Correlation-aware ordered transmissions scheme for energy-efficient detection

Abstract

Ordered transmissions is an energy-efficient scheme that improves the lifetime of a wireless sensor network (WSN) and yet achieves the same performance as the conventional unordered transmissions scheme (UTS) in which all nodes transmit. We present a novel scheme for the binary hypothesis testing problem that exploits ordered transmissions to reduce the number of transmissions for the general and practically important scenario in which the measurements of the sensor nodes are correlated. It differs from the literature that assumes that, conditioned on the hypotheses, the measurements of different nodes are statistically independent or that the covariance matrix has a special structure. In our scheme, the nodes transmit their measurements in the decreasing order of the magnitudes of the measurements. We present two novel approaches to design the decision rules. These address the presence of crossterms between the measurements of different nodes that now arise in the decision statistic due to correlation and make a distributed implementation challenging. Both our approaches markedly reduce the average number of transmissions compared to UTS and ensure that the error probability remains the same.