# Clustering-Based Energy-Efficient Self-Healing Strategy for WSNs under Jamming Attacks
## 2 Related Work  
The use of clusters in combination with self-organization and automatic configuration algorithms can overcome diverse challenges in the reliability and security of wireless networks [8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19]. In this sense, the most used clustering protocols are LEACH [8] and its variants: HEED [9], PEGASIS [10], EECS [11], and TEEN [12]. By the use of hierarchical routing based on clustering, these protocols guarantee data communication with energy efficiency. The principal differences among the protocols are based on the selection of the CHs, the hops between the nodes, the construction of the routing path, and the cost function to select the nodes. In addition, the security problem is not considered in the creation of these clusterization protocols. Some security-oriented LEACH variants have also been proposed, such as SLEACH [13], SecLEACH [14], Armor-LEACH [15], and MS-LEACH [16]. In [13], the authors propose the use of two symmetric keys for each node that are shared with the gateway to improve the authentication process. However, the authors of SecLEACH [14] state that SLEACH does not provide a complete and efficient solution for node-to-CH authentication problems. By the analysis of compromised links, the authors show that their proposed scheme improves security. However, energy efficiency is not completely met due to the generation of key pools and their distribution in the network. To improve the energy efficiency of SecLEACH, Armor-LEACH is proposed [15]. Using the SecLEACH algorithm and the TimeControlled Clustering Algorithm (TCCA) as the basis, the security and energy efficiency of the network improves. The MS-LEACH protocol [16] combines single-hop and multi-hop transmissions, which results in an improvement in the network lifetime with respect to LEACH. Nevertheless, jamming is not taken into account. The authors of SEC in [17] propose a combination of SPINS [18] and LEACH protocols to improve network security. With the addition of data authentication and data freshness, the gateway is capable of verifying the authenticity of the data and CHs. However, neither work considers the possibility of jamming attacks and nor take into account performance metrics such as information transmitted or energy efficiency. Finally, the Enhanced SLEACH protocol is proposed in [19]. With the use of pairwise keys among the cluster members and their respective CHs, it outperforms SLEACH in security, lifetime, and energy consumption aspects. However, as it happens with all the above approaches, it does not consider the presence of jamming attacks and their impact. Moreover, in the last few years the use of clustering for energy-efficiency maximization has been extensively investigated [20; 21; 22; 23; 24; 25; 26; 27; 28]. The works in [20; 21; 22; 23; 24; 25; 26; 27; 28] focus on the residual energy (or remaining battery power), while they coincide in that the cluster head (CH) selection is critical to extending the network lifetime. Using Bee Colony Optimization [20], Fuzzy Logic [21; 28], Butterfly Model [22], Hierarchical Clustering [23], Firefly Algorithm [24], Rider Optimization Algorithm (ROA) [25], Particle Swarm Optimization [26] and Fog Logic [27], these works improve the CH selection in different scenarios. On the other hand, some works focus on clustering and partition problems [29; 30]. Using machine learning techniques and proposing novel clustering routing protocols, they aim at balancing the energy efficiency of the routing path. However, none of these works deal with security or jamming. The authentication issue is considered in the IoT context [31; 32]. However, the problem of authentication in the context of the cluster with a focus on energy efficiency is only considered in [31]. In [33], jamming is considered in a specific clustering context. The work proposes a novel strategy that aims to detect and eliminate the jammer node present in the network to improve energy efficiency.