In vehicular ad hoc networks (VANETs), the topology information (TI) is updated frequently due to vehicle mobility. These frequent changes in topology increase the topology maintenance overhead. To reduce the control message overhead, cluster-based routing schemes are proposed. In cluster-based routing schemes, the nodes are divided into different virtual groups, and each group (logical node) is considered a cluster. The topology changes are accommodated within each cluster, and broadcasting TI to the whole VANET is not required. The cluster head (CH) is responsible for managing the communication of a node with other nodes outside the cluster. However, transmitting real-time data via a CH may cause delays in VANETs. Such real-time data require quick service and should be routed through the shortest path when the quality of service (QoS) is required. This paper proposes a hybrid scheme which transmits time-critical data through the QoS shortest path and normal data through CHs. In this way, the real-time data are delivered efficiently to the destination on time. Similarly, the routine data are transmitted through CHs to reduce the topology maintenance overhead. The work is validated through a series of simulations, and results show that the proposed scheme outperforms existing algorithms in terms of topology maintenance overhead, QoS and real-time and routine packet transmission.

QoS; VANETs; routing; real-time communication; IoT