Score-Based Conditional Flow Models for MIMO Receiver Design with Superimposed Pilots

TL;DR

This paper introduces a novel unsupervised generative framework called CFM-Rx for MIMO receiver design with superimposed pilots, improving channel estimation and data detection accuracy by leveraging flow-based models and score diffusion techniques.

Contribution

It proposes a conditional flow matching receiver that unifies flow matching with score-based diffusion modeling for MIMO systems, eliminating the need for labeled data and enhancing adaptability.

Findings

CFM-Rx outperforms conventional estimators in accuracy.

It achieves robust symbol detection under severe pilot contamination.

The framework offers low-latency, deterministic inference.

Abstract

Accurate channel state information (CSI) is vital for multiple-input multiple-output (MIMO) systems. However, superimposed pilots (SIP), which reduce overhead, introduce severe pilot contamination and data interference, complicating joint channel estimation and data detection. This paper proposes a conditional flow matching receiver (CFM-Rx), an unsupervised generative framework that learns directly from received signals, eliminating the need for labeled data and improving adaptability across diverse system settings. By leveraging flow-based generative modeling, CFM-Rx enables deterministic, low-latency inference and exploits model invertibility to capture the bidirectional nature of signal propagation. This framework unifies flow matching with score-based diffusion modeling via a moment-consistent ordinary differential equation (ODE), replacing stochastic differential equation (SDE) sampling with a deterministic and efficient process. Furthermore, it integrates receiver-side priors to ensure stable, data-consistent inference. Extensive simulation results across various MIMO configurations demonstrate that CFM-Rx consistently outperforms conventional estimators and state-of-the-art data-driven receivers, achieving notable gains in channel estimation accuracy and symbol detection robustness, particularly under severe pilot contamination.