Distributed Caching of Transient Contents in a Tandem of Caches

Koley, Ankita; Singh, Chandramani

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https://hdl.handle.net/2142/130283 Copy

Description

Title

Distributed Caching of Transient Contents in a Tandem of Caches

Author(s)

• Koley, Ankita
• Singh, Chandramani

Issue Date

2025-09-17

Keyword(s)

• Content caching
• Restless multi-armed bandits
• Information freshness
• Caching network

Abstract

We focus on caching of transient contents in a tandem of caches. The contents fetched from the server remain usable for a finite duration. Requests arrive at the first cache. A request is forwarded to the upstream caches until a usable version of the requested content is found and is fetched from the server if such a version is not found in any of the caches. Getting the contents from upstream caches or from the server incurs costs. We formulate an optimal content caching problem to minimize the average cost subject to the cache capacity constraints. The problem falls under the category of continuous time Markov Decision Processes and suffers from curse of dimensionality. We first consider a single cache and formulate the problem as a restless multi-armed bandit (RMAB) and propose a Whittle index-based policy with explicit index expressions. We then extend the methodology to a tandem of caches. Here, a newly fetched content is associated with multiple Whittle indices, one per cache, and the index-based caching policy maximizes the sum of Whittle indices across all caches. We also suggest a distributed implementation that does not need a centralized entity with knowledge of the contents at different caches and their ages. Finally, we demonstrate via simulations that the performance of the proposed policy is very close to optimal.

Publisher

Allerton Conference on Communication, Control, and Computing

Series/Report Name or Number

2025 61st Allerton Conference on Communication, Control, and Computing Proceedings

ISSN

2836-4503

Type of Resource

Text

Genre of Resource

Conference Paper/Presentation

Language

eng

Handle URL

https://hdl.handle.net/2142/130283&&

Copyright and License Information

Copyright 2025 is held by Ankita Koley and Chandramani Singh.

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