  Flying ad hoc network (FANET) provides portable and flexible communication
for many applications and possesses several unique design challenges; a key one
is the successful delivery of messages to the destination, reliably. For
reliable communication, routing plays an important role, which establishes a
path between source and destination on the basis of certain criteria.
Conventional routing protocols of FANET generally use a minimum hop count
criterion to find the best route between source and destination, which results
in lower latency with the consideration that there is single source/destination
network environment. However, in a network with multiple sources, the minimum
hop count routing criterion along with the 1-Hop HELLO messages broadcasted by
each node in the network may deteriorate the network performance in terms of
high End-to-End (ETE) delay and decrease in the lifetime of the network. This
research work proposes a Reliable link-adaptive position-based routing protocol
(RLPR) for FANET. It uses relative speed, signal strength, and energy of the
nodes along with the geographic distance towards the destination using a
forwarding angle. This angle is used to determine the forwarding zone that
decreases the undesirable control messages in the network in order to discover
the route. RLPR enhances the network performance by selecting those relay nodes
which are in the forwarding zone and whose geographic movement is towards the
destination. Additionally, RLPR selects the next hop with better energy level
and uses signal strength and relative speed of the nodes to achieve high
connectivity-level. Based on the performance evaluation performed in the
Network simulator (ns-2.35), it has been analysed that RLPR outperforms the
Robust and reliable predictive based routing (RARP) and Ad hoc on-demand
distance vector (AODV) protocols in different scenarios.
