# Survey on Power-Aware Optimization Solutions for MANETs
## 1 Introduction  
Mobile ad hoc networks (MANETs) have gained increasing popularity for a range of applications [1], such as emergency/rescue operations, military sector applications (e.g., battlefield), health monitoring of civil structures, homeland monitoring, and ubiquitous computing. A MANET consists of mobile nodes that communicate with each other without any infrastructure. These mobile radio autonomous nodes are arranged in a mesh topology and form a dynamic, multi-hop radio network in a decentralized way [1]. The impression of forming a MANET came from the Defense Advanced Research Projects Agency (DARPA) packet radio network [2, 3]. In the past few decades, several researchers [4, 5] have purely focused on the issue of selecting and managing the optimum set of ad hoc routers, whereas some researchers [6, 7, 8] have suggested other effective techniques to deal with routing issues, leveraging existing features of accessible Internet routing algorithms. Recently, MANETs have been developed promptly in the wireless communication arena due to their active features of rapid mobility, fast deployment capability, higher spatial multiplexingrate, and self-organizing nature [9; 10; 11; 12; 13; 14]. Despite these fascinating and striking features of MANETs, these networks last with many constraints and challenges that certainly necessitate profound investigation before their widespread implementation and deployment. MANET devices operate with limited CPU processing capabilities, constrained battery life, inadequate bandwidth support, limited storage, etc. In MANETs, the nodes are also free to roam in any random direction and can only interact with their direct neighbor nodes (i.e., the nodes which are in its transmission range). Nevertheless, this random motion can undeniably cause frequent breakage in communication links. This leads to the issue of dynamic network topology changes and hence, ultimately makes forwarding more difficult. Along with this, all the nodes have to communicate via highly error-prone, limited capacity, and exceedingly bandwidth-constrained wireless channels. In MANETs, the wireless channel is highly utilized as the transmissions by each node are broadcast in nature, and the Medium Access Control (MAC) layer algorithm tries to control access to the shared broadcast channel. Additionally, the wireless links have the interference of signals, a higher error-rate, fading, etc. Undoubtedly, such a highly constrained environment has a profound impact on network performance. Furthermore, in MANETs, all the nodes are attached to low-powered battery devices. The energy of the battery needs to be efficiently utilized to the dodge prompt cessation of wireless nodes. The network designers should keep such battery constrained operation issues in mind while designing any forwarding scheme. This consideration is vital, since node shutdown (due to energy exhaustion) ultimately confines the capability of the dead node to forward packets, and thus it reduces the lifetime of the network as well [15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25]. Consequently, in the dynamic environment of MANETs, we cannot implement the communication system via protocols of a conventional network with infrastructure (i.e., cellular network). Rather, we have to separately implement protocol policies that can work on the fly. In summary, MANETs have unique characteristics that impose a variety of challenges in the design of the routing protocol and complicate Quality of Service (QoS) provision. In the early stages, many routing policies were instructed to continuously update the routing information amongst nodes, since, in such an environment, the network topology changes a lot. Although the suggested schemes were doing their job well to some extent, still, if we talk about the case of dense network environment then all these schemes failed significantly in offering performance.