Enhancing robustness of vehicular networks using virtual frameworks

Vehicular ad-hoc network (VANET) is one of the most transforming technologies for Intelligent Transportation Systems today. In particular, wireless mesh network is widely used for VANETs due to its scalability, flexibility, and low maintenance cost. When a mesh node in such a network fails, one can simply replace it with a new mesh node, and the network automatically reconfigures itself. However, due to the environment or limited resources, it may not be feasible to replace a failed node immediately. We have witnessed over the last few years many disasters in the globe. One thing that all of those natural disasters have in common, besides the tremendous loss of life, is that they are immediately followed by an almost total loss of the ability to communicate with outside world. In the recent event of natural disaster in Japan, the communication network was still not fully recovery after weeks of the disaster. However, communication is the key to post-disaster survival. Therefore, it is important to have an alternate communication during time of disaster. In this paper, we introduce two techniques, virtual router approach and virtual link approach, for designing failure-resilient VANET’s that can retain almost their original coverage and capacity until the failed mesh nodes can be repaired or replaced, i.e., we are able to retain 80 % of original capacity with only 50 % working mesh nodes. We give simulation results, validated by analytical analysis, to show that this desirable property can be achieved, using virtual routers and/or virtual links, with minimal overhead. These virtual frameworks also balance the workload among the mesh nodes even when the mesh clients are not uniformly distributed over the application terrain. This characteristic helps improve the overall end-to-end delay and communication throughput of the network.