Lion optimization algorithm (LOA)-based reliable emergency message broadcasting system in VANET

In vehicular ad hoc network (VANET), the standard topology changes caused by the fast mobility of nodes create many challenges to the efficient data delivery in vehicular environment. The density-, mobility- and location-based dissemination technique can fulfill the needs of emergency message broadcasting. Emergency message broadcasting in both highway and urban scenarios has so many problems such as high reliability, low latency and scalability that remains unsolved. The road structure, message redundancy, channel contention are the major issues in urban scenarios. Usually, broadcast protocols for VANET use beacon messages, which is disseminated among the vehicles, in order to get neighborhood information. When the vehicles are next to each other trying to broadcast at the same time, this may lead to frequent contention and broadcast storms. On the other hand, in sparse density scenarios, vehicles have to face with failures in the message delivery. In our research, an adaptive scheduled partitioning and broadcasting technique (ASPBT) will be introduced for a reliable and efficient emergency message broadcasting. This protocol dynamically adjusts the number of partitions and beacon periodicity to reduce the number of retransmissions. In our proposed technique, partition sizes are determined using network density, and the transmission schedule for each partition is estimated using lion optimization algorithm (LOA). It is an optimization biologically inspired by the characteristics of lions. Its corporate and solitary behaviors such as prey capturing, roaming, mating and defense are helped to identify the optimal partition to broadcast the emergency messages first. To lower emergency message transmission delay and reduce message redundancy, ASPBT includes a novel forwarding node selection scheme that utilizes optimal partition, mini-slot and black burst to quickly select remote neighboring nodes, and a single forwarding node is successfully chosen by the asynchronous contention among them. Then, bidirectional broadcast, multi-directional broadcast and directional broadcast are designed according to the positions of the emergency message senders. ASPBT will work well in different network densities and both highway and urban scenarios. Our solid analytical evaluation and simulation results indicate that our proposed technique outperforms the existing broadcasting schemes in VANET in terms of efficiency, delay and reliability.