# Intersection-Based Link-Adaptive Beaconless Forwarding in Urban Vehicular Ad-Hoc Networks
## 4 Performance Analysis
### Simulation Results
#### 4.3.3 Maximum Node Velocity Variation  
This section discusses the performance of routing protocols at different maximum node velocities. Unlike highway and rural scenarios, the maximum speed of the node does not have a direct impact on the performance of routing protocols in an urban environment. This is because of the traffic signals located at various intersections due to which there is a chance that a node with high maximum node velocity may end up having less overall movement during the entire simulation when compared to node having relatively lower maximum node velocity. Hence, to analyze the network performance, instead of using line plots (used in Sections 4.3.1 and 4.3.2), individual box plots highlighting the performance of all routing protocols are plotted for different maximum node velocity conditions as shown in Figure 7.  
Specifically, six maximum node velocity conditions varying from 40 km/hr to 90 km/hr with an incremental step of 10 km/hr are tested. Also in all the conditions, the source node starts moving from the same location. Apart from this, \(R_{src}\) and node density for all the conditions are fixed to 400 kbps and 40, respectively.  
Figure 7a shows the PDR performance of all routing protocols at different maximum node velocity conditions. ILBFC due to its accurate \(\delta_{eff}\) and better relay management conditions gives the highest PDR performance followed by LBF. DBD due to its lack of forwarding zone and strict winner relay management conditions results in both packet drops and packet collision leading to low PDR. For this scenario, the average PDR performance gains of ILBFC over LBF, DBD and BLR are 1.2%, 15.2% and 9.2%, respectively. Figure 7b depicts the average ETE delay of the received data packets at destination for different maximum node velocity conditions. It can be seen that ILBFC offers superior performance having the lowest ETE delay. The mean values of average ETE delay at all maximum node velocities for ILBFC, LBF, DBD and BLR are 18.2 ms, 21.8 ms, 20.8 ms and 20 ms, respectively. The larger ETE delays for LBF in some cases is due to its \(\delta_{link}\) which lets its relay node stay in the \"winner\" state for too long. This results in packets being forwarded in wrong direction leading to an increase in average ETE delay of received data packets. DBD and BLR performs worse than ILBFC while also offering poor PDR performance. Figure 7c highlights the unicasting efficiency of all routing protocols in terms of PRC for different maximum velocity conditions. BLR with an average PRC value of 1.8, due to its relay selection process for every data packet received, ensures the lowest PRC implying high unicast efficiency. However, this comes at the expense of poor PDR and average ETE delay performance. ILBFC with an average PRC value of 7.5, results in relatively lower PRC when compared to DBD (average PRC value of 8.8) and LBF (average PRC value of 11.4) while also having superior PDR and average ETE delay performance than the rest. The impact of incorporating knowledge of road intersections during \(\delta_{eff}\) computation and better winner relay management on unicasting efficiency can be clearly observed when comparing the PRC performance of ILBFC and LBF. LBF due to its lack of road intersection knowledge and ineffective winner relay management results in higher PRC inferring lower unicast efficiency.  
Figure 7: _Cont._