## 1 Introduction  
Wireless Sensor Networks (WSNs) are composed of low-cost nodes with limited processing, communication, and detection capabilities, which interact cooperatively to perform complex monitoring tasks in a geographic area of interest [1]. Current and future applications are comprised of many important domains, such as smart cities, environmental monitoring, distributed sensing in industrial plants and health care, as well as the various areas of the Internet of Things (IoT) [2, 3].  
WSNs present challenging issues related to the reliability of communication and the efficient use of the node's battery [4]. In particular, routing is an essential problem in these networks due to possible communication failures, limited bandwidth, and energy/power available [5]. Thus, sophisticated techniques are needed to configure and maintain reliable paths, as well as to detect link failures promptly, without wasting energy and communication resources [6].  
In this work, we observe the benefits of previously known specific topology characteristics to conduct the network setup where limited resources can compromise all monitored environments. To demonstrate the practical benefits of this research, a real environment was considered. Thus, we focused on Precision Agriculture (PA), more specifically a real coffee plantation in Southeast Brazil. Figure 1 shows the three different network topologies that will be investigated in this work. Similarly, the benefits of knowing the virtual topology can help the Low-power and Lossy Network(LLN) routing protocols obtain the maximum lifetime in terms of energy consumption. In this way, our study was conducted on the Contiki Cooja platform, an open, portable, and multitasking platform to simulate sensor networks. The platform was developed for sensors with low computational and energy resources, where the typical sensor has 2 KB of RAM and 40 KB of ROM. Our main contribution is identifying the best topology and characteristics to meet the goal of balancing low cost, reliability, and the longest useful battery lifetime in a mesh WSN for the IoT environment.  
This work focuses on the benefits of fitting the network topology for PA scenarios using a mesh and Internet Engineering Task Force (IETF) standardized LLN protocol with both of its well-known objective functions, comparing them in relation to energy consumption. The results show that the Routing Protocol for LLNs (RPL) has an excellent performance in terms of the sensor network lifetime. The algorithm never leaves a node orphaned (when a parent is no longer eligible, the protocol seeks the best immediate substitute to fill this gap, preventing the isolation of any node in the network). Another good result is how significant the influence of the topology on energy consumption is. Our main results showed that the circular topology proved to be the best in terms of energy consumption compared to the grid and tree topologies, obtaining energy-savings of 30% and 15%, respectively.  
The remainder of this paper is organized as follows: in Section 2, we present the background of WSNs. Section 3 presents the related work. Section 4 introduces the evaluation methodology and numerical results. Finally, Section 5 concludes this works and presents future works.