Probabilistic trust aware data replica placement strategy for online video streaming applications in vehicular delay tolerant networks

Vehicular Delay Tolerant Networks (VDTNs) are a new class of emerging technology used in wide variety of applications. These networks use the store and forward strategy for transferring the data to other nodes. But due to frequent movement of nodes, connection with the servers does not last for a longer duration in VDTNs. To address this issue, we propose a Probabilistic Trust aware Data Replication strategy for online video streaming applications in VDTNs. A Data Replication Tree (DRT) is constructed showing all the nodes and their interconnection starting from source to destination which increases or decreases in size as the nodes leave or join the network. Also a Replica Cost Function (RCF) has been defined for managing the data replica. It is a combination of three factors, namely Data Communication Cost (DCC)(DCC), Data Storage Cost (DSC)(DSC) and Data Update Cost (DUC)(DUC). A Trust Calculation Metric (TCM) is also introduced by considering the above factors between the nodes for the placement of a data replica. Algorithms for replica location and data replication with read and update operation are proposed using the established trust between the nodes. The proposed strategy is evaluated using metrics such as replication cost by varying the link stability values (LSVs) with respect to mobility, read/write operations and trust. Moreover, the impact of increasing the cache storage space on upload/download data is also investigated. The results obtained show that with higher LSVs and low mobility, the replica cost decreases. Moreover, by increasing the cache storage space and LSV the data transfer rate also increases.