Feature interaction detection in a telephony network integrated with switch-based features and IN features.

Abstract

Telephony systems have evolved from the Plain Old Telephony System providing only the basic functionality of making phone calls, to sophisticated systems in which many features have been introduced, providing network subscribers more control on the call establishment process. The concept of Intelligent Network was developed to facilitate and accelerate the introduction of new features in a cost-effective manner. However, this objective confronts---a major obstacle known as the feature interaction problem. A feature interaction occurs when at least one feature is prevented from performing its functionality or when the system functions incorrectly due to the presence of features. In the first part of the thesis, we present a model for specifying a telephony network integrated with both switch-based features and IN features using a mixture of resource-oriented style and state-oriented style as well as a specially organized Abstract Data Type hierarchy. The model is designed in a way that independent specification and rapid introduction of features is provided. In the second part of the thesis, we present an improved formal definition of the concept of Feature Interaction and a Feature Interaction Detection System. The system is limited to interactions caused by violation of features or system properties. Feature Interaction between the given features can be detected and presented in the format of Message Sequence Charts via five steps: Test Scenario Designer, Integrator, Feature Interaction Hunter, Property Checker and Message Sequence Charts Translator. It is concluded that LOTOS is useful as a Formal Description Technique in specifying the telephony system with features and for detecting feature interactions at the abstract specification level.