# Green Communication in IoT for Enabling Next-Generation Wireless Systems
## 1 Introduction  
Internet of Things (IoT) devices have become a main subject of interest for different types of applications. Due to their extraordinary capabilities, they have become popular and common [1]. IoT is rapidly emerging as an important and influential factor in mobile computing, wireless systems, and vehicular ad hoc networks [2]. IoT devices consist of small sensing devices called sensor nodes. Sensors are tiny devices that consist of a central processing unit (for data processing), a small memory card (working as a storage device), a small battery (an energy source), and a transceiver, as shown in Figure 1[3]. A transceiver sends and receives data or signals from one sensor node to another. Sensors gather andexchange information by communicating with each other to accomplish a common task. These sensors report the collected data to a base station [4; 5]. Sensors vary in their sizes due to the types of applications. The cost of these sensors also depends on their specifications, such as CPU speed, battery size, and memory size [6]. To complete a specific task, IoT devices are deployed over a specific sensing region [7; 8; 9]. Monitoring, analyzing, combining, and responding to the data sensed by hundreds or thousands of nodes are the primary goals of IoTs [10]. Each sensor node has a coverage area depending on its sensing range (Rs). The network coverage can be explained as the total coverage by all the active nodes in the network. Furthermore, each of these sensors has radio coverage depending on its communication range (Rc), which is the area where an active sensor node can communicate with another sensor node. Sensing coverage guarantees convenient event monitoring, while radio range guarantees convenient data transmission [11]. IoT devices suffer from different resource constraints, such as limited energy and memory size. Energy consumption remains the most important challenge that limits the IoT devices' lifetime and reliability [12; 13]. The sensor nodes' limited energy supply can be depleted by performing computations and wireless data transmission. Therefore, it is essential to use energy-efficient computation and communication methods. The lifespan of sensor nodes is significantly impacted by battery life. Compared to computations, data transmission uses more energy [14]. Therefore, minimizing data transmission costs is the most important factor affecting IoT device lifetime. As a result, many researchers have proposed different routing techniques to achieve this goal. Indeed, a new energy-saving routing protocol that is intelligent and effective for IoT networks is required. Many researchers have proposed different protocols to save energy in IoT networks. However, this problem still exists, which in turn negatively affects the IoT network lifetime. So, we need to develop new solutions to tackle this challenge. Figure 2 illustrates an example of a flat multi-hop IoT network [15]. In these kinds of networks, the sensor nodes can communicate with the base station (BS) thanks to the other joined nodes in the environment. For large-scale IoT networks with numerous sensor nodes and one BS, the multi-hop IoT network topology is recommended. The contributions of this paper are as follows:  
* An energy-efficient protocol has been proposed in this work, in order to find the optimal routing protocol between the sensor nodes and the base station in IoT networks, considering various parameters and constraints. * A hybrid GA-ALO metaheuristic optimization technique has been utilized in order to find the optimal path for each communication in the network. * Haversine equation has been incorporated with the proposed approach as a separate model. The results obtained from the proposed approach will be compared against other benchmark techniques, i.e., the Greedy technique and DSR routing protocol. Figure 1: IoT architecture for next-generation wireless systems. The rest of the paper is organized as follows. Section 2 presents related works. The proposed routing protocol is described in Section 3.