A Novel Cross-Domain Channel Estimation Scheme for OFDM

TL;DR

This paper introduces a cross-domain channel estimation method for OFDM that exploits delay-Doppler domain characteristics, improving estimation accuracy in high mobility scenarios through a novel 2D twisted-convolution approach and sparse recovery techniques.

Contribution

The paper presents a new cross-domain channel estimation algorithm for OFDM that transforms pilot sequences into the delay-Doppler domain and applies a 2D twisted-convolution for better accuracy.

Findings

Significant performance improvement over conventional methods in high mobility conditions.

Effective sparse signal recovery in the time-frequency domain.

Low-complexity $$-regularized least squares estimator enhances practicality.

Abstract

In this paper, we propose a novel cross-domain channel estimation (CDCE) algorithm for orthogonal frequency division multiplexing (OFDM) systems, leveraging the unique characteristics of the delay-Doppler (DD) domain channel. Specifically, the proposed algorithm transforms the time-frequency (TF) domain pilot sequence of OFDM into the DD domain and applies a two-dimensional (2D) twisted-convolution for acquiring a coarse estimation of the underlying channel delay and Doppler. Then, the OFDM channel estimation is formulated as a sparse signal recovery problem in the TF domain according to the dictionary derived based on the obtained delay and Doppler estimates. Furthermore, a low-complexity $\ell_1$-regularized least-square estimator is proposed to effectively solve this problem. Moreover, we further develop a performance analysis framework of the proposed scheme based on the ambiguity function (AF) of the adopted pilot sequence. Our numerical results demonstrate noticeable estimation performance improvement compared to conventional OFDM channel estimation methods, particularly in the presence of high channel mobility.