Phase Semantics of MSC Traces

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Description/Abstract

Specifications for wireless telecommunications systems are often only partially defined. It is also common for the specification to consist of a set of normative scenarios together with scenarios for some of the more important exceptional behaviours. A major challenge is to find effective means of detecting feature interaction conflicts contained in such specifications. Moreover the detected conflicts should be of value in debugging the specifications and should not be cluttered with inconsequential errors that are due to the incompleteness of the specifications. The paper describes a technique for constructing a phase automaton that can be used to statically analyse the specification scenarios in order to detect certain types of interactions between them, known as phase transition conflicts. There is anecdotal evidence to suggest that these kinds of inconsistency can account for a significant proportion of feature interactions. The phase automaton is intended primarily for the purpose of detecting these phase transition errors. This means the state space in the automaton only need include that part of the feature behaviour that is significant for those conflicts. This results in a small automaton that tends to make the conflict detection problem tractable.