Link Stability and Node Energy Conscious Local Route-Repair Scheme for Mobile Ad Hoc Networks

Abstract

Problem statement: A mobile ad hoc network is a self-configuring network of mobile nodes connected by wireless links. As the nodes are free to move randomly, topology of the network may change rapidly and unpredictably. As a result, intermediate nodes in the communication routes tend to lose connection with each other during the communication process. In order to repair a broken link, an end-to-end (from source to destination) route discovery is typically performed to establish a new route for communication. The mechanism results in huge communication overhead and long delay in completion of the communication. So, it is rational to locally repair a link, as much as possible, than to discover a whole new route. Approach: In the present article, we proposed a Link Stability and Node Energy Conscious (LSNEC) local route repair scheme for mobile ad hoc networks. In case of breakage of a link from node n_a to another node n_b in between a communication session, LSNEC instructs n_a to broadcast a ROUTE-REPAIR message within its radio-range specifying n_b or any successor of n_b in the broken route, as a desirable destination. If any node residing within the radio-range of n_a has an already established single/multi-hop path to any one of those destinations mentioned in the ROUTE-REPAIR message, it sends a REPAIR-ACK message back to n_a. Attributes of REPAIR-ACK include the identification number (s) of the destination (s) as well as identification numbers, geographical positions (in terms of latitude and longitude), radio-ranges and residual energies of nodes present in the associated path to that destination along with the intuitively computed stability of links between the consecutive nodes. The stability is computed depending upon relative velocities of the involved nodes, distance between them and the history of survival of the link. The optimal path is chosen depending upon the residual energy of nodes, stability of links and number of hops in that path. Results: In simulations we compared the LSNEC embedded versions of the protocols Ad hoc On-demand Distance Vector routing (AODV) and Associatively Based Routing (ABR) with their ordinary versions as well as PATCH and "Quick Local Repair" scheme (to be referred to as QLR subsequently in this study) embedded versions. Both PATCH and QLR are well-known local repairing schemes for ad hoc networks. It is found that, LSNEC-AODV dramatically saves 57% control overhead compared to ordinary AODV, 32.7% compared to PATCH-AODV and 36.3% compared to QLR-AODV. Similarly, LSNEC-ABR saves 29.3% control overhead than ordinary ABR, 10.7% than PATCH-ABR and 12.8% than QLR-ABR. Accordingly decrease the power consumption of network nodes and delay in recovery. Conclusion: The simulation results emphatically illustrated the performance benefit of our proposed scheme LSNEC compared to the other state-of-the-art local route-repair schemes, in respect of control overhead, overall energy consumption of the network, data packet delivery ratio and route recovery delay. LSNEC has its application wherever an ad hoc network is used. Please note that ad hoc networks are extremely useful in military and other tactical applications such as emergency rescue, exploration missions and other scenarios w here cellular infrastructure is unavailable.