# Transport-Layer Limitations for NFV Orchestration in Resource-Constrained Aerial Networks
## 3 Orchestration in Intermittently Available Platforms
### Challenge Summary
  
\begin{tabular}{l l} \hline \hline
**Object of Analysis** & **Challenges/Hardles** \\ \hline \multirow{7}{*}{Limited lifetime of NVI nodes} & \multirow{7}{*}{ \begin{tabular}{} \end{tabular}  } \\  & & SUAVs are autonomous devices that require some power supply source to be operative, and performing different actions such as traffic relaying or executing software functions \\ \cline{1-1}  & & will eventually degrade their battery lifetime. \\ \cline{1-1}  & & All SVNs running inside its payload must be migrated into another operative unit to \\ \cline{1-1}  & & avoid, or mitigate, operational cuts on the services being provided. \\ \cline{1-1}  & & There are no known VIM implementations that consider battery lifetime as a limited \\ \cline{1-1}  & & resource, making VNF migration in these environments suboptimal. \\ \hline \multirow{7}{*}{Intermittent availability of control communications} & \multirow{7}{*}{\ \begin{tabular}{} \end{tabular}  } \\  & & Battery depletion turns these units into volatile nodes that must be replaced by other units. \\ \cline{1-1}  & & These disconnected will break links between the all SUAVs and the GCS, potentially leaving some nodes unavailable to the MANO system. \\ \cline{1-1}  & & This disruption will help transit between; as either the routing protocols will likely \\ \cline{1-1}  & & find a new path, and/or tuning was replaced after some time have passed to converge \\ \cline{1-1}  & & into a stable table. \\ \cline{1-1}  & & is important for a VIM to take into account that this transient state is the normal behavior \\ \cline{1-1}  & & the aircraft, and not interpret these failures as permanent. \\ \cline{1-1}  & & The inclusion of mobility and other wireless phenomena (data-way, weather, etc.) could \\ \cline{1-1}  & & increase this problem since links breakdowns will be none frequent. \\ \hline \multirow{7}{*}{Limited capacity of NVI nodes} & \multirow{7}{*}{ \begin{tabular}{} \end{tabular}  } \\  & & The reduced size of SUAVs constrain the available resources for their payload, including its weigh, size and processing power. \\ \cline{1-1}  & & Most commercial VIMs are the default application-layer protocol, which is not the most appropriate choice for resource-constrained environments, as it could be considered a process-intensive protocol for this units due to the amount of processing power required for its usage. \\ \cline{1-1}  & & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & & \\ \cline{1-1* (19) An specialized VVM could take into account battery lifetime to assign critical VNFs in healthier nodes. Moreover, orchestration could also be improved by using this parameter, as knowing the remaining capacity is essential to trigger VNF migration as well as re-allocation policies. * (20) To manage the placement of SUAVs in a geographical area, implemented the flight control engine as a VNF on every unit, providing its flight trajectories using a VSTM as configuration parameters, which could be used to specify their movement at the deployment of the NS. \begin{table}
\begin{tabular}{p{142.3 pt} p{142.3 pt} p{142.3 pt}} \hline \hline
**Object of Analysis** & **Challenges/Hardles** & **Potential Approaches** \\ \hline \multirow{7}{*}{Transport-layer protocols for control communications} & **Challenges/Hardles** & Use protocols that rely on UDP as its main transport-layer protocol, while moving its reliability mechanisms to the application layer. Examples of this solutions could be: 1) CoAP, which applies the HTTP REST model to be available in resource-constrained environments. 2) QUIC, which is a new transport-layer protocol to