This paper presents a fault-tolerant event detection scheme for wireless sensor networks. Unlike others using a single threshold, the proposed scheme employs two thresholds to cope with the trade-off between event detection accuracy and false alarm rate. An extremely low false alarm rate can be achieved by using a high threshold, while high detection accuracy is obtained by using a low threshold. A sensor node is determined to be in an event region if it passes the high threshold. It can also be determined to be in the region, as long as it passes the low threshold and has a neighbor that passes the high threshold. The dissemination of a local decision to neighboring nodes is made only once to minimize the communication overhead. A moving average filter with a threshold is employed to reduce the impact of transient faults in sensor readings. Computer simulation shows that the proposed scheme also achieves acceptable performance in detecting event regions without computational overhead.
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