# Survey on Power-Aware Optimization Solutions for MANETs
## 3 Analysis of Power-Aware Optimization Solutions in MANETs
### Routing Protocols Based on Adaptive Load Balancing
The authors extensively assessed these routing protocols in terms of parameters, such as mobility, protocols' schemes (i.e., link-failure announcement and reply via route-cache), overhearing effects, and idle power consumption. The authors determined that, in a dense network environment, the issue of overhearing severely affects the lifetime of the network, no matter the underlying network routing protocol. The authors also suggested that the performance of OLSR in terms of power consumption worsens as the network density and size increase. [PERSON] et al. [109] brought another energy-aware policy--Energy Saving DSR (ESDSR)--which also extends DSR's basic route-discovery structure. ESDSR incorporates the advantages of the minimum power control communication and adaptive load-balancing scheme together. [PERSON] et al. [110] introduced the Color-theory-based Energy-Efficient Routing (CEER) scheme, which shows more scalability than ESDSR on increasing network size. Additionally, the CEER scheme is capable of preserving more power than ESDSR in a dense network environment because it effectively utilizes the concept of optimal CH selections and effective data aggregation. Numerous energy-efficient resource allocation policies [111; 112; 113; 114] have been suggested to maximize efficiency in terms of energy usability for multiple fading wireless channels. Classically, due to the severe insufficiency of the spectrum, the network designers should consider spectrum efficiency as an important design feature in a highly dynamic MANET environment, typically for high rate multimedia communication systems. Unfortunately, spectrum efficiency and energy efficiency are two oppositely natured features, and they both mostly conflict with each other; hence, how to balance them is a hot research topic. [PERSON] et al. [115] comprehensively investigated the characteristics of the spectrum and energy efficiency required for video-streaming in MANETs, respectively. Subsequently, the authors came up with a novel technique, called Energy-Spectrum-Aware Scheduling (ESAS), which enhances video quality and decreases power consumption as well. According to [20; 23; 116; 117; 118; 119], there are two subcategories of load-balancing approaches:  
* Concurrent path forwarding/routing/transmissions-based schemes: These schemes utilize multiple available paths at once, regarding the least energy consuming path. Examples of such schemes are LEAR, MDR, ELGR, Adaptive-sleep + Adaptive MAC-Retx [22], Disjointed Multi-Path routing_Extended OLSR (DMP_EOLSR) [120]. * Alternate path forwarding/routing/transmissions-based schemes: Such schemes utilize alternate path for transmissions. Examples of schemes that utilize either single path or alternate paths for transmissions are the prediction and smart-prediction energy-aware protocol [42], Power-aware Heterogeneous AODV (PHAODV) [45; 121], Energy-level based routing protocol (ELBRP) [122], and Multi-path OLSR (MP-OLSR) [123]). According to [13; 124], there can be three subcategories of multipath routing policies:  
* The node disjointed path policy, which does not share the identical links or intermediate nodes between each available network paths. * The link non-disjointed path policy, in which the multiple available network paths can share identical links or intermediate nodes. * The link disjointed path policy, which can have an identical relaying node, but it does not allow for a shared link between each path. [PERSON] et al. [124] suggested that disjointed based routing schemes can have significant advantages over non-disjointed-based routing policies. Nevertheless, it is not always possible to fully estimate disjoint paths in MANETs, especially in high mobility scenarios [13]. [PERSON] and [PERSON] [125] developed a power-aware and multipath on-demand source routing scheme, called Multipath and Energy-Aware DSR (MEA-DSR), which effectively utilizes the residual battery power of nodes and path diversity.