A near-optimal broadcast technique for vehicular networks

A vehicular network is a promising application of mobile ad hoc networks. In this paper, we introduce a near-optimal broadcast technique, called CB-S (Cell Broadcast for Streets), for vehicular networks. In this environment, the road network is fragmented into cells such that nodes in a cell can communicate with any node within a two cell distance. Each mobile node is equipped with a GPS (Global Positioning System) unit and a map of the cells. The cell map has information about the cells including their identifier and the coordinates of the upper-right and lower-left corner of each cell. CB-S has the following desirable property. Broadcast of a message is performed by rebroadcasting the message from every other cell in the terrain. This characteristic allows CB-S to achieve near optimal performance. Our simulation results indicate that data can always reach all nodes in the wireless network. This perfect coverage is achieved with minimal overhead. That is, CB-S uses a near optimal (minimum) number of nodes to disseminate the data packets. This optimality gives it the advantage of minimum delay. To show these benefits, we give simulations results to compare CB-S with four other broadcast techniques. In practice, CB-S can be used for information dissemination, or to reduce the high cost of destination discovery in routing protocols. We also present in this paper a CB-SD (Cell Broadcast for Street Dissemination) variant that has all the advantages of CB-S, with the additional benefit of supporting partial broadcast. This scheme is more efficient when broadcast to a subset of the nodes is desirable.