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Joint Near-Field Target Tracking and Communications with Full Duplex Holographic MIMO

Ioannis Gavras, George C. Alexandropoulos

TL;DR

This paper tackles the problem of jointly tracking near-field targets and delivering downlink communications using a DMA-enabled, full-duplex holographic MIMO node. It introduces an extended Fresnel-based near-field model for UPAs, and proposes a DMA-driven hybrid analog/digital beamforming strategy along with self-interference cancellation to maximize DL performance for $U$ UEs while tracking $K$ targets via a subspace-tracking approach. The framework combines a TX optimization (alternating with a codebook-restricted search) and a tracking module based on a PASTd/MUSIC variation to estimate target parameters, leveraging reflections of DL signals. Numerical results at $f_c=120$ GHz with $N_{\rm RF}=4$ and $N_E=512$ demonstrate robust tracking and improved sum-rate, with performance depending on the number of RX chains and the number of DL UEs, showcasing the practicality of near-field JCAS with holographic DMAs.

Abstract

In this paper, we present a simultaneous target tracking and multi-user communications system realized by a full duplex holographic Multiple-Input Multiple-Output (MIMO) node equipped with Dynamic Metasurface Antennas (DMAs) at both its communication ends. Focusing on the near-field regime, we extend Fresnel's approximation to metasurfaces and devise a subspace tracking scheme with DMA-based hybrid Analog and Digital (A/D) reception as well as hybrid A/D transmission with a DMA for sum-rate maximization. The presented simulation results corroborate the efficiency of the proposed framework for various system parameters.

Joint Near-Field Target Tracking and Communications with Full Duplex Holographic MIMO

TL;DR

This paper tackles the problem of jointly tracking near-field targets and delivering downlink communications using a DMA-enabled, full-duplex holographic MIMO node. It introduces an extended Fresnel-based near-field model for UPAs, and proposes a DMA-driven hybrid analog/digital beamforming strategy along with self-interference cancellation to maximize DL performance for UEs while tracking targets via a subspace-tracking approach. The framework combines a TX optimization (alternating with a codebook-restricted search) and a tracking module based on a PASTd/MUSIC variation to estimate target parameters, leveraging reflections of DL signals. Numerical results at GHz with and demonstrate robust tracking and improved sum-rate, with performance depending on the number of RX chains and the number of DL UEs, showcasing the practicality of near-field JCAS with holographic DMAs.

Abstract

In this paper, we present a simultaneous target tracking and multi-user communications system realized by a full duplex holographic Multiple-Input Multiple-Output (MIMO) node equipped with Dynamic Metasurface Antennas (DMAs) at both its communication ends. Focusing on the near-field regime, we extend Fresnel's approximation to metasurfaces and devise a subspace tracking scheme with DMA-based hybrid Analog and Digital (A/D) reception as well as hybrid A/D transmission with a DMA for sum-rate maximization. The presented simulation results corroborate the efficiency of the proposed framework for various system parameters.
Paper Structure (10 sections, 18 equations, 2 figures)

This paper contains 10 sections, 18 equations, 2 figures.

Table of Contents

  1. Introduction
  2. System and Signal Models
  3. FD Holographic MIMO JCAS System Model
  4. Near-Field Channel Model
  5. Received Signal Models
  6. Proposed JCAS Framework
  7. TX BF, Precoding and SI Cancellation
  8. Target Tracking and RX Combining
  9. Numerical Results
  10. Conclusion

Figures (2)

  • Figure 1: Performance of the $r_{u,\ell,i,n}$ and $\theta_{u,\ell,i,n}$ approximations considering a UE with $L=2$ antennas and different values for $N_{E}$.
  • Figure 2: Tracking and DL sum-rate performance for $K=3$ targets, with $U=\{1,2,3\}$ out of which being the UEs each with $L=2$ antennas, versus the transmit power $P_{\rm max}$ for an FD holographic MIMO node with $N_{\rm RF} = 4$ TX/RX microstrips each with $N_{\rm E}=512$ metamaterials.