Iterative Channel Estimation, Detection and Decoding for Multi-Antenna Systems with RIS

TL;DR

This paper introduces an iterative scheme combining channel estimation, detection, and decoding for multi-antenna systems aided by multiple RIS, utilizing LDPC codes and exploiting temporal correlation for improved accuracy and reduced pilot overhead.

Contribution

It presents a novel iterative code-aided channel estimation technique using LDPC codes and an iterative channel tracking method that leverages channel temporal correlation.

Findings

Enhanced channel estimation accuracy demonstrated in simulations.

Reduced pilot overhead compared to traditional methods.

Effective performance under various RIS configurations and propagation conditions.

Abstract

This work proposes an iterative channel estimation, detection and decoding (ICEDD) scheme for the uplink of multi-user multi-antenna systems assisted by multiple reconfigurable intelligent surfaces (RIS)}. A novel iterative code-aided channel estimation (ICCE) technique is developed that uses low-density parity-check (LDPC) codes and iterative processing to enhance estimation accuracy while reducing pilot overhead. The core idea is to exploit encoded pilots (EP), enabling the use of both pilot and parity bits to iteratively refine channel estimates. To further improve performance, an iterative channel tracking (ICT) method is proposed that takes advantage of the temporal correlation of the channel. An analytical evaluation of the proposed estimator is provided in terms of normalized mean-squared error (NMSE), along with a study of its computational complexity and the impact of the code rate. Numerical results validate the performance of the proposed scheme in a sub-6 GHz multi-RIS scenario with non-sparse propagation, under both LOS and NLOS conditions, and different RIS architectures.