# On Optimal Proactive and Retention-Aware Caching with User Mobility

## TL;DR

This paper presents a polynomial-time algorithm for optimal proactive and retention-aware caching considering user mobility, balancing download and storage costs, and demonstrating significant performance improvements over existing methods.

## Contribution

It introduces a novel optimization framework for proactive, retention-aware caching with user mobility, providing a globally optimal polynomial-time solution.

## Key findings

- Algorithm guarantees global optimality
- Significant cost reductions compared to existing caching strategies
- Effective handling of user mobility in caching optimization

## Abstract

Caching popular contents at edge devices is an effective solution to alleviate the burden of the backhaul networks. Earlier investigations commonly neglected the storage cost in caching. More recently, retention-aware caching, where both the downloading cost and storage cost are accounted for, is attracting attention. Motivated by this, we address proactive and retention-aware caching with user mobility, optimizing the sum of the two types of costs. This is a combinatorial optimization problem. However, we derive a stream of analytical results and they together lead to an algorithm that guarantees global optimum with polynomial-time complexity. Numerical results show significant improvements in comparison to popular caching and random caching.