# Development, Implementation and Evaluation of An Epidemic Communication System
## 4 Development of the Epidemic Communication System
### Evaluation of Epidemic Communication Systems through Experiments  
The experiment involved comparing the theoretical values based on the operation depicted in Figure 9. The resolution of the flower image was set to high definition at 640 \(\times\) 480 pixels, and the acquired data size was 500 KB. The movement speed varied, as in the evaluation in Figure 10, and ranged from 0.1 to 0.5 m/s; the data amount that was actually received was then evaluated. Experiments were performed based on the conditions shown in Table 3 to align the theoretical calculations with the actual experimental conditions. The experimental method was to manually move within the communication area. In other words, the time to pass through the area was measured precisely according to the speed of movement. We provide a video of the experiment as the Supplemental Material. Figure 15 presents the results of data reception. From Figure 15, we observe that as the moving speed increases, the data reception monotonically decreases. Moreover, compared with the theoretical values in Figure 10, the characteristics of the amount of received data show a similar trend; overall, the amount of received data decreases. This is believed to be because the theoretical calculation does not include the overhead of data buffering in the bundle layer and data splitting processing in the socket function, in addition to the overhead of UDP headers, IP headers, and other components. That is, because the UDP and IP headers are added for each divided data point, the overhead increases with the number of transmissions. Moreover, the processing speed observed when performing these operations depends on the device. Because RasPi was used, high performances cannot be expected. This is because RasPi is a small, single-board computer and cannot provide sufficient processing power. However, the data transfer characteristics tend to be similar. In future practical applications, the use of a dedicated high-performance machine is desirable. High-performance machines require a board capable of multitasking and driver tuning for wireless devices in order to increase transfer processing. Figure 14: Procedure for data-transfer processing using a socket function. \begin{table}
\begin{tabular}{c c} \hline \hline
**Setting Item** & **Setting Value** \\ \hline Transmission power & 0 dBm \\ Antenna gain & 0 dBi \\ Communications standards & IEEE802.11g \\ Use channel & 1 ch–2412 MHz \\ Communication distance & 0.3 m \\ Movement speed & 0.1\(\sim\)0.5 m/s \\ Protocol & UDP \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Experimental conditions. Therefore, although the infection rate decreased, we confirmed that the epidemic communication system operated normally. We fabricated seven wireless devices, as shown in Figure 16. Flower images were first captured, and the operation was confirmed by relaying the data from the source to the destination while transferring the data. A blue LED indicates wireless devices without holding data, and a red LED indicates the state of the wireless devices infected and holding the data. The wireless devices holding the data move according to the red arrows in the figure, and when they approach other wireless stations, their states change from blue to red. This operation was repeated to confirm that all wireless devices were infected and holding the data. As the implementation uses a wireless LAN, the connection time is theoretically longer than that shown in Figure 15, resulting in a decrease in the amount of data that can be transmitted. Therefore, other communication standards must be considered. This implementation also implements IP and UDP protocol stacks, since general-purpose software was used to measure throughput in the experiment. However, actual epidemic communication is the technology for spreading information through infection, and does not require a routing protocol that uses IP, etc., and the specification can work even if the IP and UDP layer layers are removed. Figure 16: Setup of the demonstration experiment.