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Cache-Enabled Millimetre-Wave Fluid Antenna Systems: Modeling and Performance

Farshad Rostami Ghadi, Kai-Kit Wong, Kin-Fai Tong, Yangyang Zhang

TL;DR

Problem: quantify content delivery performance in cache-enabled mm-wave HetNets with fluid-antenna-equipped MUs. Approach: model SBSs as $\Psi^S$ distributed by a Poisson point process, apply probabilistic caching over a Zipf-distributed content library, and derive compact SCDP and CDD expressions via Gauss-Laguerre quadrature and Gaussian-copula channel modeling for FAS. Contributions: closed-form-like SCDP and CDD expressions that capture content placement, cache hit probability, and FAS port correlations; demonstration that a single active FAS port at the MU yields meaningful gains over fixed antennas, with further improvements from wider port spacing $W$ and larger port counts $N$. Significance: provides analytical machinery and design insights for content-centric, reconfigurable antennas in dense mm-wave deployments, enabling closer content delivery with reduced delay.

Abstract

This letter investigates the performance of content caching in a heterogeneous cellular network (HetNet) consisting of fluid antenna system (FAS)-equipped mobile users (MUs) and millimeter-wave (mm-wave) single-antenna small base stations (SBSs), distributed according to the independent homogeneous Poisson point processes (HPPP). In particular, it is assumed that the most popular contents are cached in the SBSs to serve the FAS-equipped MUs requests. To assess the system performance, we derive compact expressions for the successful content delivery probability (SCDP) and the content delivery delay (CDD) using the Gauss-Laguerre quadrature technique. Our numerical results show that the performance of cache-enabled mm-wave HetNets can be greatly improved, when the FAS is utilized at the MUs instead of traditional fixed-antenna system deployment.

Cache-Enabled Millimetre-Wave Fluid Antenna Systems: Modeling and Performance

TL;DR

Problem: quantify content delivery performance in cache-enabled mm-wave HetNets with fluid-antenna-equipped MUs. Approach: model SBSs as distributed by a Poisson point process, apply probabilistic caching over a Zipf-distributed content library, and derive compact SCDP and CDD expressions via Gauss-Laguerre quadrature and Gaussian-copula channel modeling for FAS. Contributions: closed-form-like SCDP and CDD expressions that capture content placement, cache hit probability, and FAS port correlations; demonstration that a single active FAS port at the MU yields meaningful gains over fixed antennas, with further improvements from wider port spacing and larger port counts . Significance: provides analytical machinery and design insights for content-centric, reconfigurable antennas in dense mm-wave deployments, enabling closer content delivery with reduced delay.

Abstract

This letter investigates the performance of content caching in a heterogeneous cellular network (HetNet) consisting of fluid antenna system (FAS)-equipped mobile users (MUs) and millimeter-wave (mm-wave) single-antenna small base stations (SBSs), distributed according to the independent homogeneous Poisson point processes (HPPP). In particular, it is assumed that the most popular contents are cached in the SBSs to serve the FAS-equipped MUs requests. To assess the system performance, we derive compact expressions for the successful content delivery probability (SCDP) and the content delivery delay (CDD) using the Gauss-Laguerre quadrature technique. Our numerical results show that the performance of cache-enabled mm-wave HetNets can be greatly improved, when the FAS is utilized at the MUs instead of traditional fixed-antenna system deployment.
Paper Structure (9 sections, 3 theorems, 17 equations, 6 figures)

This paper contains 9 sections, 3 theorems, 17 equations, 6 figures.

Table of Contents

  1. Introduction
  2. System Model
  3. Caching Strategy and Content Placement
  4. Signal Model and Downlink Transmission
  5. Performance Analysis
  6. SCDP Analysis
  7. CDD Analysis
  8. Numerical Results
  9. Conclusion

Key Result

Theorem 1

The SCDP for a typical MU of the considered cache-enabled mm-wave HetNet is given by eq-scdp (see top of the page), in which $\kappa_a$ denotes the $a$-th root of the Laguerre polynomial $\mathcal{L}_{A}\left(\kappa_a\right)$ and $A$ represents the parameter to ensure a complexity-accuracy trade-off

Figures (6)

  • Figure 1: A cache-enabled mm-wave HetNet with FAS-equipped MUs.
  • Figure 2: SCDP with $q_l=1$.
  • Figure 3: SCDP with $q_l=1$, $N=9$, $W=1\lambda\times 1\lambda$.
  • Figure 4: SCDP with $N=9$, $W=1\lambda\times 1\lambda$.
  • Figure 5: CDD with $q_l=1$, $M=3$.
  • ...and 1 more figures

Theorems & Definitions (6)

  • Theorem 1
  • proof
  • Theorem 2
  • proof
  • Corollary 1
  • proof