Modeling, Analysis, and Optimization of Caching in Multi-Antenna Small-Cell Networks

TL;DR

This paper investigates how deploying multiple antennas at small-cell base stations with beamforming techniques can enhance caching performance in small-cell networks, optimizing content placement for better network efficiency.

Contribution

It introduces a novel analysis of interference management via beamforming in multi-antenna small-cell networks with caching, providing optimization strategies for caching parameters.

Findings

Multiple antennas improve caching gains over traditional methods.

Beamforming techniques significantly enhance offloaded traffic and spectral efficiency.

Optimized caching parameters lead to better network performance.

Abstract

In traditional cache-enabled small-cell networks (SCNs), a user can suffer strong interference due to contentcentric base station association. This may degenerate the advantage of collaborative content caching among multiple small base stations (SBSs), including probabilistic caching and coded caching. In this work, we tackle this issue by deploying multiple antennas at each SBS for interference management. Two types of beamforming are considered. One is matched-filter (MF) to strengthen the effective channel gain of the desired signal, and the other is zero-forcing (ZF) to cancel interference within a selected SBS cooperation group. We apply these two beamforming techniques in both probabilistic caching and coded caching, and conduct performance analysis using stochastic geometry. We obtain exact and approximate compact integral expressions of system performances measured by average fractional offloaded traffic (AFOT) and average ergodic spectral efficiency (AESE). Based on these expressions, we then optimize the caching parameters for AFOT or AESE maximization. For probabilistic caching, optimal caching solutions are obtained. For coded caching, an efficient greedy-based algorithm is proposed. Numerical results show that multiple antennas can boost the advantage of probabilistic caching and coded caching over the traditional most popular caching with the proper use of beamforming.