Optimal Geographic Caching In Cellular Networks

TL;DR

This paper investigates optimal geographic content placement in cellular networks modeled by Poisson point processes, aiming to maximize user hit probability by considering coverage and content popularity.

Contribution

It introduces a novel randomized content placement policy that outperforms standard caching strategies, especially in high-coverage scenarios.

Findings

Optimal placement increases hit probability in high-coverage regimes

Standard caching policies are suboptimal under certain coverage conditions

Numerical results validate the effectiveness of the proposed policy

Abstract

In this work we consider the problem of an optimal geographic placement of content in wireless cellular networks modelled by Poisson point processes. Specifically, for the typical user requesting some particular content and whose popularity follows a given law (e.g. Zipf), we calculate the probability of finding the content cached in one of the base stations. Wireless coverage follows the usual signal-to-interference-and noise ratio (SINR) model, or some variants of it. We formulate and solve the problem of an optimal randomized content placement policy, to maximize the user's hit probability. The result dictates that it is not always optimal to follow the standard policy "cache the most popular content, everywhere". In fact, our numerical results regarding three different coverage scenarios, show that the optimal policy significantly increases the chances of hit under high-coverage regime, i.e., when the probabilities of coverage by more than just one station are high enough.