Multi-User Detection Based on Expectation Propagation for the Non-Coherent SIMO Multiple Access Channel

Khac-Hoang Ngo (1, 2) , Maxime Guillaud (2) , Alexis Decurninge (2) , Sheng Yang (1) , Philip Schniter (3)

1 CentraleSupélec
2 Mathematical and Algorithmic Sciences Lab [Paris]
3 OSU - Ohio State University [Columbus]

We consider the non-coherent single-input multipleoutput (SIMO) multiple access channel with general signaling under spatially correlated Rayleigh block fading. We propose a novel soft-output multiuser detector that computes an approximate marginal posterior of each transmitted signal using only the knowledge about the channel distribution. Our detector is based on expectation propagation (EP) approximate inference and has polynomial complexity in the number of users, number of receive antennas and channel coherence time. We also propose two simplifications of this detector with reduced complexity. With Grassmannian signaling, the proposed detectors outperform a state-of-the-art non-coherent detector with projection-based interference mitigation. With pilot-assisted signaling, the EP detector outperforms, in terms of symbol error rate, some conventional coherent pilot-based detectors, including a sphere decoder and a joint channel estimation-data detection scheme. Our EP-based detectors produce accurate approximates of the true posterior leading to high achievable sum-rates. The gains of these detectors are further observed in terms of the bit error rate when using their soft outputs for a turbo channel decoder.

Keywords: non-coherent communications; multiple access; detection; expectation propagation; Grassmannian constellations

Domains: Information Theory [math.IT]

Khac-Hoang Ngo, Maxime Guillaud, Alexis Decurninge, Sheng Yang, Philip Schniter. Multi-User Detection Based on Expectation Propagation for the Non-Coherent SIMO Multiple Access Channel. IEEE Transactions on Wireless Communications, 2020, 19 (9), pp.6145-6161. ⟨10.1109/TWC.2020.3000419⟩. ⟨hal-03420065⟩