Fault-Tolerant k-Fold Pivot Routing in Wireless Sensor Networks

Selecting a small set of nodes called pivots, from all the nodes in a network and maintaining the routing infrastructure to and among each other can reduce routing overhead and excessive broadcast redundancy. In this paper a new problem, called "k-fold cover t- set" (for short, k-fold cover), is proposed: we select a smaller set of nodes than the k-fold dominating set, to act as alternative routers for messages in the network. An advantage of the k-fold cover is that it can be defined for graphs where the k-fold dominating set cannot be defined. Computing the minimum size k-fold cover for any k ges 1 is NP-complete. Two approximation algorithms for the k-fold cover problem are proposed: one uses a greedy approach to compute the cover and the other uses randomization.