Fault Tolerance Through Redundancy For Wireless Distributed Ad-Hoc Sensor Networks

Fault recovery techniques enable Wireless Distributed Ad-hoc Sensor Networks (WDASNs) to continue operation according to their intentions even if faults of a certain type are presenting in the system. There are many potential sources of faults in WDASNs. Fault tolerance techniques have been investigating in various contexts that increase the reliability of the functionality of sensor nodes in their specific domain. The most pecu-liarly used type of these techniques is the replication of nodes. Although, redundancy has several advantages in terms of high reliability and availability, it also increases the costs of deployment. Therefore, in this thesis we develop a fault tolerance through redundancy us-ing clustering scheme that assigns one redundant backup node in each cluster and there-fore, enhance speed of backup file delivery with allowable time span for partially failed nodes in a cluster. We design a protocol, which relies on the ability of beamforming an-tenna that can detect the position of partially failed nodes by minimizing the maximum transmit power and enhance the speed of backup file delivering in allowable time span.To reach on the goal, we first design a protocol that forms dynamic clustering mecha-nism which assign only one backup node in each cluster and then, designing a Media Ac-cess Control (MAC) Protocol based on adaptive beamforming . It is needed to deliver a backup files for two or more partially failed nodes in each cluster at the same time for WDASNs. We also compare transmission power and delivering speed of four Digital sig-nal-processing algorithms named: Matched Filter (MF), Minimum Variance Distor-tionless Response (MVDR), Minimum power distortionless response (MPDR), and Minimum Mean Square Error (MMSE) beamformers, which are available to track and de-liver backup files for partially failed nodes in a cluster. We observe that MVDR has a fast convergence with less transmit power with wide beam coverage than others and adversely these lead to have less spatial reuse of bandwidth than others do. Besides, of the perform-ance of these protocols, we observe that Beamformer antenna has a total gain of 2x– 4x higher than Omni-directional Antenna's. We utilize graphical user interface of MATLAB to show convergence of transmitted beam towards nodes, to show how Direction of arrival (DOA) protocols are needed for communication among backup servers with partially failed nodes and even master to agent backup servers. Finally, we design a channel model for the system and study its performance using MATLAB for different scenarios.