| 1. |
- Zhang, Lin, et al.
(author)
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Decentralized Caching Schemes and Performance Limits in Two-Layer Networks
- 2018
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In: IEEE Transactions on Vehicular Technology. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9545 .- 1939-9359. ; 67:12, s. 12177-12192
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Journal article (peer-reviewed)abstract
- We study the decentralized caching scheme in a two-layer network, which includes a server, multiple helpers, and multiple users. Basically, the proposed caching scheme consists of two phases, i.e., placement phase and delivery phase. In the placement phase, each helper/user randomly and independently selects contents from the server and stores them into its memory. In the delivery phase, the users request contents from the server, and the server satisfies each user through a helper. Different from the existing caching scheme, the proposed caching scheme takes into account the pre- stored contents at both helpers and users in the placement phase to design the delivery phase. Meanwhile, the proposed caching scheme exploits index coding in the delivery phase and leverages multicast opportunities, even when different users request distinct contents. Besides, we analytically characterize the performance limit of the proposed caching scheme, and show that the achievable rate region of the proposed caching scheme lies within constant margins to the information-theoretic optimum. In particular, the multiplicative and additive factors are carefully sharpened to be 1/48 and 4, respectively, both of which are better than the state of arts. Finally, simulation results demonstrate the advantage of the proposed caching scheme compared with the state of arts.
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| 2. |
- Zhang, Lin, et al.
(author)
-
Order-Optimal Caching in Hierarchical Networks
- 2016
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In: 2016 IEEE/CIC INTERNATIONAL CONFERENCE ON COMMUNICATIONS IN CHINA (ICCC). - : IEEE.
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Conference paper (peer-reviewed)abstract
- The decentralized caching is studied in hierarchical networks, where users request contents through intermediate nodes (helpers) from a file server. By placing contents randomly and independently in each node and carefully designing the data delivery, the correlations of the pre-stored contents across layers can be utilized to reduce the transmission rate in each layer. A hybrid caching scheme is developed by exploiting the cross-layer storage correlations as well as the single-layer and cross-layer multicast opportunities. It is observed that the achievable rate region of the hybrid caching scheme is strictly better than the caching scheme in [1]. Furthermore, the order-optimality of the hybrid caching scheme is demonstrated by achieving the performance within constant multiplicative and additive factors of the information-theoretic optimum. In particular, the multiplicative and additive factors are carefully quantified to be 1/48 and 4, respectively.
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