Congestion is caused by shortage of network resources. Congestion control is the mechanism, which allocates the resources of the network such that the performance is acceptable, when network is operating near capacity. Differentiated Services (Diff-Serv) architecture offers services at different levels. Packets are classified and treated differently, as defined in the Service Level Agreement (SLA). A traffic policy is created which defines the shaping, dropping and marking of packets. Random Early Detection (RED) scheme is an Active Queue Management (AQM) Scheme, which can sense congestion before its occurrence and can take appropriate preventive action. In this book three types of multi-level Random Early Detection (RED) techniques for congestion control in Diff-Serv networks has been presented. The demonstrations of congestion control for each multi-level scheme has been done using Network Simulator 2 considering a number of traffic scenarios. A comparative study between different multi-level RED variants has been presented in the final stages .
One of the most crucial challenges associated with wireless mesh networks (WMN) is to handle the network congestion. Congestion control in WMN poses a number of unique challenges due to the multi-hop wireless paths, the presence of hidden terminals, and the shared nature of the wireless medium. In a congested network, packets are dropped in the intermediate nodes very frequently. Furthermore, if the packets are dropped after traversing several hops, they unnecessarily consume the limited wireless resources, and in turn, results in a reduced effective network throughput. In this thesis, we work toward developing a congestion control mechanism which increases the network throughput and minimizes the turbulence in the networks. Our scheme includes the following mechanisms to achieves the desired goals. First, we propose an efficient congestion detection mechanism which accurately measures the buffer occupancy at the downstream node. Second, we develop a congestion control mechanism which appropriately sets the forwarding rate of a node based on the congestion status of the downstream node. Finally, we propose a scheduling mechanism to forward packets from multiple queues at MAC Layer
The book presents an innovative method of “Road Traffic Congestion Detection and Management based on Active RFID and GSM technology”. Over the last decade RFID has evolved to become one of the most important and easy solution to many applications. It is being used in nearly each and every field of science and engineering. In this paper we have proposed a solution to traffic congestion detection and management using active RFID. The system developed is known as the “TrafficMonitor” which calculates two most important traffic parameters viz. average lane speed (average speed of vehicles over a period of time and over a given stretch of lane) and average waiting time. Each vehicle contains an active tag and there are two active readers placed by the road. As the vehicle travels in between these readers, time taken to cover this distance and hence, the speed of the vehicle is calculated. These values are sent to a remote station via SMS (using GSM technology) where data is analyzed and various decisions can be taken based on the received data. For example, travel time information to a particular destination, or average lane speed can be shown to the drivers. This helps daily commuter
Congestion management in multistage interconnection networks is a serious problem not completely solved. In order to avoid the degradation of network performance when congestion appears, several congestion management mechanisms have been proposed. Most of these mechanisms are based on explicit congestion notification. For this purpose, switches detect congestion and depending on the applied strategy, packets are marked to warn the source hosts. In response, source hosts apply some corrective actions to adjust their packet injection rate. Although these proposals seem quite effective, they either exhibit some drawbacks or are partial solutions. Some of them introduce some penalties over the flows not responsible for congestion, whereas others can cope only with congestion situations that last for a short time. We present different strategies to detect and correct congestion in multistage interconnection networks, and propose new mechanisms targeted to this kind of lossless networks, and based on more refined packet marking strategies combined with a fair set of corrective actions, that makes the mechanisms able to effectively manage congestion regardless of the congestion degree.
To investigate a new ant-based agent algorithm for providing survivable routing in WDM network. The major problem in survivable routing WDM network is routing wavelength and assignment (RWA) problem, It sets up light path by routing and assigning a wavelength to each connection such that no light path use the same wavelength on same link Initially, in the path, a major part of the bandwidth is allocated for primary path and this part can not be shared by other paths. Fraction of the bandwidth is allocated for backup path and this can be shared by other disjoint paths. The disjoint path can be primary or backup path. The residual bandwidth is used for future primary and backup paths computations. When the connection request arrives to the source, it looks in its pheromone and load table and send connection request (CNREQ) message to the destination along with feasibility and load values of paths. Upon receiving the CNREQ, the path that has higher feasibility value and the load value lesser than ThLOAD can be selected by the destination for further processing. Using NS-2 simualtion we show that the proposed ant based routing achives better channel utilization and throughput
Congestion is a disturbing phenomenon in Global System for Mobile Communication (GSM) Network as it leads to loss of call and/or degradation in quality of service. Several measures for controlling this such as discarding policy, acknowledgement, etc. have not been able to handle congestion based on resource allocation. In this book, a scheme that adapts user's traffic to network prevailing conditions by dynamically allocating channels using one-level buffering technique with ticket scheduling algorithm was developed. The new scheme improves the network performance and increase resource utilization.
This work investigates the congestion control state-of-the-art algorithms. Then, presents an Enhanced TCP-Friendly Rate Control protocol, called ETFRC, as a means of enhanced congestion control for media traffic over Internet. Three modifications to TFRC are proposed in this thesis so as to develop the ETFRC. The first modification is based on modifying the frequency of the feedback messages sent by TFRC receiver to its sender upon which the sending rate calculation is done. The second modification tackled the number of samples used by the TFRC receiver to calculate the loss event rate as part of the feedback report sent to sender. The third modification is developed by adjusting the sending rate at the sender side dynamically based on the current state of the network and the current state of the receiver. In other words, the ETFRC embodies a new algorithm to tune (increase or decrease) the sending rate at the sender side according to the difference between the calculated rate by the sender and the reported rate from the receiver side. The performance of the proposed ETFRC protocol is evaluated using the network simulator NS-2 considering different scenarios.
In this thesis, a method has been developed to analyze EEG signals for early detection of seizure using empirical mode decomposition (EMD) and chaos.Chaos in EEG is de?ned by the tendency to gravitate towards speci?c regions in phase space. Lyapunov exponent and Kol-mogorov complexity are the important factors regarding chaotic behavior of any dynamical system. In this thesis, the Largest Lyapunov Exponent (LLE) of the EEG signal over time is observed and decision about Epileptic Seizure is taken. It is seen that from normal to seizure state transition, the amount of chaos in EEG is drastically reduced. Thus, the behavior of chaos in EEG signal described above can be used for seizure detection.
In 2010, traffic congestion cost commuters in the U.S. approximately $101 billion in lost time and wasted fuel. Local governments and transportation agencies have used a variety of mitigation strategies to reduce the cost of traffic congestion. However, many of these mitigation strategies can be equally as costly to implement, maintain, and administer. With the federal government, and many local and state governments facing large budget deficits and dwindling tax revenues, it is imperative that these governments pursue mitigation strategies that are most cost effective. This book examines five traffic congestion mitigation strategies ranging from expanding roadway capacity to using toll-ways, to determine which ones are most and least cost effective.
Today is the era of multimedia applications such as audio or video transmission. Multimedia traffic can be classified according to bandwidth, latency and Quality of Service. For multimedia applications, there is strong need of higher transmission capacity and higher bandwidth, which leads the need of high speed network based architecture at the forefront of several current technology based networks. Due to the unpredictable fluctuations and burstiness of traffic flows within high speed network congestion can occur frequently and TCP will perform poorly in future high speed network. In this paper, we purposed the solution for the problem of frequent congestion occurrence in high speed network and it’s model that has learning capability on the basis of round trip time, node’s outlink capacity and average queue size and passes a signal to the sender to change its sending rate accordingly. Therefore, congestion occurrence in high speed network can be resolved.
This book describes, for the first time, the early and accurate pregnancy detection of water riverine buffalo using BioPRYN technology and provided the plasma levels of pregnancy-specific protein B (PSPB) using an ELISA test. The BioPRYN test differed from the other tests with earlier accuracy for detecting pregnant and non-pregnant buffaloes. Moreover, this book demonstrates the PSPB, progesterone and some biochemical parameters concentrations in amniotic fluid, allantoic fluid and fetal serum collected from slaughtered pregnant buffaloes at different months of gestation (6th, 7th and 8th). Results described the differences in PSPB and progesterone concentrations as well as blood characteristics in fetal fluids and serum during different stages of pregnancy. The placental measurements of Iraqi water buffalo during different gestation periods were also included. These findings will improve the reproductive and productive efficiency of riverine buffalo by adapting the recent management and reproductive strategies in Iraq and in the world.
Today, the fundamentals of the Internet design are no longer suitable for current and future applications. Transport Control Protocol (tcp) is the main reliable transport protocol found in the Internet. tcp offers great performance while remaining fair with the other connections. tcp uses a congestion control plane based on windows mechanisms. Despite its advantages, tcp has many limitations and is not well suited to all application models. The last decade has seen the advent of large bandwidth network and heavy multimedia applications. Many electronic devices have multiple interfaces to connect to the Internet, the end-users wish to use all of them to improve the transfer speed and the tolerance to failures. However, operate in a multipath environment is not trivial and several potential issues could result from an unaware use of a reliable transport protocol. This book study, analyzes the proposed reliable transport protocols and compare them. It then performs a set of experiments on the Concurrent Multipath Transfer transport protocol in the NS-1 software simulator. These experiments have allowed us to highlight some unfair behavior with external tcp sources.
TCP is a widely used congestion protocol in Internet, it uses packet losses as congestion signals. Delay-based protocols use observed packet delays along with packet losses as congestion signals. Delay-based congestion protocols are shown to provide may benefits in homogeneous environments, but struggle to compete against loss-based protocols such as TCP. For delay-based protocols to be practical, they need to be incrementally deployable and hence need to compete with TCP in current Internet. This book explores the design of such a delay-based protocol, PERT (enhanced), that can compete with TCP and prove this through evaluations. We show that PERT experiences lower drop rate than TCP-SACK and leads to lower overall drop rates with different mixes of PERT and other loss based congestion control protocols. We also show that a single PERT flow can fully utilize a high-speed, high-delay link. We investigate if potential noise and variability in delay measurements in environments such as cable and ADSL access networks impact the protocol behaviour significantly.
Wireless technologies are being widely used today across the globe to support the communication needs of very large number of end users for voice communications and data services. Data services include activities such as sending e-mails, instant messages and accessing the Web. Due to an increased demand the network becomes congested. The congestion control mechanism in Transmission Control Protocol (TCP) is designed for wired networks. Due to the inherent characteristics of wireless networks, TCP when applied to wireless networks suffers from poor performance because of random loss, burst loss and packet reordering and therefore needs modification from the original protocol. This thesis proposes two enhancements in the TCP Vegas algorithm. The EnhancedVegas and NewVegas algorithms control the congestion in MANETs. An enhancement in MAC layer protocol called CTMAC-F protocol is proposed to control collision in the MAC layer. GPSR routing protocol is used for an efficient routing in adhoc networks. All these provide an integrated layer approach technique to mitigate congestion and collision with efficient routing in adhoc networks.