Power Allocation for Energy Efficiency Maximization in Downlink CoMP Systems With NOMA

This paper investigates a power allocation problem
for maximizing energy efficiency (EE) in downlink Coordinated
Multi-Point (CoMP) systems with non-orthogonal multiple
access (NOMA). First, users’ achievable data rate and network
throughput are analysed under three transmission schemes: 1) all
users’ signals are jointly transmitted by coordinated base stations
(BSs); 2) only cell-edge users’ signals are jointly transmitted by
coordinated BSs; 3) each user’s signals are transmitted by only
one BS. Next, we formulate EE maximization problems for the
three schemes under the constraints of minimum users’ data
rate and maximum BS transmit power. The considered problem
is non-convex and hard to tackle. To address it, an iterative
sub-optimal algorithm is proposed by adopting fractional programming
and difference of convex programming. Numerical
results show that the near optimality performance of EE can
be achieved by using the proposed algorithm with advantages
of fast convergence and low complexity. Three transmission
schemes of NOMA have superior EE performance compared
with conventional orthogonal multiple access scheme in the same
CoMP networks.