Licentiate thesis 2000-006

A Flexible Framework for Detection of Feature Interactions in Telecommunication Systems

Gustaf Naeser

October 2000


The complexity of today's telecommunications systems grows with each new feature introduced. As the number of services an operator provides can be used to gain advantage over competitors the number of services will continue to increase. As the complexity grows, so does the possibility for feature interactions, situations where the operation of features interfere with the operation of other features. Interactions cost more to resolve the later during the introduction of a new feature they are detected. This makes the need for analysis of feature interactions during development preeminent.

There exists a multitude of frameworks and techniques for specification and analysis of models of telecommunications systems. However, we have identified that they often impose unnecessary design decisions on the models, making them untoward.

In this thesis we propose a framework for specification of models of telecommunications systems. The framework is designed to describe them as general systems of communicating processes in a flexible way which allows alterations to be made late during the design. We also present definitions of interactions and how the interaction definitions are used in the framework to detect undesired interactions.

A model for telephony systems is derived through observations made of common telephony concepts and constructs. Delving into concepts early in the design of the system is shown to avoid several sources of interactions.

To demonstrate the potential of the framework we present a case study where the system and services described in the first interaction detection contest has been implemented and searched for interactions.

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