A review of clustering algorithms in VANETs

In vehicular ad hoc network (VANET), lots of information should be delivered on a large scale in a limited time. Meanwhile, vehicles are quite dynamic with high velocities, which causes a large number of vehicle disconnections. Both of these characteristics lead to unreliable information transmission in VANET. A vehicle clustering algorithm, which organizes vehicles in groups, is introduced in VANET to improve network scalability and connection reliability. However, different clustering techniques and algorithms are required for different scenarios, such as information transmission, routing, and accident detections. This paper explores the vehicle clustering techniques from the aspects of cluster head selection, cluster formation, and cluster maintenance procedures. Meanwhile, context-based clustering algorithms are summarized, and the hybrid-clustering algorithms are highlighted. The paper also summarizes the existing clustering performance metrics and performance evaluation approaches.