# Adaptive QoS-Aware Multi-Metrics Gateway Selection Scheme for Heterogenous Vehicular Network +
## 2 Related Work
\begin{tabular}{c} Huge loads are exerted on the selected \\ gateway due to the limited number of \\ gateways available. \\ Williams of the selected vehicle to act as a \\ gateway need further investigation \\ \end{tabular}  \\ \hline
[26] & Non-cluster & Proactive & \ \begin{tabular}{c} Number of hops, \\ throughput, traffic load, \\ route expiration time \\ \end{tabular}  & SAW & MATLAB & \begin{tabular}{c} Fixed gateways are used, increasing the \\ number of handovers due to the high speed \\ of the vehicles. \\ This leads to frequency network \\ disconnection, which makes seamless \\ connection difficult to achieve \\ \end{tabular}  \\ \hline
[30] & Non-Cluster & Reactive & \ \begin{tabular}{c} Mobility, direction cost of \\ packet, number of hops, \\ RSS, position, delay, \\ throughput, packet jitter, \\ packet loss rate, network \\ security \\ \end{tabular}  & VIKOR & NS2 & \begin{tabular}{c} The computation complexity of this method is \\ not measured \\ \end{tabular}  \\ \hline
[32] & Non-Cluster & Reactive & \ \begin{tabular}{c} Speed, direction, position, \\ radio transmission range, \\ gateway load \\ \end{tabular}  & PROMETHEE & Customer & \begin{tabular}{c} The overloading condition of the base station \\ before GWS is not determined \\ \end{tabular}  \\ \hline
[34] & Non-cluster & Reactive & \ \begin{tabular}{c} Correctly decoded \\ probability, gateway delay \\ time, velocity relative \\ to gateway \\ \end{tabular}  & SAW & MATLAB & \begin{tabular}{c} The work only considers vehicles moving in \\ the same direction, movements of opposing \\ directions are not taken into account \\ \end{tabular}  \\ \hline
[36] & Cluster & Hybrid & \ \begin{tabular}{c} RSS, available route \\ capacity, link stability \\ \end{tabular}  & SAW & NS2 & \begin{tabular}{c} Cluster stability and maintenance issues are \\ not addressed \\ \end{tabular}  \\ \hline
[28] & Non-Cluster & Hybrid & \begin{tabular}{c} RSS, number buffering \\ packets, distance \\ \end{tabular}  & \ \begin{tabular}{c} Fitness value \\ functions \\ \end{tabular}  & NS2 & \begin{tabular}{c} The overloading condition of the base station \\ before GWS is not determined \\ \end{tabular}  \\ \hline
[37] & Cluster & Hybrid & \ \begin{tabular}{c} RSS, buffering queue load, \\ link connectivity duration \\ \end{tabular}  & Fuzzy logic & NS2 & \begin{tabular}{c} This work does not differentiate between \\ standard video and high-Quality video \\ High quality needs high QoS \\ \end{tabular}  \\ \hline
[38] & Non-cluster & Hybrid & \ \begin{tabular}{c} RSS, route lifetime, \\ available route capacity \\ \end{tabular}  & SAW & NS2 & \begin{tabular}{c} The scheme did not take into consideration \\ the overload issues when all vehicles were \\ allowed to directly connect to the \\ UMTS network \\ \end{tabular}  \\ \hline
[39] & Cluster-based & Reactive & \begin{tabular}{c} link lifetime, distance, \\ mobility, price \\ \end{tabular}  & \ \begin{tabular}{c} Price-based \\ selection \\ function \\ \end{tabular}  & Customer & \begin{tabular}{c} High weight is given to the price factor rather \\ than the network performance factors \\ \end{tabular}  \\ \hline
[40] & Non-cluster & Hybrid & RSS, route lifetime & \ \begin{tabular}{c} RSS indicator \\ function \\ \end{tabular}  & NS2 & \begin{tabular}{c} The research only focuses on non-safety \\ applications, such as audio, video streaming, \\ or gaming \\ Safety applications are not taken \\ into consideration \\ \end{tabular}  \\ \hline
[41] & Cluster-based & Hybrid & \ \begin{tabular}{c} RSS, mobility speed, link \\ stability \\ \end{tabular}  & SAW & NS2 & \begin{tabular}{c} The scheme shows higher complexity due to \\ the unstable cluster formation \\ \end{tabular}  \\ \hline
[22] & Cluster-based & Hybrid & \ \begin{tabular}{c} Direction, RSS, \\ IEEE80211p wireless \\ transmission range. \\ \end{tabular}  & SAW & NS2 & \begin{tabular}{c} Clusters are not stable and need to be \\ re-formulated every second \\ \end{tabular}  \\ \hline
[15] & Cluster-based & Hybrid & \