## 5 Experiment
### Evaluation
This is because congestion control is one of the core components of TCP. We conduct experiments in this download scenario, \begin{table}
\begin{tabular}{l l c c c c} \hline \hline
**DelACK** & **QoS Algorithm** & **Sta1** & **Sta2** & **Sta3** & **Total Throughput** \\ \hline
1 & Default & 6.73 & 6.75 & 6.79 & 20.27 \\
1 & General Airtime Fairness & 14.07 & 4.56 & 3.06 & 21.69 \\
1 & Our Airtime Fairness & 8.39 & 7.42 & 5.33 & 21.14 \\
2 & Default & 8.38 & 8.38 & 8.37 & 25.14 \\
2 & General Airtime Fairness & 17.36 & 5.73 & 3.86 & 26.94 \\
2 & Our Airtime Fairness & 10.38 & 9.29 & 6.36 & 26.03 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Throughput comparison of QoS algorithms in DL scenario. \begin{table}
\begin{tabular}{l l c c c c} \hline \hline
**DelACK** & **QoS Algorithm** & **Sta1** & **Sta2** & **Sta3** & **Fairness Index** \\ \hline
1 & Default & 0.16 & 0.17 & 0.24 & 0.9658 \\
1 & General Airtime Fairness & 0.33 & 0.11 & 0.1 & 0.7589 \\
1 & Our Airtime Fairness & 0.2 & 0.19 & 0.19 & 0.9992 \\
2 & Default & 0.15 & 0.17 & 0.24 & 0.9569 \\
2 & General Airtime Fairness & 0.12 & 0.11 & 0.11 & 0.7788 \\
2 & Our Airtime Fairness & 0.19 & 0.18 & 0.18 & 0.9998 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Airtime comparison of QoS algorithms in DL scenario. where we sequentially set the same congestion control algorithms (Reno [23], Vegas [27], Cubic [28], and BBR [29]) to the three STAs. All other experimental conditions are kept consistent with those previously described. The results are presented in Table 4.  
The experimental results show that our method is effective and demonstrates consistently high fairness when facing different TCP parameters and popular congestion control algorithms. The reason is that we have incorporated the TCP parameters that affect our QoS-based scheduling algorithm into the modeling analysis. **Upload Scenario. ** Next, we examined the impact of each algorithm on upload TCP flows using the network topology shown in Figure 9, with the throughput for each STA detailed in Table 5.  
Building on our airtime analysis of TCP ACKs in Section 4.3, we extended the AP-based airtime fairness to upload traffic. The comparison between the default QoS algorithm and the two airtime fairness approaches demonstrates that our algorithm effectively controls changes in upload traffic throughput at the AP, thereby achieving airtime fairness. However, in this scenario, the default QoS algorithm only achieves throughput fairness when the delayed ACK is set to 1. In contrast, our algorithm consistently achieves airtime fairness across various network environments, leading to an improvement in the overall throughput of the wireless network. The airtime for each STA in this scenario is presented in Table 6.  
In the upload scenario, the airtime results for each station generally align with those observed in the download scenario. However, it is notable that when the delayed ACK is set to 2, the general airtime fairness algorithm produces significantly higher results compared \begin{table}
\begin{tabular}{l l l l l} \hline \hline
**DelACK** & **QoS Algorithm** & **Sta1** & **Sta2** & **Sta3** & **Fairness Index** \\ \hline
1 & Default & 0.16 & 0.17 & 0.24 & 0.9642 \\
1 & General Airtime Fairness & 0.32 & 0.11 & 0.1 & 0.7659 \\
1 & Our Airtime Fairness & 0.19 & 0.18 & 0.18 & 0.9995 \\
2 & Default & 0.21 & 0.14 & 0.22 & 0.9611 \\
2 & General Airtime Fairness & 0.26 & 0.15 & 0.15 & 0.9202 \\
2 & Our Airtime Fairness & 0.2 & 0.18 & 0.19 & 0.9961 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Airtime comparison of QoS algorithms in UL scenario. \begin{table}
\begin{tabular}{l l l l} \hline \hline
**DelACK** & **TCP Congestion Control Algorithm** & **Total Throughput** & **Airtime Fairness Index** \\ \hline
1 & Reno & 21.14 & 0.9992 \\
1 & Vegas & 21.15 & 0.9992 \\
1 & Cubic & 21.14 & 0.9992 \\
1 & BBR & 21.12 & 0.9972 \\
2 & Reno & 26.03 & 0.9998 \\
2 & Vegas & 25.96 & 0.9996 \\
2 & Cubic & 25.97 & 0.9996 \\
2 & BBR & 25.97 & 0.9995 \\ \hline \hline \end{tabular}
\end{table}