C2-CODER: Coverage-controlled network CODEd repetition for vehicular ad-hoc networks

In vehicular ad-hoc networks (VANETs), vehicles are aware of the state of the vehicles in their proximity by periodically broadcasting a safety message called beacon. Based on such state information, safety applications allow people to avoid hazardous situations. Recently, network coding (NC)-based repetition schemes have been proposed for the reliable transmission of life-critical beacons, where a sender combines (XORs) beacons from neighbors and repeats the XORed packets instead of its original beacon. Repeating the XORed packets improves the beacon delivery ratio. Although it could extend the coverage of beacon transmission, vehicles are more interested in the state of vehicles nearer to them since they are more likely to be exposed to dangerous situations with closer neighbors. In this paper, we therefore propose a Coverage-Controlled network CODEd Repetition (C2-CODER) scheme in order to allow scarce channel resources not to be wasted for extending the coverage unnecessarily. C2-CODER avoids coverage extension by restricting the maximum distance between the sender and the sources of beacons being combined into a XORed packet. Through our simulation study, it is verified that C2-CODER outperforms existing schemes in terms of higher beacon delivery rate.