Energy Efficient Resource Optimization in User-Centric UDNs with NOMA
and Beamforming
Abstract
In this paper, we address the problem of energy efficient resource
optimization for downlink transmission in user-centric ultra-dense
networks enabled by wireless access via nonorthogonal multiple access
and wireless backhaul via beamforming. Our objective is to maximize the
system energy efficiency by optimizing user/access point scheduling,
subchannel assignment, and power allocation jointly. The problem is
formulated as a nonconvex mixed-integer nonlinear programming problem
which is NP-hard. We then transform it into a convex subproblem using
the sum-of-ratios decoupling and the iterative successive convex
approximation method. An overall algorithm is further developed to solve
the subproblem iteratively. Simulation results show that the proposed
algorithm has improved the system-wide energy efficiency significantly
when compared to the benchmark scheme.