Question

Q.4.     A) How Data Dissemination in Vehicular Ad hoc Networks (VANETs) is achieved?

explain in detail

Answer 1

In VANETs, vehicles exchange data with each other directly or through roadside units (RSUs). DDP4V is a new data dissemination protocol for VANETs, which disseminates the emergency messages in different scenarios under varying traffic conditions. During dense traffic conditions, DDP4V employs the segmentation of transmission region of a vehicle in order to select the most appropriate next forwarding vehicle (NFV). Accordingly, it divides the transmission region of a vehicle in three distinct segments and selects vehicle(s) inside the highest priority segment to forward the message to all neighbour vehicles, whereas it also uses implicit acknowledgements for guaranteed message delivery during sparse traffic Conditions.

This protocol evenly distributes emergency messages across the network and maximizes the data dissemination inside concerned area of a network with low overhead, low collisions, and smaller delay. It operates in both highway and urban VANET scenarios under diverse traffic conditions. It mitigates the broadcast storm though controlled number of redundant transmissions. It provides the guaranteed distribution of data across network partitions and intermittently connected networks using vehicles outside the concerned area. DDP4V employs the segmentation of transmission region (termed as wagon wheel) of a vehicle to select the most appropriate NFV and enhance the coverage.

Wagon Wheel presents a circular area around a vehicle where it can directly communicate with its neighbours. This area is divided into two distinct segments, that is, behind and ahead segments. Behind segment is further divided into two subsegments: ideal and normal. The segmentation of transmission region is based on the significance of vehicles to be selected as the next forwarder. Each segment has a unique packet forwarding priority such that ideal segment comprises the highest priority followed by normal, and then ahead segment.