# Distributed Cooperative Caching for VoD with Geographic Constraints

## TL;DR

This paper proposes a distributed algorithm for cooperative video caching in cellular networks with geographic constraints, optimizing substream placement to reduce backhaul load using layered or multiple description coding.

## Contribution

It introduces a novel distributed asynchronous algorithm for cache placement that minimizes residual bandwidth in VoD systems with geographic constraints.

## Key findings

- MDC outperforms LC when popular content is cached.
- The proposed algorithm converges rapidly.
- The difference between MDC and LC diminishes with the algorithm.

## Abstract

We consider caching of video streams in a cellular network in which each base station is equipped with a cache. Video streams are partitioned into multiple substreams and the goal is to place substreams in caches such that the residual backhaul load is minimized. We consider two coding mechanisms for the substreams: Layered coding (LC) mechanism and Multiple Description Coding (MDC). We develop a distributed asynchronous algorithm for deciding which files to store in which cache to minimize the residual bandwidth, i.e., the cost for downloading the missing substreams of the user's requested video with a certain video quality from the gateway (i.e., the main server). We show that our algorithm converges rapidly. Also, we show that MDC partitioning is better than LC mechanism when the most popular content is stored in caches; however, our algorithm diminishes this difference.