Assignment of movies to heterogeneous video servers

Yiu-Wing Leung*, R.Y.-T. Hou

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

10 Citations (Scopus)
17 Downloads (Pure)


A video-on-demand (VOD) system provides an electronic videb rental service to geographically distributed users. It can adopt multiple servers to serve many users concurrently. As a VOD system is being used and evolved, its servers probably become heterogeneous. For example, if a new server is added to expand the VOD system or replace a failed server, the new server may be faster with a larger storage size. This paper investigates how to assign movies to heterogeneous servers in order to minimize the blocking probability. It is proven that this assignment problem is NP-hard, and a lower bound is derived on the minimal blocking probability. The following approach is proposed for assignment: 1) problem relaxation - a relaxed assignment problem is formulated and solved to determine the ideal load that each server should handle, and 2) goal programming - an assignment and reassignment are performed iteratively while fulfilling all the constraints so that the load handled by each server is close to the ideal one. This approach is generic and applicable to many assignment problems. This approach is adopted to design two specific algorithms for movie assignment with and without replication. It is demonstrated that these algorithms can find optimal or close-to-optimal assignments.

Original languageEnglish
Pages (from-to)665-681
Number of pages17
JournalIEEE Transactions on Systems, Man, and Cybernetics Part A:Systems and Humans
Issue number5
Publication statusPublished - Sept 2005

Scopus Subject Areas

  • Software
  • Control and Systems Engineering
  • Human-Computer Interaction
  • Computer Science Applications
  • Electrical and Electronic Engineering

User-Defined Keywords

  • Assignment
  • Server system
  • Video-on-demand (VOD)


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