  In this paper, we investigate a multi-cell uplink non-orthogonal multiple
access (NOMA) system with imperfect successive interference cancellation (SIC).
The objective of the formulated optimization problem is to minimize the total
power consumption under users' quality-of-service constraints. The considered
problem is first transformed into a linear programming problem, upon which
centralized and distributed optimal solutions are proposed. Numerical results
are presented to verify the performance of the proposed solutions and evaluate
the impact of imperfect SIC on the system performance.
