| Wireless Sensor Networks (WSNs) consist of many spatially deployed sensor devices to cooperatively monitor selected target locations and communicate with base stations. WSNs have potential applications in various complex environments such as military surveillance, health-care systems, disaster area monitoring and etc. Due to the requirement of large-scale and real-time data processing in WSNs, security is critical in many sensor network applications.;The wireless communication of sensor devices in resource-constrained WSNs leads to many challenging and intriguing security-sensitive problems that cannot be handled using conventional security solutions. Especially, since jammers attack the broadcast nature of the transmission medium by injecting interference signals, they are considered the most critical and fatally adversarial threats to subvert or disrupt the networks. Jamming attacks do not have to modify communication packets or compromise any sensors in order to launch, which makes them difficult to detect and defend against.;Existing countermeasures against such attacks either consider sensor nodes equipped with sophisticated hardware, which is infeasible for low cost resource constraint WSNs, or have high overhead in term of time and message complexity and energy consumption. However, to overcome the problems in existing methods against reactive jamming attack, this dissertation introduces a novel approach by identifying the trigger nodes, whose transmissions activate any jammers and then constructing routing path based on the identification of sensor nodes.;This dissertation includes two main parts, identification of trigger nodes and construction of virtual backbone based on the detection. First of all, the identification of trigger nodes can help us (i) to design a better routing protocol by switching these nodes into only receivers to avoid activating jammers and (ii) to locate the jammers based on the trigger nodes, thus providing an alternative mechanism against reactive jamming attacks. Secondly, an effective construction of virtual backbone provides not only the jamming avoidance protocol but also efficient broadcast routing. For the adaptive building of virtual backbone, this dissertation investigates dominating tree and multi-factor model studying a joint optimization problem on Connected Dominating Set (CDS) in wireless ad-hoc networks.;Theoretical analysis and experimental results endorse the suitability of these identification algorithms in terms of time and message complexity. This work is the first one to design novel countermeasures against reactive jamming attack. |
