TITLE:
TCP Karak: A New TCP AIMD Algorithm Based on Duplicated Acknowledgements for MANET
AUTHORS:
Wesam A. Almobaideen, Njoud O. Al-maitah
KEYWORDS:
TCP Congestion Control, Additive Increase Multiplicative Decrease, Mobile Ad Hoc Networks, Duplicated Acknowledgement
JOURNAL NAME:
International Journal of Communications, Network and System Sciences,
Vol.7 No.9,
September
24,
2014
ABSTRACT: Transmission
Control Protocol (TCP) performance over MANET is an area of extensive research.
Congestion control mechanisms are major components of TCP which affect its
performance. The improvement of these mechanisms represents a big challenge
especially over wireless environments. Additive Increase Multiplicative
Decrease (AIMD) mechanisms control the amount of increment and decrement of the
transmission rate as a response to changes in the level of contention on routers
buffer space and links bandwidth. The role of an AIMD mechanism in transmitting
the proper amount of data is not easy, especially over MANET. This is because
MANET has a very dynamic topology and high bit error rate wireless links that
cause packet loss. Such a loss could be misinterpreted
as severe congestion by the transmitting TCP node. This leads to unnecessary
sharp reduction in the transmission rate which could degrades TCP throughput.
This paper introduces a new AIMD algorithm that takes the number of already
received duplicated ACK, when a timeout takes place, into account in deciding
the amount of multiplicative decrease. Specifically, it decides the point from
which Slow-start mechanism should begin its recovery of the congestion window
size. The new AIMD algorithm has been developed as a new TCP variant which we
call TCP Karak. The aim of TCP Karak is to be more adaptive to mobile wireless
networks conditions by being able to distinguish between loss due to severe
congestion and that due to link breakages or bit errors. Several simulated experiments
have been conducted to evaluate TCP Karak and compare its performance with TCP
NewReno. Results have shown that TCP Karak is able to achieve higher throughput
and goodput than TCP NewReno under various mobility speeds, traffic loads, and
bit error rates.