arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 1307.2672cs.ITmath.IT
收藏

带边信息库的索引编码问题

Index Coding Problem with Side Information Repositories

Karthikeyan Shanmugam, Alexandros G. Dimakis, Giuseppe Caire

摘要:

为了解决蜂窝网络中移动视频业务的预期巨大增长,已经提出了一种涉及基站以及缓存毫微微站(称为助手)的架构,其在用户附近存储流行文件[1]。缓存的主要好处是,当一个流行的文件在请求该文件的用户附近的助手处可用时,下载速率会大大提高。在这项工作中,我们通过索引编码的镜头,探索在这种架构中的缓存的第二个好处。我们假设一个系统有n个用户和恒定数量的缓存助手。只有帮助程序存储文件,即有辅助信息。我们研究以下场景:每个用户请求一个不同的文件,该文件在附近的助手集中找不到。全知基站为用户提供编码数据包(通过索引码)。每个用户从编码分组和来自附近助手的边信息分组中解码出其期望的分组。我们假设用户可以获得任何文件存储在他们的邻居助手,而不会产生传输成本。对于所采用的索引码,我们研究了两种可实现的方案:1)基于与问题相关的边信息图的着色的XOR着色和2)基于边信息图的分数着色的向量XOR着色。我们表明,一般的问题减少到一个典型的问题,每个用户连接到一个帮手在一些拓扑约束。对于正则问题,当帮助者数目为常数时,我们证明了计算最佳XOR/向量XOR着色方案的复杂性是用户数n的多项式。结果利用了一个特殊的完整的二部结构,侧信息图展示任何有限的k。

英文摘要:

To tackle the expected enormous increase in mobile video traffic in cellular networks, an architecture involving a base station along with caching femto stations (referred to as helpers), storing popular files near users, has been proposed [1]. The primary benefit of caching is the enormous increase in downloading rate when a popular file is available at helpers near a user requesting that file. In this work, we explore a secondary benefit of caching in this architecture through the lens of index coding. We assume a system with n users and constant number of caching helpers. Only helpers store files, i.e. have side information. We investigate the following scenario: Each user requests a distinct file that is not found in the set of helpers nearby. Users are served coded packets (through an index code) by an omniscient base station. Every user decodes its desired packet from the coded packets and the side information packets from helpers nearby. We assume that users can obtain any file stored in their neighboring helpers without incurring transmission costs. With respect to the index code employed, we investigate two achievable schemes: 1) XOR coloring based on coloring of the side information graph associated with the problem and 2)Vector XOR coloring based on fractional coloring of the side information graph. We show that the general problem reduces to a canonical problem where every user is connected to exactly one helper under some topological constraints. For the canonical problem, with constant number of helpers (k), we show that the complexity of computing the best XOR/vector XOR coloring schemes are polynomial in the number of users n. The result exploits a special complete bi-partite structure that the side information graphs exhibit for any finite k.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑