A Fault Tolerant Distributed Location Service for Geographic Ad Hoc Routing

We introduce a new distributed location service, the hypercubic location service (HLS) for wireless mobile ad hoc networks. It provides information about geographic position of nodes, which is required by position based routing methods. Together with a position based routing, in particular with a greedy routing in appropriate spanner graphs, HLS contributes an efficient network layer of wireless ad hoc networks. Underlying HLS is an O(logn) degree graph which is based on a dynamic version of hypercubic graphs, especially of the De Bruijn graph. We introduce the notion of effective bits of node IDs and we define the hypercubic neighborhood relation accordingly. We show how dynamic operations, insertion and deletion of a node with a random ID can be performed in logarithmic time in such hypercubic graphs. A key feature of HLS is its very strong fault tolerance as well as scalability to large changes in the number of nodes, allowing very flexible control over the network size. A large network can be gradually built from a few nodes and then again it can be reduced to a very small size with fast network topology updates. In addition the architecture is extremely fault tolerant. It resists the simultaneous failure of a constant fraction of the nodes, including even a systematic destruction within certain regions. The combination of scalability and fault tolerance results in a network which survives even a fast destruction.