Dynamic Fault Diagnosis in Mobile Ad Hoc Networks

Fault diagnosis in Mobile Ad-hoc Networks (MANETs) is very challenging task. Diagnosis algorithm should be efficient enough to find the status (either faulty or fault free) of each mobile in the network. The models in the literature are either for static fault or dynamic fault. Dynamic fault identification is more complex and difficult than static fault. In this thesis, we proposed Dynamic Distributed Diagnosis Model to identify dynamic faults arising during the testing phase of the diagnosis session. The model assumes that each node has fixed and same set of neighbours i.e. the MANET topology is static throughout the diagnosis session. Our model works on a network with $n$ number of nodes, which is $\sigma$-diagnosable. Where $\sigma$ is one less than the minimum degree of a node in the network. It has two variation based on dissemination method, first is simple flooding approach and second is based on spanning tree. The flooding based model consists of two phases; a testing phase and a dissemination phase. The spanning tree based model has three phase; a testing phase, a building phase and a dissemination phase. In testing phase, we have used the concept of heartbeat, where every mobile broadcasts a response message at fixed interval, so that a node can correctly be diagnosed by at least one fault free neighbour. Building phase constructs a spanning tree with fault-free mobiles. Dissemination phase, with the help of spanning tree, disseminates the local diagnostic views through the fault-free mobiles. After aggregating the entire views, initiator node disseminates the global diagnostic view to the fault free mobiles down the spanning tree. In this way, all fault free units reach to an agreement about the status of other nodes in the network. Further, we have given the proof of correctness and completeness of our model and found the time complexity, and compared the simulation results with the existing fault diagnosis protocols