Wireless sensor networks (WSNs) have gained wide attention from researchers in the last few years because it has a vital role in countless applications. The main function of WSN is to process extracted data and to transmit it to remote locations. A large number of sensor nodes are deployed in the monitoring area. Therefore, deploying the minimum number of nodes that maintain full coverage and connectivity is of immense importance for research. Hence, coverage and connectivity issues, besides

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... imizing the network lifetime, represented the main concern to be considered in this paper. The key point of this paper is to classify different coverage techniques in WSNs into three main parts: coverage based on classical deployment techniques, coverage based on meta-heuristic techniques, and coverage based on self-scheduling techniques. Moreover, multiple comparisons among these techniques are provided considering their advantages and disadvantages. Additionally, performance metrics that must be considered in WSNs and comparison among different WSNs simulators are provided. Finally, open research issues, as well as recommendations for researchers, are discussed. INDEX TERMS Coverage, connectivity, deployment techniques, power consumption, wireless sensor network (WSN). . His major research interests include artificial intelligence (AI), such as genetic algorithms, neural networks, particle swarm optimization, simulated annealing, and fuzzy logic. He is also interested in the application of AI in machine learning, image processing, access control, and optimization and the applications of computational intelligence CI and soft computing tool in bioinformatics. Dr. ElHosseini served as a member of the international program committees of numerous international conferences.