# Seamless Handover Scheme for MEC/SDN-Based Vehicular Networks
## 5 Performance Evaluation
### Simulation Setup  
The system was evaluated over the NS-3 platform, with an open-source traffic simulation from the Simulation of Urban Mobility (SUMO) to provide vehicle mobility. The considered vehicles' mobility was that of the highway. The simulation process ran over a machine with an Intel Core i9 processor and 64 GB RAM. All the required SDN modules for the SDN controller and OpenFlow switches were included with OpenFlow version 1.3.  
The considered simulation topology consisted of the specifications presented in Table 1. A two-lane bidirectional road of 5 Km length was considered for the simulation process. The road was served by five RSU units, with one MEC server connected to each RSU. The specifications of the RSUs and the connected MEC servers are presented in Table 1.  
The vehicles were distributed along the road according to the traffic density shown in Table 1. Three values for the total number of deployed vehicles, N, were considered to investigate the effect of the increase in traffic along the road on the performance of the developed handover scheme. Moreover, three different traffic densities were considered to investigate the effect of the change in the traffic density on the overall network performance. We considered our previously developed offloading scheme introduced in [41] for data offloading in the proposed MEC-based VANET. The offloading parameters are given in Table 1.  
Each vehicle in the developed system was assigned a computing task corresponding to the real task's workload. For the performance evaluation, we considered three performance metrics: the packet delivery ratio (PDR), the percentage of blocked computing tasks, and the percentage of failed handover processes from the total number of required handover processes.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Road length & 5 Km \\ Number of vehicles (N) & N \(\in\) [200, 400, 600] \\ Number of RSUs & 5 \\ Number of MEC units & 5 \\ MEC unit placement & Equidistant \\ Vehicle velocity & V\({}_{\text{t}}\)\(\in\) [30, 40, 50, 60, 70] Km/h \\ Traffic density & Td\({}_{\text{vi}}\)\(\in\) [0.1, 0.2, 0.3] veh./m \\ Radio transmission range of RSUs & 500 m \\ Maximum transmission level & 20 dBm \\ Storage/RAM (MEC) & 2048 Mb \\ Storage/HDD (MEC) & 5 Gb \\ Processing/CPU (MEC) & \(\in\) [0.7, 2.5] GHz \\ Maximum workload & 50 events/s \\ Service rate & 10 Mbps \\ Streaming service bandwidth & \(\in\) [10, 2048] (Kb/S) \\ Vehicle task energy & \(\in\) [20, 80] (watt/s) \\ Initial threshold level, SNR\({}_{\text{Rx-th-1}}\) & 30 dB \\ Third threshold level, SNR\({}_{\text{Rx-th-3}}\) & 20 dB \\ Data rate & 18 Mbps \\ Channel bandwidth & 10 MHz \\ Receiver sensitivity & \(-\)94.0 dBm \\ Packet transmission frequency & 10 Hz \\ Packet size & 190 bytes \\ OpenFlow switch & 1.3 \\ Service rate of controller & 30,000 req/s \\ Average request rate of switch & \(\in\) [1500, 3000] \\ SDN controller processing delay & 0.5 μs \\ OpenFlow switch processing delay & 5 μs \\ \hline \hline \end{tabular}
\end{table}
Table 1: Simulation parameters.