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On Caching with More Users than Files

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TLDR
In this paper, a coded delivery strategy is proposed to profit from the multicasting opportunities that arise because a file may be demanded by multiple users, and the proposed delivery method is proved to be optimal under the constraint of uncoded placement for centralized systems with two files, moreover it outperforms known caching strategies for both centralized and decentralized systems.
Abstract
Caching appears to be an efficient way to reduce peak hour network traffic congestion by storing some content at the user's cache without knowledge of later demands. Recently, Maddah-Ali and Niesen proposed a two-phase, placement and delivery phase, coded caching strategy for centralized systems (where coordination among users is possible in the placement phase), and for decentralized systems. This paper investigates the same setup under the further assumption that the number of users is larger than the number of files. By using the same uncoded placement strategy of Maddah-Ali and Niesen, a novel coded delivery strategy is proposed to profit from the multicasting opportunities that arise because a file may be demanded by multiple users. The proposed delivery method is proved to be optimal under the constraint of uncoded placement for centralized systems with two files, moreover it is shown to outperform known caching strategies for both centralized and decentralized systems.

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Citations
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Journal ArticleDOI

The Exact Rate-Memory Tradeoff for Caching With Uncoded Prefetching

TL;DR: A novel caching scheme is proposed, which strictly improves the state of the art by exploiting commonality among user demands and fully characterize the rate-memory tradeoff for a decentralized setting, in which users fill out their cache content without any coordination.
Journal ArticleDOI

Fog-Aided Wireless Networks for Content Delivery: Fundamental Latency Tradeoffs

TL;DR: In this article, the authors investigated the fundamental limits of a high signal-to-noise-ratio metric, termed normalized delivery time (NDT), which captures the worst case coding latency for delivering any requested content to the users.
Posted Content

On the Optimality of Uncoded Cache Placement

TL;DR: This paper connects the caching problem to an index coding problem and shows the optimality of the MAN scheme under the conditions that (i) the cache placement phase is restricted to be uncoded (i.e, pieces of the files can only copied into the user's cache), and (ii) the number of users is no more than theNumber of files.
Journal ArticleDOI

Fundamental Limits of Coded Caching: Improved Delivery Rate-Cache Capacity Tradeoff

TL;DR: In this paper, a centralized coded caching system, consisting of a server delivering popular files, each of size $F$ bits, to $K$ users through an error-free shared link, is considered.
Journal ArticleDOI

Noisy Broadcast Networks With Receiver Caching

TL;DR: In this article, the capacity-memory tradeoff of an erasure broadcast network with two disjoint sets of receivers is investigated and a joint cache-channel coding scheme is proposed.
References
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Journal ArticleDOI

Fundamental Limits of Caching

TL;DR: This paper proposes a novel coded caching scheme that exploits both local and global caching gains, leading to a multiplicative improvement in the peak rate compared with previously known schemes, and argues that the performance of the proposed scheme is within a constant factor of the information-theoretic optimum for all values of the problem parameters.
Journal ArticleDOI

Decentralized coded caching attains order-optimal memory-rate tradeoff

TL;DR: In this paper, the authors propose an efficient caching scheme, in which the content placement is performed in a decentralized manner, and despite this lack of coordination, the proposed scheme is nevertheless able to create coded-multicasting opportunities and achieves a rate close to the optimal centralized scheme.
Posted Content

Fundamental Limits of Caching

TL;DR: In this article, the authors proposed a coded caching scheme that exploits both local and global caching gains, leading to a multiplicative improvement in the peak rate compared to previously known schemes, in particular the improvement can be on the order of the number of users in the network.
Journal ArticleDOI

Order-Optimal Rate of Caching and Coded Multicasting With Random Demands

TL;DR: In this article, the authors considered the canonical shared link caching network and provided a comprehensive characterization of the order-optimal rate for all regimes of the system parameters, as well as an explicit placement and delivery scheme achieving orderoptimal rates.