# Collision Avoidance Geographic P2P-RPL in Multi-Hop Indoor Wireless Networks
## 4 Performance Evaluation
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Simulation area & \(75\times 75\) m\({}^{2}\) \\ Radio environment & UDGM with distance loss \\ Transmission success ratio (\%) & 100 \\ Reception success ratio (\%) & 90 \\ Transmission range (m) & 20 \\ \(I_{min}\) & \(2^{6}\) ms \\ \(I_{max}\) & \(2^{10}\) ms \\ Redundancy constant (\(k\)) & 1 \\ RPL mode of operation & Storing mode \\ Objective function & MRHOF \\ Routing metric & ETX \\ \hline \hline \end{tabular}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Simulation area & \(75\times 75\) m\({}^{2}\) \\ Radio environment & UDGM with distance loss \\ Transmission success ratio (\%) & 100 \\ Reception success ratio (\%) & 90 \\ Transmission range (m) & 20 \\ \(I_{min}\) & \(2^{6}\) ms \\ \(I_{max}\) & \(2^{10}\) ms \\ Redundancy constant (\(k\)) & 1 \\ RPL mode of operation & Storing mode \\ Objective function & MRHOF \\ Routing metric & ETX \\ \hline \hline \end{tabular}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Simulation area & \(75\times 75\) m\({}^{2}\) \\ Radio environment & UDGM with distance loss \\ Transmission success ratio (\%) & 100 \\ Reception success ratio (\%) & 90 \\ Transmission range (m) & 20 \\ \(I_{min}\) & \(2^{6}\) ms \\ \(I_{max}\) & \(2^{10}\) ms \\ Redundancy constant (\(k\)) & 1 \\ RPL mode of operation & Storing mode \\ Objective function & MRHOF \\ Routing metric & ETX \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The simulation model parameters. Figure 8: Average control packet overhead versus average node degree. Figure 10: The average hop count versus the average node degree. Figure 9: The average energy consumption versus the average node degree. Figure 8 shows that Collision Avoidance Geographic P2P-RPL achieved about 75.7%, 45.9%, and 6.5% less control packet overhead on average compared with P2P-RPL, ER-RPL, and Location-Aided P2P-RPL, respectively. In Collision Avoidance Geographic P2P-RPL and Location-Aided P2P-RPL, only the node inside the location-constrained forwarding zone re-broadcasts a DIO control packet. Collision Avoidance Geographic P2P-RPL and Location-Aided P2P-RPL exploit accurate location information obtained from self-localization to reduce the search space for route discovery. The search space for route discovery is limited to the location-constrained forwarding zone based on the location information of the source node and the destination node. cantly reduced control packet overhead compared to P2P-RPL and ER-RPL. In ER-RPL, the estimated localization accuracy severely depends on the network configuration and the size of the search space for route discovery. As the average node degree increases, the performance differences with ER-RPL and P2P-RPL become larger. Collision Avoidance Geographic P2P-RPL and Location-Aided P2P-RPL obtain more accurate self localization information with the increase of the average node degree. The performance difference between Collision Avoidance Geographic P2P-RPL and Location-Aided P2P-RPL comes from the difference in network convergence time. If P2P-DIO reaches the destination node earlier, the destination node sends P2P-DRO earlier and the nodes receiving P2P-DRO stop re-broadcasting a P2P-DIO for temporary DODAG formation. Figure 9 shows that Collision Avoidance Geographic P2P-RPL achieved around 34.3% less energy consumption in comparison with ER-RPL and was reduced by more than twice compared to P2P-RPL on average. The energy model only considers the transmitting and receiving states; hence, the number of control packets constitutes a significant portion of the energy consumption. In Collision Avoidance Geographic P2P-RPL, only the nodes inside the location-constrained forwarding zone re-broadcast a DIO control packet. This reduces the number of DIO control packets both transmitted and received. The impact of the average node degree is more significant on P2P-RPL and ER-RPL than onCollision Avoidance Geographic P2P-RPL.