# A Method for the Rapid Propagation of Emergency Event Notifications in a Long Vehicle Convoy
## 7 Future Work  
While the Convoy VANET system works reasonably well in simulation, there are some areas for improvement.  
First is the assumption of symmetric channel reliability. This assumption does not hold for many wireless environments. Including wireless reliability metrics for every peer vehicle in the VS may be infeasible at larger scales. However, finding correlations between transmission and reception reliability may allow for a reasonably accurate lower bound to be assumed.  
Second is the use of physical distance to scale SM retransmission delays. While this is an unambiguous metric, it suffers from differing behaviors based on convoy length, reception distance, etc. It may be beneficial to utilize the position in the convoy instead. For example, if the PRTX is node X and we are node X-2, then the retransmission delay would be scaled off of the difference in those values (i.e., 2) instead of the physical distance.  
Third, making the last vehicle recognize that it is the end of the convoy should be relatively easy to implement. However, outside of simulation, there may be situations where this is not as clear cut and straightforward. For example, the situation becomes more complex if a convoy has a non-convoy vehicle tagging along on the end with a close following distance. If the Convoy VANET is applied to a general use case, then there would need to be a threshold distance at which a trailing vehicle is not considered part of the convoy.  
Lastly, the use of uncancelable delayed transmissions should be addressed. This was a stopgap measure implemented to ensure that at least some retransmissions would occur when a node is missing an SM. It was initially assumed that the main retransmission behavior would be concluded before the VS messages would create uncancelable retransmissions. However, given that VS messages can occur at any time, then this system just creates unnecessary channel congestion. Because this is what ensures the eventual reception of every SM, great care must be taken in crafting a solution. The solution must achieve eventual reception while simultaneously allowing for transmissions to be canceled. If SM transmissions had a special tag for this situation, then the system could be modified such that only the target node's messages could cancel the remaining retransmissions. While not receiving a timely response would lead to the same issue, it should at least occur less frequently. Perhaps the channel reliability could be used, where transmissions are only allowed by nodes with a high chance of being heard and a high chance of hearing a response. This may lead to increased delays, as it is reducing the total number of possible transmitters and thus the total number of chances to be heard. Ultimately, this issue must be rigorously tested to ensure it is acceptably fast and reliable.  
Conceptualization, J.D.S., A.L. and D.M.B.; funding acquisition, A.L. and D.M.B.; project administration, A.L. and D.M.B.; resources, A.L. and D.M.B.; supervision, A.L. and D.M.B.; writing--review and editing A.L. and D.M.B.; everything else, J.D.S. All authors have read and agreed to the published version of the manuscript.  
Funding: This research was funded by Autonomous Solutions (ASI) through Army Contracting Command.  
**Data Availability Statement:** The raw data supporting the conclusions of this article will be made available by the authors upon request.  
**Acknowledgments:** The authors thank [PERSON] for reviewing the original manuscript and offering suggestions on revisions.  
**Conflicts of Interest:** The authors declare no conflict of interest.  
**Distribution Statement A:** Approved for public release; distribution is unlimited. OPSEC#8624.