## 4 Simulations
### Multiple Data Streams on Shared Medium  
In this subsection, the behavior of multiple streams on shared medium was studied. Four types of scenarios were investigated, and the summary is shown in Table 4. The scenarios differed by three variable parameters: (i) data generation throughput, (ii) order of data stream start, and (iii) starting time of specific stream. Details of the scenarios and results are described below, and the topology is shown in Figure 12. There are a total of four simulation plots. The delay of 5 s for second and third streams was selected as a value that is typical for real-field scenarios and from experience from Smart Grid network pilots. Figure 12: Simulation topology for multiple streams on shared medium. \begin{table}
\begin{tabular}{l c c c c} \hline \hline  & **NetSim** & **Riverbed Modeler** & **OMNET++** & **NS-3** \\ \hline Interface & Graphical & Graphical & Graphical, text & Text \\ Licence & Commercial & Commercial & Free & Free \\ Operating system & Windows & Windows & Windows, Linux, Mac OS & Windows, Linux \\ Latest version & 12.1 01/2020 & 17.5.A PL7 & 5.6.2-05/2020 & 3.31-06/2020 \\ Active development & YES & YES & YES & YES \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Simulators comparison. **Scenario 1A**: First two streams generate data with speed of 2/3 of maximum data throughput, and their transmission starts at time 0 s. Last stream starts to transmit data after 5 s. Figure 13 shows the results with the delay of the last stream of 5 s. First two streams completely overlap and in the beginning cover the full channel throughput. When the last stream joins, the speed starts to decrease. The last stream starts with a very low data rate but it slowly increases until the speed of all the streams is equal. **Scenario 1B**: This scenario differs from the previous in bandwidth allocation for first two streams. The first now generates data with the maximum channel throughput whereas the second with only 1/3 of the maximum. Other parameters remained unchanged. Figure 14 shows the result. First two streams stopped overlapping due to the different data rates. The first stream now occupies most of the throughput and second the stream keeps the speed approximately in between stream one and three. As in the previous case, after some time the transmission speeds of all the streams stabilized on a certain level. The speeds remain equal until one of the stream stops transmitting. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Scenario** & **1A** & **1B** & **2A** & **2B** \\ \hline DataRate Stream 1 & 2/3 & 3/3 & 2/3 & 3/3 \\ DataRate Stream 2 & 2/3 & 1/3 & 2/3 & 1/3 \\ DataRate Stream 3 & 3/3 & 3/3 & 3/3 & 3/3 \\ Start time Stream 1 & 0 & 0 & 5 & 5 \\ Start time Stream 2 & 0 & 0 & 5 & 5 \\ Start time Stream 3 & 5 & 5 & 0 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Simulation scenarios summary for multiple stream simulations. Figure 13: Scenario 1A. **Scenario 2A**: Here, the first two streams start generating data at the same time but are delayed by 5 s. In Figure 15, a third stream generates data from the time 0 s and the first two streams are delayed by 5 s. After some time, the throughput of all streams balances to the same level. **Scenario 2B**: In comparison to the previous case, generation speeds of the first two streams (delayed streams) were modified to 3/3 and 1/3 of the maximum throughput, and the major difference was only in the time of reaching the balanced throughput. First stream reaches that slightly faster then the second as shown in Figure 16.  
From the results it is obvious that generation speeds do not affect the final throughput of any stream. In all cases, the line throughput was split equally among all transmitting streams.