The scalability problem of vehicular ad hoc networks and how to solve it

Intervehicle communication (IVC) and its diverse application possibilities are experiencing growing interest both in research and industry. The dissemination of active safety messages generated by context-sensitive applications in Vehicular Ad Hoc Networks (VANETs) promises to improve passenger safety and comfort. One of the main challenges inherent to the deployment of VANETs is operability, both in very sparse and in highly overloaded networks. This scalability problem is not comprehensively addressed by existing approaches, as they only focus on parts of the problem. This article shows how a relevance-based, altruistic communication scheme helps realize scalability by optimizing the application benefit and the bandwidth usage. In-vehicle and intervehicle message selection are based on a relevance function that makes use of the current context and the content of the messages., A novel, proprietary cross-layer architecture and an IEEE 802.11e-based architecture can be used to implement the scheme.