  Hybrid aerial-terrestrial communication networks based on Low Altitude
Platforms (LAPs) are expected to optimally meet the urgent communication needs
of emergency relief and recovery operations for tackling large scale natural
disasters. The energy-efficient operation of such networks is important given
the fact that the entire network infrastructure, including the battery operated
ground terminals, exhibits requirements to operate under power-constrained
situations. In this paper, we discuss the design and evaluation of an adaptive
cooperative scheme intended to extend the survivability of the battery operated
aerial-terrestrial communication links. We propose and evaluate a real-time
adaptive cooperative transmission strategy for dynamic selection between direct
and cooperative links based on the channel conditions for improved energy
efficiency. We show that the cooperation between mobile terrestrial terminals
on the ground could improve the energy efficiency in the uplink depending on
the temporal behavior of the terrestrial and the aerial uplink channels. The
corresponding delay in having cooperative (relay-based) communications with
relay selection is also addressed. The simulation analysis corroborates that
the adaptive transmission technique improves the overall energy efficiency of
the network whilst maintaining low latency enabling real time applications.
