Introduction to the special session on formal verification of telecommunications systems

Abstract

Formal verification may be defined as a method which takes a formal description of a system and a formal specification of correctness requirements, and proves – or disproves – that the system satisfies them. Whereas the use of some formal and semi-formal languages (e.g. SDL, UML, MSC) for system description is quite well established in the telecommunications industry, when it comes to system verification, less efficient and more timeconsuming methods, such as (non-exhaustive) simulation and testing largely prevail over the use of formal verification techniques. Having recognized the significant potential benefits of applying formal verification techniques, the researchers from the Faculty of Electrical Engineering and Computing (FER) in Zagreb and from the Faculty of Electrical Engineering and Computer Science (FERI) in Maribor jointly organized a Workshop on Formal Verification of Telecommunication Systems in 2004. One of the conclusions of the Workshop was to organize a Special Session on Formal Verification of Telecommunications Systems within ConTEL 2005, with the goal to discuss this important topic in a wider forum. We primarily solicited original submissions on the application of formal verification in industrial projects and on new methods and tools for enabling such applications. Submissions related to the use of formal verification in telecommunications systems design were also welcome. A total of 10 papers have been submitted to the special session, and five of them have been accepted. The first paper is Formalizing Operator Requirements of the Development of Telecommunications Networks and Services by Krzysztof M. Brzezinski from Warsaw University of Technology, Poland. Network operators design their networks and service packages by using a set of “industrial” concepts and practices, which are relatively informal compared to other phases of the system life-cycle (protocol design using formal verification/validation, conformance and interoperability testing). This paper proposes a semi-formal operator requirements notation and tool support for handling operator requirements documents in order to increase the formalisation level of the overall telecommunications system life-cycle. The second paper is Modeling, Verifying and Testing the Mobility Management in the Mobile IPv6 Protocol by Francine Ngani Noudem and César Viho from IRISA – Université de Rennes I, France. Mobility is an important characteristic of modern telecommunications systems. The authors present an approach to modelling mobility management of mobile IPv6 with SDL, which allows them to perform validation of certain properties regarding mobility by the exhaustive simulation capability of the ObjectGeode industrial toolset. Based on the SDL model, they also present an approach to automatic test case generation in the new language TTCN-3. The third paper is Predicate Abstraction in Protocol Verification by Edgar Pek and Nikola Bogunovi from FER, Croatia. Model checking is a formal verification technique which enables automatic verification of finitestate systems. This paper reports the use of predicate abstraction on two mutual-exclusion algorithms with infinite state spaces due to unbounded data types and, respectively, real-time nature in order to obtain their finite-state representations. These could then be verified automatically by the NuSMV model checker. The fourth paper is Reducing Dependency on Network Reliability and Availability by Encapsulating the Negotiation Functionalities in ACL Messages by Marina Bagi and Marijan Kunšti from FER. In recent years, agents have become an important concept in telecommunications systems. This paper studies formal specification of agents for solving network management tasks. The agents communicate via FIPA ACL messages. The communication is modelled by using coloured Petri nets. Their correlation with AUML sequence diagrams is shown. CPN Toolsets have been applied for system simulation and validation. The fifth paper is Toward Automatic Generation of Promela Models from SDL Specification by Boštjan Vlaovi , Aleksander Vreže, Zmago Brezo nik, and Tatjana Kapus from FERI, Slovenia. It presents a tool, named sdl2pml, for translating SDL system descriptions into Promela. Such system description is better suited for formal verification since Promela is used as the input language of the well-known telecommunications system verification tool Spin. With support for SDL constructs often used in the telecommunications industry, in addition to standard set of formal verification capabilities, the sdl2pml tool offers advanced capabilities suitable for use in an industrial setting. We would like to thank all the authors that submitted papers, as well as the reviewers. We hope that this event will offer an opportunity for a lively discussion on the role of formal verification and other formal methods in contemporary telecommunications system design.