Fly-By-Wireless for Next Generation Aircraft: Challenges and Potential solutions

”Fly-By-Wireless” paradigm based on wireless connectivity in aircraft has the potential to improve efficiency and flexibility, while reducing weight, fuel consumption and maintenance costs. In this paper, first, the opportunities and challenges for wireless technologies in safety-critical avionics context are discussed. Then, the assessment of such technologies versus avionics requirements is provided in order to select the most appropriate one for a wireless aircraft application. As a result, the design of a Wireless Avionics Network based on Ultra WideBand technology is investigated, considering the issues of determinism, reliability and security

Ethernet-based AFDX simulation and time delay analysis

Nowadays, new civilian aircraft have applied new technology and the amount of embedded systems and functions raised. Traditional avionics data buses design can‘t meet the new transmission requirements regarding weight and complexity due to the number of needed buses. On the other hand, Avionics Full Duplex Switched Ethernet (AFDX) with sufficient bandwidth and guaranteed services is considered as the next generation of avionics data bus. One of the important issues in Avionics Full Duplex Switched Ethernet is to ensure the data total time delay to meet the requirements of the safety-critical systems on aircraft such as flight control system. This research aims at developing an AFDX time delay model which can be used to analyse the total time delay of the AFDX network. By applying network calculus approach, both (σ,ρ) model and Generic Cell Rate Algorithm (GCRA) model are introduced. For tighter time-delay result, GCRA model is applied. Meanwhile, the current AFDX network simulation platform, FACADE, will be enhanced by adding new functions. Moreover, avionics application simulation modules are developed to exchange data with FACADE. The total time delay analysis will be performed on the improved FACADE to validate this AFDX network simulation platform in several scenarios. Moreover, each scenario is appropriated to study the association between total time delay performance and individual variable. The results from updated FACADE reflect the correlation between total time delay and certain variables. Larger BAG and more switches between source and destination end systems introduce larger total time delay while Lmax could also affect the total time delay. However, the results illustrate that the total time delays from updated FACADE are much larger than GCRA time delay model which could up to 10 times which indicates that this updated FACADE needs further improvement

A Time-Triggered Constraint-Based Calculus for Avionic Systems

The Integrated Modular Avionics (IMA) architec- ture and the Time-Triggered Ethernet (TTEthernet) network have emerged as the key components of a typical architecture model for recent civil aircrafts. We propose a real-time constraint-based calculus targeted at the analysis of such concepts of avionic embedded systems. We show our framework at work on the modelisation of both the (IMA) architecture and the TTEthernet network, illustrating their behavior by the well-known Flight Management System (FMS)

Ethernet - a survey on its fields of application

During the last decades, Ethernet progressively became the most widely used local area networking (LAN) technology. Apart from LAN installations, Ethernet became also attractive for many other fields of application, ranging from industry to avionics, telecommunication, and multimedia. The expanded application of this technology is mainly due to its significant assets like reduced cost, backward-compatibility, flexibility, and expandability. However, this new trend raises some problems concerning the services of the protocol and the requirements for each application. Therefore, specific adaptations prove essential to integrate this communication technology in each field of application. Our primary objective is to show how Ethernet has been enhanced to comply with the specific requirements of several application fields, particularly in transport, embedded and multimedia contexts. The paper first describes the common Ethernet LAN technology and highlights its main features. It reviews the most important specific Ethernet versions with respect to each application field’s requirements. Finally, we compare these different fields of application and we particularly focus on the fundamental concepts and the quality of service capabilities of each proposal

Improving Bandwidth Utilization With Deterministic Delivery Guarantees in AFDX through Traffic Phase-Shifting

The Avionic Full-Duplex Switched Ethernet (AFDX) is a data network certified for avionic operations. AFDX closely follows the IEEE 802.3 (Ethernet) standard for packet forwarding. On top of that, bandwidth enforcement using traffic shaping is performed to provide deterministic delivery guarantees. The design of an AFDX network, however, imposes that bandwidth enforcement is performed at a coarse granularity. This, together with the tight requirements on transmission jitter, determines a low utilization of the physical links. In this work, we propose traffic phase shifting (TPS) as a way to increase the granularity of bandwidth assignment to nodes of an AFDX network using logic time synchronization among traffic sources. Specifically, we leverage the periodic nature of real-time traffic and use phase-shifing to prevent link congestion. This in turns allows a more fine-grained bandwidth control via the AFDX protocol. We show that TPS leads to significant improvements in terms of per-link utilization without violating predictability.CNS-1219064CNS-1302563Ope

Scheduling Rate Constrained traffic in End Systems of Time-Aware Networks

Nowadays, most of cyber-physical systems in avionics, automotive or recent Industry 4.0 domains require networked communication for mixed-critical applications. Ethernet-based networks such as AFDX, TTEthernet or TSN are capable to support transmission of both safety-critical and non-critical flows. This paper focuses on the TTEthernet network compliant with the avionics ARINC 664-P7 standard supporting time-triggered communication (TT) together with rate-constrained (RC) and best-effort (BE) traffic. Due to a global synchronization, TTcommunication with low latency and minimal jitter is ensured with static schedules computed offline. For event-triggered RC flows, bounded jitter at the source and end-to-end latency are guaranteed with worst-case analysis methods. With the increasing demands of applications, flows with Quality of Service (QoS) requirements such as video or audio may be transmitted as BE flows. However, on current configurations, no guarantees are offered to BE flows. In this paper, we aim at increasing the maximum RC utilization and improving the QoS of BE flows to allow the transmission of video or audio traffic with low jitter and end-to-end delay requirements. For this, we focus on the scheduling mechanisms and propose a scheduling approach based on a static slotted table that is applied at end systems. This table integrates the TT schedules usually obtained with Satisfiability Modulo Theories (SMT) approaches and establishes offsets of RC flows that reduce the end-to-end delay of BE flows. Several strategies for offset computations are proposed based on the distribution of flows locally at end system or globally at switch. We show that local strategies perform better than the global ones to reduce end-to-end delay of BE flows

Analyse pire cas exact du réseau AFDX

L'objectif principal de cette thèse est de proposer les méthodes permettant d'obtenir le délai de transmission de bout en bout pire cas exact d'un réseau AFDX. Actuellement, seules des bornes supérieures pessimistes peuvent être calculées en utilisant les approches de type Calcul Réseau ou par Trajectoires. Pour cet objectif, différentes approches et outils existent et ont été analysées dans le contexte de cette thèse. Cette analyse a mis en évidence le besoin de nouvelles approches. Dans un premier temps, la vérification de modèle a été explorée. Les automates temporisés et les outils de verification ayant fait leur preuve dans le domaine temps réel ont été utilisés. Ensuite, une technique de simulation exhaustive a été utilisée pour obtenir les délais de communication pire cas exacts. Pour ce faire, des méthodes de réduction de séquences ont été définies et un outil a été développé. Ces méthodes ont été appliquées à une configuration réelle du réseau AFDX, nous permettant ainsi de valider notre travail sur une configuration de taille industrielle du réseau AFDX telle que celle embarquée à bord des avions Airbus A380. The main objective of this thesis is to provide methodologies for finding exact worst case end to end communication delays of AFDX network. Presently, only pessimistic upper bounds of these delays can be calculated by using Network Calculus and Trajectory approach. To achieve this goal, different existing tools and approaches have been analyzed in the context of this thesis. Based on this analysis, it is deemed necessary to develop new approaches and algorithms. First, Model checking with existing well established real time model checking tools are explored, using timed automata. Then, exhaustive simulation technique is used with newly developed algorithms and their software implementation in order to find exact worst case communication delays of AFDX network. All this research work has been applied on real life implementation of AFDX network, allowing us to validate our research work on industrial scale configuration of AFDX network such as used on Airbus A380 aircraft. ABSTRACT : The main objective of this thesis is to provide methodologies for finding exact worst case end to end communication delays of AFDX network. Presently, only pessimistic upper bounds of these delays can be calculated by using Network Calculus and Trajectory approach. To achieve this goal, different existing tools and approaches have been analyzed in the context of this thesis. Based on this analysis, it is deemed necessary to develop new approaches and algorithms. First, Model checking with existing well established real time model checking tools are explored, using timed automata. Then, exhaustive simulation technique is used with newly developed algorithms and their software implementation in order to find exact worst case communication delays of AFDX network. All this research work has been applied on real life implementation of AFDX network, allowing us to validate our research work on industrial scale configuration of AFDX network such as used on Airbus A380 aircraft

System-level scheduling of mixed-criticality traffics in avionics networks

ABSTRACT: System-level mixed-criticality design aims at reducing production cost and enhancing resource efficiency. This paper studies the technology of integrating mixed-criticality avionics traffics for Avionics Full-Duplex Switched Ethernet (AFDX) network, which can transmit both critical and non-critical traffics. These two traffics have different QoS requirements, such as low latency for critical traffics and high bandwidth for non-critical traffics. We use system-level compositional scheduling to integrate mixed-criticality traffics into one network to enhance the scalability of AFDX network. In the architecture of the proposed compositional scheduling, critical traffics are scheduled by bandwidth allocation gap-based scheduler, and non-critical traffics by Round Robin manner. To estimate the delay bound meeting requirements of applications, end-to-end delay for both critical and non-critical traffics are analyzed by using network calculus. Finally, a true time-based simulation of AFDX networks is conducted to verify the effectiveness of the proposed approach