  Routing protocols help in transmitting the sensed data from UAVs monitoring
the targets (called target UAVs) to the BS. However, the highly dynamic nature
of an autonomous, decentralized UAV network leads to frequent route breaks or
traffic disruptions. Traditional routing schemes cannot quickly adapt to
dynamic UAV networks and/or incur large control overhead and delays. To
establish stable, high-quality routes from target UAVs to the BS, we design a
hybrid reactive routing scheme called pipe routing that is mobility,
congestion, and energy-aware. The pipe routing scheme discovers routes
on-demand and proactively switches to alternate high-quality routes within a
limited region around the active routes (called the pipe) when needed, reducing
the number of route breaks and increasing data throughput. We then design a
novel topology control-based pipe routing scheme to maintain robust
connectivity in the pipe region around the active routes, leading to improved
route stability and increased throughput with minimal impact on the coverage
performance of the UAV network.
