Gateway Adaptive Pacing for TCP across Multihop Wireless Networks and the Internet

In this paper, we introduce an effective congestion control scheme for TCP over hybrid wireless/wired networks comprising a multihop wireless IEEE 802.11 network and the wired Internet. We propose an adaptive pacing scheme at the Internet gateway for wired-to-wireless TCP flows. Furthermore, we analyze the causes for the unfairness of oncoming TCP flows and propose a scheme to throttle aggressive wired-to-wireless TCP flows at the Internet gateway to achieve nearly optimal fairness. Thus, we denote the introduced congestion control scheme TCP with Gateway Adaptive Pacing (TCP-GAP). For wireless-to-wired flows, we propose an adaptive pacing scheme at the TCP sender. In contrast to previous work, TCP-GAP does not impose any control traffic overhead for achieving fairness among active TCP flows. Moreover, TCP-GAP can be incrementally deployed because it does not require any modifications of TCP in the wired part of the network and is fully TCP-compatible. Extensive simulations using ns-2 show that TCPGAP is highly responsive to varying traffic conditions, provides nearly optimal fairness in all scenarios and achieves up to 42% more goodput than TCP NewReno

TCP with Adaptive Pacing for Multihop Wireless Networks

In this paper, we introduce a novel congestion control algorithm for TCP over multihop IEEE 802.11 wireless networks implementing rate-based scheduling of transmissions within the TCP congestion window. We show how a TCP sender can adapt its transmission rate close to the optimum using an estimate of the current 4-hop propagation delay and the coefficient of variation of recently measured round-trip times. The novel TCP variant is denoted as TCP with Adaptive Pacing (TCP-AP). Opposed to previous proposals for improving TCP over multihop IEEE 802.11 networks, TCP-AP retains the end-to-end semantics of TCP and does neither rely on modifications on the routing or the link layer nor requires cross-layer information from intermediate nodes along the path. A comprehensive simulation study using ns-2 shows that TCP-AP achieves up to 84% more goodput than TCP NewReno, provides excellent fairness in almost all scenarios, and is highly responsive to changing traffic conditions

A survey of performance enhancement of transmission control protocol (TCP) in wireless ad hoc networks

This Article is provided by the Brunel Open Access Publishing Fund - Copyright @ 2011 Springer OpenTransmission control protocol (TCP), which provides reliable end-to-end data delivery, performs well in traditional wired network environments, while in wireless ad hoc networks, it does not perform well. Compared to wired networks, wireless ad hoc networks have some specific characteristics such as node mobility and a shared medium. Owing to these specific characteristics of wireless ad hoc networks, TCP faces particular problems with, for example, route failure, channel contention and high bit error rates. These factors are responsible for the performance degradation of TCP in wireless ad hoc networks. The research community has produced a wide range of proposals to improve the performance of TCP in wireless ad hoc networks. This article presents a survey of these proposals (approaches). A classification of TCP improvement proposals for wireless ad hoc networks is presented, which makes it easy to compare the proposals falling under the same category. Tables which summarize the approaches for quick overview are provided. Possible directions for further improvements in this area are suggested in the conclusions. The aim of the article is to enable the reader to quickly acquire an overview of the state of TCP in wireless ad hoc networks.This study is partly funded by Kohat University of Science & Technology (KUST), Pakistan, and the Higher Education Commission, Pakistan

A Clean-Slate Architecture for Reliable Data Delivery in Wireless Mesh Networks

In this paper, we introduce a clean-slate architecture for improving the delivery of data packets in IEEE 802.11 wireless mesh networks. Opposed to the rigid TCP/IP layer architecture which exhibits serious deficiencies in such networks, we propose a unitary layer approach that combines both routing and transport functionalities in a single layer. The new Mesh Transmission Layer (MTL) incorporates cross-interacting routing and transport modules for a reliable data delivery based on the loss probabilities of wireless links. Due to the significant drawbacks of standard TCP over IEEE 802.11, we particularly focus on the transport module, proposing a pure rate-based approach for transmitting data packets according to the current contention in the network. By considering the IEEE 802.11 spatial reuse constraint and employing a novel acknowledgment scheme, the new transport module improves both goodput and fairness in wireless mesh networks. In a comparative performance study, we show that MTL achieves up to 48% more goodput and up to 100% less packet drops than TCP/IP, while maintaining excellent fairness results

Enhanced congestion control in TCP for solving hidden terminal problems in ad hoc wireless networks

This paper studies TCP performance over multihop wireless ad hoc networks that use the IEEE 802.11 protocol as the access method. The aim is to improve the TCP fairness while keeping the algorithm as simple as possible, since in previous works the algorithm designs were more complicated. We propose a simple approach to improve fairness based on scheduling (pacing) new packets according to the transmission interval formed from scaled round-trip time (RTT) and congestion window. Our simulation shows that, given specific scale parameter x, TCP achieves high fairness and throughput via improved spatial channel reuse, if it operates in a certain range of the transmission interval

Signal Strength Based Congestion Control in In MANET

All nodes in MANET (Mobile Ad-hoc Network) are mobile and dynamically connected in an arbitrary manner.  Mobility causes frequent link failure which results in packet losses. TCP assumes that these packet losses are due to congestion only. This wrong assumption requires packet retransmissions till packet arrives successfully at the receiver. Goal is to improve TCP performance by using signal strength based cross layer approach which obviously resolves the congestion. We are reviewing a signal strength based measurements to improve such packet losses and no need to retransmit packets. Node based and link based signal strength can be measured. If a link fails due to mobility, then signal strength measurement provides temporary higher transmission power to keep link alive. When a route is likely to fail due to weak signal strength of a node, it will find alternate path. consequently avoids congestion. We will make changes at MAC routing and routing layer to predict link failure. MANET hits the protocol's strength due to its highly dynamic features, thus in testing a protocol suitable for MANET implementation we have selected two routing protocols AODV and DSR. Packet Delivery Ratio, Packet Drop, Throughput and end to end delay are the metrics used for performance analysis of the AODV routing protocols. Keywords: Congestion  control, Signal strength, TCP performance ,Cross layer interaction, Route discover

TCP with gateway adaptive pacing for multihop wireless networks with Internet connectivity

This paper introduces an effective congestion control pacing scheme for TCP over multihop wireless networks with Internet connectivity. The pacing scheme is implemented at the wireless TCP sender as well as at the Internet gateway, and reacts according to the direction of TCP flows running across the wireless network and the Internet. Moreover, we analyze the causes for the unfairness of oncoming TCP flows and propose a scheme to throttle aggressive wired-to-wireless TCP flows at the Internet gateway to achieve nearly optimal fairness. The proposed scheme, which we denote as TCP with Gateway Adaptive Pacing (TCP-GAP), does not impose any control traffic overhead for achieving fairness among active TCP flows and can be incrementally deployed since it does not require any modifications of TCP in the wired part of the network. In an extensive set of experiments using ns-2 we show that TCP-GAP is highly responsive to varying traffic conditions, provides nearly optimal fairness in all scenarios and achieves up to 42% more goodput for FTP-like traffic as well as up to 70% more goodput for HTTP-like traffic than TCP NewReno. We also investigate the sensitivity of the considered TCP variants to different bandwidths of the wired and wireless links with respect to both aggregate goodput and fairness

Improving Performance of QUIC in WiFi

QUIC is a new transport protocol under standardization since 2016. Initially developed by Google as an experiment, the protocol is already deployed in large-scale, thanks to its support in Chromium and Google's servers. In this paper we experimentally analyze the performance of QUIC in WiFi networks. We perform experiments using both a controlled WiFi testbed and a production WiFi mesh network. In particular, we study how QUIC interplays with MAC layer features such as IEEE 802.11 frame aggregation. We show that the current implementation of QUIC in Chromium achieves sub-optimal throughput in wireless networks. Indeed, burstiness in modern WiFi standards may improve network performance, and we show that a Bursty QUIC (BQUIC), i.e., a customized version of QUIC that is targeted to increase its burstiness, can achieve better performance in WiFi. BQUIC outperforms the current version of QUIC in WiFi, with throughput gains ranging between 20% to 30%

Practical Rate-based Congestion Control for Wireless Mesh Networks

We introduce an adaptive pacing scheme to overcome the drawbacks of TCP in wireless mesh networks with Internet connectivity. The pacing scheme is implemented at the wireless TCP sender as well as at the mesh gateway, and reacts according to the direction of TCP flows running across the wireless network and the Internet. TCP packets are transmitted rate-based within the TCP congestion window according to the current out-of-interference delay and the coefficient of variation of recently measured round-trip times. Opposed to the majority of previous work which builds on simulations, we implement a Linux prototype of our approach and evaluate its feasibility in a real 20-node mesh testbed. In an experimental performance study, we compare the goodput and fairness of our approach against the widely deployed TCP NewReno. Experiments show that our approach, which we denote as Mesh Adaptive Pacing (MAP), can achieve up to 150% more goodput than TCP NewReno and significantly improves fairness between competing flows. MAP is incrementally deployable since it is TCP-compatible, does not require cross-layer information from intermediate nodes along the path, and requires no modifications in the wired domain

TCP Sintok: Transmission control protocol with delay-based loss detection and contention avoidance mechanisms for mobile ad hoc networks

Mobile Ad hoc Network (MANET) consists of mobile devices that are connected to each other using a wireless channel, forming a temporary network without the aid of fixed infrastructure; in which hosts are free to move randomly as well as free to join or leave. This decentralized nature of MANET comes with new challenges that violate the design concepts of Transmission Control Protocol (TCP); the current dominant protocol of the Internet. TCP always infers packet loss as an indicator of network congestion and causes it to perform a sharp reduction to its sending rate. MANET suffers from several types of packet losses due to its mobility feature and contention on wireless channel access and these would lead to poor TCP performance. This experimental study investigates mobility and contention issues by proposing a protocol named TCP Sintok. This protocol comprises two mechanisms: Delay-based Loss Detection Mechanism (LDM), and Contention Avoidance Mechanism (CAM). LDM was introduced to determine the cause of the packet loss by monitoring the trend of end-to-end delay samples. CAM was developed to adapt the sending rate (congestion window) according to the current network condition. A series of experimental studies were conducted to validate the effectiveness of TCP Sintok in identifying the cause of packet loss and adapting the sending rate appropriately. Two variants of TCP protocol known as TCP NewReno and ADTCP were chosen to evaluate the performance of TCP Sintok through simulation. The results demonstrate that TCP Sintok improves jitter, delay and throughput as compared to the two variants. The findings have significant implication in providing reliable data transfer within MANET and supporting its deployment on mobile device communication