SelectCast: Scalable Data Aggregation Scheme in Wireless Sensor Networks

In this work, for a wireless sensor network (WSN) of n randomly placed sensors with node density lambda is an element of [1, n], we study the tradeoffs between the aggregation throughput and gathering efficiency. The gathering efficiency refers to the ratio of the number of the sensors whose data have been gathered to the total number of sensors. Specifically, we design two efficient aggregation schemes, called single-hop-length (SLH) scheme and multiple-hop-length (MLH) scheme. By novelly integrating these two schemes, we theoretically prove that our protocol achieves the optimal tradeoffs, and derive the optimal aggregation throughput depending on a given threshold value (lower bound) on gathering efficiency. Particularly, we show that under the MLH scheme, for a practically important set of symmetric functions called perfectly compressible junctions, including the mean, max, or various kinds of indicator functions, etc., the data from Theta(n) sensors can be aggregated to the sink at the throughput of a constant order Theta(1), implying that our MLH scheme is indeed scalable.