# Estimation of the Achievable Performance of Mobile Ad Hoc Networks with Optimal Link State Routing
## 3 Results
### Evaluation Metrics and Performance Analysis in MANETs
#### 3.2.1 Route Acquisition Time  
This characteristic is based on measuring the time required to establish the routing table on each network node and to determine the necessary bandwidth for a specific connection based on the class of transmitted traffic. To evaluate the overall route acquisition time \(T_{m}\), we can use the following formula:  
\[T_{m}=T_{H}+T_{\mathrm{TC}}+T_{R} \tag{1}\]  
where  
\(T_{H}\)--time required to receive Hello packets;  
\(T_{TC}\)--time required to receive all TC packets;  
\begin{table}
\begin{tabular}{c c c} \hline \hline MCS index & 7 & \\ \hline Spatial streams, SS & 1 & \\ \hline Modulation scheme & 64-QAM & \\ \hline Coding & 5/6 & \\ \hline \multirow{4}{*}{Data transmission rates (Mbit/s)} & channel bandwidth, & \multirow{2}{*}{GI = 400 ns} & \multirow{2}{*}{72.2} \\  & 20 MHz & \\ \cline{1-1}  & channel bandwidth, & \multirow{2}{*}{GI = 400 ns} & \multirow{2}{*}{150} \\ \cline{1-1}  & channel bandwidth, & \multirow{2}{*}{GI = 400 ns} & \multirow{2}{*}{325} \\ \cline{1-1}  & 80 MHz & \\ \cline{1-1}  & channel bandwidth, & \multirow{2}{*}{GI = 400 ns} & \multirow{2}{*}{650} \\ \cline{1-1}  & 160 MHz & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Transmission rates for the selected modulation and coding scheme.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Network** & \multicolumn{5}{c}{**Quality of Service Classes**} & \\
**Specifications** & **0** & **1** & **2** & **3** & **4** & **5** \\ \hline IP Packet Transfer & \multirow{2}{*}{100 ms} & \multirow{2}{*}{400 ms} & \multirow{2}{*}{100 ms} & \multirow{2}{*}{400 ms} & \multirow{2}{*}{1 s} & \multirow{2}{*}{U} \\ Delay, IPTD & & & & & & \\ \hline \hline \end{tabular} Note: U stands for undefined.  
\end{table}
Table 3: Norms for the characteristics of IP networks with distribution by quality of service classes.  
\(T_{R}\)--time required to establish a channel with the necessary bandwidth between the end receiver node and the transmitting node.  
\[T_{H}=2*X_{H}/R \tag{2}\]  
where  
\(X_{H}=86\) bytes--size of Hello packet (information about one-hop neighbors, transmitted to neighbors with one-hop link);  
\(R\)--speed between the transmitting and receiving node.  
\[T_{TC}=2*(N-1)^{2}*X_{TC}/R, \tag{3}\]  
where  
\(N\)--number of nodes in the network;  
\(X_{TC}=74\) bytes--size of TC packet (information only about one-hop neighbors, transmitted only to MPR one-hop neighbors).  
\[T_{R}=2*(n-1)*X_{R}/R, \tag{4}\]  
where  
\(n\)--number of nodes from the transmitting end node to the receiving end node;  
\(X_{R}=50+16*(n-1)\)--size of RSVP packet.  
It should be noted that the delay calculation formulas were designed to estimate the maximum possible route acquisition time in the network. Figure 4 illustrates the graph depicting the relationship between route acquisition time and the number of nodes in the network. The upper curve corresponds to the network operating in the 802.11 ac standard, while the lower curve corresponds to the network operating in the 802.11n standard.  
As observed from the graph, as the number of nodes in the network increases, more time is required to establish the route. For convenience, Table 4 presents characteristic times for specific numbers of nodes.  
Figure 4: Dependency of route acquisition time on the number of nodes.  
During the calculation of \(T_{m}\), a speed value reflecting the maximum achievable speed between nodes in different standards was used. Depending on the nature of the traffic, network purpose, topology, and other factors, it may be more appropriate to utilize only a portion of the available bandwidth between nodes or allocate the bandwidth for signaling traffic at specific times. At the same time, the route acquisition time will also increase, which, in turn, will affect how much time it takes to transfer data over the network, the fault tolerance of the network, and its capabilities.