Two-phase cardinality estimation protocols for sensor networks with provable precision

Efficient cardinality estimation is a common requirement for many wireless sensor network (WSN) applications. The task must be accomplished at extremely low overhead due to severe sensor resource limitation. This poses an interesting challenge for large-scale WSNs. In this paper we present a two-phase probabilistic algorithm based on order statistics and Bernoulli scheme, which effectively estimates the cardinality of WSNs. We thoroughly examine properties of estimators used in each phase as well as the precision of the whole procedure. The algorithm discussed in this paper is a modification of a recently published idea - the modification enables us to obtain a provable precision.