1,019 research outputs found
Asymptotic Laws for Joint Content Replication and Delivery in Wireless Networks
We investigate on the scalability of multihop wireless communications, a
major concern in networking, for the case that users access content replicated
across the nodes. In contrast to the standard paradigm of randomly selected
communicating pairs, content replication is efficient for certain regimes of
file popularity, cache and network size. Our study begins with the detailed
joint content replication and delivery problem on a 2D square grid, a hard
combinatorial optimization. This is reduced to a simpler problem based on
replication density, whose performance is of the same order as the original.
Assuming a Zipf popularity law, and letting the size of content and network
both go to infinity, we identify the scaling laws and regimes of the required
link capacity, ranging from O(\sqrt{N}) down to O(1)
Caching and Coded Multicasting: Multiple Groupcast Index Coding
The capacity of caching networks has received considerable attention in the
past few years. A particularly studied setting is the case of a single server
(e.g., a base station) and multiple users, each of which caches segments of
files in a finite library. Each user requests one (whole) file in the library
and the server sends a common coded multicast message to satisfy all users at
once. The problem consists of finding the smallest possible codeword length to
satisfy such requests. In this paper we consider the generalization to the case
where each user places requests. The obvious naive scheme consists
of applying times the order-optimal scheme for a single request, obtaining
a linear in scaling of the multicast codeword length. We propose a new
achievable scheme based on multiple groupcast index coding that achieves a
significant gain over the naive scheme. Furthermore, through an information
theoretic converse we find that the proposed scheme is approximately optimal
within a constant factor of (at most) .Comment: 5 pages, 1 figure, to appear in GlobalSIP14, Dec. 201
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