Improved On-Line Broadcast Scheduling with Deadlines

  • Feifeng Zheng
  • Stanley P. Y. Fung
  • Wun-Tat Chan
  • Francis Y. L. Chin
  • Chung Keung Poon
  • Prudence W. H. Wong
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4112)


We study an on-line broadcast scheduling problem in which requests have deadlines, and the objective is to maximize the weighted throughput, i.e., the weighted total length of the satisfied requests. For the case where all requested pages have the same length, we present an online deterministic algorithm named BAR and prove that it is 4.56-competitive. This improves the previous algorithm of Kim and Chwa [11] which is shown to be 5-competitive by Chan et al. [4]. In the case that pages may have different lengths, we prove a lower bound of Ω(Δ/logΔ) on the competitive ratio where Δ is the ratio of maximum to minimum page lengths. This improves upon the previous \(\sqrt{\Delta}\) lower bound in [11,4] and is much closer to the current upper bound of (\(\Delta+2\sqrt{\Delta}+2\)) in [7]. Furthermore, for small values of Δ we give better lower bounds.


Competitive Ratio Broadcast Schedule Data Broadcast Idle Interval Tight Deadline 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Feifeng Zheng
    • 1
  • Stanley P. Y. Fung
    • 2
  • Wun-Tat Chan
    • 3
  • Francis Y. L. Chin
    • 3
  • Chung Keung Poon
    • 4
  • Prudence W. H. Wong
    • 5
  1. 1.School of ManagementXi’an JiaoTong UniversityChina
  2. 2.Department of Computer ScienceUniversity of LeicesterUnited Kingdom
  3. 3.Department of Computer ScienceThe University of Hong KongHong KongChina
  4. 4.Department of Computer ScienceCity University of Hong KongChina
  5. 5.Department of Computer ScienceUniversity of LiverpoolUnited Kingdom

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