A broadcast-based notification scheme of updated digital road map data for car navigation systems

A car navigation system requires the latest reliable digital road map database for correctly performing responsible tasks, such as map display, positioning, route planning, and route guidance. In fact, however, the pre-installed road map database is used without any updates, although the actual roads were added and/or removed, since there is no easy way to update the database. This would cause misleading behaviors of these tasks. In this paper, we propose a broadcast-based notification protocol to inform car navigation systems about the existence of the updates in the road map database, in order to reduce the misleading influence of updated roads. The results of evaluations conducted on the efficacy of our proposed protocol indicate that it achieves all notifications for updated roads by broadcasting invalidation reports of 478KB, while the total size of the road map database is 132MB.