# A Privacy-Preserving Routing Protocol Using Mix Networks in Opportunistic Networks
## 4 Evaluation
### Results
This is something already expected by the way an opportunistic mixnet works. We saw, however, that the penalty introduced in terms of delivery ratio or overall path delay is relatively tolerable. Figure 4: Latency with random mix nodes. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Size of \(\mathcal{M}\)** & **0** & **1** & **2** & **3** & **4** & **5** & **6** \\ \hline \multicolumn{8}{c}{**Cambridge**} \\ \hline
20\% & 39.7 & 37.0 & 36.7 & 35.9 & 37.1 & 36.9 & 36.5 \\
40\% & 39.7 & 36.6 & 37.4 & 34.9 & 35.8 & 35.3 & 34.5 \\
60\% & 39.7 & 36.6 & 37.7 & 35.7 & 34.5 & 35.4 & 35.4 \\
80\% & 39.7 & 35.2 & 37.3 & 35.1 & 34.9 & 34.5 & 34.8 \\
100\% & 39.7 & 41.2 & 44.1 & 43.4 & 42.3 & 43.4 & 43.0 \\ \hline \multicolumn{8}{c}{**Info5**} \\ \hline
20\% & 38.1 & 37.5 & 39.1 & 39.5 & 39.7 & 39.3 & 39.8 \\
40\% & 38.1 & 37.4 & 37.6 & 38.0 & 37.7 & 38.2 & 37.7 \\
60\% & 38.1 & 38.2 & 38.7 & 39.2 & 38.4 & 38.1 & 38.0 \\
80\% & 38.1 & 39.0 & 38.6 & 39.4 & 39.4 & 39.3 & 38.6 \\
100\% & 38.1 & 38.4 & 39.1 & 38.4 & 38.3 & 38.5 & 38.1 \\ \hline \multicolumn{8}{c}{**Taxis**} \\ \hline
20\% & 275.4 & 285.5 & 292.7 & 290.9 & 299.2 & 306.5 & 310.1 \\
40\% & 275.4 & 271.9 & 284.3 & 285.4 & 289.2 & 298.8 & 302.0 \\
60\% & 275.4 & 274.5 & 277.2 & 274.7 & 292.0 & 302.0 & 296.8 \\
80\% & 275.4 & 282.2 & 287.3 & 269.2 & 284.4 & 279.9 & 280.0 \\
100\% & 275.4 & 284.4 & 294.5 & 289.9 & 290.7 & 305.4 & 305.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Overhead ratio with random mix nodes. Figure 5: Latency with centrality mix nodes. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Mix Nodes** & **20\%** & **40\%** & **60\%** & **80\%** & **100\%** \\ \hline \hline \multicolumn{6}{c}{**Cambridge**} \\ \hline  
\hline \hline \end{tabular}
\end{table} 
Table 4: Average routing-step path length with random mix nodes. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Size of \(\mathcal{M}\)** & **0** & **1** & **2** & **3** & **4** & **5** & **6** \\ \hline \multicolumn{6}{c}{**Cambridge**} \\ \hline
20\% & 38.5 & 33.3 & 33.2 & 32.5 & 33.4 & 34.5 & 34.1 \\
40\% & 38.5 & 36.2 & 34.3 & 33.9 & 34.3 & 34.4 & 33.8 \\
60\% & 38.5 & 36.2 & 33.6 & 35.3 & 34.6 & 34.3 & 34.7 \\
80\% & 38.5 & 35.0 & 34.6 & 36.1 & 34.3 & 33.6 & 35.1 \\
100\% & 38.5 & 37.5 & 42.4 & 50.5 & 39.2 & 40.2 & 42.7 \\ \hline \multicolumn{6}{c}{**Info5**} \\ \hline
20\% & 37.6 & 37.5 & 39.3 & 39.8 & 40.2 & 39.7 & 40.1 \\
40\% & 37.6 & 37.7 & 37.8 & 38.3 & 38.2 & 38.4 & 37.9 \\
60\% & 37.6 & 37.8 & 37.5 & 37.5 & 37.2 & 36.8 & 36.6 \\
80\% & 37.6 & 37.4 & 37.4 & 39.3 & 37.4 & 37.3 & 36.8 \\
100\% & 37.6 & 38.4 & 39.5 & 39.3 & 39.0 & 39.2 & 39.1 \\ \hline \multicolumn{6}{c}{**Taxis**} \\ \hline
20\% & 277.8 & 259.3 & 246.4 & 237.9 & 234.7 & 236.9 & 230.2 \\
40\% & 277.8 & 263.0 & 252.1 & 243.4 & 243.3 & 242.2 & 234.8 \\
60\% & 277.8 & 258.2 & 253.0 & 242.2 & 244.0 & 240.4 & 244.9 \\
80\To analyze the buffer storage of each node, we saw in simulations that the average time in which a node holds messages in mix nodes is less than 1% of total delivery time. This percentage is so small since there is a lot of traffic in the network, and the minimal number of messages to forward a message is guaranteed 99% of the time. Because of this, this buffer utilization did not affect the performance of the latency of delivery time.