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The purpose of this paper is to describe how computer-aided test generation methods can benefit from the time features and extensions to MSC, SDL and TTCN which are either already available or currently under study in the EC Interval project. The implications for currently available test generation tools are shown and proposals for their improvement are made. The transformation of MSC-2000 time concepts into TTCN-3 code is described in detail.

We describe an approach for the verification of quantitative temporal properties of SDL specifications, which adapts techniques developed for timed automata [2]. With respect to other verification approaches applied to SDL, our approach broadens the class of analyzable specifications and improves the handling of non-deterministic systems, such as open systems communicating with an unspecified environment. Compared to the initial framework of timed automata, the application of these verification techniques to SDL raises two interesting issues, discussed in the paper. They are: expressing the semantics of time in SDL in terms of timed automata concepts, and employing a user friendly automata-based property specification language (GOAL [1]) to express and verify temporal properties. The paper also presents a verification tool prototype for SDL which implements these ideas.

In contrast to protocols of the network or transport layer the protocols for medium access have to consider the timing behavior of the communication medium. Although SDL is a widely used language for the specification of communication systems,in most cases time critical parts are not considered. In this paper,a design pattern is discussed that allows the specification of time critical functionality sucg as multiplexers or Quality-of-Service (QoS) schedulers. In many applications such services are running in a synchronous manner with the communication medium. A notation for timing aspects is needed for the specification of this behavior which itself is only possible in a sensible way with a formal model of time. Clocks are used to define the term real-time in a formal way,leading to the specification of timing constraints,for example sending data packets in deterministic time intervals within a communication system. In a case study from the mobile communication area,the design pattern was used to specify the MAC-Layer including time critical parts.

In this paper we propose some extensions necessary to enable the specification and description language Sdl to become a more appropriate formalism for the design of real-time and embedded systems. The extensions we envisage concern both roles of Sdl: first, in order to make Sdl a better real-time language, allowing to correctly simulate and verify real-time specifications, we propose a set of to express in a flexible way assumptions and assertions on timing issues such as execution durations, communication delays, or periodicity of external inputs; second, in order to make Sdl a better real-time language, several useful real-time programming concepts are added. In particular we propose to extend the basic Sdl timer mechanism by introducing new primitives such as cyclic timers, interruptive timers, and access to timer value. All these extensions rely on a clear and powerful time semantics for Sdl, which extends the current one, and which is based on .

This paper takes a light-hearted look at the life of ASN.1 and it relationships with other languages from the time of its birth to the year one of the third millennium — the information age.

Advanced design methods are needed to fulfill the increasing requirements of telecommunication service development. For a design method the relevant concepts for the application domain have to be de- fined, a supporting notation has to be declared and finally rules have to be developed to map design models to supporting runtime environments. The ITU-T has followed this route by defining concepts for the design of distributed telecommunication applications and supporting notations for these concepts. In the past, the ITU-T has defined several languages and notations to support structural and behavioral descriptions of distributed telecommunication systems, namely ODL, SDL-2000 and MSC- 2000. With the rise of the component age, an additional technique (DCL) is under development that enables component based manufacturing of distributed systems. Beside these languages, the ITU-T recognized the common need for open, component aware object middleware platform standards as the runtime environment for these systems. This contribution is about integration.

A set of scenarios is a useful way to capture many aspects of the requirements of a system. Use Case Maps are a method for scenario capture which is good for describing multiple scenarios, including scenario interactions, for developingan architecture, and for analysing architectural alternatives. However, once a component architecture is determined, Message Sequence Charts are better for developing and presentingthe details of interactions, and provide access to well-developed methodologies and tools for analysis and synthesis. This paper considers what must be specified in UCM scenarios and the architecture to make it possible to derive MSCs automatically, and it describes our experience in executingthese transformations within a prototype tool, the UCM Navigator.

This paper presents an SDL implementation framework for the third generation mobile communication system protocols. The framework includes specific stylistic notations of SDL and extensive usage of ASN.1. Furthermore the framework requires that all protocols should define certain packages and combine certain functionalities into one process. This framework has allowed creation of a prototype implementation of third generation mobile system protocol stacks. This prototype implementation contains nearly all protocols from mobile station, radio access network and some protocols from the core network side. This implementation has and will be used in multiple prototype and validation system implementations within Nokia.

An 11-router Internet Protocol network model based on the Open Shortest Path First (OSPF) routing protocol and Link State Advertisement (LSA) is expressed in the Specification and Description Language (SDL). The corresponding simulation data to verify the performance of a proposed more efficient OSPF LSA refreshment function is presented. Network traffic generated by the routing table refreshment activity using the new function is compared to the traffic generated in the Internet today when using the existing LSA refreshment function. The relative performance characteristics were found to depend on the number of LSA packets per router and the router startup sequence. Such dependencies when using protocol standards in natural language are not always visible until a number of implementations of the standard become available and tested in the field. SDL and tools provide an inexpensive but reliable way of verifying protocols under development in advance of implementation and final agreement.

Telecommunication services are often implemented to maintain their state in persistent storage. The application logic program then has no state variables of its own; it is seeded with a state depending on call context. Superficially, this contradicts the notion of extended state machines as they are defined by SDL-processes, where the state is part of the state machine. This paper presents an approach to separate state from program logic that is transparent to the SDL designer. This approach has been implemented in the SITE SDL runtime system in co-operation with Siemens, Berlin.