Accessing remote data over networks is an important application. However, accessing data is much more complicated over MANET, because mobile users need to learn about the data availability information without the aid of a certral server, and to access desired data in case of potential network partitioning. This means that the creator of data is often unreachable when the data is needed. Moreover, the mobile nodes are heterogeneous in nature. Some nodes may have less resources than others. Therefore, our goal is to improve data accessibility for all nodes in the network. We consider data accessibility as the ability to obtain data information from other nodes, and to access those data when needed.
Our data accessibility scheme consists of two services: 1) a fully distributed data advertising and lookup service that advertises data information to other nodes in the group, and maintains a local data availability table for data location lookup; 2) a predictive data replication service that predicts any future partitioning of the data access group, and replicates data to other portions of the group before the partitioning occurs. The prediction is based on the current location, movement direction, velocity,and transmission range information of each node.
Our data accessibility service adopts the cross-layer design principle. It shares information with an underlying location-based QoS routing protocol. The information sharing is via system profiles. The shared information includes the nodes’ location and movement pattern, as well as the data transmission requirements. The system framework is shown in Figure 6.
- Kai Chen, Samarth H. Shah, Klara Nahrstedt, Cross-Layer Design for Data Accessibility in Mobile Ad hoc Networks, Journal of Wireless Personal Communications, Special Issue on Multimedia Network Protocols and Enabling Radio Technologies, Kluwer Academic Publishers, Vol. 21, pp. 49-75, 2002.
- Kai Chen, Klara Nahrstedt, An Integrated Data Lookup and Replication Scheme in Mobile Ad Hoc Networks, in Proc. of SPIE International Symposium on the Convergence of Information Technologies and Communications (ITCom 2001), Denver, Colorado, August, 2001.
- Samarth H. Shah, Kai Chen, Klara Nahrstedt, Cross Layer Design for Data Accessibility in Mobile Ad Hoc Networks, in Proc. of 5th World Multiconference on Systemics, Cybernetics and Informatics (SCI 2001), Orlando, Florida, July, 2001.