# Predicting Topology Propagation Messages in Mobile Ad Hoc Networks: The Value of History
## 5 Evaluation of OLSR-HBP in Mobile Scenarios
### Impact of OLSR-HBP on the Network Performance
#### 5.4.1 Data Transfer Capability
\begin{table}
\begin{tabular}{c c c c} \multicolumn{4}{c}{**a** SLAW 10 nodes 1 h} \\ \hline
**Ping Period** & **10 s** & **1 s** & **0.1 s** \\ \hline OLSR & 18.2\% & 16.4\% & 16.2\% \\ OLSR-HBP & 18.1\% & 15.7\% & 16.0\% \\ Improvement & \(-\)0.5\% & \(-\)4.2\% & \(-\)1.4\% \\ \hline \multicolumn{4}{c}{**b** SLAW 10 nodes 4 h} \\ \hline
**Ping Period** & **10 s** & **1 s** & **0.1 s** \\ \hline OLSR & 22.8\% & 19.9\% & 19.2\% \\ OLSR-HBP & 22.7\% & 19.3\% & 19.1\% \\ Improvement & \(-\)0.63\% & \(-\)2.71\% & \(-\)0.59\% \\ \hline \multicolumn{4}{c}{**c** SLAW 20 nodes 1 h} \\ \hline
**Ping Period** & **10 s** & **1 s** & **0.1 s** \\ \hline OLSR & 23.5\% & 18.3\% & 18.3\% \\ OLSR-HBP & 22.6\% & 18.1\% & 17.3\% \\ Improvement & \(-\)3.70\% & \(-\)0.70\% & \(-\)5.14\% \\ \hline \multicolumn{4}{c}{**d** SLAW 20 nodes 4 h} \\ \hline
**Ping Period** & **10 s** & **1 s** & **0.1 s** \\ \hline OLSR & 32.3\% & 21.5\% & 21.2\% \\ OLSR-HBP & 31.0\% & 21.3\% & 19.9\% \\ Improvement & \(-\)4.03\% & \(-\)0.78\% & \(-\)5.9\% \\ \hline \end{tabular}
\end{table} 
Table 7: Ping delivery rates (in %). \begin{table}
\begin{tabular}{c c c c} \multicolumn{4}{c}{**a** SLAW 10 nodes 1 h} \\ \hline
**Ping Period** & **10 s** & **1 s** & **0.1 s** \\ \hline OLSR & 14.3 & 8.51 & 6.97 \\ OLSR-HBP & 12.8 & 10.1 & 6.94 \\ Improvement & 10.5\% & \(-\)18.9\% & 0.47\% \\ \hline \multicolumn{4}{c}{**b** SLAW 10 nodes 4 h} \\ \hline
**Ping Period** & **10 s** & **1 s** & **0.1 s** \\ \hline OLSR & 11.7 & 11.5 \\ OLSR-HBP & 11.7 & 10.6 \\ Improvement & 0.02\% & 7.65\% \\ \hline \multicolumn{4}{c}{**c** SLAW 20 nodes 1 h} \\ \hline
**Ping Period** & **10 s** & **1 s** & **0.1 s** \\ \hline OLSR & 12.6 & 20.4 & 12.5 \\ OLSR-HBP & 11.6 & 17.1 & 11.5 \\ Improvement & 7.93\% & 16.24\% & 8.61\% \\ \hline \multicolumn{4}{c}{**d** SLAW 20 nodes 4 h} \\ \hline
**Ping Period** & **10 s** & **1 s** & **0.1 s** \\ \hline OLSR & 15.1 & 30.8 \\ OLSR-HBP & 13.8 & 32.0 \\ Improvement & 8.5\% & \(-\)4.1\% \\ \hline \end{tabular}
\end{table} 
Table 8: Ping round-trip times (RTT, in ms). For other cases where the RTT can be computed, we observe better values (less RTT) in 8 of 13 cases. Nevertheless, there are five cases where the RTT is worse for OLSR-HBP (particularly, all three grid cases). The differences (in percentage) among RTT range from 16.24% (good) to \(-\)18.9% (bad), with a global average of 0.50% that increases to 3.69% for SLAW mobility cases. After analysing these values in detail, it was not possible to determine the exact reasons for these variations, since they are probably caused by a combination of factors. On the one hand, the decrease in the number of TP messages in the network releases communication resources that can be used to send data with less delay, and therefore with a good RTT. On the other hand, the loss of some TP messages or missed predictions at destination nodes may produce alterations in the routing information and configuration. Consequently, ping messages can be routed to a path with more hops, and therefore, it means larger RTT values.