Efficient and robust query processing for mobile wireless sensor networks

We present CNFS, an algorithm for efficient and robust query processing for mobile wireless sensor networks. CNFS is a walk-based algorithm that is biased to visit nodes close to the source first. This bias is accomplished by collecting topology information about the network as the search progresses. This information is also used to compute the shortest return path for the query result and to tolerate changes in the network topology caused by node mobility that could otherwise cause the query to fail. As a result, CNFS requires fewer messages to process a query than flooding-based algorithms, while tolerating node mobility better than random walk-based algorithms. Our experiments show that in medium-density networks (average node degree 8.3) CNFS requires about 38% fewer messages than the other algorithms studied, while experiencing significantly fewer query failures than random walk-based algorithms in both sparse and dense networks. CNFS's success rate is comparable to flooding-based algorithms in dense networks and slightly worse in sparse networks.