3rd International ICST Conference on Broadband Communications, Networks, and Systems

Research Article

TCP with Delayed Ack for Wireless Networks

  • @INPROCEEDINGS{10.1109/BROADNETS.2006.4374405,
        author={Jiwei Chen and Yeng Zhong Lee and Mario Gerla and M.Y. Sanadidi},
        title={TCP with Delayed Ack for Wireless Networks},
        proceedings={3rd International ICST Conference on Broadband Communications, Networks, and Systems},
  • Jiwei Chen
    Yeng Zhong Lee
    Mario Gerla
    M.Y. Sanadidi
    Year: 2006
    TCP with Delayed Ack for Wireless Networks
    DOI: 10.1109/BROADNETS.2006.4374405
Jiwei Chen1,*, Yeng Zhong Lee1,*, Mario Gerla1,*, M.Y. Sanadidi1,*
  • 1: University of California, Los Angeles, CA 90095
*Contact email: cjw@ee.ucla.edu, yenglee@cs.ucla.edu, gerla@cs.ucla.edu, medy@cs.ucla.edu


This paper studies the TCP performance with delayed ack in wireless networks (including ad hoc and WLANs) which use IEEE 802.11 MAC protocol as the underlying medium access control. Our analysis and simulations show that TCP throughput does not always benefit from an unrestricted delay policy. In fact, for a given topology and flow pattern, there exists an optimal delay window size at the receiver that produces best TCP throughput. If the window is set too small, the receiver generates too many acks and causes channel contention; on the other hand, if set the window too high, the bursty transmission at the sender triggered by large cumulative acks will induce interference and packet losses, thus degrading the throughout. In wireless networks, packet losses are also related to the length of TCP path; when traveling through a longer path, a packet is more likely to suffer interference. Therefore, path length is an important factor to consider when choosing appropriate delay window sizes. In this paper, we first propose an adaptive delayed ack mechanism which is suitable for ad hoc networks, then we propose a more general adaptive delayed ack scheme for ad hoc and hybrid networks. The simulated results show that our schemes can effectively improve TCP throughput by up to 30% in static networks, and provide more significant gain in mobile networks. The proposed schemes are simple and easy to deploy.