Data Delivery Delay Reduction for VANETs on Bi-Directional Roadway

In this paper, we investigate the data delivery delay from source to destination for VANETs on bi-directional roadways. The topology includes bi-directional roadways, left-turn lane, straight through lane, right-turn lane with traffic lights deployed at the intersections. Due to the multi-hop feature of data delivery and the limited range of radio transmission, the roadways' topology and the switch operations of traffic lights will jointly affect the data delivery delay. By employing the queuing theory and analyzing the traffic lights operations, we propose the formulae of data delivery delay for different scenarios and extend the analysis to a more general scenario. We find that in the scenario of single intersection, the data delivery delay can be reduced by appropriately selecting the relay nodes. Specifically, in the case of green traffic light at the intersection, opposite lane vehicles can be used to reduce the delay, while for red traffic light, left-turn lane vehicles are used to reduce the delay in a similar approach, i.e., by using multi-hop transmission. The proposed algorithm is verified on single lane roadway, opposite-only, and left-turn-only lane for different simulation time slots, the number of mobile nodes and the value of R/W (R is the wireless communication range and W is the length of the road intersection) through VanetMobiSim and NS-2. Numerical results show that for single intersection, the data delivery delay can be reduced by choosing appropriate relay nodes. Besides, the successful packet delivery rate of bi-directional roadway is better than that of single line roadway scenario.