## 4 Experimental Evaluation
### Scenario 2: Distance between STA and AP
#### 4.3.2 Results of IP Network Layer in Scenario 2  
First, we look into the communication performance obtained by the _ipperf3_. Figure 8 shows the throughput of TCP and UDP communications on the AP side. From the graphs, we can see that the increase in distance significantly impacts communication performance. In the measurement, the communication at 40 m experienced a degradation of almost 40%, and the degradation trend is not linear for the distance. In addition, there is practically no communication at 90 m. Therefore, compared with the reference data acquired in the stable environment, it can be seen that the communication quality begins to deteriorate at 10 m.  
Table 4 shows the average number of retransmitted TCP packets and connection failures for ten measurements. The retransmission of the TCP packets increased after 65 m. In addition, we can see that it is unsuitable for the communication environment because of its connection failure after 95 m. From the results, since the retransmission of the TCP packets leads to significant TCP communication degradation, a distance where retransmission does not occur is desirable.  
Next, we examine the performance indicators of UDP communication. Figure 9 shows the jitter result of UDP communication on the AP side. Note that the results of 95 m and 100 m are omitted because they cannot be appropriately evaluated due to some connection failures. The left graph shows that the jitter values start to vary at 40 m. Furthermore, in the right figure with the y-axis scale spanning from 0 to 0.4 ms, the jitter and the variance increase as the distance increases. From the results, we can see that even if an application requirement meets the throughput, the jitter requirement may not be met.  
Let us look at the communication performance for the _ping_. Figures 10 and 11 show the RTT and packet loss rates of TCP and UDP communication on both sides, respectively. Packet loss was observed after 60 m, and RTT increased after 60 m.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Dist. (m)** & **10** & **20** & **30** & **40** & **50** & **60** & **65** & **70** & **75** & **80** & **85** & **90** & **95** & **100** \\ \hline \hline \multirow{2}{*}{Retry Failure} & 0 & 0 & 0 & 0 & 0 & 0 & 0.2 & 4.4 & 0.2 & 0.3 & 0 & 0.1 & 67.9 & 17 \\  & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0.3 & 0.4 \\ \hline \hline \end{tabular}
\end{table}
Table 4: The average number of retransmitted TCP packets and connection failures (Scenario 2).  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & & & & & & & & \\ \hline
**Mb/s** & **A/A** & **A/B** & **A/C** & **A/D** & **B/B** & **C/C** & **D/D** \\ \hline
27.5 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
385.0 & 0 & 0.08 & 0.42 & 0.42 & 0.17 & 0 & 0 \\
770.0 & 0 & 0 & 0 & 0.33 & 0.25 & 0 & 0 \\
962.5 & 0.42 & 0.33 & 0.25 & 1.17 & 0.50 & 0 & 0.50 \\
1155.0 & 0 & 0 & 0.25 & 1.58 & 0.83 & 0 & 0 \\
1540.0 & 0.75 & 0 & 0.50 & 1.92 & 1.83 & 0 & 0 \\
1925.0 & 2.75 & 2.92 & 7.08 & 8.50 & 7.08 & 4.42 & 2.75 \\
2310.0 & **96.08** & **96.67** & **91.50** & **86.08** & **89.33** & **95.58** & **96.75** \\ \hline \hline \end{tabular}
\end{table}
Table 3: Tx bitrates on sender side (Scenario 1).