# TARCS: A Topology Change Aware-Based Routing Protocol Choosing Scheme of FANETs
## 5 Conclusions  
On the basis of analyzing the factors affecting the topology changes between nodes in FANETs, a mobility metric named topology change degree (TCD) is first proposed to describe the topology changes of highly dynamic FANETs. Meanwhile, a topology change awareness method is applied to measure topology changes by periodically sensing the topology changes of FANETs and to distinguish the mobility modes of nodes. Then a heuristic routing protocol scheme, TARCS, is proposed in this paper. The TARCS strategy is based on the periodic topology change sensing method, and adaptively selects appropriate routing protocols according to the comparison results of the measured topology change degree and the topology change degree threshold.  
Different from the other single routing protocols proposed in other papers, the TARCS proposed in this paper is an adaptive routing strategy. It is based on the topology change perception between nodes and adaptively selects the routing protocol based on the perceived result. Essentially, it is a flexible routing protocol usage framework. Theoretical analysis and experiments show that:  
* The topology change perception method can sense the topology changes of the network and distinguish several common mobility models of FANET.
* The combined use of routing protocols is more flexible and adaptable than using a single routing protocol in complex scenarios.
* Proper use of the TARCS scheme in complex scenarios can improve network performance.  
Like mobile awareness, topology change perception opens the door to coping with and addressing the problems of highly dynamic FANETs topology changes. As an adaptive routing protocol framework, TARCS is only one of the applications of topology change perception and it proposes a routing implementation idea in a complex scenario of a FANET network. However, all of the above are just a preliminary framework, and there are a series of issues that need to be discussed and resolved. For example, how to effectively set the topology change perception interval? How to accurately calculate the topology change threshold? How to configure the weight factors among the influencing factors? How to deal with the problems of changes in the number of nodes? Subsequent work will continue to study in depth on the above issues.  
**Author Contributions:** [PERSON] is the project administrator. [PERSON] made the investigation. [PERSON] and [PERSON] proposed the methodology. [PERSON] did the validation work and finished the original draft writing. [PERSON] finished the review & editing writing.  
**Funding:** This research received no external funding.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Types of Route Protocols** & **Characteristics** & **Advantages** & **Disadvantages** \\ \hline \multirow{3}{*}{Proactive routing protocol} & Periodically maintain & Short delay; high quality of & High energy consumption; \\  & routing links; suitable for & service; long-pass link. & heavy network load and high \\  & small networks. & & node congestion level. \\ \cline{1-1}  & & & The pass-link is not \\ \cline{1-1}  & & & guaranteed. It takes time to \\ \cline{1-1}  & & when needed. & routing load. & establish a link. Once the link \\ \cline{1-1}  & & & is interrupted, it needs to be \\ \cline{1-1}  & & Combined with proactive & \\ \cline{1-1}  & and reactive routing. & Using proactive routing within the & Only suitable for hierarchical \\ \cline{1-1}  & & & clusters. \\ \cline{1-1}  & & & networks. \\ \cline{1-1} Topology-change-driven & Reselect the appropriate & Nodes obtain information of the & \\ \cline{1-1}  & route based on topology & surrounding topology changes in & Dependent on reference \\ \cline{1-1}  & & & time. Multiple routing protocols & threshold settings and specific \\ \cline{1-1}  & & & are used in combination to suit & routing strategies. \\ \cline{1-1}  & & & complex scenarios. \\ \hline \hline \end{tabular}
\end{table}
Table 5: T Comparisons of topology-change-driven route and other route protocols.