NDLI: Improved Approximation Algorithms for Broadcast Scheduling

Content Provider	Society for Industrial and Applied Mathematics (SIAM)
Author	Sviridenko, Maxim Bansal, Nikhil Coppersmith, Don
Copyright Year	2008
Abstract	We consider scheduling policies in a client-server system where the server delivers data by broadcasting it to the users. In thesimplest model of the problem, there is a single server that holds n pages of unit size. Multiple requests for these pages arrive over time. At each time slot the server broadcasts exactly one page which satisfies all of the outstanding requests for this page at that time. We consider the problem of minimizing the average response time of requests, where the response time of the request is the duration since the request is placed until the time it is satisfied. For the offline version of this problem we give an algorithm with an approximation ratio of $O(\log^2(n) / \log \log(n))$. More generally, for any $\epsilon>0$, the algorithm achieves an average response time of $(2+\epsilon) \cdot \text{OPT} + O(\log n \cdot \log_{(1+\epsilon)} n)$, which is useful when the optimum value is large. This substantially improves the previously best known approximation factor of $O(\sqrt{n})$ for the problem [N. Bansal, M. Charikar, S. Khanna, and J. Naor, Proceedings of the Sixteenth Annual ACM-SIAM Symposium on Discrete Algorithms, Vancouver, British Columbia, ACM, New York, SIAM, Philadelphia, 2005, pp. 215221]. Our result is based on iteratively relaxing and rounding an auxiliary linear program derived from a natural linear programming relaxation of the problem.
Starting Page	1157
Ending Page	1174
Page Count	18
File Format	PDF
ISSN	00975397
DOI	10.1137/060674417
e-ISSN	10957111
Journal	SIAM Journal on Computing (SMJCAT)
Issue Number	3
Volume Number	38
Language	English
Publisher	Society for Industrial and Applied Mathematics
Publisher Date	2008-07-16
Access Restriction	Subscribed
Subject Keyword	Analysis of algorithms and problem complexity LP rounding Performance evaluation; queueing; scheduling Approximation methods and heuristics approximation algorithm Approximation algorithms Scheduling theory, deterministic Analysis of algorithms broadcast scheduling
Content Type	Text
Resource Type	Article
Subject	Mathematics Computer Science

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