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Two-Stage Hybrid Transceiver Design Relying on Low-Resolution ADCs in Partially Connected MU Terahertz (THz) MIMO Systems

Abhisha Garg, Akash Kumar, Suraj Srivastava, Aditya K. Jagannatham, Lajos Hanzo

Abstract

A two-stage hybrid transceiver is designed by considering a partially connected architecture at the base station (BS) for a low-resolution multi-user (MU) THz massive multiple input multiple output (MIMO) system. Due to its high bandwidth coupled with a high number of antennas, the THz band suffers from the deleterious spatial-wideband and frequency-wideband effects jointly termed as the dual-wideband effect. To address this undesired phenomenon, we rigorously model the THz MIMO channel at each subarray corresponding to each user by incorporating the absorption, reflection, and free-space losses. Subsequently, a novel beamforming technique is proposed that employs only a few true time delay (TTD) lines for eliminating the beam-split effect, which is the manifestation of the spatial-wideband effect in the frequency domain. Our simulation results demonstrate a performance improvement of around 13% in terms of spectral efficiency over the existing state-of-the-art techniques.

Two-Stage Hybrid Transceiver Design Relying on Low-Resolution ADCs in Partially Connected MU Terahertz (THz) MIMO Systems

Abstract

A two-stage hybrid transceiver is designed by considering a partially connected architecture at the base station (BS) for a low-resolution multi-user (MU) THz massive multiple input multiple output (MIMO) system. Due to its high bandwidth coupled with a high number of antennas, the THz band suffers from the deleterious spatial-wideband and frequency-wideband effects jointly termed as the dual-wideband effect. To address this undesired phenomenon, we rigorously model the THz MIMO channel at each subarray corresponding to each user by incorporating the absorption, reflection, and free-space losses. Subsequently, a novel beamforming technique is proposed that employs only a few true time delay (TTD) lines for eliminating the beam-split effect, which is the manifestation of the spatial-wideband effect in the frequency domain. Our simulation results demonstrate a performance improvement of around 13% in terms of spectral efficiency over the existing state-of-the-art techniques.
Paper Structure (10 sections, 26 equations, 2 figures, 1 table, 2 algorithms)

This paper contains 10 sections, 26 equations, 2 figures, 1 table, 2 algorithms.

Table of Contents

  1. Introduction
  2. Contributions
  3. Notation
  4. Partially connected MU THz MIMO system and channel models
  5. Dual-wideband THz channel model
  6. True Time Delay (TTD) based two-stage optimization and compensation framework
  7. Design of frequency-independent optimal beamformers
  8. Generation of frequency-dependent beamformers
  9. Simulation Results
  10. Conclusion

Figures (2)

  • Figure 1: Subarray-based combining with ADCs and time delay elements
  • Figure 2: $\left(a\right)$ NAG versus physical direction comparison (left) considering traditional precoding (right) for the proposed beamforming technique $\left(b\right)$ Spectral efficiency comparison versus SNR for the proposed and existing state-of-the-art techniques. Note that, for simulation purposes, we have modified their existing system and channel models to ensure a fair comparison. $\left(c\right)$ Spectral efficiency comparison for the RRC-PSF based and Rect-PSF based dual-wideband channels with different transceiver schemes. $\left(d\right)$ The spectral efficiency vs. SNR(dB) for different ADC resolutions.