# Review and Comparison of Emerging Routing Protocols in Flying Ad Hoc Networks
## 2 Differences between FANETs and Traditional Ad Hoc Networks  
Wireless ad hoc networks are categorized according to their usage, deployment, communications, and mission objectives. Mobile Ad Hoc Network (MANET) is a kind of ad hoc network, which consists of autonomous wireless devices with no backbone or infrastructure but exhibits self-configuration features. MANET has a wide range of applications, such as disaster relief, military communications, and emergency business meetings. The main advantages of MANET are portability and mobility. The wide application of MANET has enabled sub-categories of ad hoc networking technologies, such as vehicle ad hoc network (VANET) and flying ad hoc network (FANET). In general, these networks have higher mobility and rapid topology changes than typical MANET, because in VANET and FANET, most of the nodes are vehicles and UAVs. VANET is a network that supports vehicle-to-vehicle (V2V) and vehicle-to-perennstalled infrastructure. The main goals of VANETs are to improve traffic efficiency and traffic congestion, access information and news to avoid accidents, \begin{table}
\begin{tabular}{l l l l l l l l l} \hline
**SUBVY** & **YEAR** & **NETWORK** & **DESIGN** & **ROUTING** & **PERFORMANCE** & **QOS** & **COMPARATIVE** & **OPENING** \\
**PAFT** & **YEAR** & **ARCHITECTURE** & **CONSIDERATIONS** & **CATEGORIES** & **ANALYSE** & **METRICS** & **STUDY** & **ISSUES** \\ \hline
[15] & 2013 & x & ✓ & ✓ & x & x & x & ✓ \\
[16] & 2015 & x & ✓ & ✓ & x & x & ✓ & ✓ \\
[17] & 2017 & x & x & ✓ & ✓ & ✓ & ✓ & ✓ \\
[18] & 2017 & x & ✓ & ✓ & ✓ & x & x & x \\
[19] & 2018 & x & ✓ & ✓ & x & x & ✓ & x \\
[20] & 2018 & x & x & ✓ & ✓ & x & ✓ & x \\
[21] & 2019 & ✓ & x & ✓ & ✓ & x & ✓ & ✓ \\
[22] & 2019 & ✓ & x & ✓ & ✓ & x & ✓ & ✓ \\
[23] & 2020 & ✓ & x & ✓ & x & ✓ & ✓ \\
**Ours** & 2020 & ✓ & ✓ & ✓ & ✓ & ✓ & ✓ & ✓ \\ \hline \end{tabular}
\end{table} 
Table 1: Comparison of existing survey literatures. and for entertainment purposes while driving. The flying ad hoc network (FANET) is a special type of MANET with high maneuverability. In FANETs, the nodes are usually unmanned aerial vehicles (UAVs) in an unmanned Ariel system environment. Although FANET is derived from the traditional ad hoc networks, it also can be clearly identified from existing ad hoc networks based on its utility, applications, communication, and target objectives. The following presents some pivotal differences between FANETs and traditional ad hoc networks. **A. Node mobility**  
Node mobility is the most significant difference between FANET and other ad hoc networks. Compared with FANETs, nodes of VANETs and MANETs move relatively slowly. According to the article [26], the speed of a UAV is 30-460 km/h, which leads to some new challenges in communication design [27]. **B. Mobility models**  
The MANET node moves in a defined domain, the VANET node moves on the highway, and the FANET node flies in the air. In the multi-UAVs system, the flight plan is not fixed. Due to the deviation of the environment or the update of operation, the flying trajectory also needs to be recalculated at any moment. **C. Node density**  
Node density refers to the number of nodes in a unit area. Because the flying environment of the UAV is the sky far from the ground, and the flying speed is fast, the distance between the nodes is very long, so the node density is relatively sparse. **D. Topological changes**  
Link quality changes very quickly due to UAV scheduling and FANET node distance changes, which will also cause link interruption and topology changes [28]. **E. Radio propagation model**  
The operating environment of FANETs affects the propagation characteristics of radio. The MANET and VANET nodes are very close to the ground, and in most cases there is no line of sight between the sender and the receiver, and the radio signal is mainly affected by the geographical structure. On the contrary, FANET nodes are far from the ground and can be driven remotely at maximum distance, with a line of sight between UAVs [15].