Mobility Information and Mobile Transaction Processing

In a mobile environment. system and application performance is impacted by mobili ty factors such as varying bandwidt h. frequent disconnect ion, and changing locations. These factors make rnobility information more important in the design of distributed algorit hms. However, at present , no general mode1 exists for exploit ing the availability of mobility information. Focusing on this issue. this thesis investigates mobility environment modelling: especially the classification, representat ion. and utilisation of mobility factors. Based on the concepts and met hods of modelling mobility factors proposed in this research, an adaptive transaction scheduling (ATS) approach for mobile transaction processing. chosen as a particular application domain. is developed to demonstrate the feasibility of designing better distributed applications by making use of mobility information. The ATS approach is designed to support autonomous operations during network disconnect ion and dynamicallÿ select the si t e of transaction execir tion based on mobiIi ty information such as bandwidt h and disconnection ratio. The performance of the ATS approach is evaluated against fixed transaction processing policies by the means of simulation experiments. A queue simulation mode1 is designed and implernented in discrete-event simulation language. The results of the simulation experiments show that adaptive transaction processing produces better performance and confirms that the design of applications in mobile environments can benefit from available mobili ty in format ion.