# Adaptive QoS-Aware Multi-Metrics Gateway Selection Scheme for Heterogenous Vehicular Network +
## 5 Results and Discussions  
### Evaluation of Fixed Vehicle Applications versus Number of Vehicles  
In this scenario, we measured the impact of the application type on the execution of the AQAGS, CMGM, and Adroit schemes. Our objective was to investigate how these three algorithms behaved on maintaining the QoS of vehicle applications (i.e., VoIP and FTP) in both sparse and dense scenarios. The number of vehicles ranged from 50 to 500, at 50 vehicle intervals. VoIP or FTP traffic were generated by 20% of the vehicles. The vehicles' high speed was limited to 60 km/h, and the IEEE 802.11p wireless communication range was limited to 300 m.  
Figure 6a demonstrates that the PDR decreased as the number of vehicles rose. Both the tested applications and strategies exhibited this trend. In contrast to the CMGM and Adroit algorithms, the PDR for AQAGS with VoIP applications was slightly lower. When there were only 50 vehicles, the PDR for AQAGS with VoIP was 99.83%, which was 21.6% and 16.29% higher than in VoIP applications with CMGM and Adroit, respectively. Only the first 250 vehicles appear to have had a reliable PDR in the VoIP application. The PDR dropped by 1.33% as the number of vehicles exceeded 250. Congestion on the LTE side is what caused this drop. In contrast, the PDR for CMGM and Adroit using VoIP noticeably decreased during peak hours: from 78.23% to 55.01% for CMGM, and from 83.54% to 69.32% for Adroit, respectively. Comparing the VoIP applications with CMGM and Adroit, respectively, AQAGS's PDR was generally 29.81% and 23.64% higher. These findings demonstrate that the AQAGS scheme kept the VoIP application's QoS for several mobile vehicles. This is due to AQAGS giving VoIP connections a higher priority to the LTE infrastructure. When this traffic is active, no MGW needs to be defined. This reduces the packet drops, which typically happens when the packets are transferred through the MGW. In contrast, the AQAGS scheme exhibited a PDR value that is comparable to that of the VoIP application when FTP was used in a sparse scenario. This is because all of the IVs have the option to link directly to the LTE infrastructure network at lower vehicle densities without specifying an MGW. However, as the number of vehicles increases, MGWs are required for FTP applications to connect to an LTE-eNB. As the number of vehicles reached 500, the PDR of the FTP application decreased to 83.07%, which was 16.76% lower than when the number of vehicles was 50. The suggested AQAGS scheme only chooses a mobile gateway when the FTP application is running and when the usable load capacity of the LTE network exceeds a predetermined threshold. All packets must pass through the MGW, which must be established at this location. For the CMGM and Adroit schemes, this is not the case. When the number of vehicles increased, CMGM exhibited a higher packet loss. When the number of vehicles was increased from 50 to 500, the PDRs of CMGM and Adroit decreased from 82.21% to 53.23% and 90.34% to 70.32%, respectively. This astounding drop occurred due to the constant requirement of both mechanisms to define the MGW for IV traffic transmission. Additionally, the CMGM scheme organizes the vehicles in these extremely dynamic environments using clusters, which frequently results in cluster reformation. As a result, the packet loss increases, and the PDR is impacted. As a result, the PDR reported by CMGM is 7.43% lower than Adroit's. Overall, the results demonstrate that even though the MGW must be established in the cases of larger vehicle numbers to reduce congestion in the LTE infrastructure, the PDR reported by AQAGS was above 80%, which was higher than that of CMGM and Adroit by 29.84% and 12.75%, respectively, with respect to FTP. Figure 6: Evaluation of fixed vehicle applications (FTP vs. VoIP) vs. the number of vehicles: **(a)** the number of vehicles vs. the PDR; **(b)** the number of vehicles vs. the throughput. The throughput for two of the evaluated applications is shown in Figure 6b.