RHBS: Roteamento Hierárquico Baseado em Setores para Redes Veiculares

Abstract

In vehicular networks ad hoc, one of the biggest difficulties encountered is maintaining stable communication between vehicles. The high mobility and dynamic topology of the vehicles interrupt routes established between two communicating vehicles. To try to minimize this problem, a large number of routing protocols have been developed and classified according to their properties. Among them, cluster-based protocols and geographical protocols have gained prominence. These two classes of protocols, in general, allow for a smaller overhead of control messages and a shorter latency time. However, they are not always adapted to the unique characteristics of cities. Aiming at better performance for the urban environment, this work proposes the Sector-Based Hierarchical Routing (SBHR) protocol. In this protocol, each cluster is a sector bounded by a set of streets that have parking lots. Vehicles parked in these car parks form a backbone that interconnects all sectors. The backbone is used to route control messages and data messages geographically. In each sector, there is also a vehicle parked with the Cluster Head (CH) function. The CH receives the mobile vehicles’ position in its sector and provides a vehicle’s position when requested. In addition to this special status vehicle, there is also a vehicle parked with Second Level Cluster Head (CH2) status close to the center of the geographical area where the sectors are located. This vehicle receives update tables from the CHs and therefore knows all the vehicles in motion in each sector. CH2 is also consulted when a CH does not know a vehicle’s position. In the SBHR, when a source mobile vehicle receives a destination mobile vehicle’s position via a CH or CH2, it sends a data message towards this position. The SBHR after its development was compared with the reactive Ad-hoc On-Demand Distance Vector (AODV) protocol showing a shorter latency time and a smaller number of messages in four of the five evaluated communications.