document: Semantic data broadcast for a mobile environment based on dynamic and adaptive chunking Database broadcast is an effective and scalable approach to disseminate information of high affinity to a large collection of mobile clients . A common problem of existing broadcast approaches is the lack of knowledge for a client to determine if all data items satisfying its query could be obtained from the broadcast . We therefore propose a semantic-based broadcast approach . A semantic descriptor is attached to each broadcast unit , called a data chunk . This semantic descriptor allows a client to determine if a query can be answered entirely based on broadcast items and , if needed , identify the precise definition of the remaining items in the form of a `` supplementary '' query . Data chunks can be of static or dynamic sizes and organized hierarchically . Their boundary can be determined on-the-fly , adaptive to the nature of client queries . We investigate different ways of organizing the data chunks over a broadcast channel to improve access performance . We introduce the data affinity index metric , which more accurately reflects client-perceived performance . A simulation model is built to evaluate our semantic-based broadcast schemes
doc_bio_tags: B I I O O O O O O O O B I O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O
extractive_keyphrases: semantic data broadcast mobile clients semantic descriptor data affinity index adaptive chunking
abstractive_keyphrases: mobile databases mobile computing data chunking query processing answerability