This thesis considers the problem of distributed sequential detection in wireless sensor networks (WSNs), where the number of operating sensors is unknown to the fusion center. Since the energy and bandwidth of communication channel are limited in WSNs, we employ the censoring scheme in the sequential detection to achieve energy-efficiency and low communication rate. Specifically, we show by simulations that employing censoring scheme can reduce the number of local decisions that required for the fusion center to make a final decision. The results implies that the energy conservation does not necessary degrade the performance of sequential detection in terms of the expected local decisions required for making a final decisions.

The energy efficiency issue, which is subjected to an energy constraint, is important for the applications in wireless sensor network. For the distributed detection problem considered in this thesis, the sensor makes a local decision based on its observation and transmits a one-bit message to the fusion center. We consider the local sensors employing a censoring scheme, where the sensors are silent and transmit nothing to fusion center if their observations are not very informative. The goal of this thesis is to achieve an energy efficiency design when the distributed detection employs the censoring scheme. Simulation results show that we can have the same error probabilities of decision fusion while conserving more energy simultaneously as compared with the detection without using censoring schemes. In this thesis, we also demonstrate that the error probability of decision fusion is a convex function of the censoring probability.