Cross-Domain Joint Channel and Data Estimation for mmWave MIMO-OFDM Systems With Low-Resolution ADCs

This paper proposes a novel cross-domain joint channel and data estimation (JCDE) algorithm based on expectation propagation (EP) for millimeter-wave (mmWave) multipleinput multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems equipped with low-resolution analog-todigital converters (ADCs). In the design of an EP-based messagepassing algorithm (MPA), messages are formulated by projecting the true posterior distribution of the unknown signal onto a Gaussian distribution through <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">moment matching (MM)</i>, which can be modeled as the additive white Gaussian noise (AWGN) channel output of the unknown signal. Consequently, executing domain conversion within this <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">message space</i> enables signal processing in a suitable domain unaffected by quantization distortion. Specifically, the proposed algorithm consists of an antenna-delay (AD)-domain de-quantization (DQ) process that reconstructs the original signal prior to ADCs from quantized observations, a beam-delay (BD)-domain channel estimation (CE) that leverages the stochastic sparse structure of wireless channels, and an antenna-frequency (AF)-domain data detection (DD) that aligns with the OFDM format. This cross-domain strategy, tailored to the EP framework, facilitates low-overhead and high-precision JCDE. Computer simulations show that the proposed method not only significantly outperforms the state-of-the-art (SotA) but also approaches the performance of an idealized Genie-aided scheme under certain system conditions.