Replica Allocation Methods in Ad Hoc Networks with Data Update

In ad hoc networks, since mobile hosts move freely, network division occurs frequently, and thus data accessibility is lower than that in conventional fixed networks. In this paper, assuming an environment where each data item is periodically updated, we propose three replica allocation methods to improve data accessibility by replicating data items on mobile hosts. In these three methods, we take into account the access frequency from mobile hosts to each data item, the status of the network connection, and the time remaining until each item is updated next. We also show the results of simulation experiments regarding the performance evaluation of our proposed methods. We further extend the proposed methods to adapt to an environment where aperiodic data updates occur.