A vehicular ad hoc network (VANET) could deliver safety-related messages reliably within a short time to increase road safety.\nSince safety-related messages should be sent to a set of unspecified receivers, they are delivered by broadcast method. However, the\nbroadcast method specified in the IEEE 802.11p does not have a collision avoidance procedure and receivers do not acknowledge\nwhen they receive a broadcast frame. In addition, frames could be lost and corrupted. Therefore, as the portion of nodes that do not\nreceive a broadcast frame increases, the effectiveness of a safety application decreases. To tackle the problem, we propose a reliable\nand swift message broadcast method (RSMB). In RSMB, to expedite message dissemination process, a relay node is selected in a\ndistributed manner considering the progress made to a frame and the delay requirements of an application. In addition, a relay\nnode broadcasts a message multiple times to assure that the probability that the other nodes successfully receive the message at\nleast once is larger than a given threshold value. Since the number of rebroadcasts is regulated based on the successful message\nreception probability, the additional bandwidth needed to increase the reliability of broadcast is reasonably small.
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