Faults may appears in embedded networks: vibrations, temperature conditions, cybersecurity attacks, etc. may cause a port to stop sending frames, requiring a network reconfiguration. In real-time networks, the new configuration must continue ensuring real-time guarantees. In the French Resilient Time-Sensitive Networks (ResTSN) project, ONERA and THALES are developing a solution to enable the reconfiguration of embedded Time-Sensitive Networks. This paper presents the core ideas driving the development of the architecture and associated algorithms of TSN reconfiguration. The approach will ultimately be applied on a Multi-Role Armoured Vehicle (MRAV) use-case. This paper also presents our cybersecurity risk assessment approach to the use of TSN on this MRAV use-case.

The study finds that in urban environments, the performance of non-cross-layer routing protocols (AODV, OLSR, DSDV) becomes nearly identical, contradicting earlier research that ranked their effectiveness. Using a new building-aware loss model in ns-3, we show that realistic urban conditions, unlike traditional open-field models, cause end-to-end delay to increase up to tenfold, with high variability due to unstable links. We also investigate whether adjusting parameters in open-field models could mimic urban connectivity. While this tuning matched some network connectivity metrics, it failed to replicate more complex concepts linked with propagation dynamics of cities, proving that open-field models cannot accurately simulate urban networks without fundamental changes.

The Network Calculus theory has been designed to compute upper bounds on delay and backlog in data networks. A lot of results have been developed to address different aspects. However, they are not all compatible with each other since they make different assumptions on the continuity of a core aspect of the model (the cumulative curves). However, real systems may mix several mechanisms. When modeling such a system, one has to choose one continuity hypothesis and limit the analysis to a subset of existing results. This paper addresses the continuity problem and argues formally that continuity issues are mathematical details that can be solved as long as the min-plus properties are used (minimal and maximal service, shaping). Conversely, it gives a counter-example for properties based on strict service, requiring a generalisation of the backlogged interval notion.

Real-time systems often consist of numerous sub-systems engaged in extensive data exchange. Despite their complexity, a critical challenge lies in effectively incorporating real-time constraints within these systems. To address this challenge, designers typically conduct analyses to establish upper bounds on delays, ensuring they remain within the deadlines of incoming requests. However, adopting a pessimistic approach often results in over-dimensioning the systems. Then, to reduce the pessimism, we want to take into account the fact that a subsystem cannot propagate more requests/data than it can execute. This phenomenon is well-known in network analysis as it reduces the burst of data. As a consequence, this notion is easier to grasp in theories developed to compute delay bounds in networks. That is why we choose, in this paper, to perform the analysis using the Network Calculus theory, since it offers the possibility to easily aggregate flows (i.e. sum flows) and then take into account the phenomenon of smoothing the traffic. To handle tasks and networks, our model relies on packetization and workload scaling. In this paper, we improve some results regarding the already existing elements of Network Calculus and the aggregation. Also, we update and complete definitions and results related to workload scaling.

We introduce a new paradigm for synthesizing time-triggered schedules that guarantees the correct temporal behavior of time-triggered (TT) tasks and the schedulability of sporadic event-triggered (ET) tasks with arbitrary deadlines at design time. The approach first expresses a constraint for the TT task schedule in the form of a maximal affine envelope that ensures that as long as the schedule generation respects this envelope, all sporadic ET tasks meet their deadline. The second step consists of modeling this envelope as a burst limiting constraint (BLC) and building the schedule. The BLC constraint can be added to any existing TT schedule generation method as an additional constraint on the TT slot positioning. Here, we propose an efficient TT schedule generation method that integrates the BLC constraint via simulating a modified Least-Laxity-First (LLF) scheduler. We show via synthetic and real-world test cases that our novel method achieves better schedulability and a faster schedule generation for most use cases compared to other approaches inspired by, e.g., hierarchical scheduling. Moreover, we present an extension to our method that finds the most favorable schedule for TT tasks with respect to ET schedulability, thus increasing the probability that the system remains feasible when ET tasks are later added or changed.

Cyclic Queuing and Forwarding (CQF) is a mechanism defined by IEEE TSN for providing low jitter in a deterministic network. CQF uses a common time cycle and two buffers per node output port: during one cycle incoming packets are stored in one buffer while packets in the other buffer are being transmitted; at the end of a cycle, the roles of the two buffers are exchanged. The cycle start times are determined by a time offset that may be different for every output buffer. A guard band at both cycle ends is devised in order to compensate for misalignment and timing inaccuracies. The proper operation of CQF requires that the guard band and the offsets are computed such that nodes are sufficiently time-aligned. First, we give necessary and sufficient conditions for this to be guaranteed. The sufficient conditions lend themselves to tractable computations and we show that they are close to optimal. Our conditions account for nonideal clocks and non-zero propagation times; we show that accounting for these two elements does matter. Second, we give a method for computing the minimal duration of the guard band, given prior choices of time offsets. Third, a judicious choice of time offsets can considerably decrease the required duration of the guard band: we give a practical algorithm, based on a Mixed Integer Linear Program, for computing offsets that minimize the guard band. We illustrate our results on several CQF network topologies with or without cyclic dependencies.

Total Flow Analysis (TFA) is a method for the worstcase analysis of time-sensitive networks. It uses service curve characterizations of the network nodes and arrival curves of flows at their sources; for tractability, the latter are often taken to be linear functions. For periodic flows, which are common in timesensitive networks, linear arrival curves are known to provide less good bounds than ultimately pseudo-periodic (UPP) arrival curves, which exactly capture the periodic behaviours. However, in existing tools, applying TFA with many flows and UPP curves quickly becomes intractable because when aggregating several UPP curves, the pseudo-period of the aggregate might become extremely large. We propose a solution to this problem, called Finite-Horizon TFA. The method computes finite horizons over which arrival and service curves can be restricted without affecting the end-results of TFA. It can be applied to networks with cyclic dependencies. We numerically show that, while remaining computationally feasible, the method significantly improves the bounds obtained by TFA when using linear curves.

Computing response times for resources shared by periodic workloads (tasks or data flows) can be very time consuming as it depends on the least common multiple of the periods. In a previous study, a quadratic algorithm was provided to upper bound the response time of a set of periodic tasks with a fixed-priority scheduling. This paper generalises this result by considering a rate-latency server and sporadic workloads and gives a response time and residual curve that can be used in other contexts. It also provides a formal proof in the Coq language.

Formal analysis methods of embedded systems provide safe, but unfortunately often pessimistic bounds on response times. An important source of pessimism is the common approach to characterize service request either by the amount of data or the number of events to be processed. Several works, e.g. [1]-[4], have demonstrated that a dual model - which includes information on both data and events - is more accurate, especially for more complex scheduling problems. In this paper, we enrich Compositional Performance Analysis (CPA) by a new component interface which, as we show, is consistent with the generic dual model proposed in [3]. Furthermore, we discuss how composition of components should be realized and how the new information should be integrated into the analysis technique. The improved CPA is called CPA+, and we identify different types of scenarios where CPA+ is particularly beneficial.

Network calculus (also known as real-time calculus) and event stream theory are two theories designed to compute upper bounds on response time for real-time systems. Both generalise the common periodic request arrival to any kind of workload using cumulative functions. In network calculus, a data flow is modelled by its cumulative curve, A(t), representing the amount of data sent by the flow up to time t, whereas the event stream theory counts the number of packets sent up to t, denoted by E(t). Of course, the size of packets is a link between both functions. This work presents a formal model embedding both A, E, the packet function, and their basic relations.

OBJECTIVES: This article summarizes past and current data mining activities at the United States Food and Drug Administration (FDA). TARGET AUDIENCE: We address data miners in all sectors, anyone interested in the safety of products regulated by the FDA (predominantly medical products, food, veterinary products and nutrition, and tobacco products), and those interested in FDA activities. SCOPE: Topics include routine and developmental data mining activities, short descriptions of mined FDA data, advantages and challenges of data mining at the FDA, and future directions of data mining at the FDA.

The AFDX technology is used as backbone in several aircraft. It offers a high bandwidth (commonly 100Mb/s), and guaranteed per data flow a bound on the network traversal delay, while being a shared resource. To do so, it uses a segregation mechanism, the Virtual Link (VL), designed as a bus abstraction. Nevertheless, there may exist applications with such stringent latency requirements that a given AFDX topology can not ensure it. To provide low latency, the AFDX technology provides priority levels: but even in the highest priority level, the latency bound can still be too high with regard to applicative requirements. One cause of latency is the non-preemptive aspect of priority policy: when a high priority frame reaches an output port, it may have to wait the emission of a low priority frame. Then, a high priority frame might have to face a delay equal to the maximum packet emission time of the low priority flows per crossed switch. The scheduling policy called Disrupted Static Priority (DSP) aims to improve the latency guarantees, by interrupting low priority frames, and re-emitting them from the beginning. This policy is a trade-off between simplicity and efficiency. A quantitative comparison between the NP-SP and the DSP scheduling systems' performance on a realistic case-study is provided in this article.

The paper addresses performance analysis of embedded real time networks. We use network calculus to assess the quality of service of a residual flow in a context of aggregation with non preemptive fixed priority scheduling. The main contribution concerns the evaluation of the residual service, given to the low priority flows. In previous works, the effect of the non-preemption seems to be not well taken into account. In particular, when a non preemptive flow is served, it benefits from the full speed from the server, even if, from a long term point of view, it gets only a fractional part. The modeling of this aspect is the starting point of this work.

Embedded systems have specific real-time requirements that led to the development of dedicated communication protocols. Such systems often face increasing communication needs and the integration of switched Ethernet architecture. But moving from existing dedicated field-buses architectures to new Ethernet based architectures is not always easily feasible, due to industrial constraints. In this paper, we propose a solution for integrating existing data busses (such as CAN, which is an important standard in automotive context) on a global architecture that respects increasing bandwidth requirements. We consider a time triggered CAN application and propose CAN/Ethernet bridging strategies that respect the time-triggered real time behaviour of CAN End System when communicating through a switched Ethernet network that can also be shared by (non CAN) applications