Contents I. Introduction
As a part of the intelligent transport systems (ITS), vehicular ad hoc networks (VANETs) have attracted extensive attention in recent years. VANETs can provide V2V (Vehicle-to-vehicle) and V2I (Vehicle-to-Infrastructure) communication for safety and non-safety vehicular applications [1]–[3]. However, with the widespread deployment of fourth-generation (4G) mobile communication network, it is not economical to build a fixed infrastructure only for the VANETs [4]. So, based on clustering technology, many researchers focus on the heterogeneous architecture which uses the typical random access protocol IEEE 802.11p of the VANETs within each cluster and uses 4G cellular network among the clusters. In such a heterogeneous architecture, constructing a stable cluster not only improves the quality of the network but also reduces the overhead of network maintenance and message dissemination [5]. Based on the clustering algorithm, we can improve the routing performance greatly for VANETs by constructing stable clusters.
