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

Survey on wireless technology trade-offs for the industrial internet of things

Aside from vast deployment cost reduction, Industrial Wireless Sensor and Actuator Networks (IWSAN) introduce a new level of industrial connectivity. Wireless connection of sensors and actuators in industrial environments not only enables wireless monitoring and actuation, it also enables coordination of production stages, connecting mobile robots and autonomous transport vehicles, as well as localization and tracking of assets. All these opportunities already inspired the development of many wireless technologies in an effort to fully enable Industry 4.0. However, different technologies significantly differ in performance and capabilities, none being capable of supporting all industrial use cases. When designing a network solution, one must be aware of the capabilities and the trade-offs that prospective technologies have. This paper evaluates the technologies potentially suitable for IWSAN solutions covering an entire industrial site with limited infrastructure cost and discusses their trade-offs in an effort to provide information for choosing the most suitable technology for the use case of interest. The comparative discussion presented in this paper aims to enable engineers to choose the most suitable wireless technology for their specific IWSAN deployment

Wired and Wireless Reliable Real-Time Communication in Industrial Systems

In modern factory automation systems, data communication plays a vital role. Different nodes like control systems, sensors and actuators can communicate over a wireless or wired industrial network. The data traffic generated is often scheduled for periodic transmission, where each single message or packet must arrive in time. For this real-time communication, methods have been developed to support communication services with a guaranteed throughput and delay bound for such periodic traffic, but merely under the assumption of error-free communication. However, the possibility for errors in the transmission still exists due to, e.g. noise or interference. A node receiving sensor values from a sensor in the system might then be forced to rely upon an older sensor value from the latest period, possibly leading to inaccuracies in control loops which can compromise the functioning of the system. In safety-critical systems, redundant networks or communication channels are frequently added to cope with errors, leading to more expensive systems. In this chapter, we will describe an alternative approach where erroneous data packets are retransmitted in a way that does not jeopardise any earlier stated real-time guarantees for ordinary transmissions. Using our framework, the reliability of real-time communication can be increased in a more cost-efficient way. We describe in this chapter an overview of our framework for reliable real-time communication, while details of our approach can be found in our earlier publications. In the light of the emerging use of wireless communication, the framework proves to be especially useful due to the high bit error rate inherent to the wireless medium. However, the framework is naturally also attractive for wired communication systems

System Support for Bandwidth Management and Content Adaptation in Internet Applications

This paper describes the implementation and evaluation of an operating system module, the Congestion Manager (CM), which provides integrated network flow management and exports a convenient programming interface that allows applications to be notified of, and adapt to, changing network conditions. We describe the API by which applications interface with the CM, and the architectural considerations that factored into the design. To evaluate the architecture and API, we describe our implementations of TCP; a streaming layered audio/video application; and an interactive audio application using the CM, and show that they achieve adaptive behavior without incurring much end-system overhead. All flows including TCP benefit from the sharing of congestion information, and applications are able to incorporate new functionality such as congestion control and adaptive behavior.Comment: 14 pages, appeared in OSDI 200

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 packet error recovery scheme for vertical handovers mobility management protocols

Mobile devices are connecting to the Internet through an increasingly heterogeneous network environment. This connectivity via multiple types of wireless networks allows the mobile devices to take advantage of the high speed and the low cost of wireless local area networks and the large coverage of wireless wide area networks. In this context, we propose a new handoff framework for switching seamlessly between the different network technologies by taking advantage of the temporary availability of both the old and the new network technology through the use of an “on the fly” erasure coding method. The goal is to demonstrate that our framework, based on a real implementation of such coding scheme, 1) allows the application to achieve higher goodput rate compared to existing bicasting proposals and other erasure coding schemes; 2) is easy to configure and as a result 3) is a perfect candidate to ensure the reliability of vertical handovers mobility management protocols. In this paper, we present the implementation of such framework and show that our proposal allows to maintain the TCP goodput (with a negligible transmission overhead) while providing in a timely manner a full reliability in challenged conditions

EOAODV: Routing Protocol for Cognitive Radio Network

Cognitive Radio (CR) technology provides promising and a new solution to improve the spectrum utilization. In recent years, cognitive radio technology (CR) has been proposed to allow unlicensed secondary users (SUs) to opportunistically access the channels unused by primary users (PU). This paper focuses on designing Enhancement of Opportunistic Ad-hoc On Demand Distance Vector (EOAODV) routing protocol that uses shortest distance, Expected Transmissions Count (ETC) and residual energy as a parameter to select the most reliable link and the next forwarding node. The selection of route in the network by the traditional AODV is based on hop count. It is proposed to achieve a gain of Opportunistic Routing (OR) with AODV for cognitive radio wireless sensor networks (CRWSN) to improve its efficiency. In the OR work the nexthop node selection was based on only Expected Transmission Count (ETC). In this case if the same node is selected as nexthop for many times, energy of that node is drained and node may be dead. To overcome this problem, a technique is contributed that is energy based nexthop selection ie. EOAODV. The ETC is computed based on the quantized value of RSSI of the links with residue energy in the forwarding node. Using ETC the reliable link is computed and stored in routing table. The packets are tranmitted to the destination using channel details and the next hop, available in the routing table. The next hop selection is based on high energy in the nodes, shortest distance and least ETC