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In multi-hop dissemination, timer-based and probabilistic methods are high performing methods in Vehicular Ad-hoc Networks (VANETs), owing to their simplicity, low overhead and high efficiency. However, such approaches neglect the fact that vehicle transmission ranges are typically heterogeneous, which could be due to dynamic adjustment of the transmission power value. In our previous work, we introduced a new timer-based method that considers heterogeneous transmission power: area defer transmission (ADT). ADT proves its efficiency over distance-based versions by its high delivery ratio, high propagation speed and reachability. We have extended this work to introduce a probabilistic approach to reduce unnecessary redundancy in heterogeneous environments. We have also examined the integration of the timer area-based and probabilistic area-based methods. Moreover, we have thoroughly investigated the influence of the parameter Tmax in the defer time formula on both approaches. We evaluated the performance of the proposed methods using an actual road map with complex road scenarios and real movement traces. The simulation results show that the probabilistic area-based approach is very fast at disseminating data. It also achieves a reduction in redundancy, but at the expense of reaching more vehicles and long distances. Redundancy and retransmission are reduced more with controlling defer time parameters in timer area-based approaches, without compromising reachability in the network and the same delivery ratio. |
