Spatiotemporal 2-D Polar Codes over Non-Uniform MIMO Channels: A Reliability-Aware Construction Approach

2026-04-23

AI Summary

This work addresses the performance limitations of conventional two-dimensional polar codes in non-uniform MIMO channels, where the assumption of uniform reliability across spatial streams fails to meet the stringent requirements of ultra-reliable low-latency communication (URLLC). To overcome this, the authors propose a reliability-aware spatio-temporal two-dimensional polar coding framework. By incorporating a reciprocity-based channel approximation (RCA) method, the scheme accurately captures spatially heterogeneous signal-to-noise ratio characteristics without relying on assumptions about log-likelihood ratio distributions, and jointly optimizes polarization across both time and space dimensions. Simulation results demonstrate that the proposed approach significantly outperforms existing methods in non-uniform MIMO channels, achieving higher reliability, enhanced robustness, and notable performance gains, thereby effectively supporting URLLC applications.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Cognitive Modeling & Cognitive Systems: Neural Spike Coding
• Machine Learning: Calibration & Uncertainty Quantification

Application Category

• Graph Algorithms and Modeling for the Web: Algorithms and analysis for heterogeneous, signed, attributed, multi-relational, temporal, higher-order, and annotated Web-related graphs
• Systems and Infrastructure for Web, Mobile and WoT: Data management and stream processing for Web, mobile and wireless applications
• Search and Retrieval-Augmented AI: Web learning to rank, online learning, and counterfactual learning for ranking

Abstract

With the increasing demand for ultra-reliable and low-latency communication (URLLC), spatiotemporal two-dimensional (2-D) channel coding has received growing interest. By leveraging the spatial degrees of freedom in massive multiple-input multiple-output (MIMO) systems, it shortens the time-domain blocklength, thereby reducing latency and enhancing reliability. However, existing spatiotemporal coding schemes typically assume uniform reliability across spatial streams. This assumption does not hold in practical MIMO channels, where the underlying propagation environment generally leads to unequal spatial-eigenmode gains and reliabilities, making the conventional Gaussian-approximation-based construction for 2-D polar codes less effective. This paper investigates spatiotemporal 2-D polar coding over non-uniform MIMO channels, where the spatial domain exhibits inherently heterogeneous signal-to-noise ratios (SNRs). We propose a reciprocal channel approximation (RCA)-based reliability-aware 2-D polar coding framework that accurately characterizes such heterogeneous SNRs without relying on log-likelihood-ratio distribution assumptions. Simulation results demonstrate that the proposed RCA-based spatiotemporal 2-D polar coding scheme achieves clear performance gains and strong robustness, confirming its effectiveness in jointly exploiting temporal and spatial polarization for URLLC in practical MIMO systems.

Problem

• spatiotemporal coding
• 2-D polar codes
• non-uniform MIMO channels
• heterogeneous SNRs
• reliability-aware construction

Innovation

• spatiotemporal 2-D polar codes
• non-uniform MIMO channels
• reliability-aware construction
• reciprocal channel approximation
• URLLC