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THz RHS Transceiver for Low-Latency Multi-User VR Transmission with MEC

Liangshun Wu, Wen Chen, Honghao Wang, Zhendong Li, Ying Wang

TL;DR

An end-to-end model for the 3D field-of-view (FoV) generation pipeline is developed and significant latency reductions under tight resource constraints are shown.

Abstract

This paper investigates a Terahertz (THz)-enabled mobile edge computing (MEC)-assisted virtual reality (VR) system using reconfigurable holographic surfaces (RHS) as transceiver for multi-user beamforming and holographic-pattern division multiple access (HDMA). We develop an end-to-end model for the 3D field-of-view (FoV) generation pipeline and optimize content prefetching, rendering offloading under memory and power constraints, and beamforming accommodating user movement by adjusting holographic pattern weights for beamshaping and feeds power allocation for excitation amplitude adjustment. For homogeneous FoVs, we derive closed-form policies for prefetching 2D or 3D FoVs or direct transmission of 3D FoVs. For heterogeneous FoVs, we exploit the timescale separation between prefetching/rendering and fast RHS beamforming, decomposing the optimization into a rendering-prefetching combinatorial optimization problem and a short-timescale beamforming convex optimization problem. Simulations show significant latency reductions under tight resource constraints.

THz RHS Transceiver for Low-Latency Multi-User VR Transmission with MEC

TL;DR

An end-to-end model for the 3D field-of-view (FoV) generation pipeline is developed and significant latency reductions under tight resource constraints are shown.

Abstract

This paper investigates a Terahertz (THz)-enabled mobile edge computing (MEC)-assisted virtual reality (VR) system using reconfigurable holographic surfaces (RHS) as transceiver for multi-user beamforming and holographic-pattern division multiple access (HDMA). We develop an end-to-end model for the 3D field-of-view (FoV) generation pipeline and optimize content prefetching, rendering offloading under memory and power constraints, and beamforming accommodating user movement by adjusting holographic pattern weights for beamshaping and feeds power allocation for excitation amplitude adjustment. For homogeneous FoVs, we derive closed-form policies for prefetching 2D or 3D FoVs or direct transmission of 3D FoVs. For heterogeneous FoVs, we exploit the timescale separation between prefetching/rendering and fast RHS beamforming, decomposing the optimization into a rendering-prefetching combinatorial optimization problem and a short-timescale beamforming convex optimization problem. Simulations show significant latency reductions under tight resource constraints.
Paper Structure (24 sections, 5 theorems, 22 equations, 7 figures, 4 algorithms)

This paper contains 24 sections, 5 theorems, 22 equations, 7 figures, 4 algorithms.

Table of Contents

  1. Introduction
  2. VR Transmission with MEC
  3. RHS
  4. Contributions
  5. System Model
  6. THz RHS Channel Model
  7. Frequency-Selective THz Channel
  8. Inter-Band Interference (IBI)
  9. HDMA-Based RHS Holographic Beamforming
  10. VR Transmission Model with MEC
  11. Problem Formulation
  12. Equivalent Reformulation under the Homogeneity and Staticity Assumption
  13. Equivalent Reformulation under the Heterogeneity and Non-Staticity Assumption
  14. Simulation
  15. Simulation for the Homogenous Setting ($\mathcal{P}$1')
  16. ...and 9 more sections

Key Result

Proposition 1

For any FoV $i \in \mathcal{V}$, if $p_i^{3\mathrm{D}} = 1$, then in the optimal solution we have $p_i^{2\mathrm{D}} = 0$ and $r_i = 0$.

Figures (7)

  • Figure 1: A typical $360^\circ$ VR video production pipline using THz RHS transceiver for wireless transmission with MEC.
  • Figure 2: RHS-assisted THz multi-user VR transmission.
  • Figure 3: An equivalent multi-port circuit model of the mutual coupling effect at the transmitting end (Tx) in RHS.
  • Figure 4: Four projection paths.
  • Figure 5: Simulation results for prefetching and rendering offloading in homogenous setting($\mathcal{P}$1').
  • ...and 2 more figures

Theorems & Definitions (14)

  • Proposition 1: 3D prefetching eliminates the need for 2D prefetching and rendering
  • proof
  • Proposition 2: 2D prefetching must be accompanied by local rendering
  • proof
  • Proposition 3: the memory constraint is tight at the optimum
  • proof
  • Definition 1: remote 3D transmission priority zone
  • Definition 2: on-device rendering priority zone
  • Proposition 4: the optimal strategy for the remote 3D transmission priority zone is closed-form
  • proof
  • ...and 4 more