52 research outputs found
A Survey of Scheduling in Time-Sensitive Networking (TSN)
TSN is an enhancement of Ethernet which provides various mechanisms for
real-time communication. Time-triggered (TT) traffic represents periodic data
streams with strict real-time requirements. Amongst others, TSN supports
scheduled transmission of TT streams, i.e., the transmission of their packets
by edge nodes is coordinated in such a way that none or very little queuing
delay occurs in intermediate nodes. TSN supports multiple priority queues per
egress port. The TAS uses so-called gates to explicitly allow and block these
queues for transmission on a short periodic timescale. The TAS is utilized to
protect scheduled traffic from other traffic to minimize its queuing delay. In
this work, we consider scheduling in TSN which comprises the computation of
periodic transmission instants at edge nodes and the periodic opening and
closing of queue gates.
In this paper, we first give a brief overview of TSN features and standards.
We state the TSN scheduling problem and explain common extensions which also
include optimization problems. We review scheduling and optimization methods
that have been used in this context. Then, the contribution of currently
available research work is surveyed. We extract and compile optimization
objectives, solved problem instances, and evaluation results. Research domains
are identified, and specific contributions are analyzed. Finally, we discuss
potential research directions and open problems.Comment: 34 pages, 19 figures, 9 tables 110 reference
Design Optimization of Cyber-Physical Distributed Systems using IEEE Time-sensitive Networks (TSN)
In this paper we are interested in safety-critical real-time applications implemented on distributed architectures supporting the Time-SensitiveNetworking (TSN) standard. The ongoing standardization of TSN is an IEEE effort to bring deterministic real-time capabilities into the IEEE 802.1 Ethernet standard supporting safety-critical systems and guaranteed Quality-of-Service. TSN will support Time-Triggered (TT) communication based on schedule tables, Audio-Video-Bridging (AVB) flows with bounded end-to-end latency as well as Best-Effort messages. We first present a survey of research related to the optimization of distributed cyber-physical systems using real-time Ethernet for communication. Then, we formulate two novel optimization problems related to the scheduling and routing of TT and AVB traffic in TSN. Thus, we consider that we know the topology of the network as well as the set of TT and AVB flows. We are interested to determine the routing of both TT and AVB flows as well as the scheduling of the TT flows such that all frames are schedulable and the AVB worst-case end-to-end delay is minimized. We have proposed an Integer Linear Programming (ILP) formulation for the scheduling problem and a Greedy Randomized Adaptive Search Procedure (GRASP)-based heuristic for the routing problem. The proposed approaches have been evaluated using several test cases
Real-Time Scheduling for Time-Sensitive Networking: A Systematic Review and Experimental Study
Time-Sensitive Networking (TSN) has been recognized as one of the key
enabling technologies for Industry 4.0 and has been deployed in many time- and
mission-critical industrial applications, e.g., automotive and aerospace
systems. Given the stringent real-time communication requirements raised by
these applications, the Time-Aware Shaper (TAS) draws special attention among
the many traffic shapers developed for TSN, due to its ability to achieve
deterministic latency guarantees. Extensive efforts on the designs of
scheduling methods for TAS shapers have been reported in recent years to
improve the system schedulability, each with their own distinct focuses and
concerns. However, these scheduling methods have yet to be thoroughly
evaluated, especially through experimental comparisons, to provide a
systematical understanding on their performance using different evaluation
metrics in various application scenarios. In this paper, we fill this gap by
presenting a comprehensive experimental study on the existing TAS-based
scheduling methods for TSN. We first categorize the system models employed in
these work along with their formulated problems, and outline the fundamental
considerations in the designs of TAS-based scheduling methods. We then perform
extensive evaluation on 16 representative solutions and compare their
performance under both synthetic scenarios and real-life industrial use cases.
Through these experimental studies, we identify the limitations of individual
scheduling methods and highlight several important findings. This work will
provide foundational knowledge for the future studies on TSN real-time
scheduling problems, and serve as the performance benchmarking for scheduling
method development in TSN.Comment: 22 pages, ac
Design of Time-Sensitive Networks For Safety-Critical Cyber-Physical Systems
A new era of Cyber-Physical Systems (CPSs) is emerging due to the vast growth in computation and communication technologies. A fault-tolerant and timely communication is the backbone of any CPS to interconnect the distributed controllers to the physical processes. Such reliability and timing requirements become more stringent in safety-critical applications, such as avionics and automotive. Future networks have to meet increasing bandwidth and coverage demands without compromising their reliability and timing. Ethernet technology is efficient in providing a low-cost scalable networking solution. However, the non-deterministic queuing delay and the packet collisions deny low latency communication in Ethernet. In this context, IEEE 802.1 Time Sensitive Network (TSN) standard has been introduced as an extension of the Ethernet technology to realize switched network architecture with real-time capabilities. TSN offers Time-Triggered (TT) traffic deterministic communication. Bounded Worst-Case end-to-end Delay (WCD) delivery is yielded by Audio Video Bridging (AVB) traffic. In this thesis, we are interested in the TSN design and verification.
TSN design and verification are challenging tasks, especially for realistic safety-critical applications. The increasing complexity of CPSs widens the gap between the underlying networks' scale and the design techniques' capabilities. The existing TSN's scheduling techniques, which are limited to small and medium networks, are good examples of such a gap. On the other hand, the TSN has to handle dynamic traffic in some applications, e.g., Fog computing applications. Other challenges are related to satisfying the fault-tolerance constraints of mixed-criticality traffic in resource-efficient manners. Furthermore, in space and avionics applications, the harsh radiation environment implies verifying the TSN's availability under Single Event Upset (SEU)-induced failures. In other words, TSN design has to manage a large variety of constraints regarding the cost, redundancy, and delivery latency where no single design approach fits all applications. Therefore, TSN's efficient employment demands a flexible design framework that offers several design approaches to meet the broad range of timing, reliability, and cost constraints.
This thesis aims to develop a TSN design framework that enables TSN deployment in a broad spectrum of CPSs. The framework introduces a set of methods to address the reliability, timing, and scalability aspects. Topology synthesis, traffic planning, and early-stage modeling and analysis are considered in this framework. The proposed methods work together to meet a large variety of constraints in CPSs. This thesis proposes a scalable heuristic-based method for topology synthesis and ILP formulations for reliability-aware AVB traffic routing to address the fault-tolerance transmission. A novel method for scalable scheduling of TT traffic to attain real-time transmission. To optimize the TSN for dynamic traffic, we propose a new priority assignment technique based on reinforcement learning. Regarding the TSN verification in harsh radiation environments, we introduce formal models to investigate the impact of the SEU-induced switches failures on the TSN availability. The proposed analysis adopts the model checking and statistical model checking techniques to discover and characterize the vulnerable design candidates
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
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