# Opportunistic Content Delivery in Fading Broadcast Channels

## TL;DR

This paper introduces an opportunistic content delivery scheme for fading broadcast channels that leverages coded caching and user selection to achieve a linear increase in sum delivery rate with the number of users.

## Contribution

It proposes a novel delivery scheme combining superposition coding and power allocation, demonstrating scalability through user selection in fading channels.

## Key findings

- Coded caching with user selection yields linear rate scaling.
- The scheme outperforms baseline methods in fading broadcast channels.
- Long-term sum content delivery rate scales with the number of users.

## Abstract

We consider content delivery over fading broadcast channels. A server wants to transmit K files to K users, each equipped with a cache of finite size. Using the coded caching scheme of Maddah-Ali and Niesen, we design an opportunistic delivery scheme where the long-term sum content delivery rate scales with K the number of users in the system. The proposed delivery scheme combines superposition coding together with appropriate power allocation across sub-files intended to different subsets of users. We analyze the long-term average sum content delivery rate achieved by two special cases of our scheme: a) a selection scheme that chooses the subset of users with the largest weighted rate, and b) a baseline scheme that transmits to K users using the scheme of Maddah-Ali and Niesen. We prove that coded caching with appropriate user selection is scalable since it yields a linear increase of the average sum content delivery rate.