On Hierarchical Coded Caching with Offline Users

Rashid Ummer N. T.; B. Sundar Rajan

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arXiv · 2507.00727

On Hierarchical Coded Caching with Offline Users

Rashid Ummer N. T.·B. Sundar Rajan

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Abstract

This paper studies a two-layer hierarchical network in which some users are offline during the content delivery phase. A two-layer hierarchical network consists of a single server connected to multiple cache-aided mirror sites, and each mirror site is connected to a distinct set of cache-aided users. A scheme for such a hierarchical system with offline users has been proposed recently but considered a special case where all mirror caches have zero memory, which is a significant limitation. We propose an array known as a hierarchical hotplug placement delivery array (HHPDA), which describes the placement and delivery phases of a coded caching scheme for a general two-layer hierarchical network with offline users. Further, we construct a class of HHPDAs using combinatorial t-designs.

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Rashid Ummer N. T., B. Sundar Rajan. 2025-07-01. On Hierarchical Coded Caching with Offline Users. https://arxiv.org/abs/2507.00727

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