Performance Evaluation of Sensor Medium Access Control Protocol Using Coloured Petri Nets

AbstractFormal modeling techniques can be used for analysis of wireless sensor networks (WSNs). Coloured Petri nets (CPNs) that is an extension of Petri nets is a powerful modeling technique. In this paper, we present a CPN model for modeling and performance evaluation of a medium access control protocol in WSNs named sensor-medium access control protocol (S-MAC). S-MAC is an energy-aware MAC protocol with nodes scheduling. The proposed model for this protocol uses the hierarchical modeling capability of CPNs. By using CPNs in this case study and the proposed method for modeling packet broadcast, we have demonstrated the possibility of modeling and evaluation of any other MAC protocol in WSNs or mobile ad-hoc networks (MANET)

Probabilistic Analysis of Wireless Systems Using Theorem Proving

Probabilistic techniques play a major role in the design and analysis of wirelesssystems as they contain a significant amount of random or unpredictable components. Traditionally, computer simulation techniques are used to perform probabilisticanalysis of wirelesssystems but they provide inaccurate results and usually require enormous amount of CPU time in order to attain reasonable estimates. To overcome these limitations, we propose to use a higher-order-logic theorem prover (HOL) for the analysis of wirelesssystems. The paper presents a concise description of the formal foundations required to conduct the analysis of a wirelesssystem in a theorem prover, such as the higher-order-logic modeling of random variables and the verification of their corresponding probabilistic and statistical properties in a theorem prover. In order to illustrate the utilization and effectiveness of the proposed idea for handling real-world wirelesssystemanalysis problems, we present an analysis of the automated repeat request (ARQ) mechanism at the logic link control (LLC) layer of the General Packet Radio Service (GPRS), which is a packet oriented mobile data service available to the users of Global System for Mobile Communications (GSM)

Formal Verification of Real-Time Wireless Sensor Networks Protocols with Realistic Radio Links

International audienceMany critical applications which rely on Wireless Sensor Networks (WSNs) are proposed. Forest fire detection, land- slide detection and intrusion detection are some examples. Critical applications require correct behavior, reliability, and the respect of time constraints. Otherwise, if they fail, con- sequences on human life and the environment could be catas- trophic. For this reason, the WSN protocols used in these applications must be formally verified. Unfortunately the radio link is unreliable, it is thus difficult to give hard guar- antees on the temporal behavior of the protocols (on wired systems the link error probability is very low [7], so they are considered reliable). Indeed, a message may experience a very high number of retransmissions. The temporal guaran- tee has thus to be given with a probability that it is achieved. This probability must meet the requirements of the applica- tion. Network protocols have been successfully verified on a given network topology without taking into account unre- liable links. Nevertheless, the probabilistic nature of radio links may change the topology (links which appear and dis- appear). Thus instead of a single topology we have a set of possible topologies, each topology having a probability to exist. In this paper, we propose a method that produces the set of topologies, checks the property on every topology, and gives the probability that the property is verified. This technique is independent from the verification technique, i.e. each topology can be verified using any formal method which can give a "yes" or "no" answer to the question: "Does the model of the protocol respect the property?". In this paper we apply this method on f-MAC [23] pro- tocol. F-MAC is a real-time medium access protocol for WSNs. We use UPPAAL model checker [10] as verification tool. We perform simulations to observe the difference be- tween average and worst case behaviors

Specification and Analysis of Priced Systems in Priced-Timed Maude

This thesis investigates the suitability of extending the rewriting-logic-based Maude framework, in particular Real-Time Maude, to support the formal modeling and analysis of untimed and timed priced systems. The first contribution of this thesis is to define priced and priced-timed rewrite theories, show the soundness of these definitions, and prove that priced-time rewrite theories contain as a proper subset the set of priced-timed automata (PTA). Since all priced systems that I have encountered have been real-time systems, I focus on priced real-time (priced-timed) systems. The second main contribution of the thesis is the development of a tool, Priced-Timed Maude, supporting the specification and analysis of useful subclasses of priced and priced-timed rewrite theories. In particular, Priced-Timed Maude supports the specification of the large and important class of ``flat'' object-oriented priced-timed systems, for which I have developed useful and intuitive specification techniques. This thesis then applies Priced-Timed Maude to three larger systems, two of which can be considered benchmarks for priced-timed systems and are often encountered in the literature, and one which has been inspired by a ``regular'' problem found in optimization literature. I have also modeled and analyzed one of these systems using the only well known formal tool for priced-timed systems that I have found, the PTA tool Uppaal CORA, and have compared the performance of these Priced-Timed Maude and Uppaal CORA specifications. Unsurprisingly, Uppaal CORA outperforms Priced-Timed Maude when analyzing this problem. This is natural, since the PTA model is quite restrictive. On the other hand, Priced-Timed Maude is more general and expressive, and lets us model more complex systems with advanced data types and communication features in an elegant and intuitive style. Furthermore, Priced-Timed Maude supports a wide range of formal analysis methods, including: rewriting for simulation, search for reachability analysis, linear temporal logic model checking, and finding cost- and time-optimal solutions

Proposition et vérification formelle de protocoles de communications temps-réel pour les réseaux de capteurs sans fil

Les RCsF sont des réseaux ad hoc, sans fil, large échelle déployés pour mesurer des paramètres de l'environnement et remonter les informations à un ou plusieurs emplacements (nommés puits). Les éléments qui composent le réseau sont de petits équipements électroniques qui ont de faibles capacités en termes de mémoire et de calcul ; et fonctionnent sur batterie. Ces caractéristiques font que les protocoles développés, dans la littérature scientifique de ces dernières années, visent principalement à auto-organiser le réseau et à réduire la consommation d'énergie. Avec l'apparition d'applications critiques pour les réseaux de capteurs sans fil, de nouveau besoins émergent, comme le respect de bornes temporelles et de fiabilité. En effet, les applications critiques sont des applications dont dépendent des vies humaines ou l'environnement, un mauvais fonctionnement peut donc avoir des conséquences catastrophiques. Nous nous intéressons spécifiquement aux applications de détection d'événements et à la remontée d'alarmes (détection de feu de forêt, d'intrusion, etc), ces applications ont des contraintes temporelles strictes. D'une part, dans la littérature, on trouve peu de protocoles qui permettent d'assurer des délais de bout en bout bornés. Parmi les propositions, on trouve des protocoles qui permettent effectivement de respecter des contraintes temporelles mais qui ne prennent pas en compte les spécificités des RCsF (énergie, large échelle, etc). D'autres propositions prennent en compte ces aspects, mais ne permettent pas de garantir des bornes temporelles. D'autre part, les applications critiques nécessitent un niveau de confiance très élevé, dans ce contexte les tests et simulations ne suffisent pas, il faut être capable de fournir des preuves formelles du respect des spécifications. A notre connaissance cet aspect est très peu étudié pour les RcsF. Nos contributions sont donc de deux types : * Nous proposons un protocole de remontée d'alarmes, en temps borné, X-layer (MAC/routage, nommé RTXP) basé sur un système de coordonnées virtuelles originales permettant de discriminer le 2-voisinage. L'exploitation de ces coordonnées permet d'introduire du déterminisme et de construire un gradient visant à contraindre le nombre maximum de sauts depuis toute source vers le puits. Nous proposons par ailleurs un mécanisme d'agrégation temps-réel des alarmes remontées pour lutter contre les tempêtes de détection qui entraînent congestion et collision, et donc limitent la fiabilité du système. * Nous proposons une méthodologie de vérification formelle basée sur les techniques de Model Checking. Cette méthodologie se déroule en trois points, qui visent à modéliser de manière efficace la nature diffusante des réseaux sans fil, vérifier les RCsF en prenant en compte la non-fiabilité du lien radio et permettre le passage à l'échelle de la vérification en mixant Network Calculus et Model Checking. Nous appliquons ensuite cette méthodologie pour vérifier RTXP.Wireless Sensor Networks (WSNs) are ad hoc wireless large scale networks deployed in order to monitor physical parameters of the environment and report the measurements to one or more nodes of the network (called sinks). The small electronic devices which compose the network have low computing and memory capacities and run on batteries, researches in this field have thus focused mostly on self-organization and energy consumption reduction aspects. Nevertheless, critical applications for WSNs are emerging and require more than those aspects, they have real-time and reliability requirements. Critical applications are applications on which depend human lives and the environment, a failure of a critical application can thus have dramatic consequences. We are especially interested in anomaly detection applications (forest fire detection, landslide detection, intrusion detection, etc), which require bounded end to end delays and high delivery ratio. Few WSNs protocols of the literature allow to bound end to end delays. Among the proposed solutions, some allow to effectively bound the end to end delays, but do not take into account the characteristics of WSNs (limited energy, large scale, etc). Others, take into account those aspects, but do not give strict guaranties on the end to end delays. Moreover, critical applications require a very high confidence level, simulations and tests are not sufficient in this context, formal proofs of compliance with the specifications of the application have to be provided. The application of formal methods to WSNs is still an open problem. Our contributions are thus twofold : * We propose a real-time cross-layer protocol for WSNs (named RTXP) based on a virtual coordinate system which allows to discriminate nodes in a 2-hop neighborhood. Thanks to these coordinates it is possible to introduce determinism in the accesses to the medium and to bound the hop-count, this allows to bound the end to end delay. Besides, we propose a real-time aggregation scheme to mitigate the alarm storm problem which causes collisions and congestion and thus limit the network lifetime. * We propose a formal verification methodology based on the Model Checking technique. This methodology is composed of three elements, (1) an efficient modeling of the broadcast nature of wireless networks, (2) a verification technique which takes into account the unreliability of the wireless link and (3) a verification technique which mixes Network Calculus and Model Checking in order to be both scalable and exhaustive. We apply this methodology in order to formally verify our proposition, RTXP.VILLEURBANNE-DOC'INSA-Bib. elec. (692669901) / SudocSudocFranceF