  A high-rate yet low-cost air-to-ground (A2G) communication backbone is
conceived for integrating the space and terrestrial network by harnessing the
opportunistic assistance of the passenger planes or high altitude platforms
(HAPs) as mobile base stations (BSs) and millimetre wave communication. The
airliners act as the network-provider for the terrestrial users while relying
on satellite backhaul. A null-steered beamforming technique relying on a
large-scale planar array is used for transmission by the airliner/HAP for
achieving a high directional gain, hence minimizing the interference between
the users. Furthermore, approximate spectral efficiency (SE) and area spectral
efficiency (ASE) expressions are derived and quantified for diverse system
parameters.
