Formal Modeling and Verification of Time-Constrained ARQ Protocols with Event-B

Automatic Repeat Request (ARQ) is a control error mechanism based on the retransmissions of lost packet. This mechanism is adequate for an important number of communication protocols where reliability is of prime importance. Formal methods are indispensable for the development of these protocols in order to ensure their correctness. In this paper, we study the practical aspects of applying Event-B and UPPAAL for modeling and verification of time-constrained ARQ protocols. We start by introducing a pattern for the retransmission time-out within Event-B and transform this pattern to pattern in UPPAAL. We have used UPPAAL to augmenting Event-B modeling with real-time verification, since the modeling of timing properties is not directly supported in Event-B. At last, we illustrate our approach with a case study based on the stop-and-wait protocol.