IEEE Technology and Society Magazine - June 2016 - 69

rooms. However, the sensitivity of the data requires high
accuracy for prompt action. All such surveillance missions are complex in nature and generally intolerant to
false alarms.

Traffic Monitoring
Roadway traffic monitoring is also a potential application in which FANETs can replace intensive labor and
complicated observational infrastructure [6]. The
deployment of detectors or human personnel throughout a roadway network is costly and time sensitive.
UAVs that can monitor and report incidents or traffic
management data are an economically and socially
feasible option as they do not require travel over roads.
Moreover, due to UAVs' high speeds, urgent event-specific data can be transferred to assist search and rescue missions.

Agricultural Management
Agriculture production management requires crop
plant health to be monitored. Although manned aircraft are used in this sector, the emerging concept of
small networks of autonomous UAV swarms is believed
to be more beneficial because the UAV swarms can
perform field operations over smaller as well as wider
fields, and with greater precision. Information related
to quality of crops, growth, and other possible issues
can be retrieved within a matter of minutes and adequate measures can be taken. This means that UAVs
can focus on specific sites, and fertilizers can be
applied accordingly [7].

Relaying Networks
Autonomously operated UAVs are being used as airborne communication relays to efficiently and securely
transmit information collected by ground sensors to distant control centers, and for increasing the communication range of ground relaying nodes [8], [9]. A relaying
network is used to maintain communication links
between a remote source and destination that cannot
communicate directly due to obstacles. Areas such as
forests and marshlands, which are inaccessible by
ground vehicles due to their remote locations, can be
protected from disasters such as wildfires by wireless
sensor networks (WSN) and UAV networks. These networks not only help prevent such incidents by transmitting the sensed information related to the location of
wildfire-prone areas, but they also assist in post-fire
tasks as well [10]. Also, the lifetime of remote sensor networks can be increased by using UAVs as mobile relays.

Technical Aspects
In addition to social considerations, there are numerous
technological aspects of FANETs that must be
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considered in order to enhance our quality of life and
surrounding environment. FANETs are expected to
improve the performance of UAV relaying networks, as
the use of multiple UAVs can further increase the communication range. Moreover, in comparison to ground
relaying networks, swarms of UAVs can relay data with
minimal latency due to high mobility and robust connectivity. They move high up in the sky and are not met
with terrain constraints. Also, there is a clear line of
sight between ground nodes and UAVs, which further
ensures reliable delivery. The energy of sensor nodes in
distant areas can be preserved by dedicating a group of
nodes to directly communicate with the UAV network.
This in turn minimizes the number of hops required to
relay the information - i.e., in the absence of FANETs,
multiple hops and ground relaying nodes are required.
In this manner scientists can conduct quality research
in unsafe and dangerous remote areas, without
humans being physically present - for example in volcano-prone areas.

Communication Challenges
FANETs present challenges such as high mobility, frequent topology changes, minimal delay, and high reliability requirements. In order to produce efficient and
reliable communications between UAVs, these challenges must be overcome.

High Mobility
FANET nodes are highly mobile, with typical UAV speeds
of 30-460 km/hr [1]. Such highly mobile UAVs cannot be
served by conventional methods such as mobile Internet protocol (IP) [18]. Moreover, the efficiency of routing
decisions and the quality of wireless links fluctuates
due to the high speed of UAVs, leading to performance
degradation. A media access control (MAC) layer
addresses this issue by maintaining Quality of Service
(QoS) for one hop transmission [19], whereas the routing layer ensures reliable end-to-end delivery [20]. One
potential solution to encountering the high mobility of
UAVs has to predict the location and movement of UAVs
using heuristic techniques [21]. On the favorable side,
when FANETs are used as relaying networks, the high
mobility factor gives desired outcomes in the establishment of delay-tolerant links between geographically distant infrastructures.

Rapid Topology Change
Frequent topology changes result from high mobility.
These must be considered when designing FANETs.
Other factors that require redefinition of routes include
environmental obstacles such as mountains, failures of
existing UAVs in the network, injection of new UAVs,
possible mission updates, operational requirements,

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