# Smart Bandwidth Assignation in an Underlay Cellular Network for Internet of Vehicles
## 5 Proposed Solution Tests and Validation
### Simulation Results
Figure 7b provides evidence that our proposal offers the highest spectral efficiency compared with the other alternatives evaluated. Therefore, according to the results obtained, the presented RRM methodology is able to take advantage of RBs sending a higher number of bytes than the alternatives. This fact allows us to provide a service to a higher number of users, or at least, to provide better service to the users. Table 6 summarizes the results presented in Figure 7b and remarks the better performance of the RRM solution proposed in this paper. As it is defined in Table 1, the maximum spectral efficiency per RB is 180 bytes. Therefore, from Figure 7a where the maximum value reached by our RRM proposal is 160 bytes, we could say this proposal accomplishes the 88.89% of the maximum spectral efficiency value and, on average, it reaches 66.32%. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**CUE’s Message** & **Underlay V2V** & **Our Approach V2V** & **Overlay V2V** \\
**Size (Bytes)** & **Spectral Efficiency (Bytes)** & **Spectral Efficiency (Bytes)** & **Spectral Efficiency (Bytes)** \\ \hline
100 & 75.5158 & 111.5009 & 82.0601 \\
200 & 74.5242 & 105.0593 & 82.1765 \\
300 & 74.6291 & 102.4324 & 82.4734 \\
400 & 74.5778 & 1  
This section finishes with the analysis of energy efficiency, i.e., the number of bytes transmitted per watt. First, Figure 8 shows the energy efficiency offered to V2V links. On the one hand, Figure 8 presents the energy efficiency of V-UEs' transmissions in each scenario and, on the other hand, Figure 8 reveals the total average results of this metric for the different RRM evaluated. In Figure 8a, similar results are presented for all the scenarios except at the Scenario 9, which provides higher energy efficiency. Furthermore, Figure 8b demonstrates that the proposed solution provides higher energy efficiency for V2V links than the other RRM methodologies evaluated. These values are summarized in Table 7 which also evidences that the energy efficiency of V2V communications is not related with the C-UEs' packet size. Finally, Figure 9 presents the total energy efficiency offered by the RRMs to users. In this way, Figure 9a shows the total energy efficiency in each scenario and Figure 9b presents the total average energy efficiency for all the scenarios. \begin{table}
\begin{tabular}{c c c c} \hline
**CUE’s Message** & **Underlay V2V** & **Our Approach V2V** & **Overlay V2V** \\
**Size (Bytes)** & **Spectral Efficiency (Bytes)** & **Spectral Efficiency (Bytes)** & **Spectral Efficiency (Bytes)** \\ \hline
100 & 95.7937 & 129.2273 & 82.1711 \\
200 & 99.1588 & 133.1300 & 83.8041 \\
300 & 102.5021 & 134.4520 & 84.8239 \\
400 & 103. In Figure 9a, the highest values for energy efficiency are reached in Scenario 1, where there are 5 C-UEs and 45 V-UEs. This means that the energy efficiency of V2V communications is higher than the common cellular communications, which makes sense because the distance between transmitter and receiver in a V2V communication is usually lower than a cellular one. However, Figure 9b shows that in some cases the overlay RRM offers higher energy efficiency than the RRM proposed in this paper. This is owing to the fact that overlay RRM does not have to mitigate interferences between cellular and V2V users. This values are exposed in Table 8 and provide evidence that for small C-UEs' packet size, from 100 to 600 bytes, the energy efficiency offered by our RRM proposal performs better than the overlay one, but, for bigger C-UEs' packet size, the overlay RRM offers better performance. In any case, for the simulations carried out in this evaluation the total average energy efficiency offered by our RRM proposal is higher that the overlay one.