Group-based data and location management in mobile environments

vii, 113 leaves : ill. ; 30 cm.PolyU Library Call No.: [THS] LG51 .H577M COMP 2005 LamHPervasive and ubiquitous mobile applications have sprung following the proliferation of wireless communication devices. With the ability to detect the positions of mobile devices, value-added location-dependent services can be offered to mobile users by taking advantage of a user's location information. Location management is crucial in supporting location-dependent applications. While location management is relatively straightforward in infrastructures that allow the physical tracking of mobile client location at the server, there are challenges for systems in which mobile hosts have to keep track of their own locations, reporting to the location server themselves. Location-dependent queries are then issued from location-dependent applications to the location server, resolving the geo-referencing matters for result generation and filtering. We focus in this research on systems in which mobile clients detect and report their own location with devices like GPS. Noticing that the majority of computation and data storage tasks are assigned to servers due to the resource limitation in mobile devices, we need to address the complementary data accessing need from servers residing over the fixed network, in enabling mobile application development. We identify data accessing and location management to be complementary and yet competing for the expensive uplink channel for sending in data requests and location information to servers. It is crucial to reduce the aggregate communication overhead, owing to the high cost of uplink bandwidth for data accessing and location reporting. Traditional research efforts are dedicated to reducing the communication overhead while preserving the system performance. However, most research works are based on the client/server model. In this thesis, a group-based model is defined by taking advantage of integrating mobile ad hoc network with the client/server model. A group-based framework that provides supports for data and location management is proposed. To realize the framework, a dynamic group formation algorithm is developed for clustering together mobile hosts with similar mobility into groups. Additional group management mechanisms are designed to cater for mobile hosts joining, departing and changing groups. The group functionalities are basically supported by the group leader, for which appropriate leadership maintenance schemes are proposed. Two applications of the group-based framework were explored, namely, group-based location management and group-based data management schemes. Performance study is conducted for evaluating the effectiveness of several variants of group-based location and data management schemes. The results demonstrate the advantages brought about by the group-based paradigm, in reducing the communication cost.Department of ComputingM.Phil., Dept. of Computing, The Hong Kong Polytechnic University, 200