Improve TCP performance over mobile ad hoc network by retransmission timeout adjustment

Abstract

conventional TCP suffers from inability to detect frequent link failure in MANET and consequently could not adjust RTO for reconstructed route. Packet losses due to link breakage must be differentiated from congestion loss to discover link breakage. Moreover, after link breakage, retransmission timeout in standard TCP becomes too long due to successive back-off executions. Using this long RTO for rebuilt route forces sender to remain idle unnecessarily in case of future packet loss. In this paper, a new End-to-End approach which entirely works in transport layer is proposed to improve TCP performance. It distinguishes link failure loss from congestion loss based on fluctuation in history of queue usage rate. Ascending growth of queue usage value intensifies probabilities of congestion losses while averaged queue usage values around fixed value can be sign of link failure losses. After temporary link failure detected and packets from rebuilt route received, new approach compares characteristics of reestablished route with broken route in term of Relative On way Trip Time and number of Hops. Then sender decides to increases RTO to prevent packet retransmission overhead or decreases RTO to resume transmission during unnecessary idle time. Simulation results which are done under different conditions by ns2 illustrated that new approach enhances TCP performance up to 10%.

Multipath Transport Analysis Over Cellular and LEO Access for Aerial Vehicles

“…Lastly, transport-layer retransmissions become unnecessary in our scenario due to the stringent application delay requirements with respect to the default RTO in MPTCP. Fine-tuning the RTO may bring benefit [67], [68] however, there is only a small room for fine-tuning since the link-layer RTT are already within 60-100 ms range.…”

A Method Based on RTO and Selective Acknowledgement for Improving SCTP Protocol Performance in Mobile Ad Hoc Networks

“…Furthermore, in (Fard, Bakar, Karamizadeh & Foladizadeh, 2011), in capacity of TCP protocol in recognizing route failure or error and network congestion in mobile Ad hoc network has been tested in which a new method for end-to-end transport is offered. This method uses change record of queue rate to distinguish the difference or variance between route failure and congestion which sudden shifts in using queue and queue rate shows losses caused by congestion and moderate shifts based on queue application rate mean caused by route failure .…”