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B. Tahir, S. Schwarz, M. Rupp:
"Low-Complexity Detection of Uplink NOMA by Exploiting Properties of the Propagation Channel";
Talk: IEEE International Conference on Communications (ICC 2020), Dublin, Ireland (virtual); 06-07-2020 - 06-11-2020; in: "Proceedings of the IEEE International Conference on Communications (ICC 2020)", IEEE, (2020), ISBN: 978-1-7281-5089-5.

Uplink non-orthogonal multiple access (NOMA) has been proposed as an efficient technique to support massive connectivity and reduce access-latency. However, due to the inherent multiuser interference within such a system, iterative joint detection is required, which is of high-complexity. In this paper, we exploit the propagation properties of wireless channels to reduce the detection complexity. In particular, when neighboring spreading-blocks on the time-frequency grid experience similar channel conditions, then it is possible to reuse the calculated filter weights between them. We propose four detection strategies and compare them across a wide range of time- and frequency- selectively. Then, assuming the base station is equipped with a sufficient number of antennas, we replace the MMSE filter with a lower-complexity approximation using Neumann series expansion. The results show that our strategies incur only a small performance loss, while substantially cutting down complexity.

https://publik.tuwien.ac.at/files/publik_289176.pdf