Using Mobile Host Cooperative Cache Sharing Approach to Improve the Query Efficiency

Abstract

In a conventional mobile environment, queries issued by Mobile Hosts (MHs) are directly sent to base stations for retrieving results. As the demand increases, the quality of query services inevitably degrades. With the rapid evolution of storage, networking, and power management on mobile devices, nowadays most of MHs are capable of caching a reasonable amount of previous query results in their local buffers and are connected through peer channels on MANET-like networks. Such a technology can be utilized to distributively cache popular query results on mobile hosts. Therefore, MHs can communicate among themselves to share query results rather than having to rely on the communication link to a base station. As a result, the server workload can be alleviated, and thus the query delay and link congestion can be also improved. In this paper, we reform the query process and propose Mobile-host Cooperative Caching (MCC) to improve the quality of providing range query services. MHs can avoid issuing new queries or narrow the query range by utilizing the results cached by nearby MHs. We also discuss five approaches to select Candidate MHs (CMHs) to download their cached similar results, which are First Come First Download (FCFD), Largest Range First Download (LRFD), Smallest Range First Download (SRFD), Largest Non-Overlap Download (LNOD), and the hybrid method of SRFD and LNOD, namely SRFD & LNOD Hybrid Download (SLHD). The experiment results show that the proposed MCC scheme achieves better performance with regard to answering range queries. In particular, the SLHD-1 provides acceptable performance in all aspects on average as expected.