Mobility Protocols and Handover Optimization: Design, Evaluation and Application

Chapter 4Modeling Mobility

In this chapter, we develop a system model for the mobility event by incorporating the state transitions associated with the basic operations that take place during handoff. This system model decomposes the mobility event into various tasks and subtasks and analyzes the primitive operations.

4.1 Summary of Key Contributions and Indicative Results

In the absence of any formal mechanism to analyze the dynamics of handoff systems, it is difficult to predict or verify the systems performance of unoptimized handover or any specific handoff optimization technique. Without a model for a mobility system, it is difficult to design new mobility protocols or new optimization techniques for existing mobility protocols in a systematic way.

We have modeled the handoff-related processes as a discrete-event dynamic system (Cao and Ho, 1990) and used deterministic timed-transition Petri nets to build various unoptimized mobility models and devise associated optimization techniques. We have performed data dependency analysis and resource analysis of handoff-related operations to determine the possible sequences of operations and investigated behavioral properties such as deadlocks and liveness associated with handoff operations using Petri nets.

The proposed framework for the mobility model has the following key features:

• It allows us to analyze the data dependency among the handover components and illustrates how the handoff operations are distributed over the network ...