Coded Caching and Spatial Multiplexing Gain Trade-off in Dynamic MISO Networks

TL;DR

This paper analyzes the trade-off between caching and spatial multiplexing gains in dynamic MISO networks, providing closed-form DoF expressions for hybrid schemes involving phantom users and unicast transmissions.

Contribution

It introduces a comprehensive analysis of caching and multiplexing trade-offs in dynamic networks, deriving closed-form DoF formulas for hybrid caching schemes.

Findings

Closed-form DoF expressions for hybrid caching schemes.

Trade-off characterization between caching gains and spatial multiplexing.

Impact of phantom users and unicast serving on network performance.

Abstract

The global caching gain of multi-antenna coded caching techniques can be also mostly achieved in dynamic network setups, where the cache contents of users are dictated by a central server, and each user can freely join or leave the network at any moment. In the dynamic setup, users are assigned to a limited set of caching profiles and the non-uniformness in the number of users assigned to each profile is compensated during the delivery phase by either adding phantom users for multicasting or serving a subset of users with unicast transmissions. In this paper, we perform a thorough analysis and provide closed-form representations of the achievable degrees of freedom (DoF) in such hybrid schemes, and assess the inherent trade-off between the global caching and spatial multiplexing gains caused by either adding phantom users or serving parts of the data through unicasting.