An efficient data dissemination scheme for nearest neighbour query processing

Location dependent information services (LDISs) produce answers to queries according to the location of the client issuing the query. In LDIS, techniques such as caching, prefetching and broadcasting are effective approaches to reducing the wireless bandwidth requirement and query response time. However, the client's mobility may lead to inconsistency problems. In this paper, we introduce the broadcast-based LDIS scheme (BBS) for the mobile computing environment. In the BBS, broadcasted data items are sorted sequentially based on their location and the server broadcasts the location dependent data (LDD) along with an index segment. Then, we present a data prefetching scheme and OBC (Object Boundary Circle), in order to reduce the query response time. The performance of the proposed scheme is investigated in relation to various environmental variables, such as the distributions of the data items, the average speed of the clients and the size of the service area.