# A Novel Dynamic Transmission Power of Cluster Heads Based Clustering Scheme
###### Abstract
In addition, the cluster network structure can improve the network scalability. Since the CH is important for a cluster, it is necessary to design a reasonable cluster head selection strategy, to guarantee the stability of the clustering structure. Moreover, because the CH needs to receive, process and send a lot of information, the energy consumption of the CH is very heavy, which is fatal to the lifetime of the whole FANET. Therefore, reducing the energy consumption of the CH should be considered. However, most existing clustering algorithms such as [7; 9] do not simultaneously optimize the cluster number, the CH selection, the communication resource allocation, and the cluster structure stability. Some algorithms such as [8] even randomly assign the CHs and the cluster number, degrading the stability of the whole network. Therefore, it is necessary to design a scheme to overcome the shortcomings of the above algorithms and improve the overall performance of FANETs. To address the related issues, this paper proposes a dynamic transmission power of the cluster heads based clustering (DTPCH-C) scheme, developed using the new K-means algorithm. Different from the traditional K-means algorithm, the clustering process is optimized in the new K-means algorithm. The number of clusters and the selection of CHs are optimized. Firstly, in the clustering process, to reduce the clustering overhead, the primary number of clusters needs to be optimally determined for the initial clustering center selection. Subsequently, according to the CH election strategy, the UAV node with the highest fitness value is selected as the CH in a cluster, while the remainders are CMs, which can improve the reliability of FANETs. We also design a moving prediction model-based dynamic transmission strategy to allocate the power of the CH. By predicting the distance between cluster heads and CMs, the transmission power of the CHs is adjusted, so as to reduce the energy consumption of CHs and enhance the life of the cluster network. The key contributions of this paper are summarized as follows:  
1. A novel clustering scheme with dynamic transmission power of CHs is presented for FANETs to improve reliability and lifetime of FANETs. The proposed DTPCH-C scheme is realized by initialing the cluster, reducing the energy consumption of the CHs, selecting CHs and maintaining clusters. 2. The variable transmission power mechanism of the CH is proposed. Using grid mode-based transmission power adjustment and movement prediction, the CH can flexibly adjust its transmitting power according to its distance to different CMs, which saves energy and improves the lifetime of FANETs. 3. Meanwhile, we propose a weighted summation-based CH selection algorithm, where the adaptive node degree, the remaining energy ratio and the distance between nodes are all involved in the selection criteria. The UAV node with the maximum weight is selected as the CH. As a result, the probability of the most appropriate node becoming a CH is improved so that the packet delivery ratio (PDR) grows. Therefore, the reliability of the network is enhanced. 4. According to the simulation results, the proposed DTPCH-C scheme has more advantages than the existing clustering methods in terms of reliability, lifetime and energy consumption. The rest of this paper is organized as follows: Section 2 describes the background about FANETs and related works. The system model is introduced in Section 3. In Section 4, the proposed DTPCH-C scheme is presented in detail. In Section 5, we compare the performance of the DTPCH-C algorithm with the other two algorithms and draw the conclusion that the performances of the DTPCH-C is better than the others. In Section 6, we summarize of the whole paper.