Managing continuous k-nearest neighbor queries in mobile peer-to-peer networks

A continuous k nearest neighbor (CKNN) query retrieves the set of k mobile nodes that are nearest to a query point, and provides real-time updates whenever this set of nodes changes. A CKNN query can be either stationary or mobile, depending on the mobility of its query point. Efficient processing of CKNN queries is essential to many applications, yet most existing techniques assume a centralized system, where one or more central servers are used for query management. In this thesis, we assume a fully distributed mobile peer-to-peer system, where mobile nodes are the only computing devices, and present a unified platform for efficient processing of both stationary and mobile CKNN queries. For each query, our technique computes a set of safe boundaries and lets mobile nodes monitor their movement with respect to these boundaries. We show that the result of a query does not change unless a node crosses over a safe boundary. As such, our technique requires a query to be re-evaluated only when there is a crossing event, thus minimizing the cost of query evaluation. For performance study, we model the communication cost incurred in query processing with a detailed mathematical analysis and verify its accuracy using simulation. Our extensive study shows that the proposed technique is able to provide real-time and accurate query results with a reasonable cost

Managing motion triggered executables in distributed mobile databases

Mobile devices have brought new applications into our daily life. However, ecient man- agement of these objects to support new applications is challenging due to the distributed nature and mobility of mobile objects. This dissertation describes a new type of mobile peer- to-peer (M-P2P) computing, namely geotasking, and presents ecient management of mobile objects to support geotasking. Geotasking mimics human interaction with the physical world. Humans generate information using sensing ability and store information to geographical lo- cations. Humans also retrieve this information from the physical locations. For instance, an installation of a new stop sign at some intersection in town is analogous to an insertion of a new data item into the database. Instead of processing regular data as in traditional data management systems, geotasking manages a collection of geotasks, each dened as a computer program bound to a geographical region. The hardware platform for geotasking consists of popular networked position-aware mobile devices such as cell phones, personal digital assis- tants, and laptops. We design and implement novel system software to facilitate programming and ecient management of geotasks. Such management includes inserts, deletes, updates, retrieval and execution of a geotask triggered by mobile object correlations, geotask mobil- ity, and geotask dependency. Geotasking enables useful applications ranging from warning of dangerous areas for military and search-and-rescue missions to monitoring the population in a certain area for trac management to informing tourists of exciting events in an area and other such applications. Geotasking provides a distributed and unied solution for supporting various types of applications