Fast and Reliable Dissemination of Road and Traffic Information by Combining Cellular V2X and DSRC

Dedicated short range communication (DSRC) in the 5.9 GHz band has been considered as the main inter-vehicle communication (IVC) method in the past. Recently, IVC by cellular V2X (LTE support for V2X services) has attracted much attention, which includes two schemes: sidelink by which vehicles communicate directly with each other and broadcast via eNodeB for dissemination to farther vehicles. In this paper, we will show that none of these methods alone can fulfill the reliable and low delay communication, and investigate a basic method that combines DSRC for fast dissemination in a short distance and cellular V2X (broadcast via eNodeB) for reliable dissemination in a wide range. We notice that vehicles near the same event (e.g., falling object) may repeatedly disseminate the same message and some messages may be disseminated beyond their required range, which degrade network performance. Therefore, we further improve the efficiency of the basic method from two aspects: (i) dissemination range control that constrains the dissemination of each message within its required range, and (ii) duplicate dissemination control that avoids disseminating the message containing the same information in the network. Simulations on network simulator with LTE release-14 confirm that the method combining DSRC and cellular V2X reduces the delay by up to 66% compared to the method using only cellular V2X, and the extended method further improves the reachability by up to 15%.