Hybrid-Field 6D Movable Antenna for Terahertz Communications: Channel Modeling and Estimation

2025-05-07

AI Summary

To address the challenges of hybrid far-/near-field propagation modeling, excessive pilot overhead, and high computational complexity in terahertz (THz) communications with six-dimensional movable antenna (6DMA) networks, this paper proposes: (1) the first generalized 6DMA channel model unifying planar-wave propagation over a single surface and spherical-wave propagation across multiple surfaces under a hybrid-field framework; (2) a full-candidate pose-based channel map reconstruction method leveraging directional sparsity, overcoming the dimensionality bottleneck inherent in conventional near-field modeling; and (3) an adaptive wavefront modeling strategy—switching between near- and far-field approximations—combined with 6D pose-space parameterization. Experiments demonstrate that the proposed model closely approximates realistic near-field behavior, while achieving high-accuracy channel estimation with over 60% reduction in pilot overhead and significantly lower computational complexity. The results validate the effectiveness and feasibility of 6DMA systems for multi-user THz access.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Application Domains: Mobility, Driving & Flight
• Search and Optimization: Sampling/Simulation-based Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Security and Privacy: Large-scale security measurements
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

In this work, we study a six-dimensional movable antenna (6DMA)-enhanced Terahertz (THz) network that supports a large number of users with a few antennas by controlling the three-dimensional (3D) positions and 3D rotations of antenna surfaces/subarrays at the base station (BS). However, the short wavelength of THz signals combined with a large 6DMA movement range extends the near-field region. As a result, a user can be in the far-field region relative to the antennas on one 6DMA surface, while simultaneously residing in the near-field region relative to other 6DMA surfaces. Moreover, 6DMA THz channel estimation suffers from increased computational complexity and pilot overhead due to uneven power distribution across the large number of candidate position-rotation pairs, as well as the limited number of radio frequency (RF) chains in THz bands. To address these issues, we propose an efficient hybrid-field generalized 6DMA THz channel model, which accounts for planar wave propagation within individual 6DMA surfaces and spherical waves among different 6DMA surfaces. Furthermore, we propose a low-overhead channel estimation algorithm that leverages directional sparsity to construct a complete channel map for all potential antenna position-rotation pairs. Numerical results show that the proposed hybrid-field channel model achieves a sum rate close to that of the ground-truth near-field channel model and confirm that the channel estimation method yields accurate results with low complexity.

Problem

• Modeling hybrid-field THz channels for 6DMA systems
• Reducing computational complexity in 6DMA channel estimation
• Minimizing pilot overhead in THz band channel estimation

Innovation

• Hybrid-field 6DMA model for THz communications
• Planar and spherical wave propagation combined
• Low-overhead channel estimation with directional sparsity