TITLE:
Adaptive TCP: A Sender Side Mechanism with Dynamic Adjustment of Congestion Control Parameters for Performance Improvement in WLAN
AUTHORS:
Purvang Dalal, Mohanchur Sarkar, Kankar Dasgupta, Nikhil Kothari
KEYWORDS:
Bandwidth Estimation, Round Trip Time, Congestion Estimator, Network Utilization Factor, Bit Error Rate, Fast Retransmit and Recovery
JOURNAL NAME:
International Journal of Communications, Network and System Sciences,
Vol.8 No.5,
May
11,
2015
ABSTRACT: This
paper presents a sender side only TCP mechanism to prevent compromise for bandwidth
utilization in IEEE 802.11 wireless networks. In absence of mechanism for
accurate and immediate loss discrimination, the TCP sender unnecessarily
reduces its Loss Window in response to the packet losses due to transmission errors.
At the same time, frequent transmission losses and associated link
retransmissions cause inaccuracy for available bandwidth estimate. The
proposal, Adaptive TCP tackles the above issues using two refinements. First,
sender estimates the degree of congestion by exploiting the statistics for
estimated Round Trip Time (RTT). With
this, it prevents unnecessary shrinkage of Loss Window and bandwidth estimate.
Second, by concluding the uninterrupted evolution of its sending rate in recent
past, the Adaptive TCP advances bandwidth estimate under favorable network
conditions. This in turn, facilitates for quick growth in TCP’s sending rate
after loss recovery and consequently alleviates bandwidth utilization. The
authors implement the algorithm on top of TCP NewReno, evaluate and compare its
performance with the wireless TCP variants deployed in current Internet. Through intensive simulations
it is demonstrated that the Adaptive TCP outperforms other well-established TCP
variants, and yields more than 100% of the throughput performance and more than
60% of improvement for bandwidth utilization, compared to TCP NewReno. The
simulation results also demonstrated compatibility of Adaptive TCP in a shared
wireless environment.