  MIMO-NOMA combines Multiple-Input Multiple-Output (MIMO) and Non-Orthogonal
Multiple Access (NOMA), which can address heterogeneous challenges, such as
massive connectivity, low latency, and high reliability. In this paper, a
practical coded MIMO-NOMA system with capacityapproaching performance as well
as low implementation complexity is proposed. Specifically, the employed
receiver consists of a multi-user Linear Minimum Mean-Square Error (LMMSE)
detector and a bank of single-user message-passing decoders, which decompose
the overall signal recovery into distributed low-complexity calculations. An
asymptotic extrinsic information transfer analysis is proposed to estimate the
performance of iterative receiver, where practical channel codes that match
with the LMMSE detector in the iterative decoding perspective are constructed.
As a result, the proposed coded MIMO-NOMA system achieves asymptotic
performances within 0.2 dB from the theoretical capacity. Simulation results
validate the reliability and robustness of the proposed system in practical
settings, including various system loads, iteration numbers, code lengths, and
channel conditions.
