Variable bit-rate coding of video signals for ATM networks

A hierarchical discrete cosine transform (DCT) coding scheme is described for 135-Mb/s HDTV (high-definition television) transmission in ATM (asynchronous transfer mode) networks. Cell loss due to network congestion and cell misdelivery in the ATM may seriously degrade picture quality. To cope with cell loss, a hierarchical system employing an intrafield 8*4 DCT that segments the coefficients into a main signal and an enhancement signal is proposed. The two signals are separately assembled into cells for transmission over the ATM networks. The cells from the main signal are protected by labeling them with a high priority. The enhancement signal is labeled with a lower priority and is subject to higher cell-loss rates. Considerations for signal segmentation, packet assembling, and effect of cell loss on picture quality are addressed. Computer simulation of the hierarchical DCT system was performed on two HDTV sequences. For comparison, simulations were also applied to nonhierarchical DCT systems with and without cell concealment. The results indicate that the hierarchical system offers very effective protection against cell loss. >

This paper proposes an implementation of a Java networking application programming interface (API) for asynchronous transfer mode (ATM) networks. ATM is considered to be the network of the future. Since more and more Web-based applications are written in Java, it is important to support Java network programming on ATM in order to facilitate the development of World Wide Web style applications on ATM networks. In this paper, we first give a brief introduction of ATM networks. We then give an overview of the architecture of applications on ATM networks. Next, we describe the implementation of our Java networking API on ATM. Finally, we point out the weakness of the current Java networking API in relation to ATM networking and discuss future research directions. Our implementation provides a platform for developing Java applications on native ATM protocols and demonstrates the feasibility of designing a new Java networking API on native ATM protocols.

With networks increasingly moving into virtually every aspect of our daily life, security is gaining importance, not only from the traditional perspective of communication but the network's growing role in modern automation and control. The traditional, certification based approach attempts to guarantee the security of a network through certification. Certified networks are generally confined to a limited domain and, as a result, they are isolated, costly, and under-utilized. In contrast, this paper presents a new principle – user-level, security-on-demand system, wherein the network allocates, where possible, the security resources commensurate with the user's request for transporting message(s) through the network securely. This principle is successfully demonstrated for the current Asynchronous Transfer Mode (ATM) networks, and is the result of an integration of the fundamental framework for network security, recently proposed by the authors in the literature, with the unique characteristics of ATM networks. The framework encapsulates the fundamental knowledge and set of relationships in network security and permits scientific and systematic reasoning about network security. It also enables all user groups – military, government, industry, and academia, to define their security requirements in a uniform manner. The security-on-demand approach promises the development of a "mixed use" class of networks in the future that may be simultaneously shared by different groups of users, with the system sustaining the diverse security requirements of each user. A unique characteristic in ATM network design is the dynamic call setup process. Under it, a network first establishes a virtual path or route for a user's call, guided by the user's requirements, and then transports the messages when a route has been successfully determined. This unique ATM characteristic is integrated with the framework to yield a successful demonstration of the proposed, user-level, security-on-demand approach. Utilizing the security framework as the foundation, every element of the network – node and link, is characterized by a security matrix that reflects its security resources. Every user is permitted to specify the security requirement for the call through a matrix, which expresses the limits of the security resources that the traffic cells must encounter during their transport through the network. Thus, during the dynamic establishment of the virtual path, every node and link is examined to ensure that the user-specified security is met, in addition to bandwidth and other Quality of Service (QoS) requirements. Traffic is launched when the call setup succeeds, otherwise, the call fails. Like all networks, the ATM network inherently consists of geographically dispersed entities and, as a result, the resource allocation strategy is necessarily distributed. Furthermore, as the network operation progresses, the resource availability scene changes dynamically. This paper proposes a unique function that reduces the key network resource parameters at a node to a single value, termed Node Status Indicator (NSI). The NSI value is computed dynamically at every node and disseminated across the network to be utilized by a node to refine its determination of a virtual path for a user call. The aim of the NSI is to improve the resource utilization in the network. The proposed approach is modeled for a large-scale, representative, 40-node ATM network. Utilizing stochastic input traffic that is synthesized to reflect realistic operating conditions, the model is simulated extensively on a testbed of 35+ Pentium workstations, under Linux, configured as a loosely-coupled parallel processor, utilizing an accurate, asynchronous, distributed simulator. The simulator implements the key characteristics of the ATM Forum proposed P-NNI 1.0 and UNI 3.0 standards. While the simulation results reflect a successful realization of the proposed approach, analysis reveals minimal impact of incorporating security on ATM network performance, as measured through call success rates and call setup times. In contrast, the tradition has been to incorporate security into large-scale systems and networks as an afterthought, i.e. adding hardware and software devices after the design has been completed, resulting in performance degradation. Also, while the use of NSI is observed to yield slightly lower average call setup rates and slightly higher average call setup times, a careful analysis of the trace of the calls as they progress through the system, reveals that, in general, calls are dispersed throughout the network, seeking to utilize all available resources of the network more evenly.

Mobsen Guizani and Ammar Rayes McGraw-Hill Series on Computer Communications McGraw-Hill, New York, NY, 1999, 224 pp. ISBN 0-07-025217-3, $59.95 Asynchronous Transfer Mode (ATM) has emerged in the 1980s as a promising transfer mode for high speed computer networking, particularly for Broadband Integrated Services Digital Network (B-ISDN) systems. The motivations for this new emerging technology arise from the promising advantages provided by ATM such as statistical multiplexing, high speed switching capabilities, inter-operability, portability, reliability and its support for conventional, real time and non-real time multimedia and Internet applications. The composition of traffic carried by ATM networks is a mixture of low speed voice and data, along with high speed video, image, and interactive traffic. The development of efficient ATM traffic management and network (switching and transmission) design methods rely heavily on understanding of Quality of Service requirements of various services and the traffic characteristics. Managing the service quality in the ATM networks is a complex and essential task for network engineers and service provider companies. The development of appropriate traffic and capacity management models and methods depends crucially on a clear understanding of Quality of Service requirements, statistical characteristics of the traffic, and performance evaluation methods. While there is over one hundred years of experience in voice networks, little is known about the networks that carry a mixture of voice, data, video, and interactive traffic. Due to the interactions among these traffic streams, routing involves complex decision rules that are tightly intertwined; it is critical to understand such interactions, and thereby decouple the decision rules in order to crystallize the essence of routing polices being formulated. Due to the importance of this subject for both industry and research areas, the need for a book that covers these subjects in details arises. Throughout the book entitled Designing ATM Switching Networks, major concepts are first explained in a simple non-mathematical way. This followed by careful descriptions of the modeling issues and then mathematical analysis. The analysis to be gained are explained and examples are given to clarify the more subtle issues. The book stresses the fundamentals of ATM operations, switch architecture and functions, protocol modeling, Quality of Service requirements, traffic modeling and control, fault tolerant, traffic and capacity management functions, and routing. The book provides the fundamental concepts necessary for the traffic management, design, use, performance issues and implementation of ATM networks. ATM routing algorithms are introduced and then analyzed in the book. Moreover, the authors present algorithms to evaluate the performance of the routing schemes presented and compares them against simulation results. Since optical networks are a potential candidates for future telecommunication infrastructure, an overview of optical ATM networks is presented in the book. it introduces the advantages of optical technology and the architecture of ATM optical switches designed by different scientists. Recent projects developed in this area are also presented. The book compares different modeling techniques to evaluate the performance of computer communication networks to direct measurement techniques. Then, introduces analytical modeling and queuing networks. Alter that a review of the discrete time arrival processes is presented. Finally, different types of stochastic processes and the analysis of a single MINI/I queue, MID/i, and network of queues are summarized. In addition, the book covers a review of the main advantages and disadvantages for the use of simulation to perform the analysis of computer communication networks is done. Some of the commercial software packages that are used to perform such simulation studies and the main features that are supported by each package are reviewed. Finally, the book discusses most of the required traffic measurements and the transport performance objectives for broadband switching systems as specified in Bellcore Generic Requirements. This book is meant to be used as a reference for systems designers, hardware and software engineers, R&D managers, and market planners who seek an understanding of local and wide area broadband networks. The first part of the book (Chapters 1, 2, 3, 4, 5, 6, and 10) can be used for an undergraduate senior course. The second part (Chapters 3, 4, 5, 6, 7, 8, 9, and 10) can be used for a graduate course with emphasis on research topics in the field. There are many research ideas open problems presented in chapters 4, 5, 6, 7, and 8. Problems at the end of each are not available at this point, but authors are producing a set of problems that can be supplied to whoever will be using the book for teaching a course. Overall, I found the book extremely useful both in its fundamental and practical treatment of ATM networks. Such a dual purpose is lacking from current books on the topic. As a result, I strongly urge researchers working on this area and students wanting to know more about this topic to take a look at this book. It will be all the help that they can get. Mounir Hamdi Hong Kong University of Science and Technology, China

In order to take advantage of the low entry cost of the future public ATM (asynchronous transfer mode) network with shared facilities, it is highly desirable to interconnect different hosts and local area networks (LANs) to the ATM network. The interface between the computer hosts or LANs and the ATM network, commonly called a broadband terminal adaptor (BTA), provides the necessary format conversion for the data packets and the ATM cells. It is conceivable that multiple packets from different virtual channels are interleaved as they arrive at the receive‐end BTA. The BTA must have a sufficiently large buffer, called a virtual channel queue (VCQ), to temporarily store the partially received packets. Once a complete packet has been received, it is forwarded to the host or LAN. Whenever the buffer fills with all incomplete packets, a packet must be discarded to make room for others. In this paper, we first study, through computer simulations, the buffer size requirement of a shared‐memory VCQ for different numbers of virtual channels at various packet loss probabilities. We then present two different implementation architectures for the shared‐memory VCQ, and compare their hardware complexity. The second architecture with linked‐queue approach, adopted in our work, requires less buffer and has better scalability to accommodate a large number of virtual channels. Various possible error conditions, such as cell losses in the ATM network and the VCQ buffer overflow, are considered. Corresponding solutions are proposed and included in the VCQ designs.

In this Paper, Computer – based Simulation models for effective Congestion control and Traffic management in Asynchronous Transfer Mode (ATM) network have been developed providing a basis for monitoring ATM networks performance for traffic and congestion control purposes ,providing a system with a reduce short -term congestion in ATM networks, and enhancing a fair operation of networks in spite of the challenges in designing ATM traffic management system to make maximal use of network resources. An IDCC scheme was implemented, applying IDCC methodology to the ATM Network. Using analysis performance, limits were created for robust controlled network behaviour, as dictated by reference values of the desired queue length. By tightly controlling output of the controller, the overall network performance was adjusted and also controlled. A simulation tool, MATLAB/SIMULINK, was used for this purpose. An improvement was observed in the delay performance of ATM networks. The results were obtained by running several simulations and populating a table with the outcome over a number of simulation runs. The effectiveness of the congestion control techniques was tested by analysing the dynamic performance of the model through variation of some parameters. The performance of this model proved to be efficient if applied in the ATM network of today.

: This report investigates the feasibility of an Asynchronous Transfer Mode (ATM) network to support Test and Evaluation (T&E) requirements such as the Joint Advanced Distributed Simulation (JADS) phase two end-to-end (ETE) test. It gives a broad overview of ATM and discusses how an ATM network could support JADS ETE T&E efforts. This report reviews key concepts behind ATM such as service classes, quality of service, and available signaling types. Two methods of running Internet Protocols (IP) applications over ATM are discussed. These two methods are: classical IP over ATM and Local Area Network Emulation (LANE). Applications running ATM in the native mode are also discussed. A JADS phase two ETE test configuration for T&E is discussed and a potential configuration for running this test over an ATM network is presented. Equipment costs and ATM service costs are given. Questions raised by the JADS T&E community are answered.

Circuit emulation in ATM (asynchronous transfer mode) networks is considered. In a circuit-emulation session the source node generates a periodic cell stream. As this stream passes through the ATM network, it is distorted by cell delay jitter and loss, and a corrupted aperiodic copy of the source stream arrives at the receiver (destination). Considering a special case of the problem (fixed rate and small delay jitter), a simple scheme is devised that can reconstruct the continuous bit stream from the received cell stream. Allowing for variable rate sources (e.g. fixed quality, variable rate video), the author generalizes the problem and models the received cell stream as a point process whose intensity is a bandlimited function. Based on this model, the author devises an easily implementable mechanism that reconstructs a continuous bit stream from the received cell stream at the receiver (destination). Furthermore, some strategies for improving the performance of the proposed schemes are described. These strategies include assigning a higher priority for circuit-emulation cells, providing cell header error control, and possibly using positioned cells for emulated circuits inside the network. >

The International Telecommunication Union (ITU) has completed work on a series of standards on asynchronous transfer mode (ATM) equipment functional operations and network element management. The objective of these standards is to enable flexible design and interoperability of network elements for use in a global ATM network, independent of any specific implementation. This article discusses these standards with respect to their development and application in planning ATM networks. Specifically, it addresses the following: the modeling approach taken in the development of the ITU standards, key operational features specified in the ATM network element functional model, and the capabilities of the ATM network element management interface. Examples of ATM equipment are provided to illustrate how the functional models specified in the ITU standards may be used by network planners and equipment manufacturers to specify and develop ATM equipment tailored to specific needs, while ensuring network interoperability. The article concludes with some points on the future enhancement of these and related ATM equipment operations standards.

We describe the design and implementation of Java multimedia applications over asynchronous transfer mode (ATM) networks on Linux operating systems (OS). We propose a Java application programming interface (API) that allows Java multimedia applications to run over ATM networks. We present the results of a performance evaluation of the Java ATM API. We also demonstrate how the Java ATM API and Java media framework (JMF) can be used to develop Java multimedia applications over ATM networks. By combining Java's programming advantages and ATM's network capabilities, multimedia applications can take advantage of both technologies using the Java ATM API.

Asynchronous Transfer Mode (ATM) is expected to be one of the important variable-bit-rate methods for video transmission. Packet loss has the greatest influence on picture quality in video network. This paper proposes a layered coding technique suitable for ATM using discrete cosine transform (DCT) cod-ing. The proposed layered coding separates coded information into most significant parts (MSPs) and least significant parts (LSPs) and gives MSP packets priority over LSP packets to reduce the influence of packet loss on picture quality. The influence of packet loss on picture quality is also described, and the effectiveness of the proposed layered coding is confirmed with decoded pictures.

Virtual path layout in ATM networks based on the P-median problem

In future broadband networks based on asynchronous transfer mode (ATM) transmission and switching technology, the dominant kind of impairment is expected to be packet (ATM cell) losses. The use of forward error correction (FEC) codes has been proposed as a way to overcome these losses. However, the maximum length of a lost packet string that a packet loss recovery scheme can be designed to recover highly depends upon the temporal behavior between the adjacent packet loss bursts. Thus, a realistic model for describing the packet loss process is needed. The Gilbert model proposed for such purpose turns out to be an unrealistic model, since it fails to consider some important characteristics during the packet loss process. A more realistic model is advanced in this paper.

The arrangement of data in a variable bit rate (VBR) video codec, making it suitable for the transmission over ATM (asynchronous transfer mode) networks, is addressed. Attention is focused on two aspects specifically belonging to the ATM environment: the impairment due to the loss of ATM data cells and the statistical analysis of a real VBR video source. A particular implementation of a hybrid DCT (discrete cosine transform) broadcast video codec, which adheres to the recent specifications proposed by the European Telecommunications Standards Institute, is addressed. In order to optimize the performance with respect to cell losses, a specific solution based on the concept of organizing data into video packets is explored. The statistical characteristics of the available VBR video source are investigated, using a real-time acquisition system. >

This paper describes a video scheme which is capable of compensating for the information losses due to packet loss. Packet losses in ATM (asynchronous transfer mode) networks have such a great impact on the design of coding algorithms and network architectures that they should be exhaustively discussed and resolved. One solution to this problem is the transmission of the video signal over the network with different levels of protection. The information which is considered sufficient to generating the minimum acceptable quality in a video signal is transmitted in a very protected way. On the contrary, other parts of the information necessary to increase the quality of the coded images up to the desired level are sent in a normal channel. In this paper a hierarchical approach is presented and its performances are compared with MPEG-2 system coding in the same circumstances.