1 research outputs found
NOMA-Based Hybrid Satellite-UAV-Terrestrial Networks for Beyond 5G Maritime Internet of Things
Current fifth-generation (5G) networks do not cover the maritime area,
causing difficulties in developing maritime Internet of Things (IoT). To tackle
this problem, we establish a nearshore network by collaboratively using
on-shore terrestrial base stations (TBSs) and tethered unmanned aerial vehicles
(UAVs). These TBSs and UAVs form virtual clusters in a user-centric manner.
Within each virtual cluster, non-orthogonal multiple access (NOMA) is adopted
for agilely including various maritime IoT devices, which are usually sparsely
distributed on the vast ocean. The nearshore network also shares spectrum with
marine satellites. In such a NOMA-based hybrid satellite-UAV-terrestrial
network, interference among different network segments, different clusters, as
well as different users occurs. We thereby formulate a joint power allocation
problem to maximize the sum rate of the network. Different from existing
studies, we use large-scale channel state information (CSI) only for
optimization to reduce system overhead. The large-scale CSI is obtained by
using the position information of maritime IoT devices. The problem is
non-convex with intractable nonlinear constraints. We tackle these difficulties
by adopting the relaxation methods, max-min optimization and the successive
convex approximation technique. An iterative power allocation algorithm is
accordingly proposed, which is shown effective for coverage enhancement by
simulations. This shows the potential of NOMA-based hybrid
satellite-UAV-terrestrial networks for maritime on-demand coverage