Cable-less avionics implementation will clearly improve the efficiency of aircraft while reducing weight and maintenance costs. Therefore, with the technological progress of wireless technologies, an alternative avionic communication architecture based on Ultra WideBand (UWB) technology is proposed to fulfill these new needs. To adapt this wireless technology to safetycritical avionics, first, the tuning process of the MAC layer and the integration of accurate reliability mechanisms to achieve timely and reliable communications are presented. Then, an efficient timing and reliability analysis of such a communication network based on Network Calculus is detailed. This analysis integrates the impact of non-preemptive message transmission, various service policies in end-systems, e.g., First In First Out (FIFO) and Fixed Priority (FP), and transmission errors. Third, this general analysis is illustrated in the case of a realistic avionic application to replace the AFDX backup network with our proposed UWBbased network to support timely and reliable communications.

Abstract-"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.

Most of the efforts to characterize DTN routing are focused on the trade-off between delivery ratio and delay. Buffer occupancy is usually not considered a problem and most of the related work assumes infinite buffers. In the present work, we focus on the drop ratio for message forwarding considering finite buffers. We model message drops with a continuous time Markov chain (CTMC). To the best of our knowledge, there is no previous work with such approach. We focus on the worst case with 1-packet buffers for message forwarding in homogeneous inter-contact times (ICT) and 2-class heterogeneous ICT. Our main contribution is to link the encounter rate(s) with the drop ratio. We show that the modeled drop ratio fits simulation results obtained with synthetic traces for both cases.

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. Abstract-To reduce the aircraft weight and maintenance costs while guaranteeing system performance and reliability, an alternative avionic communication architecture based on Ultra Wide Band (UWB) and TDMA protocol is proposed to replace the back-up part of safety-critical avionics network. The analysis and performance optimization of such a proposal is tackled as follows. First, appropriate system modeling and timing analysis, using Network Calculus and Integer Linear Programing (ILP) approach, are provided to evaluate the end-to-end delays and verify system predictability. Then, an optimization approach to find the optimal TDMA cycle duration, which minimizes the endto-end delays, is proposed. Finally, the efficiency of our proposal to enhance the system performance is validated through a realistic avionic case study.