# A TCP Acceleration Algorithm for Aerospace-Ground Service Networks
## 4 Experimental Results
### Results Analysis
#### 4.2.1 Average Throughput  
The average throughput curves of the four congestion control algorithms at a bandwidth of 1 Gbps and network delays of 20 ms, 30 ms, 50 ms, and 80 ms are presented in Figures 5-8, respectively. The throughput was tested three times and averaged at each packet loss rate. The average throughput rate of BoostTCP was always the highest among all algorithms, and its predominant position became more apparent with packet loss, achieving a 26-41% enhancement over the BBR. The average throughput rate of the Reno algorithm was always the lowest among all algorithms. The average throughput rate of the Cubic algorithm decreased the most rapidly with the packet loss rate among all algorithms. Figure 5: The throughput curves of the four congestion control algorithms as a function of the packet loss rate at a network delay of 20 ms. The average throughput results of the four congestion control algorithms at a packet loss rate of 0.05% and a bandwidth of 1 Gbps is shown in Figure 9. The results presented in Figure 9 were averaged for each time delay. The average throughput rate of the BoostTCP algorithm was always the highest among all algorithms, and its advantage over the other algorithms became even more obvious at a longer time delay. Compared to the BBR algorithm, the average throughput of the BoostTCP algorithm was nearly identical in the early stages and increased to 2.3 times that of the BBR algorithm at a network delay of 100 ms. Among all algorithms, the Reno algorithm had the lowest average throughput. The average throughput rates of the Cubic and BBR algorithms decreased more rapidly than that of the BoostTCP algorithm with a time delay. Figure 6: The throughput curves of the four congestion control algorithms as a function of the packet loss rate at a network delay of 30 ms.  
Figure 7: The throughput curves of the four congestion control algorithms as a function of the packet loss rate at a network delay of 50 ms. According to the experimental results, BoostTCP had the highest average throughput under most conditions among all algorithms. This was because BoostTCP's bandwidth detection mechanism was based on learning transmission history and considered actual throughput and roundtrip time factors, which could fully use the link's excess bandwidth. Compared to the BoostTCP algorithm, the BBR algorithm's throughput was less, and the rate dropped more rapidly with a longer time delay. The reasons for this were that the convergence speed of the BBR algorithm was too slow, the sensitivity of the bandwidth detection stage was insufficient, and issues, such as delay and jitter, were ignored. The  
Figure 8: The throughput curves of the four congestion control algorithms as a function of the packet loss rate at a network delay of 80 ms.  
Figure 9: The throughput curves of the four congestion control algorithms versus the network delay at a packet loss rate of 0.05%. Reno algorithm had the lowest average throughput for various random packet loss rates among all algorithms. Further, the Cubic algorithm had a higher throughput than the Reno algorithm, but the throughput rapidly decreased as the rate of random packet loss increased. Since the Cubic congestion control was based on packet loss, this was necessary. Random packet loss could significantly impact its judgment of network conditions, resulting in performance degradation. The main idea of the BBR algorithm is to detect the maximum bandwidth and minimum roundtrip time continuously and alternately and then estimate overall network congestion using the two extreme values. Thus, the minimum roundtrip time accuracy is critical in determining the BBR algorithm's impact on network congestion. The ground network environment's primary characteristics are a high delay and sufficient bandwidth. In this case, the minimum roundtrip time is no longer capable of responding to network congestion accurately.