85,468 research outputs found
Dynamic Edge Caching with Popularity Drifting
Caching at the network edge devices such as wireless caching stations (WCS)
is a key technology in the 5G network. The spatial-temporal diversity of
content popularity requires different content to be cached in different WCSs
and periodically updated to adapt to temporal changes. In this paper, we study
how the popularity drifting speed affects the number of required broadcast
transmissions by the MBS and then design coded transmission schemes by
leveraging the broadcast advantage under the index coding framework. The key
idea is that files already cached in WCSs, which although may be currently
unpopular, can serve as side information to facilitate coded broadcast
transmission for cache updating. Our algorithm extends existing index
coding-based schemes from a single-request scenario to a multiple-request
scenario via a "dynamic coloring" approach. Simulation results indicate that a
significant bandwidth saving can be achieved by adopting our scheme
Correlation Functions of Warped CFT
Warped conformal field theory (WCFT) is a two dimensional quantum field
theory whose local symmetry algebra consists of a Virasoro algebra and a U(1)
Kac-Moody algebra. In this paper, we study correlation functions for primary
operators in WCFT. Similar to conformal symmetry, warped conformal symmetry is
very constraining. The form of the two and three point functions are determined
by the global warped conformal symmetry while the four point functions can be
determined up to an arbitrary function of the cross ratio. The warped conformal
bootstrap equation are constructed by formulating the notion of crossing
symmetry. In the large central charge limit, four point functions can be
decomposed into global warped conformal blocks, which can be solved exactly.
Furthermore, we revisit the scattering problem in warped AdS spacetime (WAdS),
and give a prescription on how to match the bulk result to a WCFT retarded
Green's function. Our result is consistent with the conjectured holographic
dualities between WCFT and WAdS.Comment: 20 pages, 0 figur
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