Joint Iterative Detection and Decoding for Polar-Coded MIMO-IDMA Systems

Non orthogonal multiple access (NOMA) was one of the key potential physicallayer technologies considered for the fifth generation (5G) wireless communication systems. Interleave division multiple access (IDMA), which uses packet level interleavers to distinguish multiple access users, is a promising NOMA scheme. Recently, polar codes have received extensive attention as a capacity approaching code and have already been adopted as the channel coding technique for the physical-layer control channel of 5G New Radio (NR). On the other hand, Multiple-Input Multiple Output (MIMO) has been one of the key enabling technologies in the recent standardized wireless communication systems. The performance benefits of both IDMA and MIMO can be obtained by combining two technologies. In this paper, a polar-coded MIMO-IDMA uplink system model with QPSK modulation is proposed. Moreover, we propose an joint iterative detection and decoding (JIDD) receiver. In the proposed JIDD receiver, at each iteration, likelihood messages are exchanged between the soft multiuser MIMO detector and belief propagation (BP) polar decoders. The numerical results confirm that polar coding offers significant performance improvement over the uncoded MIMOIDMA system. Furthermore, considerably improved error performance can be obtained by using the proposed JIDD receiver scheme over single-pass (non-iterative) multiuser MIMO detection and decoding.