A Survey on an Effective Defense Mechanism against Reactive Jamming   Attacks in WSN
  A Wireless Sensor Network (WSN) is a self-configure network of sensor nodes communicate among themselves using radio signals and deployed in quantity to sense, monitor and to understand the physical world. A jammer is an entity which interferes with the physical transmission and reception of wireless communications. Reactive jamming attack is a major security problem in the wireless sensor network. The reactive jammer stays quiet when the channel is idle. The jammer starts transmitting a radio signal as soon as it senses activity on the channel. The reactive jammer nodes will be deactivated by identifying all the trigger nodes, at the same time a jammer node is localized by exploiting the changes in the neighbor nodes. The affected node can be identified, by analyzing the changes in its communication range, compared to its neighbors. The paper proposes a survey on trigger node identification and a detailed survey on techniques to identify trigger nodes and highly concentrated on the reactive jammer. 
Manojkumar.M.K, Sathya.D
cs.NI