## 5 Conclusions and Future Work  
With the VaNetChain, we have presented a solution to allow robust, reliable, and traceable communications in VANETs, which can provide foundations for the development of new applications that depend on ensuring certain properties for the data generated and transmitted by the vehicles. This is achieved by entwining the blockchain protocols with the architecture and the procedures of a virtualization layer. On the one hand, this serves to overcome the limitations of the consensus and reputation mechanisms presented in the past. On the other, it is the key to guaranteeing proper operation of blockchain technology, whereas previous approaches failed to cope with the challenging environment of VANETs.  
The simulation experiments demonstrate the feasibility of the proposal, while reflecting the optimal number of mRNAs to deploy. The effort due to emulating a network of virtual nodes pays off in terms of packet delivery ratios and end-to-end delays. The findings about the density of mRNAs suggest that the mRNAs can be turned on or off depending on the traffic conditions observed at any given moment.  
Currently, we are investigating the adoption of the IEEE 802.11 bd standard (an evolution of IEEE 802.11p) in our simulation environment, in order to study the impact on VaNetChain performance of having connections with better spectral efficiency, greater reliability and a wider range [66].  
\begin{table}
\begin{tabular}{l l l l} \hline \hline
**Smart Contract** & **Gas Used** & **Actual Cost [Ether]** & **USD** \\ \hline Whitelist & 70254 & 0.000140508 & 0.056 \\ \hline Blacklist & 77100 & 0.0001542 & 0.061 \\ \hline Announcement & 34041 & 0.000068082 & 0.027 \\ \hline Verification & 94375 & 0.00018875 & 0.075 \\ \hline Acceptance & 95863 & 0.000191726 & 0.076 \\ \hline Valuation & 164100 & 0.0003282 & 0.13 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Cost of intelligent contract execution (Gas price = 2 Gwei, 1 Ether = 395.02 USD, Date: October 2020).  
**Author Contributions:** Investigation, [PERSON]; methodology, [PERSON] and [PERSON]; software, [PERSON], [PERSON], and [PERSON]; supervision [PERSON]; validation, [PERSON] and [PERSON]; visualization, [PERSON]; writing--original draft, [PERSON] and [PERSON]; writing--review and editing, [PERSON] and [PERSON]. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work has been supported by the European Regional Development Fund (ERDF) through the Ministerio de Economia, Industria y Competitividad (Gobierno de Espa) research project TIN2017-87604-R, and through the Galician Regional Government under the agreement for funding the atlanTTic Research Center for Telecommunication Technologies and its Program for the Consolidation and Structuring of Competitive Research Groups.  
**Acknowledgments:** I would like to express my gratitude to the Universidad Politecnica Salesiana and its Grupo de Investigacion en Telecomunicaciones y Telematica (GITEL) for the scholarship granted to study the program of Maestria de Investigacion en Telematica (P.V.-T.).  
**Conflicts of Interest:** The authors declare no conflict of interest.