Validating mobility management solutions for interworking UMTS and IEEE 802.11 networks

An important step towards seamless heterogeneous systems is the integration between WLAN and 3G cellular systems. Their interoperability has been frequently discussed in literature, however, there is still room for research in this issue. Since IEEE 802.11 networks reach relatively high data transmission rates when compared to other wireless networks, it has gained the attention of the cellular networks operators, such as UMTS operators, which have been considering IEEE 802.11 networks as a complement to their access networks. Notwithstanding, specification and development of real-time systems with mobility support are still a challenge due to their characteristic of criticality and safety. In this context, formal methods have shown effectiveness in real-time system development. The main advantage of formal methods is allowing a rigorous and nonambiguous system description. Thus, this work presents the specification and validation of two mobility management approaches to integrate UMTS and IEEE 802.11 networks: the first one is based on SIP, and the other one is based on MIP version 6. These specifications extend the Loose Interworking architecture and reach the fourth integration level of the 3GPP specification. These approaches are modeled using SDL and MSC formal description techniques, which are largely used to specify telecommunications systems. SDL also provides simulation and validation results that are analyzed to evaluate the proposed approaches with the goal of proving that formal methods can lead to a more precise and correct final system.