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A Novel Non-Stationary Channel Emulator for 6G MIMO Wireless Channels

Yuan Zong, Lijian Xin, Jie Huang, Cheng-Xiang Wang

TL;DR

The paper addresses the lack of repeatable STF non-stationary channel emulators for 6G MIMO by introducing a 3D non-stationary GBSM and a subspace-based, frequency-domain emulator. A subspace expansion using chirp bases reconstructs time-varying CTFs on FPGA, while an SDR/PC preprocessing workflow reduces hardware load. Key contributions include a Markov birth–death parameterization of cluster dynamics, a precise CTF reconstruction technique, and a full SDR-to-FPGA architecture with validated CTF, Doppler PSD, and delay PSD fidelity. The work enables realistic, repeatable lab testing for 6G MIMO systems with non-stationary channels, improving benchmarking and protocol validation in controlled environments.

Abstract

The performance evaluation of sixth generation (6G) communication systems is anticipated to be a controlled and repeatable process in the lab, which brings up the demand for wireless channel emulators. However, channel emulation for 6G space-time-frequency (STF) non-stationary channels is missing currently. In this paper, a non-stationary multiple-input multiple-output (MIMO) geometry-based stochastic model (GBSM) that accurately characterizes the channel STF properties is introduced firstly. Then, a subspace-based method is proposed for reconstructing the channel fading obtained from the GBSM and a channel emulator architecture with frequency domain processing is presented for 6G MIMO systems. Moreover, the spatial time-varying channel transfer functions (CTFs) of the channel simulation and the channel emulation are compared and analyzed. The Doppler power spectral density (PSD) and delay PSD are further derived and compared between the channel model simulation and subspace-based emulation. The results demonstrate that the proposed channel emulator is capable of reproducing the non-stationary channel characteristics.

A Novel Non-Stationary Channel Emulator for 6G MIMO Wireless Channels

TL;DR

The paper addresses the lack of repeatable STF non-stationary channel emulators for 6G MIMO by introducing a 3D non-stationary GBSM and a subspace-based, frequency-domain emulator. A subspace expansion using chirp bases reconstructs time-varying CTFs on FPGA, while an SDR/PC preprocessing workflow reduces hardware load. Key contributions include a Markov birth–death parameterization of cluster dynamics, a precise CTF reconstruction technique, and a full SDR-to-FPGA architecture with validated CTF, Doppler PSD, and delay PSD fidelity. The work enables realistic, repeatable lab testing for 6G MIMO systems with non-stationary channels, improving benchmarking and protocol validation in controlled environments.

Abstract

The performance evaluation of sixth generation (6G) communication systems is anticipated to be a controlled and repeatable process in the lab, which brings up the demand for wireless channel emulators. However, channel emulation for 6G space-time-frequency (STF) non-stationary channels is missing currently. In this paper, a non-stationary multiple-input multiple-output (MIMO) geometry-based stochastic model (GBSM) that accurately characterizes the channel STF properties is introduced firstly. Then, a subspace-based method is proposed for reconstructing the channel fading obtained from the GBSM and a channel emulator architecture with frequency domain processing is presented for 6G MIMO systems. Moreover, the spatial time-varying channel transfer functions (CTFs) of the channel simulation and the channel emulation are compared and analyzed. The Doppler power spectral density (PSD) and delay PSD are further derived and compared between the channel model simulation and subspace-based emulation. The results demonstrate that the proposed channel emulator is capable of reproducing the non-stationary channel characteristics.
Paper Structure (13 sections, 24 equations, 6 figures)

This paper contains 13 sections, 24 equations, 6 figures.

Table of Contents

  1. Introduction
  2. The 3D Non-Stationary GBSM
  3. Channel Parameter Calculation Methods
  4. The STF Non-Stationary CTF
  5. Channel Emulation Based on Subspace Expansion
  6. Channel Emulation Architecture For GBSM
  7. Project of Original CTF to Subspace
  8. Frequency Domain Processing
  9. Simulation and Validation
  10. CTF
  11. Doppler PSD
  12. Delay PSD
  13. Conclusions

Figures (6)

  • Figure 1: The 3D non-stationary GBSM for MIMO systems6GPCM.
  • Figure 2: Channel emulator structure for GBSM.
  • Figure 3: Frequency domain processing diagram.
  • Figure 4: (a) Original and reconstructed CTF, (b) CTF error ($f_c$=2.6 GHz, $B$=60 MHz, $N$=23, $M$=20, $K$=30).
  • Figure 5: Comparisons of Doppler PSDs at different time instants ($f_c$=$\text{2.6}$ GHz, $A_1^T (0)$=$(\text{0},\text{0},\text{35})$ m, $A_1^R (0)$=$(\text{10},\text{0},\text{1.5})$ m, $v^R$=$(\text{10}, \text{0}, \text{0})$ m/s).
  • ...and 1 more figures