Cross-layer multi-hop wireless routing for inter-vehicle communication

Ad-hoc networking provides a cost-effective support structure for inter-vehicle communication. A decentralized peer-to-peer information dissemination architecture is well suited for automotive applications that need to exchange data having local relevance. Routing, however, is challenge in a vehicular scenario because of the associated dynamism in network topology and variations in driving conditions. In this work we present a cross-layer ad-hoc routing approach based on link connectivity assessment in the network topology. We suggest a framework for proactive enhancements to the Optimized Link State Routing (OLSR) [1] protocol and implement the proposed measures within the protocol format. We further deploy an IEEE 802.11b based vehicular network and demonstrate the effectiveness of link-quality assessment based enhancements in improving the performance of inter-vehicle ad-hoc routing. Through actual test-runs, we show that the enhanced protocol is more responsive to variations in network connectivity and can take preemptive actions in choosing stable and durable routes. The routing methodology suggested in this work leverages cross-layer interactions among the networking, data-link, and physical layers, for enhanced adaptability to varying network topology and link states. The main contributions of this work are as follows: introduction of link-quality assessment methodology for enhanced adaptability of ad-hoc routing in a dynamically changing topology, delineation of the framework of a proactive topology-adaptive ad-hoc routing protocol in a vehicular scenario, and demonstration of effectiveness of the proposed routing enhancements in an IEEE 802.11b based vehicular test-bed.