# Survey on Power-Aware Optimization Solutions for MANETs
## 1 Introduction
Meanwhile, in such policies, the process of updating the routing table for each and every node increases the network overhead to a great extent and that makes such schemes highly infeasible for large dense network environments [26]. Additional traffic intensity is also generated if intense heterogeneous multimedia data (i.e., video, audio, images, etc.) are transmitted over MANET, while such multimedia data traffic can significantly increase the energy exhaustion of mobile devices. In particular, when an application sends multimedia data, such as video over a MANET, the network traffic intensity level is greater than before. Therefore, a large increase in energy consumption takes place [27], while new challenges are imposed for video streaming over MANETs [28]. This quick growth in heterogeneous traffic causes higher packet losses and excessive network delays, hence, it ultimately increases energy consumption and reduces QoS performance [27]. Indeed, congestion ensues when the total amount of transmitted load over the network exceeds the entire obtainable capacity. Such a condition causes escalated buffer usage over the available network path, leading to higher packet losses during the case of unavailability of network resources. In MANETs, higher network congestion occurs than that of a wired network due to its unique characteristics [29]: (1) problems related to exposed and hidden terminals; (2) constraints on resources; (3) error-prone shared broadcast channel; (4) node mobility. Congestion control for MANETs requires extra demands (except efficiency of bandwidth usage and fairness in network traffic) because network congestion is not only due to the traffic of the network, but it can also be due to other factors, such as wireless signal noise, interference node, mobility, and contention [30]. Meanwhile, each node in a MANET is a relay for routing packets to other nodes [1]. When the node mobility increases, the Packet Loss Ratio (PLR) also increases, resulting in increased energy consumption during dynamic routing. The intermediate node that becomes the network relay often experiences network traffic overloading. Dynamic routing in the MANET must be energy efficient as this feature resolves the extension of how the network is practically valuable [31]. In MANETs, the routing algorithm and the congestion control scheme must be energy efficient and must reduce packet loss retransmission as much as possible to reduce energy consumption on each node. Energy conservation improves the lifespan of a MANET and ensures that the communication process is effective [32]. In MANETs, the most significant energy consumer is employed for wireless communication rather than the computing tasks from the mobile device microprocessor. Indeed, energy consumption for computation is at least 50% lower than energy consumption for communication [33; 34]. As a result, energy consumption can be reduced by saving the transmission (energy) power of nodes. Over the years, researchers have focused on investigating how to reduce energy consumption in MANETs. Most of their studies have considered the energy efficiency of routing and tried to prolong the lifetime of nodes and the network. The majority of these studies [15; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45] have introduced single-path energy-efficient routing protocols. However, in single-path routing, the nodes in the selected path quickly deplete their batteries. In light of this evidence, we understand that single-path routing schemes are incomplete. Moreover, in single-path routing, some nodes are highly congested, as they transmit most of the network traffic. As a result, single-path routing does not distribute the load among the nodes in a fair and balanced way. This, in turn, can lead to the significant degradation of network performance. The disadvantages of single-path routing protocols have led to intelligent multipath routing algorithms that address the problem of energy consumption at the network layer.