Enhanced TCP Congestion Control with Higher Utilization in Under-Buffered Links

Dowon HYUN  Ju Wook JANG  

Publication
IEICE TRANSACTIONS on Communications   Vol.E95-B   No.4   pp.1427-1430
Publication Date: 2012/04/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E95.B.1427
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Network
Keyword: 
link utilization,  TCP Reno,  under-buffered link,  congestion window,  

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Summary: 
TCP Reno is not fully utilized in under-buffered links. We propose a new TCP congestion control algorithm that can utilize the link almost up to 100% except the first congestion avoidance cycle. Our scheme estimates the minimum congestion window size for full link utilization in every congestion avoidance cycle and sends extra packets without touching TCP Reno congestion control. It has the same RTT fairness and the same saw-tooth wave as TCP Reno does. Our scheme does not affect competing TCP Reno flows since it uses only unused link capacity. We provide a simple mathematical modeling as well as ns-2 simulation results which show that the link utilization is improved by up to 19.88% for k=1/8 against TCP Reno when the buffer is k times the optimal buffer size. We claim that our scheme is useful for transmitting large amount of data in under-buffered links.