Abstract: Data transmission among wireless sensor network relies on cooperation between nodes, but nodes are easily captured by malicious intruder and then captured nodes launch gray-hole attacks, which thereby significantly reduce network performance. Existing detection algorithms mainly rely on statistical receiving and forwarding behavior to detect gray holes. But these algorithms can’t effectively distinguish natural loss due to unstable link quality of sensor network and the gray hole. To solve this problem, a watchdog algorithm based on link quality is proposed. To improve performance, this algorithm uses link quality to revise statistical observation and adjust the threshold according to the network environment. Simulation results show that the proposed algorithm can effectively reduce the false positive and false negative rate.

Key words: gray hole detection, link quality, watchdog algorithm