# Insights from the Experimentation of Named Data Networks in Mobile Wireless Environments
## 4 Experimentation Setup and Results
### NDN in Single Wireless Radio Scenarios
Figure 8 presents the raw number of unique content chunks received by both types of mobile nodes in the network-vehicle and pedestrian. By interlacing the jumps in the amount of data received with the layout of the edge nodes in the network, we can observe the first itinerary of the vehicle (between 100 and 450 s in Figure 8a). Following this initial behavior, we see that the vehicle stops receiving content for a while, while the pedestrian starts to receive content, despite being isolated from the infrastructure, which proves that both mobile nodes made contact and the latter received the data through cache's vehicle. Then, the vehicle entering the second part of the circuit received the exclusive additional data, while the pedestrian retrieved all the additional content available in the second cycle. In general, we see that, although the vehicle could not retrieve the full extent of the available files, it was able to properly download data from RSUs placed around the city and deliver its content to other nodes via caching mechanisms. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Experiment Duration** & 1700 s \\ \hline
**Interest Timeout** & & 4s \\ \hline
**Chunk Size** & & 1490 \\ \hline
**Communication Type** & & ITS-G5 \\ \hline \multirow{6}{*}{**Content**} & **Type** & **Size** & **Number of Chunks** \\ \cline{2-3}  &.docx & 16 KB & 11 \\ \cline{2-3}  & jpg & 36 KB & 23 \\ \cline{2-3}  & jpg & 68 KB & 46 \\ \cline{2-3}  & jpg & 104 KB & 71 \\ \cline{2-3}  &.pdf & 8.2 MB & 5760 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: City scenario parameters. Figure 9a presents an overview of the number of packets (Interests and Data) transmitted and received by the vehicle. On the one hand, the number of packets shown by the red (satisfied Interests) and yellow (sent Data) bars shows that few retransmissions occurred when contact with the network was possible. On the other hand, the blue bar shows the small amount of replicated data due to the vehicle's simultaneous contact with several RSUs, mainly in the central part of the city where three edge nodes coexist. The results related to the mobile node representing the pedestrian were unconsidered as they took full advantage of the connection time to the vehicle, downloading all available cached contents with minimal retransmissions. Any Interest packets that resulted in timeouts and subsequent retransmission by the mobile nodes occur due to absence of contact with the network as opposed to issues regarding efficient Forwarding of the content through available paths. This can be addressed by adding more points of contact to the network. Figure 9b depicts the period of time each mobile node was successfully connected to the infrastructure, and thus able to send and receive content, compared to the total time elapsed. We can conclude that part of the reason the mobile nodes were not able to completely transfer all intended files was due to the reduced contact time with any cache node, totalling 26% for the vehicle (442 s over 1700 s) and 6% for the pedestrian (192 s over 1700 s), which only had the other mobile node as a source of content. Therefore, it  
Figure 8: Number of unique data (chunks) received during the experiment. (**a**) Data downloaded by the vehicle. (**b**) Data downloaded by the pedestrian. Figure 9: Network overhead. (**a**) Total amount of packets transmitted/received by the vehicle. (**b**) Total contact time between each mobile node and the infrastructure. can be implied that increasing the amount of contact time with the network could directly improve the Interest satisfaction ratio.