Time-Sensitive Networking Research Articles

Time-sensitive networking for interlock propagation in the IFMIF-DONES facility

In this study, we have proposed the use of time-sensitive networking (TSN) technologies for the distribution of the interlock signals of the machine protection system of the future IFMIF-DONES particle accelerator, required for implementing the protection mechanisms of the different systems in the facility. Such facilities usually rely on different fieldbus technologies or direct wiring for their transmission, typically leading to complex network infrastructures and interoperability problems. We provide insights of how TSN could simplify the deployment of the interlock network by aggregating all the traffic under the same network infrastructure, whilst guaranteeing the latency and timing constraints. Since TSN is built on top of Ethernet technology, it also benefits from other network services and all its related developments, including redundancy and bandwidth improvements. The main challenge to address is the transmission of the interlock signals with very low latency between devices located in different points of the facility. We have characterized our initial TSN architecture prototype, evaluated the latency and bandwidth obtained with this solution, identified applications to effectively shape the attainable determinism, and found shortcomings and areas of future improvements.

Quantum enhanced time synchronisation for communication network

It is essential to establish precise times in future communication networks. Any real-time task’s ability to function depends on the system’s ability to synchronise time. In the current communication network, time synchronisation is critical and must be maintained to transmit data packets. The functionality of 6G, the Tactile Internet, Time-Sensitive Networking, and ultra-reliable low-latency communications is highly susceptible to time synchronisation. We investigated the idea of employing time synchronisation across different communication network nodes. The current state-of-the-art employs network protocols like Precision Time Protocol for clock synchronisation across different nodes. These network protocols are not very robust and can generate jitters in data transmission. In this paper, we suggested synchronising the time of the node clocks at three different places using quantum technology. Notably, the oscillation frequencies of each qubit (or oscillator) located at these nodes can be synchronised using quantum synchronisation technique. This set of three oscillators will work as a single clock and will be the master clock of the network. We propose distributing precise time and frequency standards using quantum synchronisation on node clocks. We can synchronise the three qubits (each placed at one node) to oscillate at an identical frequency by applying an external field of a wavelength of 813.32nm. We analysed our model for different coupling constants and dissipation rates to provide an analysis of the behaviour of the amount of synchronisation in different experimental configurations. The optimal accuracy for our system is 1.6×1015 signals per second. Further, we used the Allan deviation to examine the stability of our system for various noise strengths.

Assessing the traffic scheduling method for time-sensitive networking (TSN) by practical implementation

Time-sensitive networking (TSN), as standardized and maintained by the IEEE 802.1 Task Group, enhances the real-time and deterministic capabilities of the Ethernet. However, traffic scheduling is not standardized, and is being extensively researched. Most studies are theoretical in nature; practical validation studies are rare. To fill this gap, we first constructed a real-world TSN-based process automation system and presented fine-grained guidelines regarding how a traffic scheduling method (TSM) can be deployed in industrial facilities. We experimentally investigated the feasibility of our method, and compared its performance to that of a commercial TSN scheduler. The results show that our method precisely schedules traffic to satisfy firm real-time requirements and achieves ultra-low latency by eliminating the queuing delays. The scheduling calculation times for 500 random cases show that our TSM can appropriately schedule flows in milliseconds, more than 571-fold faster than the commercial scheduler.

Time sensitive networking security: issues of precision time protocol and its implementation

Time Sensitive Networking (TSN) will be an integral component of industrial networking. Time synchronization in TSN is provided by the IEEE-1588, Precision Time Protocol (PTP) protocol. The standard, dating back to 2008, marginally addresses security aspects, notably not encompassing the frames designed for management purposes (Type Length Values or TLVs). In this work we show that the TLVs can be abused by an attacker to reconfigure, manipulate, or shut down time synchronization. The effects of such an attack can be serious, ranging from interruption of operations to actual unintended behavior of industrial devices, possibly resulting in physical damages or even harm to operators. The paper analyzes the root causes of this vulnerability, and provides concrete examples of attacks leveraging it to de-synchronize the clocks, showing that they can succeed with limited resources, realistically available to a malicious actor.

Simple Bounds on Delay-Constrained Capacity and Delay-Violation Probability of Joint Queue and Channel-Aware Wireless Transmissions

The emerging Ultra-Reliable and Low-Latency Communication (URLLC) is expected to meet a hard or probabilistic delay constraint that plays a key role in Time Sensitive Networking (TSN) and Deterministic Networking (DetNet). In this paper, we are interested in simple bounds for delay-constrained wireless communications with deterministic or even random packet arrivals. More specifically, we present a sufficient condition and derive a legitimate data arrival rate, with which the bounded delay can be guaranteed deterministically with an average power constraint. Our derived results will show that the delay-bounded data rate increases with the average power and the tolerated latency normalized to the coherent time. Furthermore, we derive the upper and lower bounds of the delay-violation probability (DVP) when the bounded delay condition cannot be satisfied. It is revealed that in the log coordinate, the DVP as a function of the normalized tolerated latency may enjoy a non-linear decay, with a decay rate that increases with the latency bound. This is in contrast to the large deviation based performance analysis that focuses on the low-latency transmission policies achieving linearly decayed DVP only. Our result demonstrates that the joint channel-aware and queue-aware scheduling may significantly reduce the DVP, compared to the single-layer approaches.

Deadline-Aware Online Scheduling of TSN Flows for Automotive Applications

The Time-Sensitive Networking (TSN) set of standards allows to support on the same channel the different kinds of traffic flows that are typically found in automotive scenarios. This article proposes the introduction of online Earliest Deadline First-based scheduling in TSN to provide support for event-driven real-time traffic. The proposed approach, called Deadline-TSN, is an online approach, and therefore, unlike other approaches in the literature, it does not require complex offline schedule calculations. Moreover, Deadline-TSN is able to uniformly deal with real-time periodic and event-driven traffic flows. This article presents Deadline-TSN and provides both worst-case response time analysis and simulative assessments in realistic automotive scenarios.

Dynamic QoS mapping and adaptive semi-persistent scheduling in 5G-TSN integrated networks

The ubiquitous and deterministic communication systems are becoming indispensable for future vertical applications such as industrial automation systems and smart grids. 5G-TSN (Time-Sensitive Networking) integrated networks with the 5G system (5GS) as a TSN bridge are promising to provide the required communication service. To guarantee the end-to-end (E2E) QoS (Quality of Service) performance of traffic is a great challenge in 5G-TSN integrated networks. A dynamic QoS mapping method is proposed in this paper. It is based on the improved K-means clustering algorithm and the rough set theory (IKC-RQM). The IKC-RQM designs a dynamic and load-aware QoS mapping algorithm to improve its flexibility. An adaptive semi-persistent scheduling (ASPS) mechanism is proposed to solve the challenging deterministic scheduling in 5GS. It includes two parts: one part is the persistent resource allocation for timesensitive flows, and the other part is the dynamic resource allocation based on the max-min fair share algorithm. Simulation results show that the proposed IKC-RQM algorithm achieves flexible and appropriate QoS mapping, and the ASPS performs corresponding resource allocations to guarantee the deterministic transmissions of time-sensitive flows in 5G-TSN integrated networks.

Modeling and Analysis of Time-Aware Shaper on Half-Duplex Ethernet PLCA Multidrop

Recently, there has been an interest from the automotive industry in a novel single-pair, half-duplex Ethernet multidrop provision (i.e., 10BASE-T1S), which relies on a coordinated channel access method provided by Physical Layer Collision Avoidance (PLCA). PLCA avoids frame collisions and provides bounded latency, while guaranteeing fairness among nodes and optimal bandwidth utilization. However, despite these advantageous features, PLCA is not aware of flow priorities and, consequently, does not provide priority-based Quality of Service (QoS). Thus, there is an opportunity for integrating QoS-aware schemes, such as the Time-Sensitive Networking (TSN)-based Time-Aware Shaper (TAS) algorithm, into PLCA. In this paper, we present modeling and analysis strategies using Network Calculus for integrating TAS with PLCA to support scheduled traffic, and we compare our modeling and analysis with a baseline work which previously modeled TAS for full-duplex point-to-point Ethernet only. We show that replacing full-duplex point-to-point links with half-duplex PLCA multidrop links still complies with end-to-end delay deadlines, while leading to a reduction of system costs due to the fewer number of Ethernet transceivers in a PLCA multidrop. Moreover, we also show that our results for TAS, when applied only on full-duplex point-to-point links, outperform the results of the baseline work in most use cases.

TSN-Based Automotive E/E Architecture

Time-Sensitive Networking, also known as TSN, is a deterministic network based on traditional Ethernet. It offers a bunch of standards or profiles specified by IEEE 802.1 task group which has been evolved from the former IEEE802.1 Audio Video Bridging task group. In Automotive Industry, especially in ADAS domain, TSN backbone communication will gradually merge with or even replace the traditional in-vechile communication like CAN/CANFD/LIN/MOST/FlexRay due to below properties, it plays a key bridge role in heterogeneous SOC communication network.

Time-Sensitive Networking Mechanism Aided by Multilevel Cyclic Queues in LEO Satellite Networks

With the proliferation of low-Earth-orbit (LEO) satellites, existing satellite networks need to be enhanced to better handle time-sensitive flows (TSFs). However, the migration of time-sensitive network (TSN) technology to satellite networks is challenged by the large space–time range and limited on-board resources, particularly in providing differentiated quality-of-service guarantees for multilevel TSFs. To address this issue, we propose a multilevel queue-based TSN technique that uses latency requirements as an indicator for traffic scheduling. This approach improves the time-sensitive transmission capability of services with different requirements in LEO satellite networks. We conducted a simulation evaluation under a Walker constellation, and the results demonstrate that our proposed method could significantly improve network throughput, and reduce the packet loss ratio by 90% and the time-out ratio by 14.5%. Additionally, our proposed mechanism could accommodate more TSFs with acceptable latency requirements.

Multi-Topology Routing based traffic optimization for IEEE 802.1 Time Sensitive Networking

Multi-Topology Routing based traffic optimization for IEEE 802.1 Time Sensitive Networking

Composable distributed real-time systems with deterministic network channels

A system that needs to interact with the physical world in a timely manner is called a real-time system. When such a system is composed of multiple subsystems, or nodes, each of which is a geographically separate system, such a system of systems is called a distributed real-time system. The computation at each node must adhere to the timing requirements, and the connecting communication channels must never cause delays that trigger further timing violations. In this paper, we introduce Deterministic Network Channels, a network construct using Time Sensitive Networking QoS mechanisms that add reliable and deterministic communication for distributed tasks. Introducing such network channels as a construct allows designers to focus on higher-level primitives when building distributed systems. We describe our reference implementation and evaluate it by extending Timed C with network channels. Building on this, we also perform a thorough performance evaluation to determine practical bounds for both Linux and TSN under heavy workloads and adverse network conditions to show how the proposed reference implementation performs in real-world scenarios. In our tests, we can synchronize two separate machines running commercial off-the-shelf hardware to within 15μs of each other under severe internal and external interference.

Joint Routing and Scheduling With Cyclic Queuing and Forwarding for Time-Sensitive Networks

Various Industrial Internet of Things (IIoT) devices and their compelling applications have witnessed exponential growth over the past few years. Compared to the consumer internet, the industrial IoT often faces tough communication latency boundaries and low packet loss. Recently, time-sensitive networks (TSN) technique has been considered the most promising solution to tackle these issues, providing deterministic communication guarantees for time-sensitive applications. In TSN, to achieve bounded low latency, it introduces the Cyclic Queuing and Forwarding (CQF) mechanism to shape and regulate the transmission selection to provide the protected transmission window for time-triggered (TT) flows. Currently, a considerable amount of literature has explored traffic scheduling with the CQF mechanism in TSN. However, these methods ignore the impact of routing policy on scheduling optimization. In this paper, we design two algorithms to tackle the problem of joint routing and scheduling optimization with the CQF mechanism for TSN. We propose a TT flow sorting algorithm (JDPS) to measure the scheduling priority weight of each TT flow, which uses the normalization method to calculate the weight based on the flow's deadline, period, and size. Then, we propose a joint routing and scheduling optimization with load balance algorithm (JRS-LB) to improve the scheduling success radio and the network resource utilization, which jointly considers the injection time slot offset, scheduling, and routing of TT traffic. The evaluation results mainly focus on the scheduling success ratio, execution time, and resource utilization for the proposed algorithm compared to the Tabu and Naive algorithms. Extensive simulations indicate that the proposed JDPS and JRS-LB algorithms can improve the scheduling success radio compared with the other algorithms.

Flexible Cyclic Queuing and Forwarding for Time-Sensitive Software-Defined Networks

Time-Sensitive Networking (TSN) is emerging to support critical real-time applications in Industry 4.0. Recent proposals leverage Cyclic Queuing and Forwarding (CQF) to achieve bounded-delay transmission for cyclic flows in TSN. However, the CQF is not flexible enough in two aspects. First, it cannot achieve zero jitter. The Ping-Pong queue-based model in CQF will introduce the jitter of two cycles, which is inapplicable to industrial automation scenarios where isochronous flows require zero jitter. Second, it may require setting the maximum queue length to a fixed value in advance and scheduling the flows offline, which is challenging for dynamic traffic scheduling. In this paper, we firstly present a time-aware cyclic-queuing (TACQ) mechanism to enable zero jitter for CQF. TACQ consists of a novel no-wait shaper (NWS) and a cyclic-queuing shaper (CQS). The NWS handles isochronous flows by strictly limiting the transmission time of flows that do not overlap on each output port and each period. The CQS is extended from CQF to schedule cyclic flows. Then, we propose a variable time slot mechanism and a novel incremental routing and scheduling (IRAS) algorithm based on software-defined networking (SDN) to online schedule dynamic flows. Simulation results show that TACQ significantly reduces the delay of isochronous flows and achieves zero jitter compared with CQF. And the IRAS algorithm approaches 96.1% of the optimal solution in scheduling 2000 flows with a feasible per-flow computational time.

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.

ReTSN: Resilient and Efficient Time-Sensitive Network for Automotive In-Vehicle Communication

Time-sensitive networking (TSN) is being widely investigated to provide Ethernet capabilities for in-vehicle backbone communication. However, the gate control list (GCL), as a simple mechanism for achieving timing determinism for safety-critical traffic (ST) frames with hard deadlines, is too rigid to handle the intrinsic timing uncertainty of automated driving systems (ADSs). Due to the complexity and the unpredictable operating environment, there can be delayed ST frames that can disrupt the solidly fixed timing behavior. In this work, we present one novel approach to effectively use bandwidth resources to deal with delayed ST frames, which cannot be handled by a traditional fixed GCL, and the discarding of them should be reduced to improve the system’s integrity. An acceptance test is implemented to report to the application layer when an ST frame will miss its deadline and hence be rejected, i.e., prevented from entering the switch. To further improve the efficiency of bandwidth usage, we investigate how to improve the performance of the more important Class A frames in an audio-video-bridging (AVB) switch, which adopts a credit-based shaper mechanism, and we propose a constant bandwidth server to replace the credit-based shaper while taking fairness into consideration. Evaluation with extensive experiments shows that both resilience and efficiency of the TSN are significantly enhanced compared with a credit-based shaper, especially when the traffic load is relatively high. For the delayed ST frames and event-triggered traffic, our approach is able to schedule more than the solution using the AVB switch even with a high network load.

A Cyber-Physical System for Integrated Remote Control and Protection of Smart grid Critical Infrastructures

This work proposes a Cyber-Physical System (CPS) for protecting smart electric grid critical infrastructures using video surveillance while remotely monitoring them. Due to the critical nature of the smart grid, it is necessary to guarantee an adequate level of safety, security and reliability. Thus, this CPS is back-boned by a Time-Sensitive Network solution providing concurrent support for smart video surveillance and smart grid control over a single communication infrastructure. To this end, TSN delivers high-bandwidth communication for video surveillance and deterministic quality of service, latency and bandwidth guarantees, required by the time-critical revision smart grid control. On the one hand, the CPS utilizes High-availability Seamless Redundancy in the control subsystem via Remote Terminal Units (RTUs) guaranteeing seamless failover against failures in smart grid. On the other hand, the smart video surveillance subsystem applies machine learning to monitor secured perimeters and detect people around the smart grid critical infrastructure. Moreover, it is also able to directly interoperate with RTUs to send alarms in case of for example, an intrusion. The work evaluates the accuracy and performance of the detection using common metrics in surveillance field. An integrated monitoring dashboard has also been developed in which all CPS information is available in real time.

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.

MSS: Exploiting Mapping Score for CQF Start Time Planning in Time-Sensitive Networking

Time-sensitive networking (TSN), an emerging network technology, requires high-performance scheduling mechanisms to deliver deterministic service in Industry 5.0. Cyclic queuing and forwarding (CQF) is launched to simplify the configuration complexity of the early stage mechanism time-aware shaper in TSN flow scheduling. Previous CQF studies adopt an inflexible incremental flow scheduling scheme, which consists of flow sorting, offset search, and resource judgment. However, we observe that flow sorting and offset search are mutually interdependent. The offset of a flow helps determine the resource status on the flow path, which can guide flow sorting. By utilizing the interaction between flow and offset, we design a novel scheduling approach that achieves high scheduling performance and time efficiency. Specifically, the proposed approach combines flow sorting and offset search together to select flow and its offset (i.e., ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">flow, offset</i> )) simultaneously. To effectively determine the selecting priority and select the potential optimal flow-offset combination, we define a unified metric, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$mapping\,score$</tex-math></inline-formula> , to quantify the schedulability of different flow and offset combinations. The extensive experiments demonstrate that the scheduling success rate of our proposed approach is on average 31.69% higher than the baseline and 4.57% higher than the state-of-the-art flow judgement approach (FLJ) method. Moreover, it outperforms the state-of-art FLJ method by 7.62% in large-scale linear topologies, indicating its great scalability in different network scales and complex topologies.

An Intelligent Deterministic Scheduling Method for Ultralow Latency Communication in Edge Enabled Industrial Internet of Things

Edge enabled Industrial Internet of Things (IIoT) platform is of great significance to accelerate the development of smart industry. However, with the dramatic increase in real-time IIoT applications, it is a great challenge to support fast response time, low latency, and efficient bandwidth utilization. To address this issue, time sensitive network (TSN) is recently researched to realize low latency communication via deterministic scheduling. To the best of our knowledge, the combinability of multiple flows, which can significantly affect the scheduling performance, has never been systematically analyzed before. In this article, we first analyze the combinability problem. Then, a noncollision theory based deterministic scheduling (NDS) method is proposed to achieve ultralow latency communication for the time-sensitive flows. Moreover, to improve bandwidth utilization, a dynamic queue scheduling (DQS) method is presented for the best-effort flows. Experiment results demonstrate that NDS/DQS can well support deterministic ultralow latency services and guarantee efficient bandwidth utilization.