TCP westwood: end-to-end congestion control for wired/wireless networks
Wireless Networks
Distinguishing Congestion Losses from Wireless Transmission Losses: A Negative Result
IC3N '98 Proceedings of the International Conference on Computer Communications and Networks
End-to-end differentiation of congestion and wireless losses
IEEE/ACM Transactions on Networking (TON)
IEEE Transactions on Multimedia
TCP-Jersey for wireless IP communications
IEEE Journal on Selected Areas in Communications
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In this paper, we are interested in improving TCP flow performance when a short loss of 802.11 signal leads to losing segments and triggers inappropriately TCP congestion control mechanisms. A set of measurements in a common wireless environment with signal losses due to mobility or interference is made to highlight the distinct MAC and TCP loss recovery levels and the lack of interactions between them. Initially, we demonstrate the interest of adapting the 802.11 MAC layer Retry Limit parameter in the case of signal losses due to distance or obstacles (mobility). Thus, a first-level loss differentiation algorithm (LDA) acting at the MAC layer is proposed to improve TCP flow performance in the case of segment losses due to mobility. Hence, for a signal failure, the MAC layer reacts consequently by dynamically adapting the Retry Limit parameter. This adaptation allows avoiding a costly end-to-end TCP loss recovery. Segment losses due to interference are differentiated from those due to congestion through the use of a second-level LDA. The latter is a cross-layer LDA acting at the TCP layer but using a specific 802.11 parameter, the AckFailureCount, to realize the targeted loss differentiation. The TCP NewReno version is then adapted in order to integrate the cross-layer LDA results and to avoid reducing the TCP congestion window unsuitably. The efficiency and completeness of a solution integrating both LDA schemes is then discussed.