Optimal Caching Placement for D2D Assisted Wireless Caching Networks

TL;DR

This paper presents an optimal caching placement strategy for D2D-assisted wireless caching networks to maximize offloading probability, using DC programming and analyzing extreme cases for helpers and users.

Contribution

It introduces a novel DC programming approach for optimal caching placement and analyzes extreme cases to simplify the problem.

Findings

Significant performance gain over existing caching strategies.

Helpers and users prefer different caching strategies based on node density.

Effective solutions for both helper-only and user-only caching scenarios.

Abstract

In this paper, we devise the optimal caching placement to maximize the offloading probability for a two-tier wireless caching system, where the helpers and a part of users have caching ability. The offloading comes from the local caching, D2D sharing and the helper transmission. In particular, to maximize the offloading probability we reformulate the caching placement problem for users and helpers into a difference of convex (DC) problem which can be effectively solved by DC programming. Moreover, we analyze the two extreme cases where there is only help-tier caching network and only user-tier. Specifically, the placement problem for the helper-tier caching network is reduced to a convex problem, and can be effectively solved by the classical water-filling method. We notice that users and helpers prefer to cache popular contents under low node density and prefer to cache different contents evenly under high node density. Simulation results indicate a great performance gain of the proposed caching placement over existing approaches.