# Adaptive QoS-Aware Multi-Metrics Gateway Selection Scheme for Heterogenous Vehicular Network +
## 6 Conclusions and Future Work  
In this paper, we introduced a non-cluster-based adaptive gateway selection scheme that manages the QoS for a variety of vehicular applications. The suggested AQAGS scheme focuses on maintaining the QoS of vehicle applications. Furthermore, the AQAGS ensures that the LTE network is fully used in delivering high-quality services to VANET users. The proposed scheme utilizes several metrics in the gateway section process, and the SAW technique was adopted to optimize the selection process. Moreover, the AQAGS scheme was validated using simulation and benchmarked with cluster-based (i.e., CMGM) and non-cluster-based schemes (i.e., Adroit). FTP and VoIP applications were utilized for evaluation purposes. In several number-checked scenarios, the AQAGS scheme retained the delay requirement values for both FTP and VoIP. However, the results show that when the number of vehicles increases, the QoS becomes difficult to maintain due to the congestion that is normally experienced on the LTE side. This enforces the AQAGS method to route the delay-tolerant application FTP to the MGW, which slightly increases the delay and packet  
Figure 11: Evaluation of mixed application types (FTP vs. VoIP) vs. vehicle speed: (**a**) the vehicle speed vs. the average delay; (**b**) the vehicle speed vs. the CPO. loss. Moreover, the results highlight that the AQAGS algorithm reduces the overhead that is normally experienced with a cluster-based scheme such as CMGM by eradicating the formation of clusters in the highly dynamic environment of VANETS. The AQAGS scheme improves the link failure that is normally experienced in a non-cluster-based scheme such as Adroit by considering the link lifetime prediction that can give prior information on when the link might be broken. This saves the packet delay and increases the throughput and packet delivery ratio. Overall, the AQAGS method shows a better maintenance of the QoS compared with the benchmarked schemes. The main limitation of the current research is that the investigation of the proposed scheme's performance has been done by using a network simulation. The results from the network simulation cannot be guaranteed to be the same as in real-world scenarios. Moreover, the suggested parameters in this study are not considered the obstacles and the noise signaling that may be potentially present in real-world scenarios. Aside from these points, the behavior of the driver on the road was not taken into the consideration in the current study in the case of the proposed AQAGS scheme. Driver behavior is considered a crucial parameter in VANETs that influences much of the stability of the gateway selected. Therefore, we recommend that future works investigate the AQAGS scheme in a real-world scenario by considering the driver behavior parameter beside the issues related to traffic obstacles and noise signaling that occurs in a real-world scenario. In addition, we aim to investigate the performance of the AQAGS method in a large-scale network to validate its efficiency in maintaining the QoS in large vehicle densities with several application requests. Conceptualization: M.A. ([PERSON]), R.A. ([PERSON]), E.S. and M.I. ; methodology: M.A. ([PERSON]) and R.A. ([PERSON]); software: M.A. ([PERSON]); validation: R.A. ([PERSON]) and B.S. ; formal analysis: M.A. ([PERSON]) and R.A. ([PERSON]); investigation: M.A. ([PERSON]), R.A. ([PERSON]) and B.S. ; resources: R.A. ([PERSON]), M.A. ([PERSON]) and B.S. ; data curation: M.A. ([PERSON]), R.A. ([PERSON]), E.S., M.I. and R.A. ([PERSON]); writing--original draft preparation: M.A. ([PERSON]); writing--review and editing: M.A. ([PERSON]), [PERSON] ([PERSON]), M.A. ([PERSON]), B.S. and R.A. ([PERSON]); visualization: M.A. ([PERSON]) and [PERSON] ([PERSON]); supervision: [PERSON]. ([PERSON]), E.S. and M.I. ; project administration: [PERSON]. ([PERSON]), [PERSON] and M.I. ; funding acquisition: M.A. ([PERSON]). All authors have read and agreed to the published version of the manuscript.