Robust end-to-end loss differentiation scheme for transport control protocol over wired/wireless networks

Abstract

The authors propose a robust end-to-end loss differentiation scheme to identify the packet losses because of congestion for transport control protocol (TCP) connections over wired/wireless networks. The authors use the measured round trip time (RTT) values to determine whether the cause of packet loss is because of the congestion over wired path or regular bit errors over wireless paths. The classification should be as accurate as possible to achieve high throughput and maximum fairness for the TCP connections sharing the wired/wireless paths. The accuracies of previous schemes in the literature depends on varying network parameters such as RTT, buffer size, amount of cross traffic, wireless loss rate and congestion loss rate. The proposed scheme is robust in that the accuracy remains rather stable under varying network parameters. The basic idea behind the scheme is to set the threshold for the classification to be a function of the minimum RTT and the current sample RTT, so that it may automatically adapt itself to the current congestion level. When the congestion level of the path is estimated to be low, the threshold for a packet loss to be classified as a congestion loss is increased. This avoids unnecessary halving of the congestion window on packet loss because of the regular bit errors over the wireless path and hence improves the TCP throughput. When the congestion level of the path is estimated to be high, the threshold for a packet loss to be classified as the congestion loss not to miss any congestion loss is decreased and hence improves the TCP fairness. In ns 2 simulations, the proposed scheme correctly classifies the congestion losses under varying network parameters whereas the previous schemes show some dependency on subsets of parameters.

TCP’s dynamic adjustment of transmission rate to packet losses in wirelessnetworks

“…Some loss differentiation schemes such as Westwood [8], JTCP [9], and RELDS [10] have been proposed to detect wireless FRRs/RTOs. These schemes distinguish wireless losses from congestion losses, and let TCP avoid reducing unnecessarily its transmission rate when any of FRRs/RTOs are triggered by wireless losses.…”

“…Some loss differentiation schemes such as Westwood [8], JTCP [9], and RELDS [10] have been proposed to differentiate wireless losses from congestion losses. Other schemes such as Eifel [11][12][13], F-RTO [14,15], and STODER [16] have been suggested to remove the unnecessary retransmissions by detecting spurious FRRs/RTOs.…”

End-to-End Loss Differentiation Algorithm Based on Estimation of Queue Usage in Multi-Hop Wireless Networks

“…If the two conditions are satisfied, it ascribes the packet loss to congestion; otherwise, it assumes it as wireless losses. Lim and Jang [3] suggested a robust end-to-end loss differentiation scheme (RELDS) to precisely discriminate between congestion losses and wireless losses. This scheme employs a moving threshold which is defined as a function of minimum and sample RTT.…”

“…These algorithms [1], [3]- [5], [12] distinguish the cause of packet losses based on information available at Transport Layer. Although these schemes can identify some of the packet losses due to wireless transmission errors as wireless losses, their accuracy is not high as much as we expect, and these schemes cannot avoid sacrificing the accuracy of congestion loss discrimination by misclassifying congestion losses as wireless losses.…”

Loss Discrimination Algorithm for Wired/Wireless Networks

“…However, this is considered inappropriate as the channel capacity in wired network in this study is very limited. (Lim and Jang, 2008) proposed Indirect-TCP (I-TCP) that splits the connection on the wireless edge to protect TCP session from wireless media inconsistencies and losses. This results in two different flow and congestion controls in wired and wireless sections separately.…”