“…As an innovative data acquisition method in precision agriculture, farmland WSNs can continuously monitor indispensable environmental factors for crop growth and generate remarkable labor-saving benefits to farmers [15]. Compared with other WSN applications, influenced by the agriculture production mode, farmland WSNs present unique characteristics in terms of network topology, information transmission, and load capacity [16]. First, due to the largescale monitoring area, multiple transmission constraints, and limited cost budget, it is essential to introduce multilevel relay nodes to achieve reliable data transfer with low-density deployment, and the network topology displays the feature of hierarchical clustering [17,18].…”