Joint high-dimensional soft bit estimation and quantization using deep learning

Forward error correction using soft probability estimates is a central component in modern digital communication receivers and impacts end-to-end system performance. In this work, we introduce EQ-Net: a deep learning approach for joint soft bit estimation (E) and quantization (Q) in high-dimensional multiple-input multiple-output (MIMO) systems. We propose a two-stage algorithm that uses soft bit quantization as pretraining for estimation and is motivated by a theoretical analysis of soft bit representation sizes in MIMO channels. Our experiments demonstrate that a single deep learning model achieves competitive results on both tasks when compared to previous methods, with gains in quantization efficiency as high as 20 % and reduced estimation latency by at least 21 % compared to other deep learning approaches that achieve the same end-to-end performance. We also demonstrate that the quantization approach is feasible in single-user MIMO scenarios of up to 64 × 64 and can be used with different soft bit estimation algorithms than the ones during training. We investigate the robustness of the proposed approach and demonstrate that the model is robust to distributional shifts when used for soft bit quantization and is competitive with state-of-the-art deep learning approaches when faced with channel estimation errors in soft bit estimation.