# Improved Proactive Routing Protocol Considering Node Density Using Game Theory in Dense Networks
## 2 Related Work  
### Improvement of OLSR in Dense Networks  
The OLSR has the advantage of optimizing the existent bandwidth usage and is suited for high-density networks. OLSR routing protocol also has some limitation. It is proved that the calculation of the minimum MPRs is a nondeterministic polynomial time (NP)-complete problem [7; 8; 9]. Thus, there are several extensions to improve the MPR selection. However, for this paper, we focused on the minimization of the MPR sets in dense networks. Table 1 summarizes the related works. [PERSON] et al. [10] proposed using shared MPR sets to achieve a more efficient MPR selection in moderately dense multihop networks than the conventional MPR selection. They analyzed moderately dense networks to show that a node close to the two-hop border had a small probability of being a two-hop neighbor. Further, they noted there is a chance of the node's MPRs being shared with its neighbors, thus the proposal of shared MPR sets. However, the authors did not investigate node mobility, which is crucial in wireless ad-hoc networks as they simulated only a static environment due to the high computational complexity of their algorithm. The battery level of the node is another consideration for the MPR selection, as proposed by [PERSON] et al. [11]. They proposed a novel energy aware MPR election policy, denoted by Energy Efficient OLSR, that allows the energy node to be preserved for a longer time in a dense network. In the Energy EfficientOLSR, each node calculates its own energetic status and then declare an appropriate willingness. The willingness of the node is based on the battery capacity and the predicted lifetime. Similarly, [PERSON] et al. [12] considered the implication of a wireless node's power status and its MPR willingness. They changed the willingness of a wireless node based on its power status. This paper, however, used a limited number of wireless devices thus could not make adequate comparison with existing networks. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**References** & **Objective of the Work** & **Advantages** & **Disadvantages** & **Metric Studied** \\ \hline [PERSON] et al [10] & MPR shared sets to reduce routing overhead in dense networks. & Significantly reduced the MPR ratio and MPR and topology control redundancy. & Only considered a static environment. No mobility model was used. & MPR ratio, MPR and TC message redundancy, number of (MPR’s, TC messages, OLSR packets, total packets) per node. \\ \hline [PERSON] et al. [11] & Preserve a node’s energy in a dense network. & Network life time increased. & Residual battery power for route computation not considered. & Network throughput, expiration time, average node energy, node lifetime. \\ \hline [PERSON] et al [12] & Analyze the relationship between the battery power and the willingness of a node in OLSR. & Changed the willingness based on the node’s battery life. & Limited number of devices. Did not consider mobility. & Willingness, battery life. \\ \hline [PERSON] et al. [13] & Reduce MPR redundancy by using a cooperative MPR selection. & Topology control packets were significantly reduced. & Node density was not considered. & Topology Control packets, arrival time of pinged packets. \\ \hline [PERSON] et al. [14] & Improve OLSR in networks with high mobility. & Significantly reduced control overhead and more link bandwidth for a dynamic topology. & Considered a minimal network load. & Packet Delivery ratio, routing overhead, End to end delay, throughput. \\ \hline [PERSON] et al. [15] & Reduce control overhead by nodes deciding to update or not update its HELLO and TC messages. & Reduced control overhead while average throughput remains unchanged. & Average throughput was decreased. Packet loss was not considered. & Routing overhead ratio, throughput, normalized overhead ratio. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparative study of related work. [PERSON] et al. [13] proposed a cooperative MPR selection procedure to reduce topology control (TC) packets in dense networks.