## 5 Experimental Results
### Comparative Analysis
#### 5.2.1 Impact of Coverage Rate  
The coverage rate refers to the amount of area covered by the sensor nodes in the region. In Figure 5, the coverage rate of the proposed MiA-CODER mechanism is compared with other existing research works with respect to the number of sensor nodes. The figure makes it clear that the coverage rate and number of sensor nodes are directly proportional to each other, which means that as the number of sensor nodes in the region increases the coverage rate also increases. The coverage rate of the proposed work is high as it performs both hole prevention and hole repair processes. The hole prevention is carried out by increasing the energy efficiency of the nodes and the hole repair is implemented by executing the multi-agent SARSA algorithm in which the base station covers the hole by moving the mobile node. The existing works perform either hole prevention or hole detection which are not efficient to achieve higher coverage rate.  
Figure 6 depicts the comparison of the proposed MiA-CODER mechanism and several existing works in terms of coverage rate with respect to the simulation time. From the figure, it is clear that the coverage rate is inversely proportional to the simulation time which means that as the simulation time increases the coverage rate decreases eventually. The formation of cluster-tree topology using the Sierpinski triangle increases the energy efficiency of the sensor nodes which prevents the formation of coverage holes in the network. Further, the hole repair process performed by the base station eliminates the  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & Processor & NS3.26 \\ \cline{2-3}
**Hardware Specifications** & RAM & 8 GB \\ \cline{2-3}  & Hard Disk & 60 GB \\ \hline \multirow{2}{*}{**Software Specifications**} & Network Simulator & Pentium Dual Core and Above \\ \cline{2-3}  & OS & Ubuntu 14.04 LTS \\ \hline \hline \end{tabular}
\end{table}
Table 4: System configuration.  
holes resulting in better QoSensing. The lack of implementation of both hole prevention and hole repair reduces the coverage rate of these approaches.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Description** \\ \hline Simulation area & 1000 m \(\times\) 1000 m \\ Number of static nodes & 25 \\ Number of mobile nodes & 50 \\ Number of base stations & 1 \\ Sensing range & 35 m \\ Data acquired bytes & 1 KB \\ Number of bits transmitted & 450 bits \\ Duration of single operation & 0.140 \(\mu\)s \\ Rmax & 50 m \\ Pmax & 300 mW \\ Path loss exponent & 1 \\ Hole size & 80 m\({}^{2}\) \\ Energy & 1 J \\ Simulation time & 150 s \\ Queue length & 10,000 packets \\ Node placement & Uniformly Random \\ Simulation rounds & 1000 \\ Network interface type & Physical wireless \\ Packet carry duration & 1 s \\ Neighbor wait duration & 0.5 s \\ \hline \multicolumn{2}{c}{**Algorithm Parameters**} \\ \hline \multicolumn{2}{c}{**SARSA**} \\ \hline Epsilon & 1 \\ Learning rate & 0.8 \\ Discount factor & 0.8 \\ Decay & 0.6 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Simulation parameters.  
Figure 5: Number of sensor nodes vs. coverage rate.