both best-effort and real-time traffic. Time-Sensitive Networking (TSN) was introduced by the IEEE TSN Task Group as an enhancement to Ethernet to provide high quality of service (QoS) for real-time traffic. In a TSN network, applications signal their QoS requirements to the network before transmitting data. The network then allocates resources to meet these requirements. However, TSN-unaware applications can neither perform this registration process nor profit from TSN’s QoS benefits.The contributions of this paper are twofold. First, we introduce a novel network architecture in which an additional device acts as a central user configuration (CUC) for TSN-unaware applications and autonomously signals their QoS requirements to the network. Second, we propose a processing method to detect real-time streams in a network and extract the necessary information for the TSN stream signaling. It leverages a Deep Recurrent Neural Network (DRNN) to detect periodic traffic, extracts an accurate traffic description, and uses traffic classification to determine the source application. As a result, our proposal allows TSN-unaware applications to benefit from TSNs QoS guarantees. Our evaluations underline the effectiveness of the proposed architecture and processing method.

Analysis of End-to-End Delay in the Transport Segment of Fronthaul 4G/5G Networks Based on TSN Technology

One of the characteristic features of 4G/5G mobile networks is the spatial separation of functional blocks. The corresponding segments of the xHaul transport network are used to connect these blocks. One of them is the Fronthaul front end segment, which connects remote radio equipment with their control equipment. The data streams of standard CPRI/eCPRI radio interfaces in this segment impose strict requirements on the quality of service and, above all, on delays. To meet these requirements, it was proposed to use in the Fronthaul segment Ethernet bridge network based on the technology of time-sensitive networks TSN (Time Sensitive Networking), which provides determinated delays, reliable packet delivery and high accuracy of synchronization of nodes in the network. The IEEE 802.1CM standard describes profiles of TSN networks that defines the functions, options, configurations, default values, protocols and procedures of bridges, stations and local networks required to build the Fronthaul transport segment. The article presents a methodology for determining the maximum end-to-end traffic delays of standard CPRI/eCPRI radio interfaces in the Fronthaul segment of 4G/5G networks, built on the basis of TSN technology, in accordance with the requirements of IEEE 802.1CM standard. Two main components of end-to-end delay are identified ‒ delays in TSN bridges and delays in xEthernet channels. For high-priority traffic flows of CPRI/eCPRI radio interfaces in bridges, characteristic cases of mutual influence of flows arriving simultaneously at different input ports are given. An example of numerical calculation is given, which allowed to determine the permissible physical length of the Fronthaul segment at a given boundary end-to-end delay of transmission of high-priority traffic.

Scheduling Time-Critical Traffic With Virtual Queues in Software-Defined Time-Sensitive Networking

The emerging applications in vertical industries generate diverse time-critical traffic flows with bounded delay requirements. Time-Sensitive Networking (TSN) enhances the traditional Ethernet by using Time-Aware Shaper (TAS), providing delay guarantees for traffic flow transmission. However, the fixed scheduling granularity of physical queues in TAS can bring an obstacle for the flow isolation in per-flow scheduling, such as the complex computing and configuration. This paper proposes a method of Virtual Queues-based Time-Aware Traffic Scheduling (VQ-TATS) in Software-Defined Time-Sensitive Networking (SD-TSN). SD-TSN is a networking architecture that integrates the determinism guarantees of TSN and flexible network resource allocation of Software-Defined Networking (SDN). Through the capability of SD-TSN, the physical queues resource is virtualized for VQ-TATS. VQ-TATS includes the VQ clustering and VQ mapping stages. VQ clustering aggerates virtual queues to adapt to the scheduling granularity of TAS. VQ mapping builds the relationship between virtual and physical queues and generates the gate control list of TAS. The clustering and mapping algorithms are also designed to perform VQ-TATS. The evaluation in an industrial control use case shows the effectiveness of the proposed method in schedulability and runtime.

TSN Network Scheduling—Challenges and Approaches

Time-Sensitive Networking (TSN) is a set of Ethernet standards aimed to improve determinism in packet delivery for converged networks. The main goal is to provide mechanisms that enable low and predictable transmission latency and high availability for demanding applications such as real-time audio/video streaming, automotive, and industrial control. To provide the required guarantees, TSN integrates different traffic shaping mechanisms including 802.1Qbv, 802.1Qch, and 802.1Qcr, allowing for the coexistence of different traffic classes with different priorities on the same network. Achieving the required quality of service (QoS) level needs proper selection and configuration of shaping mechanisms, which is difficult due to the diversity in the requirements of the coexisting streams under the presence of potential end-system-induced jitter. This paper discusses the suitability of the TSN traffic shaping mechanisms for the different traffic types, analyzes the TSN network configuration problem, i.e., finds the optimal path and shaper configurations for all TSN elements in the network to provide the required QoS, discusses the goals, constraints, and challenges of time-aware scheduling, and elaborates on the evaluation criteria of both the network-wide schedules and the scheduling algorithms that derive the configurations to present a common ground for comparison between the different approaches. Finally, we analyze the evolution of the scheduling task, identify shortcomings, and suggest future research directions.

Reinforcement Learning-Based Particle Swarm Optimization for End-to-End Traffic Scheduling in TSN-5G Networks

With the rapid development of the Industrial Internet of Things (IIoT), massive IIoT devices connect to industrial networks via wired and wireless. Furthermore, industrial networks pose new requirements on communications, such as strict latency boundaries, ultra-reliable transmission, and so on. To this end, time-sensitive networking (TSN) embedded fifth-generation (5G) wireless communication technology (i.e., TSN-5G networks), is considered the most promising solution to address these challenges. TSN can provide deterministic end-to-end latency and reliability for real-time applications in wired networks. 5G supports ultra-reliable and low-latency communications (uRLLC), providing increased flexibility and inherent mobility support in the wireless network. Thus, the integration of TSN and 5G provides numerous benefits, including increased flexibility, lower commissioning costs, and seamless interoperability of various devices, regardless of whether they use a wired or wireless interface. Nonetheless, the potential barriers between the TSN and 5G systems, such as clock synchronization and end-to-end traffic scheduling, are inevitable. Time synchronization has been studied in many works, so this paper focuses on the end-to-end traffic scheduling problem in TSN-5G networks. We propose a novel integrated TSN and 5G industrial network architecture, where the 5G system acts as a logical TSN-capable bridge. Based on this network architecture, we design a Double Q-learning based hierarchical particle swarm optimization algorithm (DQHPSO) to search for the optimal scheduling solution. The DQHPSO algorithm adopts a level-based population structure and introduces Double Q-learning to adjust the number of levels in the population, which evades the local optimum to further improve the search efficiency. Extensive simulations demonstrate that the DQHPSO algorithm can increase the scheduling success ratio of time-triggered flows compared to other algorithms.

A Deterministic Embedded End-System Tightly Coupled With TSN Schedule

Distributed real-time systems (DRTS) composed of many embedded end-systems have been widely adopted in the industrial fields. Time-sensitive Networking (TSN), as a promising communication infrastructure for DRTS, has shown great potential in industry and academia. TSN assumes that an end-system can release critical tasks to process critical packets strictly according to the pre-scheduled time. Unfortunately, two factors currently damage this assumption: (1) the jitter caused by system architecture during task release, task execution and packet transmission; (2) a TSN schedule result may exceed the execution capability of the end-system and cause conflicts. This paper proposed DetChip, a system-on-chip capable of deterministically implementing the TSN schedule result. DetChip supports time-triggered task release, time-predictable task execution and precise network transmission. Based on DetChip, this paper first formalizes the execution capability of the end-system as end-system constraints (ECs). Existing TSN scheduling algorithms integrating ECs can solve conflicts by co-scheduling end-systems and the TSN network. Compared with previous works, DetChip only introduces few clock cycles jitter for critical task execution according to the TSN schedule result. The proposed ECs obtain 2 8x more conflict-free solutions for advanced scheduling algorithms with a linear increase in time overhead. Compared with the general end-system, DetChip can reduce 6 20x processing jitter to achieve better clock synchronization.

Controlled Channel Access for IEEE 802.11-Based Wireless TSN Networks

In the recent years, a growing number of applications have been demanding more and more stringent communication requirements to deliver services with the requested quality. Application fields range from industrial control systems to entertainment (e.g., Extended Reality) and telemedicine (e.g., remote surgery). Meeting the stringent communication requirements of such applications necessitates extending the currently used network technologies, which have not been conceived to guarantee extremely low latency (< 1 ms) to specific data flows. In response to such needs, the IEEE 802.1 TSN (Time Sensitive Networking) task group has been formed with the goal of standardizing new techniques allowing network technologies to provide deterministic service guarantees to selected data flows. While the developed standards are easily applicable to wired technologies like Ethernet, it is more challenging to achieve similar guarantees with wireless technologies, whose utilization is of interest for the many benefits they bring in several contexts. In this article, we consider Wi-Fi networks based on the IEEE 802.11 standard, revise the features recently introduced or under standardization and propose an approach to meet stringent latency requirements. Simulations conducted with the ns-3 network simulator show that the proposed approach enables to keep the latency of time sensitive packets below one millisecond, thus confirming the feasibility of a wireless TSN paradigm.

Fast incremental reconfiguration of dynamic time-sensitive networks at runtime

Static configurations in Time-sensitive Networking (TSN) using the Time-aware Shaper allow precise calculations of deterministic, tight bandwidth and latency guarantees for real-time industrial application streams. However, this static configuration makes introducing flexible changes to a TSN system at runtime very hard. Scenarios of adaptive TSN networks envision that the network configuration evolves with time in accordance with anticipated changes, such as the dynamicity of machine formations and machine reconfigurations.In this paper, we propose a notion of flexibility of scheduler configurations along a network path that facilitates introducing changes to TSN network configurations at runtime. Based on this notion, we develop and analyze algorithms to incrementally reconfigure TSN using the Time-Aware Shaper. These reconfigurations include determining the admissibility of new or changed streams that may possess individual deadlines.

Ultra Wideband-based wireless synchronization of IEEE 1588 clocks

Time-Sensitive Networking (TSN) requires clock synchronization superior to the well-known Network Time Protocol (NTP). The IEEE 802.1AS-2020 used for synchronization in TSN networks is based on the IEEE 1588-2019 standard (also known as Precision Time Protocol, PTP) defines methods and tools to perform sub-microsecond time synchronization over vari- ous communication channels. However, the IEEE 1588 implementation is commonly used with wired communication protocols, although there are use cases that could gain an advantage from a wireless solution. This paper investigates the possibility of PTP clock synchronization through wireless Ultra Wideband (UWB) communication. UWB excels where other wireless technologies are lacking: it provides high accuracy timestamping even if multipath propagation is present. The method is evaluated using commercial, well-accessible cheap hardware, resulting in the order of 10-nanosecond accuracy. The paper also highlights the main error components and requirements for improving wireless PTP synchronization.

Tackling the Challenges of the Integration of Wired and Wireless TSN With a Technology Proof-of-Concept

Standard wireless systems are rapidly evolving to support the strict requirements of industrial applications. In this research line, wireless time-sensitive networking (TSN) is gaining momentum, thanks to the interest of wired TSN among the industries. A critical aspect of the wireless TSN research is the integration of wired and wireless TSN to create large-scale hybrid TSN networks. This integration is currently being discussed for 5G, whereas the integration between wired TSN and IEEE 802.11 is a step behind. To address this gap in the state of the art, this article discusses the integration challenges of wired TSN and wireless local area network technologies and proposes a hybrid TSN device architecture. Based on the architecture, we have developed a hybrid TSN network proof-of-concept. The proof-of-concept demonstrates that the hybrid TSN architecture can maintain the essential TSN services, including providing guaranteed latency in the 100-microsecond level.

Joint Traffic Routing and Scheduling Algorithm Eliminating the Nondeterministic Interruption for TSN Networks Used in IIoT

Recently, time-sensitive networking (TSN) has been developed to incorporate real-time capabilities to the standard Ethernet for the incompatible issue in existing industrial communication solutions and is considered a promising solution to satisfy the requirements of the Industrial Internet of Things (IIoT). However, the routing and scheduling methods are left out of the TSN standard. This study developed a novel joint traffic routing and scheduling algorithm to compute routes for time-critical flows and construct the schedules. The validity of the proposed algorithm was verified using a random synthetic test scenario. The simulation results demonstrated that the real-time requirements of time-critical traffic could be satisfied with the proposed algorithm. Subsequently, we evaluated the scalability of the proposed algorithm from the perspective of the number of flows that can be scheduled and the network size. The results showed that the computational times for 4000 flows in the realistic industrial network topology and random network topologies (with up to 21 switches and 105 end stations) are at the subsecond level, which indicated the perfect scalability of the proposed algorithm. In addition, compared with the well-known integer linear programming (ILP)-based approach, Degree of Conflict (DoC)-aware iterative routing and scheduling (DA/IRS) approach, and hybrid genetic algorithm (HGA)-based approach, the proposed algorithm is faster than the three approaches by at least an order of magnitude.

Prototype of 5G Integrated with TSN for Edge-Controlled Mobile Robotics

The digitization of industries enables a rapid transformation from mass production to individualized manufacturing. Communication plays an essential role in this digital transformation; in particular, wireless communication enables a high degree of flexibility, dynamic interactions, and mobility support in production systems. This paper presents an implementation of a 5G system with Time-Sensitive Networking (TSN) and analyzes a typical industrial use case involving cloud-controlled mobile robots. A prototype setup integrating 5G in a TSN network has been completed to evaluate the 5G-TSN performance for industrial applications. The integrated 5G and TSN prototype has been evaluated with over the air tests in an industrial shopfloor using TSN features of traffic shaping and scheduling.

IEEE 802.1AS Clock Synchronization Performance Evaluation of an Integrated Wired–Wireless TSN Architecture

Industrial control systems present numerous challenges from the communication systems perspective: clock synchronization, deterministic behavior, low latency, high reliability, flexibility, and scalability. These challenges are mostly solved with standard technologies over Ethernet, e.g., time-sensitive networking (TSN). As a research trend, it is expected that TSN will converge with wireless, leading to the Wireless TSN paradigm. Also, Wireless TSN is expected to be integrated with Ethernet TSN to create large-scale wired–wireless (Hybrid) TSN networks. The first step toward Hybrid TSN is the distribution of the clock reference from the wired to the wireless domain. In this article, we leverage existing Ethernet TSN and wireless technologies implementations (Wi-Fi and w-SHARP) and present two hardware architectures specifically engineered to enable the clock synchronization distribution among the network domains. The hardware architectures have been implemented over a system-on-chip field-programmable gate array platform. We demonstrate through several experiments that the implementation is able to fulfill the synchronization performance required by TSN.

Time Sensitive Networking Protocol Implementation for Linux End Equipment

By bringing industrial-grade robustness and reliability to Ethernet, Time Sensitive Networking (TSN) offers an IEEE standard communication technology that enables interoperability between standard-conformant industrial devices from any vendor. It also eliminates the need for physical separation of critical and non-critical communication networks, which allows a direct exchange of data between operation centers and companies, a concept at the heart of the Industrial Internet of Things (IIoT). This article describes creating an end-to-end TSN network using specialized PCI Express (PCIe) cards and two final Linux endpoints. For this purpose, the two primary standards of TSN, IEEE 802.1AS (regarding clock synchronization), and IEEE 802.1Qbv (regarding time scheduled traffic) have been implemented in Linux equipment as well as a configuration and monitoring system.

Implications of Various Preemption Configurations in TSN Networks

Time-sensitive networking (TSN) is a set of standards developed by the IEEE 802.1 task group to support high-bandwidth and low-latency predictable network communication. Configuration of TSN networks is a daunting task as there are several novel features in TSN and numerous possibilities can arise by considering combinations of these features. This letter investigates the impact of various unexplored frame-preemption configurations in TSN networks on the timing behaviors of various traffic classes. These configurations correspond to different combinations of settings in TSN with respect to the credit-based shaper, time-aware shaper, hold and release mechanism, and frame preemption. This letter provides the evaluation of these configurations by means of an analytical discussion and simulation experiments. The results and implications discussed in this letter can serve as useful guidelines for the network designers when configuring TSN networks with regards to the addressed features.

Delay-Guaranteeing Admission Control for Time-Sensitive Networking Using the Credit-Based Shaper

With real-time communication being a key part of the fourth industrial revolution, the need for Quality of Service (QoS) in industrial networks is gaining increasing importance. Time-Sensitive Networking (TSN) faces this need, for example, by introducing new scheduling mechanisms. The Credit-Based Shaper (CBS) has been introduced to TSN to offer low delays for multiple traffic classes by applying rate limitations. Currently, flows are reserved decentrally in CBS networks using a Stream Reservation Protocol (SRP). In contrast, the new TSN standard IEEE 802.1Qcc allows for a centralized architecture to favor short reconfiguration latencies. However, no online admission control scheme which offers safe delay bounds has been proposed for this central architecture. To close this gap, we propose two models for admission control in TSN networks using CBS. Both models offer deadline-guaranteeing flow allocation, including routing and prioritization of flows, and configure forwarding devices while eliminating packet loss. Our models utilize the mathematical framework of Network Calculus to calculate worst-case flow delays and buffer sizes. We show how our models allow for more reservations than the decentralized standard approach by improved resource utilization. We validate our models both in synthetic and industrial network scenarios. Additionally, we compare the effects and parameters of our two models, providing guidance on when to choose them.

Performance analysis of cost effective multi-hop Time Sensitive Network for IEEE 802.1Qbv and IEEE 802.1Qbu standards

Time-Sensitive Networking (TSN) is an emerging technology, which enables advancements in applications like industrial automation, automatic vehicle-to-vehicle communication, etc. which hosts various time-critical applications, ensuring bounded latency. The novel idea of this paper is to present OMNET++ simulation-based complex multi-hop TSN network using the native VLAN concept to bring out a cost-effective model for inter-TSN and Intra-TSN domains. This paper investigates the performance of hybrid IEEE standards, ie.IEEE 802.1Qbu and IEEE 802.1Qbv standards. The simulation results show that the combination of these standards, when effectively scheduled in switches will reduce the latency by 3.3 µseconds in time-critical applications. Further, it is observed that in Best effort traffic, frame loss is also very less in the range of 2-5 frames out of 1385 frames. These results certainly will be of great value in more complex TSN deployments.

Design of coordinated transmission mechanism of heterogeneoustime-sensitive data flow for industrial internet

<p indent="0mm">Industrial internet needs to realize the integration of IT (information technology) and OT (operation technology). The construction of the field-level industrial network is key to truly realizing seamless access of production line data from OT to IT and the intelligent operation and maintenance of the production line from IT to OT. For OT, the data in the industrial system is highly time-sensitive, and the deterministic behavior of perceived data and control instructions in time is the foundation for reliable and stable industrial system operation. However, the industrial field is plagued by problems such as heterogeneous perceived data, incompatible protocols, and varying transmission requirements, which pose significant challenges to the deterministic transmission of heterogeneous time-sensitive flow. One feasible solution to this problem is to design a unified time-aware gating mechanism with low delay and jitter, allowing precise control of data flow transmission behavior; this is one of the key technologies in the time-sensitive networking (TSN) standard. This paper mainly studies the coordinated transmission of heterogeneous time-sensitive flow in multi-hop TSN networks. First, heterogeneous time-sensitive traffic is modeled into two categories: periodic time-sensitive (PTS) flow and sporadic time-sensitive (STS) flow. Then, the schedulability of the PTS flow set and the design method of the gate control lists are analyzed, the sufficient and necessary conditions of schedulability are defined, and a schedulability discriminant algorithm is designed to determine the schedulability of any decision set. Then, a coordinated transmission framework of heterogeneous time-sensitive flow is proposed, followed by the construction of the constraint set of heterogeneous data scheduling. This paper employs the design method of no-wait slot scheduling and constructs the heterogeneous time-sensitive flow scheduling problem with the optimization goal of minimizing the maximum slot occupation in the scheduling unit to achieve the minimum end-to-end deterministic delay of PTS flow and to reduce the impact of PTS scheduling mechanism on STS flow transmission as much as possible. Then, a uniform arrangement and filling (UAF) algorithm is developed to minimize slot occupation of scheduling units by uniformly arranging the flow of the same period and filling the idle time slots generated during pre-period scheduling. Finally, simulation and experiment results corroborate the effectiveness of the two kinds of heterogeneous time-sensitive flow coordinated transmission framework and the efficiency of the UAF scheduling algorithm based on ensuring the same scheduling performance.

Reliability Analysis of the Proactive Transmission of Replicated Frames Mechanism over Time-Sensitive Networking.

The Time-Sensitive Networking (TSN) Task Group has standardised different mechanisms to provide Ethernet with hard real-time guarantees and reliability in layer 2 of the network architecture. Specifically, TSN proposes using space redundancy to increase the reliability of Ethernet networks, but using space redundancy to tolerate temporary faults is not a cost-effective solution. For this reason, we propose to use time redundancy to tolerate temporary faults in the links of TSN-based networks. Specifically, in previous works we proposed the Proactive Transmission of Replicated Frames (PTRF) mechanism to tolerate temporary faults in the links. Now, in this work we present a series of models of TSN and PTRF developed using PRISM, a probabilistic model checker that can be used to evaluate the reliability of systems. After that, we carry out a parametric sensitivity analysis of the reliability achievable by TSN and PTRF and we show that we can increase the reliability of TSN-based networks using PTRF to tolerate temporary faults in the links of TSN networks. This is the first work that presents a quantitative analysis of the reliability of TSN networks.