Dynamic TCP acknowledgment with sliding window

  • Authors:
  • Hisashi Koga

  • Affiliations:
  • Graduate School of Information Systems, University of Electro-Communications, 1-5-1 Chofugaoka Chofu-si, Tokyo 1828585, Japan

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2009

Quantified Score

Hi-index 5.23

Visualization

Abstract

The dynamic TCP acknowledgement problem which focuses theacknowledgment mechanism in TCP protocol has been intensivelystudied in the area of competitive analysis. However, its frameworkdoes not consider the sliding window in the TCP protocol thatrestricts the maximum number of packets that the sender can injectinto the network without an acknowledgement. This paper proposes anew problem in which the sliding window is realisticallyintegrated. We study how the ability of on-line algorithms changes,depending on whether the receiver is taught the window size. Thegreater part of this paper assumes that the window size is aconstant integer W. We first show that, if W isgiven, the optimal on-line algorithm for the previous framework canbe extended to our new framework and achieves the optimalcompetitive ratio of 2. Next we prove that, if W is notgiven, the lower bound of the competitive ratio for an algorithmclass which contains the optimal algorithm for the previousframework depends on the peak packet rate T from the senderand W, and is not better than(T/W+[T/W]-1)-competitive. Then, weprove that there exists an on-line algorithm that is([T/W]+2)-competitive, when W is unknown. Anoptimal off-line algorithm is also presented in this paper.Significantly, our problem models the situation in which an on-linealgorithm involuntarily transforms the input and processes themodified input without noticing the transformation.