Timed automata for metric interval temporal logic formulae in prototype verification system

Based on analysis of the syntax structure and semantics model of the metric interval temporal logic （MITL） formulas, it is shown how to transform a formula written in the real-time temporal logic MITL formula into a fair timed automaton （TA） that recognizes its satisfying models with prototype verification system （PVS） in this paper. Both the tabular construction＇s principles and the PVS implementation details are given for the different type of MITL formula according to the corresponding semantics interpretations. After this transformation procedure, specifications expressed with MITL formula can be verified formally in the timed automata framework developed previously.

Towards a Formal Semantics for UML/MARTE State Machines Based on Hierarchical Timed Automata

UML is a widely-used, general purpose modeling language. But its lack of a rigorous semantics forbids the thorough analysis of designed solution, and thus precludes the discovery of significant problems at design time. To bridge the gap, the paper investigates the underlying semantics of UML state machine diagrams, along with the time-related modeling elements of MARTE, the profile for modeling and analysis of real-time embedded systems, and proposes a formal operational semantics based on extended hierarchical timed automata. The approach is exemplified on a simple example taken from the automotive domain. Verification is accomplished by translating designed models into the input language of the UPPAAL model checker.

Formal Specification and Model-Checking of CSMA/CA Using Finite Precision Timed Automata

This paper presents the formal specification and model-checklng of Carrier Sense Multiple Access with Collision Avoidance（ CSMA/CA） protocol using the model checker we developed for real-time systems, which are specified as networks of finite precision timed automata. The CSMA/CA protocol proposed in the IEEE 802.11 standard is designed to reduce the probability of collision during a transmission in wireless random access environments. However, it does not eliminate completely the possibility of a collision between two or more frames transmitted simultaneously. We investigate what will give rise to a collision between frames and use our automatic verification tool for model-checking.

Distributed intrusion detection for mobile ad hoc networks

Mobile ad hoc networking （MANET） has become an exciting and important technology in recent years, because of the rapid proliferation of wireless devices. Mobile ad hoc networks is highly vulnerable to attacks due to the open medium, dynamically changing network topology, cooperative algorithms, and lack of centralized monitoring and management point. The traditional way of protecting networks with firewalls and encryption software is no longer sufficient and effective for those features. A distributed intrusion detection approach based on timed automata is given. A cluster-based detection scheme is presented, where periodically a node is elected as the monitor node for a cluster. These monitor nodes can not only make local intrusion detection decisions, but also cooperatively take part in global intrusion detection. And then the timed automata is constructed by the way of manually abstracting the correct behaviours of the node according to the routing protocol of dynamic source routing （DSR）. The monitor nodes can verify the behaviour of every nodes by timed automata, and validly detect real-time attacks without signatures of intrusion or trained data. Compared with the architecture where each node is its own IDS agent, the approach is much more efficient while maintaining the same level of effectiveness. Finally, the intrusion detection method is evaluated through simulation experiments.

Verifying Automata Specification ofDistributed Probabilistic Real-Time Systems

In this paper, a qualitative model checking algorithm for verification of distributed probabilistic real-time systems (DPRS) is presented. The model of DPRS, called real-time probabilistic process model (RPPM), is over continuous time domain. The properties of DPRS aredescribed by using deterministic timed automata (DTA). The key part in the algorithm is tomap continuous time to finite time intervals with flag variables. Compared with the existingalgorithms, this algorithm uses more general delay time equivalence classes instead of the unitdelay time equivalence classes restricted by event sequence, and avoids generating the equivalence classes of states only due to the passage of time. The result shows that this algorithm ischeaper.

A formal method to real-time protocol interoperability testing

Interoperability testing is an important technique to ensure the quality of implementations of network communication protocol. In the next generation Internet protocol, real-time applications should be supported effectively. However, time constraints were not considered in the related studies of protocol interoperability testing, so existing interoperability testing methods are difficult to be applied in real-time protocol interoperability testing. In this paper, a formal method to real-time protocol interoperability testing is proposed. Firstly, a formal model CMpTIOA （communicating multi-port timed input output automata） is defined to specify the system under test （SUT） in real-time protocol interoperability testing; based on this model, timed interoperability relation is then defined. In order to check this relation, a test generation method is presented to generate a parameterized test behavior tree from SUT model; a mechanism of executability pre-determination is also integrated in the test generation method to alleviate state space explosion problem to some extent. The proposed theory and method are then applied in interoperability testing of IPv6 neighbor discovery protocol to show the feasibility of this method.