PREPRINTS 11th International Workshop on REAL Time Networks RTN’12 Pisa, Italy, July 10, 2012 In conjunction with the 24 th ECRTS http://irt.enseeiht.fr/scharbarg/rtn2012/rtn2012.htm Chairman: Jean-Luc Scharbarg Université de Toulouse – IRIT/INPT/ENSEEIHT Workshop Chair Jean-Luc Scharbarg, Universit´ede Toulouse - IRIT/INPT/ENSEEIHT, France Program Committee Luis Almeida, University of Porto, Portugal Leandro Buss Becker, Federal University of Santa Catarina, Brazil Gianluca Cena, Politecnico di Torino, Italy Jean-Dominique Decotignie, CSEM, Switzerland Christian Fraboul, Universit´ede Toulouse - IRIT/INPT/ENSEEIHT, France Anis Koubaa, Al-Imam University, KSA and CISTER Res. Unit, Portugal Lucia Lo Bello, University of Catania, Italy Pau Marti, Technical University of Catalonia, Spain Daniel Mosse, University of Pittsburg, USA Luca Mottola, SICS, Sweden Thomas Nolte, MRTC/Mlardalen University, Vsteras, Sweden Binoy Ravindran, Virginia Tech, USA Thilo Sauter, Austria Academy of Science, Austria Michael Short, Teesside University, UK Ye-Qiong Song, LORIA, France Eduardo Tovar, IPP-HURRAY, Portugal Andreas Willig, University of Canterbury, New Zealand Advance Program 8:30-9:15 Registration 9:15-9:30 Welcome and opening remarks 9:30-11:00 Session 1 - Keynote Talk 1 Avionics embedded networks Christian Fraboul, Lionel Loudet 11:00-11:30 Coffee Break 11:30-13:00 Session 2 Exploring alternatives to use master/slave full duplex switched Ethernet for avionics embedded applications Ahlem Mifdaoui, Moris Behnam, Thomas Nolte, Paulo Pedreiras, Luis Almeida, Ricardo Marau Networked embedded systems for active flow control in aircraft Eduardo Tovar, Nuno Pereira, Iain Bate, Leandro Indrusiak, Sergio Penna, Jose Negrao, Julio C. Viana, Francois Philipp, Dirk Mayer, Jose Heras, Filipe Pacheco, Joao Loureiro Worst-case delay analysis for a wireless point-to-point transmission Katia Jaffres-Runser 13:00-14:30 Lunch 14:30-16:00 Session 3 - Keynote Talk 2 Satellites embedded networks Olivier Notebaert 16:00-16:30 Coffee Break 16:30-17:30 Session 4 - Keynote Talk 3 Performance evaluation of real-time traffic in aggregate-scheduling networks Giovanni Stea 17:30-18:00 Panel discussion and closing remarks Session 1 - Keynote Talk 1 Avionics embedded networks Christian Fraboul Universit´ede Toulouse - IRIT/INPT/ENSEEIHT, France Lionel Loudet Airbus, France Abstract The evolution of civilian aircraft avionics systems is mainly due to an increasing complexity which is illustrated by a larger number of inte- grated functions, a larger volume of exchanged data, and a larger number of connections between functions. Consequently, the growth of the num- ber of multi-point communication links cannot be taken into account by classical avionics mono-emitter data-buses. The solution consists in the utilization of a switched Ethernet technology (named AFDX: Avionics Full Duplex Switched Ethernet), which allows a re-use of development tools as well as of existing communication components while achieving better performance and which has been standardized in ARINC 664. This new communication standard represents a major step in the deployment of modular avionics architectures. The main problem is due to the indeter- minism of the switched Ethernet. A network designer must prove that no frame will be lost by the AFDX and must evaluate the end-to-end transfer delay through the network (guaranteed upper bound) according to a given avionics applications traffic. This talk will explain the main evolutions of avionics systems. It will present the main concepts and mechanisms as well as the methods and tools which are needed mainly for certification purpose. The reasons for the choices will be explained. A feedback will be given as well as some trends for the future. Session 2 Exploring Alternatives to use Master/Slave Full Duplex Switched Ethernet for Avionics Embedded Applications A. Mifdaoui1, M. Behnam2, T. Nolte2, P. Pedreiras3, L. Almeida4, R. Marau4 1University of Toulouse, France 2Malardalen¨ Real-Time Research Centre, Vaster¨ as,˚ Sweden 3IT / DETI, University of Aveiro, Portugal 4IT / DEEC, Fac. Engineering, University of Porto, Portugal Abstract— The complexity of distributed real-time systems, mechanisms added to switches, this technology succeeds in including military embedded applications, is increasing due to exchanging large amounts of data in time ([6]). It is worth an increasing number of nodes, their functionality and higher to note that this technology was initially designed to support amounts of exchanged data. This higher complexity imposes major development challenges when nonfunctional properties civil requirements, where only periodic traffic is considered, must be enforced. On the other hand, the current military whereas military environments require periodic and aperiodic communication networks are a generation old and are no longer traffic, both with strict temporal constraints. effective in facing such increasingly complex requirements. As a first step, the authors proposed in [7] a network with a A new communication network, based on Full Duplex Switched distributed communication scheme based upon Full Duplex Ethernet and Master/slave approach, has been proposed previ- ously. However, this initial approach is not efficient in terms of Switched Ethernet for military applications. The obtained network bandwidth utilization. In this paper we propose two results for a realistic military application show the ability of new alternative approaches that can use the network bandwidth this proposal to improve global throughput and system’s flex- more efficiently. In addition we provide a preliminary qualitative ibility while satisfying the real time constraints. However, the assessment of the three approaches concerning different factors existing subsystems typically use a centralized communication such as performance, scalability, complexity and flexibility. scheme, influenced by the widely used command/response data bus MIL STD 1553B. Therefore, migrating all existing appli- I. INTRODUCTION cations into a compliant distributed communication scheme During the last few decades, many specific data buses have could be a complicated and expensive step. To avoid this been successfully used in various military avionics embedded process, the proposal in [8] consists in keeping the current applications, like MIL STD 1553B [1], STANAG 3910 [2] military centralized communication scheme upon Switched and SCI links [3]. However, with the increasing complexity of Ethernet by using a master/ slave protocol. interconnected subsystems and growing amount of exchanged Among the most relevant solutions using the Master/ Slave data, these data buses are a generation old and are no longer approach upon Switched Ethernet ([9], [10]), FTT-SE [11] effective in meeting the requirements of the next generation presents several advantages that are relevant to our application embedded applications in terms of bandwidth, latency and scope such as its optimized Master/ Slave transmission control flexibility. In addition, using these data buses makes the and its flexibility. To adapt FTT-SE to the context of the global communication network heterogeneous with real time referred applications, new mechanisms were introduced in [8] guarantees difficult to prove. Clearly, a new homogeneous to handle periodic and aperiodic traffic based on a bandwidth communication network is needed to fulfil these requirements. reservation method to guarantee predictable transmissions and Currently, there is a new trend to use Commercial Off the stability of the system temporal behavior. Then, in order to The Shelf (COTS) technologies instead of dedicated solutions deal with the worst case performance prediction of such pro- in many application domains to reduce development costs posal, schedulability analysis were used based on the Network and facilitate maintenance. Among several high speed COTS Calculus formalism [12]. The obtained results for a realistic networks, Switched Ethernet is incontestably the most cost military applications showed the proposal’s ability to support effective solution thanks to its ubiquity, simplicity, matu- the required time constrained communication. However, this rity and relative low cost, which made it the dominating solution led to a pessimistic bandwidth utilization due to the communication technology in many application domains. For over-dimensioning of the bandwidth reservation mechanism example, the ARINC 664-compliant Avionics Full Duplex parameters. Switched Ethernet (AFDX) [4] network has been integrated Hence, in order to enhance the bandwidth consumption recently into new generation civil aircrafts like the A380, to efficiency when using Master/Slave Switched Ethernet, two replace the ARINC 429 data buses [5]. Thanks to control proposed alternatives are presented and compared in this paper, in terms of performance, scalability and costs integration, subsystems on each used MIL STD 1553B. The different using the proposal in [8] as reference. The first solution is categories of the Real-time traffic are described in tables I based on a similar hardware architecture but with a more and II. As it can be noticed, the largest period for periodic optimized schedulability test and an hierarchical server-based messages is about 160 ms and the most common value is 20 scheduling [13] within the master to handle the periodic and ms, while for aperiodic messages, there are different response aperiodic traffic, respectively. The second solution is based time bounds and the most urgent one is