## 2 Energy Efficiency (EE) Studies in LAR of Ad Hoc Networks  
The LAR protocol is an interesting area for researchers. Several studies have tackled the limitation of the LAR protocol with different categories. This section presents the summaries of related studies with the LAR protocol and the related study of the PSO algorithm. Several efforts have been exerted to diminish the amount of power wastage. For instance, an energy-efficient scheme adopted by the AODV as a new model using the LAR protocol to reduce energy consumption aids the routing corresponding to the location. This study proposes a new location-based energy-efficient scheme with the AODV protocol. The main disadvantage of this new development is that the network nodes do not record their energy consumption, resulting in high energy usage [26]. Researchers on MANETs aimed to reduce the energy consumption of the node. For instance, [PERSON]. [27] proposed a model to enhance the performance of the MANET protocol to ensure efficient performance by using a LAR-1 model that can reduce energy consumption by extending the network lifetime in a dynamic network. The antennas have some dismissed route discovery through untargeted flooding of the route request packets outside the coverage area between the source node and the destination node. This study has a concern about the flooding of the LAR protocol in the request zone. Adding adaptive LAR with directional antenna could reduce the propagation of the redundant route using restricted flooding antennae and directional antennae [20]. Some studies have focused on another aspect given its importance can contribute to MANET protocols the overhead during the limitation of the network effects to increase the number of packets to the sender (request node). Hence, the continuation by sending the packet minimizes the battery life until shutdown. [PERSON]. [28] has suggested a new location-aided zone routing protocol (ZRP) to elucidate the mechanism used to seek the route from the source node to the destination node with high probability. However, this method creates many idle paths in the network and high overhead cost. Therefore, this study proposed a model using geographical information based on ZRP to minimize the discovered area and decrease the number of sent packets, thereby diminishing the overhead. In the same content, [PERSON] [29] developed an energy-efficient LAR protocol (PA-LAR) that uses linear regression and curve intersection point area to minimize the request zone and organize node behavior on the basis of the battery level. The PA-LAR protocol determines the dependent node to save the energy to improve network survival along with the routing capability based on the curve and location for the LAR and AODV protocols. [PERSON] et al. [30] established the cost-efficient QoS routing protocol (CEQRP). The rules of this protocol consist of two aspects. First is the path_bandwith from the node of source to the node of destination. Second is that the routing_cost requirement to select the middle node (host) should be the lowest possible. For proactive routing protocols, [PERSON]. [31] proposed the quantum genetic-based OLSR protocol (QG-OLSR). This study considered two aspects in reducing network topology consumption and the time delay for E2E delay packet transmission between nodes by using the newly augmented Q-Learning algorithm and combining with OLSR to optimize the selection of multipoint relay sets. Previous studies aimed to enhance QoS to maintain the optimal performance of the MANET environment. Therefore, this study followed previous procedures to develop the QoS in the energy part. Table 1 provides a summary of the previous studies and the points of differences. Nature-inspired algorithms can be used to solve various real-world optimization problems; thus, such algorithms have continued to receive research attention in recent decades. In addition, optimization problems are faced with the problem of search space complexity.