Broadcasting and caching policies for location-dependent queries in urban areas

The results of location-dependent queries (LDQ) queries generally depend on the current locations of query issuers. Many mechanisms, e.g. broadcast scheme, hoarding, or caching policy have been developed to improve system performance and provide better service, which are specialized for LDQs. It is necessary to design them considering geographical adjacency and characteristics of target area in LDQ. For this reason, this paper proposes the caching policy and broadcast scheme, which these features are reflected in. To develop the caching policy suitable for LDQ in urban area, we apply the moving distance of MH to our caching policy. Moreover, Based on the adjacency of data in LDQ, our broadcast scheme use space-filling curve to cluster data. We evaluate the performance of the caching policy measuring the workload of MHs and the correctness of LDQ results, and the performance of the broadcast scheme measuring the average setup-time of MHs in our experiments. Finally, we expect that our caching policy provides more correct answers when executing LDQ in local cache and leads significant improvement of the workload of MHs. It also seems quite probable that our broadcast scheme leads improvement of battery life of the MH.