# Review and Comparison of Emerging Routing Protocols in Flying Ad Hoc Networks
## 4 Routing Protocols
### Position Aware Routing Protocols
#### 4.2.5 Discussion and Analysis  
Table 3 provides the comparison of the QoS parameters which were used for evaluation of above-mentioned protocols. Form the table, it can been seen that each protocol just focuses on 3 or 4 performance indexes, and none of them can include all the parameters. Furthermore, compared with the topology aware routing protocols, the indexes of channel utilization, link quality, and collision safety are all not considered, but a few new performance indexes, such as network disconnection time and energy consumption, are included. From the comparison of performance indexes utilized, we can see that different kinds of routing protocols have different advantages and can be adapted to different application scenarios. The author of [42] used the three-dimensional (3D) estimation method to choose intermediate nodes. In this paper, the author considered flying nodes in 3D conditions, combined directional and omnidirectional transmission in protocol. Article [43] predicted the nodes's position by locally weighted linear regression method. This paper is mainly focused on the dynamic adjustment of beacon frequency to cope with the dynamic changes in the network, without considering the stereoscopic nature of network. Because the routing requirement in FANET is higher than in MANET, the authors of [45] comprehensively considered link, traffic, and spacial distance in network and designed a new routing protocol to prevent network interruption. This article provides researchers with many directions for further study for FANET. However, article of [46] combined FANET with ground base station to form a new network, which could help UAVs handle the transfer of a large number of data traffic. From what has been discussed above, as far as the actual application of FANET is concerned, RARP [42] is the most suitable routing protocol.  
This type of protocols have achieved a high data transmission success rate, but there are still some deficiencies, as described below.  
(1) The increase in node density reduces the packets delivery rate of during transmission process.  
(2) In the directional data transmission, very frequent location changes will lead to route fails.  
(3) A lot of routing overhead is generated during route setup and maintenance.  
Therefore, there is an urgent need to develop a routing mechanism capable of handling node density changes and frequent changes in node locations to reduce routing failures as well as increasing average path survival time.  
\begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline  & **PACKET** & **PACKET** & **END-TO-END** & **END-TO-END** & **ROUING** & **NETWORK** & **ENERGY** & **ENERGY** \\
**PROTOCOL** & **DELIVERY** & **LOSS** & **DELAY** & **THEROIGHT** & **OVERHEAD** & **TIME** & **CONSUMPTION** \\ \hline
**RARP**[42] & \(\checkmark\) & x & x & x & x & \(\checkmark\) & x \\
**ABPT**[43] & \(\checkmark\) & x & x & x & \(\checkmark\) & x & x \\
**JarmRout**[45] & \(\checkmark\) & \(\checkmark\) & \(\checkmark\) & x & x & \(\checkmark\) & \(\checkmark\) \\
**GCS**[46] & x & x & x & \(\checkmark\) & x & \(\checkmark\) & x \\ \hline \hline \end{tabular}
\end{table}
Table 3: Comparison of metrics used in position aware routing protocols.