Layered Coding Schemes for Video Transmission on ATM Networks

For distinctively transporting voice data with silence suppression over asynchronous transfer mode (ATM) networks via the variable bit rate (VBR) service, the problem of jitter introduced from the network often renders the speech unintelligible. It is thus indispensable to offer intramedia synchronization to remove jitter while retaining minimal playout delay. We propose a neural-network-based intra-voice synchronization mechanism, called the intelligent voice smoother (IVoS). The IVoS is composed of three components: smoother buffer, neural network (NN) traffic predictor, and constant bit rate (CBR) enforcer. Newly arriving frames, being assumed to follow a generic Markov modulated Bernoulli process (MMBP), are queued in the smoother buffer. The NN traffic predictor employs an on-line-trained backpropagation neural network (BPNN) to predict three traffic characteristics of every newly encountered talkspurt period. Based on the predicted characteristics, the CBR enforcer derives an adaptive buffering delay by means of a near-optimal, simple, closed-form formula. It then imposes such delay on the playout of the first frame in the talkspurt period. The CBR enforcer in turn regulates CBR-based departures for the remaining frames of the talkspurt, aimed at assuring minimal mean and variance of distortion of talkspurts (DOT) and mean playout delay (PD). Simulation results reveal that, compared to three other playout approaches, the IVoS achieves superior playout yielding negligible DOT and PD irrespective of traffic variation.

A fuzzy approach to MPEG video transmission in ATM networks

This paper presents a general traffic control framework for Asynchronous Transfer Mode (ATM) networks with its performance evaluation. The proposed traffic control scheme can incorporate all the recently considered ATM service classes including Constant Bit Rate (CBR), real time Variable Bit Rate (rtVBR), non-real time Variable Bit Rate (nrVBR), Available Bit Rate (ABR) and Unspecified Bit Rate (UBR) services. The control is based on a complete buffer partitioning architecture and on the associated buffer scheduling rule with adaptive weighting functions. We present, the formulation of the traffic control as an optimization problem in a 3-dimensional Quality of Service (QoS) state space. A solution approach based on dynamic programming is also suggested. A comprehensive performance evaluation of the method has been performed based on simulations and results are presented with several examples. The QoS dependence on CBR load, VBR load, VBR burstiness, UBR load are investigated and results are demonstrated with explanations.

The synchronous residual time stamp method (SRTS) is one of the proposed timing recovery methods for constant bit rate (CBR) services over asynchronous transfer mode (ATM) networks. ATM adaption layer 1 (AAL1) is used to specify these CBR services and is usually called the circuit emulation application such as DS1 and DS3. The paper gives both a characteristic and conformance testing method for RTS parameters in a synchronous optical network (SONET) based broadband integrated service digital network (BISDN), which has the reference clock hierarchy derived from a 155.52 MHz network.

Traffic prediction and dynamic bandwidth allocation over ATM: a neural network approach

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 recent years, there has been a strong interest in transmitting compressed video over packet switched networks, such as asynchronous transfer mode (ATM). Previous work has dealt with transmitting MPEG over constant bit rate (CBR) and variable bit rate (VBR) services of ATM. The available bit rate (ABR) service of ATM is expected to be much more cost effective than CBR or VBR. However, there hasn't been much work done on running interactive client/server applications (for example, video on demand) over ABR. We have developed a framework to design interactive video systems transmitting MPEG video over the ATM ABR service. We have developed models to determine the network connection parameters required to run interactive client/server multimedia applications over an ATM network using the ABR service. We solve our model using real-time dynamic equilation (RTDE) analysis. We conclude that by proper dimensioning of the buffers at the client and the server, it is possible to run interactive video over the ATM ABR service.

A Review on Bandwidth Utilization for Bursty Traffic in Asynchronous Transfer Mode Networks

A mixed bit rate (MBR) video coding method is presented for asynchronous transfer mode (ATM) networks which has communication compatibility between constant bit rate (CBR) video codecs and variable bit rate (VBR) codecs. In MBR video coding, essential information is encoded at a CBR by using a conventional CBR coding method such as H.261 and enhancement information is encoded at a VBR to attain constant image quality. To realize the MBR coding of video, the conventional embedded pulse code modulation (PCM) quantization is extended by applying the requantization method only to the least significant bit (LSB) of the quantizer output. In the EX-EMB PCM method, the most significant part and least significant part (MSP/LSP) separation of embedded PCM and an additional threshold for the requantizer are dynamically determined to attain a desired distortion. The MBR codec with EX-EMB PCM was evaluated by computer simulations. The simulation results showed that the proposed method was effective not only for improving video quality but also it prevented the degradations of image quality at the scene change by increasing the bit rate for the VBR channel. >

In recent years, there has been a strong interest in transmitting compressed video over packet switched networks, such as asynchronous transfer mode (ATM). Previous work has dealt with transmitting MPEG over constant bit rate (CBR) and variable bit rate (VBR) services of ATM. The available bit rate (ABR) service of ATM is expected to be much more cost effective than CBR or VBR. However, there hasn't been much work done on running interactive client/server applications (for example, video on demand) over ABR. We have developed a framework to design interactive video systems transmitting MPEG video over the ATM ABR service. We have developed models to determine the network connection parameters required to run interactive client/server multimedia applications over an ATM network using the ABR service. We solve our model using real-time dynamic equilation (RTDE) analysis. We conclude that by proper dimensioning of the buffers at the client and the server, it is possible to run interactive video over the ATM ABR service.

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 investigates the application of multicode spread-spectrum code-division multiple-access (SS-CDMA) techniques to three-dimensional (3-D) stereoscopic video transmission over wireless asynchronous transfer mode (ATM) networks. Three-dimensional visual communications, made through the use of stereoscopic images, are able to achieve total display realism. Such services allow users to share the virtual reality (VR) world without any geographical restrictions. In order to create a 3-D system with two images (left and right) that should be transmitted over a bandlimited mobile channel simultaneously, a cost-effective motion picture experts group (MPEG)-based wavelet multiresolution coding with a joint motion and disparity compensation is developed to reduce a large amount of information contained in the images to meet the low-transmission rate limitation of mobile channels. However, the rapidly variable bit rate (VBR) characteristics of the MPEG-based 3-D videos seems a weakness to the transmission of such videos via a constant bit-rate (CBR) mobile channel. The ATM technique is especially well suited for VBR MPEG-based 3-D video because of its ability to allocate bandwidth on demand to these services. However, since the mobile radio has a limited channel capacity, the overall capacity of the traditional ATM-based SS-CDMA system may not be sufficient to accommodate the MPEG-based 3-D video services requested by the multiple mobile users simultaneously. To tackle this difficulty, a multicode CDMA technique is proposed to provide VBR MPEG-based 3-D video services by varying the number of spreading codes assigned to the 3-D video to meet its dynamic throughput requirement. Powerful forward error correction (FEC) codes are necessary to protect the video data so that it can be successfully transmitted at an acceptable signal power level. Two separate FEC code schemes are applied to the header and payload of an ATM cell containing 3-D video data, respectively. The ATM cell header is protected by a relatively powerful FEC code to ensure correct delivery and low cell loss rate (CLR). On the other hand, the ATM cell payload is encoded for varying degrees of error protection according to the priority of the payload data in 3-D videos. An adaptive FEC code combining scheme is proposed to provide the good protection for payload data with the maximization of its code rate to minimize the extra bandwidth for FEC overhead.

For video sources the Moving Picture Experts Group (MPEG) compression scheme has become the defacto standard for video compression since then. However, even with the huge reduction of bits that MPEG compression provides, it does not smooth the video traffic. Indeed the variable bit rate (VBR) MPEG compression algorithm guarantees that the MPEG stream will be bursty. A service, where an asynchronous transfer mode (ATM) client requests and receives from an ATM server VBR MPEG coded video sequences, is considered. An algorithm for streaming VBR MPEG coded video delivery over ATM networks, which dynamically allocates the transmission parameters, is proposed. A scheme for optimal choice of the prediction window's size is also presented. The results obtained show that the proposed dynamic allocation algorithm can provide an efficient solution for VBR MPEG coded video transport with guaranteed quality of service (QoS) over ATM networks.

Recently, there has been much interest in sending video over Broadband Integrated Services Digital Networks (B-ISDN) using Asynchronous Transfer Mode (ATM). ATM affords a flexible multiplexing and switching capability for integrated delivery of bursty traffic. As such, video can be transported either with a constant bit-rate (CBR) or with a variable bit-rate (VBR). VBR video has several potential advantages over traditional CBR video: improved image quality and shorter delay. In addition, through statistical multiplexing, improved channel allocation may be obtained compared to CBR transport.

The future broadband wireless asynchronous transfer mode (ATM) networks must provide seamless extension of multimedia services from the wireline ATM networks. This requires an efficient wireless access protocol to fulfil varying quality-of-service (QoS) requirements for multimedia applications. In this paper, we propose a multiple access protocol using centralized and distributed channel access control techniques to provide QoS guarantees for multimedia services by taking advantage of the characteristics of different kinds of ATM traffic. Multimedia traffic, including constant bit rate (CBR), variable bit rate (VBR) and available bit rate (ABR) with different kinds of applications, such as voice, video-conferencing, MPEG video and Web-browsing, is considered to evaluate the proposed protocol. Simulation results show that the proposed multiple access protocol can support a wide range of telecommunication applications at the same time with high efficiency and guaranteed QoS.