# A Converse Bound for Cache-Aided Interference Networks

## TL;DR

This paper derives a new lower bound on the delivery time for cache-aided interference networks, improving existing bounds for small caches and analyzing both peak and expected NDT.

## Contribution

It introduces a tighter converse bound for the peak NDT and characterizes the feasibility region for the expected NDT in cache-aided interference networks.

## Key findings

- Lower bound on peak NDT is tighter for small caches.
- Feasibility region for expected NDT is larger than that for peak NDT.
- Provides theoretical limits for cache-aided interference networks.

## Abstract

In this paper, an interference network with arbitrary number of transmitters and receivers is studied, where each transmitter is equipped with a finite size cache. We obtain an information-theoretic lower bound on both the peak normalized delivery time (NDT), and the \textit{expected} NDT of cache-aided interference networks with uniform content popularity. For the peak NDT, we show that our lower bound is strictly tighter than the bound in the literature for small cache sizes. Moreover, we show that the feasibility region on the expected NDT is bigger than that of the peak NDT.