## 4 Simulation Results  
This section will evaluate the performance of the proposed scheme through numerical simulation. Three typical interference mitigation mechanisms are used as comparison algorithms, which are eICIC [17], UMA-ABS [18] and Synchronous [19]. The performance of the algorithm in this paper and the above three algorithms are compared. Consider a co-channel TDD heterogeneous cellular network in the simulation. One HAPS is deployed in the center, and several GBS are randomly deployed around the HAPS. In the simulation, each user generates a downlink service flow with probability 1, and an uplink service flow with probability 0.5. The probability that the service flow generated by the user is soft QoS service flow and BE service flow each account for 50%. The target signal-to-noise ratio of the user's transmit signal is 15 dB, and the user's maximum transmit power is 23 dBm. Table 2 presents the detailed simulation parameters of the HAPS-IMT network. The minimum transmit power of HAPS on LP-ABS is 20 dBm, and the step size is 3 dB. For the utility function in Section 2.4, \(p_{1}=0.2\), \(q_{1}=13\), \(p_{2}=0.4\), and \(q_{2}=13\). The rate requirement of soft QoS service is 3.5 Mbps. In this section, the proposed resource allocation algorithm based on power control and dynamic transmiss \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Value** \\ \hline System Bandwidth & 20 MHz \\ Cell topology of HAPS and GBS & Regular hexagonal cell \\ Cell radius of HAPS & 20 km \\ Cell radius of GBS & 800 m \\ Number of HAPS & 1 \\ Number of GBS & 20 \\ Transmit power of HAPS and GBS & 46 dBm \\ Antenna gain & 15 dBi \\ Number of UE per HAPS & 80 \\ Number of UE per GBS & 20 \\ Path Loss Model of GBS & 3 GPP 36.942 [20] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Simulation parameters. as PCDT. Based on PCDT, the transmission protocol configuration scheme \(\left(\Phi^{n,d},\Phi^{n,u},\Phi^{l}\right)\) can be obtained. In the simulation comparison scheme, it is assumed that the transmission protocol configuration of eICIC's HAPS downlink transmission, uplink transmission and APS is also \(\left(\Phi^{n,d},\Phi^{n,u},\Phi^{l}\right)\). However, each GBS and HAPS maintains synchronization on downlink and uplink transmission. Each GBS and HAPS performs dynamic TDD transmission during the ABS cycle. In the UM-ABS algorithm, the ratio of HAPS downlink and uplink transmission frames is \(\Phi^{n,d}:\left(\Phi^{n,u}+\Phi^{l}\right)\). Each GBS maintains synchronization on the downlink transmission of HAPS and sets dynamic TDD transmission on the uplink transmission of HAPS. In the Synchronous algorithm, HAPS and GBS maintain a synchronized configuration, and the ratio of downlink and uplink transmission frames is \(\left(\Phi^{n,d}+\Phi^{l}\right):\Phi^{n,u}\). Figures 7 and 8 evaluate the relationship between the average throughput and load of the downlink and uplink service flows. As shown in Figure 7, the PCDT algorithm can achieve better throughput performance than other algorithms in the downlink. The reason is that the interference mitigation mechanism is adopted in the PCDT algorithm. That is, the downlink transmission resources of HAPS are effectively used through the power control strategy. In addition, it can be seen from Figure 7 that the throughput performance of the eICIC algorithm is higher than that of the synchronization algorithm. This indicates that the performance gain of the ABS frame through interference avoidance is higher than the loss caused by the waste of resources. Figures 9 and 10 show the relationship curve between the outage probability of soft QoS service flow and the number of UEs. The outage probability is defined as the proportion of service flows whose achievable rate is less than the rate requirement in soft QoS service flows. It can be seen from the figure that the PCDT algorithm can obtain the lowest average outage probability in the downlink.