Jechan Han

Enhancements to the Fast Recovery Algorithm of TCP NewReno

Transmission control protocol (TCP) suffers significant performance degradation over wireless networks where packet losses are not always caused by network congestion. In order to prevent frequent retransmission timeout (RTO), which is the main reason for the degradation, we propose enhancements that make it possible for a TCP sender to recover packet losses occurred during fast recovery period. The proposed scheme consists of two algorithms called Duplicate Acknowledgement Counting (DAC) and Extended Fast Recovery (EFR). Simulation results show that the proposed scheme improves the throughput of TCP NewReno by reducing the number of RTO.

Enhanced Response Algorithm for Spurious TCP Timeout(ER-SRTO)

Eifel and F-RTO have been reported representative solutions for spurious TCP timeout. However, these algorithms do not work well in case that delay spike and packet loss occur simultaneously. In this paper, we propose ER-SRTO algorithm which detects the packet loss during delay spike and conducts an efficient recovery in the RTO procedure based on ACK sequence number of retransmission packet. Proposed scheme recovers the lost packet without invoking additional loss recovery procedure. Simulation result shows that proposed algorithm outperforms previous ones.

Reverse acknowledgment (ra) scheme: fast detection of retransmission failures for SR-ARQ

This letter proposes a simple modification called reverse acknowledgement (RA) scheme to a negative acknowledgement (NAK)-based selective repeat automatic repeat request (SR-ARQ) protocol for its fast loss recovery. By adopting the RA scheme, a NAK-based SR-ARQ receiver can detect and recover retransmission failures without invoking retransmission timeouts (RTOs). By OPNET simulations, we evaluate the performance of the RA scheme in terms of the transport delay and re-sequencing delay and show that the RA scheme considerably improves the performance of NAK-based SR-ARQ.

A New Receiver-Based Retransmission Scheme with TFRC

This letter proposes a new receiver-based retransmission scheme for efficient retransmission with TFRC. The proposed scheme consists of an adaptive packet loss (APL) detection method and a receiver-based retransmission mechanism that efficiently accomplishes retransmission. Simulation results show that the proposed scheme not only improves effective retransmission but also reduces unnecessary retransmissions.

Queuing Analysis Model for the SR-ARQ Protocol with a Finite Retransmission Persistence

In this paper, we analyze the mean queuing delay of selective-repeat automatic repeat request (SR-ARQ) protocol with the finite retransmission persistence. The retransmission persistence means the willingness of the protocol to retransmit a lost (or corrupted) packet to ensure reliable packet delivery across a lossy link. According to the retransmission persistence, SR-ARQ protocols have a different performance in terms of both packet delay and link reliability. So far, however, there is no serious study in the effect of the retransmission persistence on the SR-ARQ performance. We present a simple M/G/1 queuing model for the SR-ARQ protocol with the finite retransmission persistence by using the ideal SR-ARQ approximation. The mean queuing delay is obtained from the queuing model and verified its accuracy through the simulation results using the OPNET simulator. Both the analytical predictions and simulation results clearly show the effect of retransmission persistence on the queuing delay of the SR-ARQ protocol in various network conditions: packet loss rate and traffic condition over a wireless link.

SR-ARQ Retramsission Persistence Management to Avoid TCP Spurious Timeout in a Wireless Environment

To detect and recover packet losses over wireless links is very important in terms of reliability in packet transmission. Most wireless communication systems adopt an automatic repeat request (ARQ) protocol operating at link layer. However, it has been constantly addressed that the interaction not harmonized sufficiently between ARQ and TCP rather degrades TCP performance. In this paper, therefore, we propose an improved scheme from the aspect of the interaction with TCP loss recovery mechanism that can be applied to selective repeat ARQ (SR-ARQ) protocol and prove that the proposed scheme improves TCP performance significantly by OPNET simulations.