Coded caching and content delivery with heterogeneous distortion requirements
File(s)
Accepted version
Author(s)
Yang, Qianqian
Gunduz, D
Type
Journal Article
Abstract
Cache-aided coded content delivery is studied for devices with diverse quality-of-service requirements, specified by a different average distortion target. The network consists of a server holding a database of independent contents, and users equipped with local caches of different capacities. User caches are filled by the server during a low traffic period without the knowledge of particular user demands. As opposed to the current literature, which assumes that the users request files in their entirety, it is assumed that the users in the system have distinct distortion requirements; and therefore, each user requests a single file from the database to be served at a different distortion level. Our goal in this paper is to characterize the minimum delivery rate the server needs to transmit over an error-free shared link to satisfy all possible demand combinations at the requested distortion levels, considering both centralized and decentralized cache placement. For centralized cache placement, the optimal delivery rate is characterized for the two-file two-user scenario for any pair of target distortion requirements, when the underlying source distribution is successively refinable. For the two-user scenario with more than two successively refinable files, the optimal scheme is characterized when the cache capacities of the users are the same and the number of files is a multiple of 3. For the general source distribution, not necessarily successively refinable, and with arbitrary number of users and files, a layered caching and delivery scheme is proposed, assuming that scalable source coding is employed at the server. This allows dividing the problem into two subproblems: the lossless caching of each layer with heterogeneous cache sizes, and cache allocation among layers. A delivery rate minimization problem is formulated and solved numerically for each layer; while two different schemes are proposed to allocate user caches among layers, namely, proportional cache allocation and ordered cache allocation. A decentralized lossy coded caching scheme is also proposed, and its delivery rate performance is studied. Simulation results validate the effectiveness of the proposed schemes in both settings.
Date Issued
2018-06-01
Date Acceptance
2018-01-20
Citation
IEEE Transactions on Information Theory, 2018, 64 (6), pp.4347-4364
ISSN
0018-9448
Publisher
Institute of Electrical and Electronics Engineers
Start Page
4347
End Page
4364
Journal / Book Title
IEEE Transactions on Information Theory
Volume
64
Issue
6
Copyright Statement
© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
Sponsor
Commission of the European Communities
Grant Number
677854
Subjects
0801 Artificial Intelligence And Image Processing
0906 Electrical And Electronic Engineering
1005 Communications Technologies
Networking & Telecommunications
Publication Status
Published
Date Publish Online
2018-02-14