Shielding TCP from Wireless Link Errors: Retransmission Effort and Fragmentation (original) (raw)

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

EURASIP Journal on Wireless Communications and Networking

Based on the assumption of transmission control protocol (TCP) that packets are lost due to congestion, TCP’s congestion control algorithms such as fast retransmit/recovery (FRR) and retransmission timeouts (RTO) unconditionally reduce the transmission rate for every packet loss. When TCP operates in wireless networks, however, FRRs/RTOs are often triggered regardless of congestion due to sudden delay and wireless transmission errors. The congestion irrelative FRRs/RTOs incur TCP’s misbehavior such as blindly halving the transmission rate, unnecessarily retransmitting the outstanding packets which may be in the bottleneck queue. Although many previous studies have been proposed to detect the congestion irrelative FRRs/RTOs, they paid little attention on effectively adjusting the transmission rate for the detected congestion irrelative FRRs/RTOs. In this article, we propose an enhanced TCP to dynamically adjust its transmission rate according to network conditions. Our scheme adjusts...

Link-Layer Error Recovery Techniques to improve TCP Performance over Wireless Links

2005

Recent technology has involved TCP in wireless applications even if it was originally designed to work over wired links. It is well known that wireless links are usually characterized by phenomena like shadowing, multipath propagation and path loss that cause an increase in the bit error rate. Moreover, TCP protocol was supposed to interpret all the losses as due to congestion because of it was designed to work over wired networks. All these problems caused by the wireless application of TCP usually degrade TCP performances. In order to improve TCP behavior over wireless links several solutions have been proposed in literature as: the split connection approach, the end-to-end approach and the link-layer approach. Starting from the link-layer solution that have been studied by Barman and Matta, the main contribution of this thesis is the study of the effects of different modulation formats on the maximum achievable value of an objective function, defined as the ratio between the TCP throughput and a cost function. Appropriate power management and error correction techniques are assumed to improve the link reliability observed by TCP and increase the objective function performance accordingly.

Comparative study of various TCP versions over a wireless link with correlated losses

2003

Abstract We investigate the behavior of the various transmission control protocol (TCP) algorithms over wireless links with correlated packet losses. For such a scenario, we show that the performance of NewReno is worse than the performance of Tahoe in many situations and even OldTahoe in a few situations because of the inefficient fast recovery method of NewReno.

A Comparison of Mechanisms for Improving TCP Performance over Wireless Links

IEEE/ACM Transactions on Networking, 1997

Reliable transport protocols such as TCP are tuned to perform well in traditional networks where packet losses occur mostly because of congestion. However, networks with wireless and other lossy links also suffer from significant losses due to bit errors and handoffs. TCP responds to all losses by invoking congestion control and avoidance algorithms, resulting in degraded end-to-end performance in wireless and lossy systems. In this paper, we compare several schemes designed to improve the performance of TCP in such networks. We classify these schemes into three broad categories: end-to-end protocols, where loss recovery is performed by the sender; link-layer protocols, that provide local reliability; and split-connection protocols, that break the end-to-end connection into two parts at the base station. We present the results of several experiments performed in both LAN and WAN environments, using throughput and goodput as the metrics for comparison.

"Improving TCP Performance over Wireless Networks"

Reliable transport protocols such as TCP are tuned to perform well in traditional networks where packet losses occur mostly because of congestion. However, networks with wireless and other lossy links also suffer from significant non-congestion-related losses due to reasons such as bit errors and handoffs. TCP responds to all losses by invoking congestion control and avoidance algorithms, resulting in degraded end-to-end performance in wireless and lossy systems. In this paper, we compare several schemes designed to improve the performance of TCP in such networks. These schemes are classified into three broad categories: end-toend protocols, where the sender is aware of the wireless link; link-layer protocols, that provide local reliability; and split-connection protocols,that break the end-to-end connection into two parts at the base station. We present the results of several experiments performed in both LAN and WAN environments, using throughput and good put as the metrics for comparison.

WTCP: An efficient mechanism for improving TCP performance over wireless links

… , 1998. ISCC'98. Proceedings. Third IEEE …, 1998

The Transmission Control Protocol (TCP) used in the Internet has been mainly designed assuming a relatively reliable wireline network. TCP assumes that any loss is due to congestion and consequently invokes congestion control measures. This has been shown to yield poor performance in the presence of wireless links as a large number of segment losses will occur more often because of wireless channel errors or host mobility. We present an e cient transmission control scheme (WTCP) that requires the base station to bu er data packets destined for the mobile host and retransmit lost packets. Through simulations, we show that our scheme yields better throughput than other existing proposals while maintaining TCP's end-to-end semantics. One salient feature of WTCP is that it e ectively hides the time spent by the base station to locally recover so that the TCP's round trip time estimation at the source is not a ected. This is critical since otherwise the ability of the source to e ectively detect congestion in the wireline network will be hindered.

Improving TCP performance over wired–wireless networks

Computer Networks, 2007

Today there is a growing demand for Internet services over WLAN hotspots. Majority of the Internet services today are based on TCP. However, TCP is not well-suited for heterogeneous networks consisting of wired and wireless networks. Losses in wireless network, which are quite frequent, are often misinterpreted by the TCP sender as loss due to congestion, which leads to poor performance of TCP. Hence, it is important to shield the TCP sender from wireless error. In this paper, we propose an improved method for identifying cases of wireless losses and tackling the loss at the local link level through MAC layer retransmissions. We then evaluate the effect of MAC layer retransmissions on the performance of TCP both analytically and empirically. Our empirical results show that significant improvement in TCP performance is possible through MAC layer retransmission.

Analyzing the Performance I-TCP and TCP with Explicit Lose Notification over Wireless Links for the Purpose of Further Improvement

International Journal of Engineering Sciences & Research Technology, 2014

Many researchers have been proposed different enhancements over wireless network for the Purpose of Further Improvement .in this research we do comparative study on the performance of the standard TCP over two other approaches meant for the advancement namely Indirect TCP (I-TCP) and TCP with Explicit Loss Notification (ELN-TCP).the main aim of this research is to improve the performance of TCP by providing analyzing approach for the I-TCP) and TCP with Explicit Loss Notification (ELN-TCP).

Study of Proposed Methods for Improving TCP Performance Over Wireless Links

Computing Research Repository, 2009

TCP is designed for networks with assumption that major losses occur only due to congestion of network traffic. On a wireless network TCP misinterprets the transmission losses due to bit errors and handoffs as losses caused by congestion, and triggers congestion control mechanisms. Because of its end to end delivery model, congestion handling and avoidance mechanisms, TCP has been widely accepted as Transport layer protocol for internetworks. Extension of Internetworks over wireless links is inevitable with the spread of ubiquitous computing and mobile communications. This paper presents study of different mechanisms proposed to extend Transport Control Protocol and other alternate solutions to enhance end to end performance over lossy wireless links. The paper studies details of different design choices proposed and their technical advantages and disadvantages. Finally, an analysis and proposal for best choice of proposed schemes are made for wireless networks.