Abstract
In this paper, we study the clustering problem for crossroads in Vehicular Ad hoc Networks (VANETs). Considering the load balancing of both the whole network and each cluster based on the multiple metrics, an Enhanced Low Overhead and Stable Clustering (EnLOSC) scheme is presented to ensure the stability and security of clusters and to reduce the communication overhead in this case. The proposed capability metric, designed to find the vehicles with similar direction and better channel quality, is exploited in the processes of formation and maintenance to determine which node is suitable for a cluster head. Based on this, a Cluster Head Electing in Advance Mechanism (CHEAM) is developed in order to fairly select a new head for “isolated” vehicles that may not belong to a cluster. Meanwhile, other metrics are related to the node density and cluster size, which are exploited in the Cluster Merging and Splitting Mechanisms to keep the system load balancing and to improve the communication quality. Furthermore, the proposed Discovery and Elimination Scheme (DES) is designed to tackle the malicious nodes that may hurt the cluster communication. Accordingly, an enhanced cluster maintenance strategy with multi-metrics and a secure scheme is proposed so as to reduce the number of isolated vehicles, keep appropriate loading for each cluster head, and protect the whole link over cluster communication. Numerical results and discussion indicate that the cluster stability, communication overhead, load balance, and security can be significantly enhanced by our proposed scheme.
Highlights
1 Introduction Communication in Vehicular Ad hoc Networks (VANETs), which are considered to be a special class of Mobile Ad hoc Networks (MANETs), becomes an important research topic with the spectrum allocation for Intelligent Transportation System (ITS) and the development of Dedicated Short Range Communication (DSRC) standards [1, 2]
Algorithm 5 Cluster Maintenance Scheme Require: cluster member: j; cluster head: i; cluster set: ; Direct Neighbors List (DNL) set: 1: Start Discovery & Elimination Scheme during data transmission 2: Each node broadcasts Cluster Head Announcement (CHA), Cluster Member Announcement (CMA) or HELLO packets periodically with Tc 3: Recalculate M for every nodes in cluster i periodically 4: if M(j) < M(i) 5: Replace the cluster head with a member as a new head 6: end if 7: Execute Cluster Head Electing in Advance Mechanism (CHEAM) described in Algorithm 2 as soon as a node joins in a cluster 8: Head i periodically calculates kd(i) and the ks(i) 9: if 0 < ks(i) ≤ kd(i) or kd(i) > 1 & 0.5 ≤ ks(i) ≤ 1 10: Head i maintains itself based on LOSC proposed in
A new capability metric M, which is related to the relative velocity and the power loss, is introduced to describe a node’s capability of being a cluster head and exploited in the maintenance algorithm to achieve the cluster head electing
Summary
Communication in Vehicular Ad hoc Networks (VANETs), which are considered to be a special class of Mobile Ad hoc Networks (MANETs), becomes an important research topic with the spectrum allocation for Intelligent Transportation System (ITS) and the development of Dedicated Short Range Communication (DSRC) standards [1, 2]. A node with a smaller PLM value is more likely to have a shorter communication distance and better channel quality with its direct neighbors. Taking both RVM(i) and PLM(i) into consideration, we define a capability metric M to describe the capability of a node to be a cluster head: M(i) = RVM(i) + PLM(i). We decide to take into account the communication load on each cluster head, which is represented by the number of members in this cluster, for the purpose of the load balancing and well-performed clustering scheme that is suitable for the high node density scenario. The maximum number of cluster head i’s members
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