TCP-Ho: A Congestion Control Algorithm with Design and Performance Evaluation

Cheng-Yuan HO
Yi-Cheng CHAN
Yaw-Chung CHEN

IEICE TRANSACTIONS on Communications   Vol.E90-B    No.3    pp.516-526
Publication Date: 2007/03/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e90-b.3.516
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Network
congestion control,  TCP,  slow start,  congestion avoidance,  transport protocol,  

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A critical design issue of Transmission Control Protocol (TCP) is its congestion control that allows the protocol to adjust the end-to-end communication rate based on the detection of packet loss. However, TCP congestion control may function poorly during its slow start and congestion avoidance phases. This is because TCP sends bursts of packets with the fast window increase and the ACK-clock based transmission in slow start, and respond slowly with large congestion windows especially in high bandwidth-delay product (BDP) networks during congestion avoidance. In this article, we propose an improved version of TCP, TCP-Ho, that uses an efficient congestion window control algorithm for a TCP source. According to the estimated available bandwidth and measured round-trip times (RTTs), the proposed algorithm adjusts the congestion window size with a rate between exponential growth and linear growth intelligently. Our extensive simulation results show that TCP-Ho significantly improves the performance of connections as well as remaining fair and stable when the BDP increases. Furthermore, it is feasible to implement because only sending part needs to be modified.