# Beam-Hopping-Based Resource Allocation in Integrated Satellite-Terrestrial Networks
## 6 Simulation Results
### Simulation Results for MMCDR  
To evaluate the performance of the proposed resource allocation schemes for MMCDR, the following schemes are used as the baselines in the simulations:  
* The resource allocation scheme aiming at maximizing the minimum CDR of the satellite system (MMCS) [25]. The satellite allocates the time slots according to the average traffic demands of the satellite terminals, and the terrestrial BSs outside the dynamical protection zones can perform transmission. * The RRA scheme. * The DRA scheme, where the MMCS scheme is adopted in the satellite system with half of the bandwidth. Figure 7 depicts the minimum CDR in the ISTN as a function of the average total traffic demand of the satellite system in Gbps. The average total traffic demand of the satellite system is the sum of the average traffic demand of each satellite terminal, and the average traffic demand of each terrestrial system is evenly distributed from 250 to 1050 Mbps. The minimum CDR of the proposed optimal algorithm is always higher than that of the other schemes since it provides the optimal resource allocation results for the ISTN. Regardless of the change in the traffic demand, the gap between the minimum CDRs of the greedy algorithm and the optimal algorithm is relatively small. The MMCS, RRA, and DRA schemes cannot achieve the desirable performance since part of the terrestrial BSs or satellite terminals has not been allocated enough transmission resources. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Requested** & **Optimal** & **Greedy** & **MTCS** & **RRA** & **DRA** \\ \hline
1 Gbps & 100\% & 100\% & 99.90\% & 88.54\% & 49.98\% \\
2 Gbps & 100\% & 100\% & 98.53\% & 88.87\% & 49.89\% \\
3 Gbps & 100\% & 100\% & 94.69\% & 88.59\% & 49.77\% \\
4 Gbps & 100\% & 100\% & 91.16\% & 88.60\% & 49.98\% \\
5 Gbps & 100\% & 100\% & 89.53\% & 88.83\% & 50.02\% \\
6 Gbps & 100\% & 100\% & 88.43\% & 88.57\% & 50.04\% \\
7 Gbps & 100\% & 100\% & 86.09\% & 88.82\% & 49.82\% \\
8 Gbps & 100\% & 100\% & 85.56\% & 88.95\% & 50.10\% \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The satisfaction of the terrestrial systems. Figure 6: CDF of the CDR of satellite terminal. To reveal the intrinsic factors affecting the minimum CDR in the ISTN, Figure 8 and Figure 9 show the minimum CDR of the satellite terminals and the minimum CDR of the terrestrial systems, respectively. The MMCS scheme can maximize the minimum CDR of the satellite terminals, but the minimum CDR in the ISTN is mainly limited by the minimum CDR of the terrestrial systems. The RRA scheme and the DRA scheme do not consider the traffic demands of the terrestrial systems, so the minimum CDR of the terrestrial systems remains at a certain value. When the average traffic demand is relatively low, the minimum CDR in the ISTN is subject to the minimum CDR of the terrestrial systems. As the average traffic demand increases, the minimum CDR of the satellite terminals degrades significantly, so the minimum CDR in the ISTN reduces accordingly. By comparison, both the optimal algorithm and the greedy algorithm can keep the minimum CDR of the satellite terminals and the minimum CDR of the terrestrial systems at the same level, which guarantees fairness in the ISTN. Figure 8: Minimum CDR of the satellite terminals with varying traffic demand of the satellite system. Figure 7: Minimum CDR in the ISTN with varying traffic demand of the satellite system. Furthermore, Figure 10 and Figure 11 present the CDF of the CDR of the satellite terminal and the CDR of the terrestrial system, respectively. The average total traffic demand of the satellite system is set to 3 Gbps. Because the MMCS scheme only considers the traffic demands of the satellite terminals, the CDRs of the satellite terminals are controlled within a desirable range, while some of the terrestrial systems cannot obtain enough transmission resources. The RRA scheme results in large differences among the CDRs of the satellite terminals because of the mismatch between the transmission capacity and traffic demands.