Statistical multiplexing and connection admission control in ATM networks

Asynchronous Transfer Mode (ATM) technology is widely employed for the transport of network traffic, and has the potential to be the base technology for the next generation of global communications. Connection Admission Control (CAC) is the effective traffic control mechanism which is necessary in ATM networks in order to avoid possible congestion at each network node and to achieve the Quality-of-Service (QoS) requested by each connection. CAC determines whether or not the network should accept a new connection. A new connection will only be accepted if the network has sufficient resources to meet its QoS requirements without affecting the QoS commitments already made by the network for existing connections. The design of a high-performance CAC is based on an in-depth understanding of the statistical characteristics of the traffic sources

Network Externalities and Technology Adoption: Lessons from Electronic Payments

We seek to analyze the extent and sources of network externalities for the automated clearinghouse (ACH) electronic payments system using a quarterly panel data set on individual bank adoption and usage of ACH. We provide three methods to identify network externalities using this panel data. The first method identifies network externalities from the clustering of ACH adoption. The second method identifies them by examining whether banks in areas with higher market concentration or larger competitors are more likely to adopt ACH. The third method identifies them by examining whether the ACH adoption by small branches of large banks affects the adoption by local competitors. Using fixed effects and panel data these methods separately identify network externalities from technological advancement, peer-group effects, economies of scale and market power. We find evidence that the network externalities are moderately large.

Application of learning algorithms to traffic management in integrated services networks.

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN027131 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Prospects in Agricultural Engineering in the Information Age - Technological Development for the Producer and the Consumer

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is an Invited article from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 1 (1999): N. Sigrimis, Y. Hashimoto, A. Munack and J. De Baerdemaker. Prospects in Agricultural Engineering in the Information Age - Technological Development for the Producer and the Consumer

Evaluating Network Analysis and Agent Based Modeling for Investigating the Stability of Commercial Air Carrier Schedules

For a number of years, the United States Federal Government has been formulating the Next Generation Air Transportation System plans for National Airspace System improvement. These improvements attempt to address air transportation holistically, but often address individual improvements in one arena such as ground or in-flight equipment. In fact, air transportation system designers have had only limited success using traditional Operations Research and parametric modeling approaches in their analyses of innovative operations. They need a systemic methodology for modeling of safety-critical infrastructure that is comprehensive, objective, and sufficiently concrete, yet simple enough to be deployed with reasonable investment. The methodology must also be amenable to quantitative analysis so issues of system safety and stability can be rigorously addressed

Sustaining a Vertically Disintegrated Network through a Bearer Service Market

Based upon the Internet perspective, this chapter will attempt to clarify and revise several ideas about the separation between infrastructure facilities and service offerings in digital communications networks. The key notions that we will focus on in this paper are: i) the bearer service as a technology-independent interface which exports blind network functionality to applications development; ii) the sustainability of an independent market for bearer service and the organizational consequences associated with such a market

Quality of service management for non-guaranteed networks

The increasing dominance of multimedia communication posed new requirements for the underlying systems. Multimedia data, formally called continuous media, has time constraints that impose real time limitations for their transmission. Certain levels of service, called Quality of Service (QoS), need to be considered when handling continuous media. The present work utilizes QoS concepts for networks that do not have inherent QoS support. The thesis aims at verifying the possibility of having QoS-controlled communication on non-guaranteed networks. A basic QoS architecture is designed where already existing QoS concepts are adapted to work with non-guaranteed networks. The architecture provides the facilities of QoS specification, mapping, admission, maintenance, monitoring and notification. In addition, a new concept for predictive QoS admission is introduced. The proposed architecture was verified using a prototype system. The results showed an increased percentage of continuous media that arrive on time to their receivers (good put) with higher network loads. The increased good put was at the expense of high network overhead

Efficient topology update on high speed wide area networks

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (leaves 42-43).by Mathias David Siebler.M.Eng

Financial innovations and bank performance in Kenya: evidence from branchless banking models

PhD (Finance), School of Economic and Business Sciences, UNIVERSITY OF THE WITWATERSRAND, JOHANNESBURG 8th June, 2016This study examines the relationship between financial innovation and financial performance of commercial banks in Kenya, as well as the drivers of financial innovations at both firm and macro levels. The financial innovations covered are the branchless banking models, which represent a departure from the traditional branch-based banking. More specifically, the financial innovations covered are: Mobile banking, agency banking, internet banking and Automated Teller Machines (ATMs). The study uses 10-year panel (secondary) data for the period spanning year 2004 to 2013. The study conducts an empirical analysis of the four types of financial innovations using three econometric models. The models have been specified using Koyck distributed lag models and estimated using dynamic panel estimation with System Generalised Method of Moments (GMM). The speed of adjustment of bank financial performance to financial innovation as well as the speed of adjustment of financial innovation to the financial innovation drivers has been tested using Koyck mean and median lags. The empirical results provide strong evidence of the link between financial innovations and bank financial performance with respect to Kenyan commercial banks. The study makes a number of other findings. Firstly, financial innovations significantly contribute to firm financial performance and that firm-specific factors are more important to the firm’s current financial performance than industry factors. Secondly, firm-specific variables significantly drive financial innovations at firm level with firm size being the most significant driver of financial innovation at firm level. The firm specific factors include firm size, transaction costs, agency costs, and technological infrastructure at firm level. Thirdly, macro level variables significantly drive financial innovation at firm level with regulation being the most important driver at macro level. The macro level drivers reviewed include: Regulation and taxes, incompleteness in financial markets, technological infrastructure at macro level and globalisation. Lastly, the existence of reverse causation between firm financial performance and firm financial innovation is established. The speed of adjustment of firm financial performance to financial innovation has been determined. The results show that it takes on average 1.179 years for bank financial performance to adjust to the four financial innovations studied. Secondly, it takes less than a year (0.368 years) to accomplish 50% of the total change in firm performance following a unit-sustained change in the financial innovations. Moreover, mobile banking has the shortest mean lag (2.849) while ATMs have the longest mean lag (4.926). Therefore, it takes approximately three years for mobile banking to adjust to financial innovation drivers at firm level and on average five years for ATMs to adjust to the financial innovation drivers. By and large, the speed of adjustment of financial innovations to macro level drivers is higher than the speed of adjustment of financial innovations to firm level drivers. This study has made significant contribution to the body of knowledge in the field of financial innovations. The study has developed an econometric model which captures four financial innovations in a single study and empirically used the model to test their link to firm financial performance. The second and third econometric models have also captured the drivers of financial innovations at firm and macro levels. The reviewed literature observes that previous studies have largely focused on financial products in developed countries at the expense of emerging financial innovations in developing countries. In addition, previous studies have also largely ignored empirical approaches to the study of financial innovations. This study has empirically established the link between financial innovations and firm performance by modelling the four innovations in single model in a developing country (Kenya) context. One of the major contributions of this study is the establishment of the speed of adjustment of firm performance to financial innovations and the speed of adjustment of financial innovations to financial innovation drivers at both firm and macro levels. Lastly, the study has developed an original conceptual financial innovation value model (Fig. 6.1), which will be used in future financial innovation studies. This study has a number of managerial and policy implications which have been reviewed in the study.MT201

Some aspects of traffic control and performance evaluation of ATM networks

The emerging high-speed Asynchronous Transfer Mode (ATM) networks are expected to integrate through statistical multiplexing large numbers of traffic sources having a broad range of statistical characteristics and different Quality of Service (QOS) requirements. To achieve high utilisation of network resources while maintaining the QOS, efficient traffic management strategies have to be developed. This thesis considers the problem of traffic control for ATM networks. The thesis studies the application of neural networks to various ATM traffic control issues such as feedback congestion control, traffic characterization, bandwidth estimation, and Call Admission Control (CAC). A novel adaptive congestion control approach based on a neural network that uses reinforcement learning is developed. It is shown that the neural controller is very effective in providing general QOS control. A Finite Impulse Response (FIR) neural network is proposed to adaptively predict the traffic arrival process by learning the relationship between the past and future traffic variations. On the basis of this prediction, a feedback flow control scheme at input access nodes of the network is presented. Simulation results demonstrate significant performance improvement over conventional control mechanisms. In addition, an accurate yet computationally efficient approach to effective bandwidth estimation for multiplexed connections is investigated. In this method, a feed forward neural network is employed to model the nonlinear relationship between the effective bandwidth and the traffic situations and a QOS measure. Applications of this approach to admission control, bandwidth allocation and dynamic routing are also discussed. A detailed investigation has indicated that CAC schemes based on effective bandwidth approximation can be very conservative and prevent optimal use of network resources. A modified effective bandwidth CAC approach is therefore proposed to overcome the drawback of conventional methods. Considering statistical multiplexing between traffic sources, we directly calculate the effective bandwidth of the aggregate traffic which is modelled by a two-state Markov modulated Poisson process via matching four important statistics. We use the theory of large deviations to provide a unified description of effective bandwidths for various traffic sources and the associated ATM multiplexer queueing performance approximations, illustrating their strengths and limitations. In addition, a more accurate estimation method for ATM QOS parameters based on the Bahadur-Rao theorem is proposed, which is a refinement of the original effective bandwidth approximation and can lead to higher link utilisation