Statistical multiplexing of variable bit rate video sources in asynchronous transfer mode networks

Congestion control mechanisms are required in asynchronous transfer mode (ATM) networks to fairly and efficiently allocate network resources to the various service types. Bandwidth assignment is a preventive control mechanism. A bandwidth called equivalent bandwidth is allocated in order to ensure the cell transport objectives. A definition is proposed of equivalent bandwidth for stream, bursty data and variable bit rate video sources. The equivalent bandwidth values are evaluated by simulation considering both homogeneous and heterogeneous sources. In the heterogeneous mixes with different cell loss probability requirements the selective discarding mechanism permits a more efficient utilization of the network resources. >

A fuzzy approach to MPEG video transmission in ATM networks

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. >

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

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

We propose a scheme for transmission of variable bit rate (VBR) compressed video for interactive applications using the explicit-rate congestion-control mechanisms proposed for the available bit rate (ABR) service in asynchronous transfer mode networks. Compressed video is inherently bursty, with rate fluctuations over both short and long time scales. This source behavior can be accommodated by the ABR service, since the explicit-rate scheme allows sources to request varying amounts of bandwidth over time. Moreover, when the bandwidth demand cannot be met, the network provides feedback indicating the bandwidth currently available to a connection. In our scheme, the video source rate is matched to the available bandwidth by modifying the quantization level used during compression. We use trace-driven simulations to examine how effective the enhanced explicit-rate scheme is in "rate matching" between the network and the source and the effect on end-to-end delay. We also look at the sensitivity of the proposed scheme to the estimates of the network round-trip times and to inaccuracies in the rate requests made by sources.

It is anticipated that video traffic will constitute a significant portion of the load in ATM(Asynchronous Transfer Mode) networks. In this paper, the congestion control due to transient video source has been studied. We propose an algorithm for the congestion occurring,especially, due to scene changes in variable bit rate video source in ATM network.Firstly, video source is modeled by three-state Markov chains including the effects of scene-change at which the bit rate of video source be abruptly increased. Secondly, the scene-change in video source is detected by using the first and second-order statisticparameters (Mean, Variance and Autocorrelation Function). Finally, based on the statistic parameters, the algorithm for the congestion control is developed. We confirm the effectiveness of the proposed algorithm by numerical calculation and simulation results.

A variable-bit-rate (VBR) MPEG video compression encoder is introduced, and the performance of a statistically multiplexed asynchronous transfer mode (ATM) network supporting a number of such VBR video sources is evaluated. Bit-rate characteristics obtained from a detailed simulation are provided for a VBR MPEG encoder for CCIR601 video (operating in the 5-10 Mb/s regime) appropriate for medium-quality multimedia or broadcasting applications. The results presented include bit-rate traces and signal-to-noise-ratio data for typical test sequences, along with summary statistics such as the marginal distribution of frame rate. Data from a study of statistical multiplexing on an ATM network are also given. Simulation results for an ATM statistical multiplexer with N>>1 VBR MPEG sources are presented in terms of key performance measures such as cell loss rate and delay versus throughput. The results confirm that ATM channel efficiencies of approximately 80-90% can be obtained at reasonable cell loss rate and delay levels.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design and performance analysis of a new RTM algorithm for VBR traffic in ATM networks

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.

Video traffic is expected to account for a significant share of the traffic volume in the future asynchronous transfer mode (ATM) networks. MPEG-2 proposed by Moving Picture Expert Group is one of the most promising compression techniques for such applications. One of the critical issues in MPEG-2 is to realize effective variable bit rate (VBR) video transfer thorough ATM networks. The Leaky Bucket (LB) scheme has been widely accepted as the usage parameter control (UPC) mechanism to police the VBR sources. We proposed a new Adaptive Dynamic Leaky Bucket (ADLB) congestion control mechanism, which is based on the LB scheme. Unlike the conventional LB, the leak rate of the ADLB is controlled using delayed feedback information of available bandwidth sent by the network. This scheme allows sources to get varying amounts of bandwidth over time, while reserving a minimum guaranteed bandwidth (MCR) for the entire duration of the connection. At the time of congestion, the leak rate of the ADLB is adjusted according to the feedback indicating the currently available bandwidth to the connection. The simulation results show that the end-to-end cell transfer delay and cell loss of each source has been improved significantly.

Video traffic is expected to account for a significant share of the traffic volume in future asynchronous transfer mode (ATM) networks. MPEG-2, proposed by the Moving Picture Expert Group, is one of the most promising compression techniques for such applications. One of the critical issues in MPEG-2 is to realize effective variable bit rate (VBR) video transfer thorough ATM networks. The leaky bucket (LB) scheme has been widely accepted as the usage parameter control (UPC) mechanism to police the VBR sources. We propose a new adaptive dynamic leaky bucket (ADLB) congestion control mechanism, which is based on the LB scheme. Unlike the conventional LB, the leak rate of the ADLB is controlled using delayed feedback information of available bandwidth sent by the network. The simulation results show that overall cell loss and delay are reduced significantly at the ATM switch node.

Real-time applications in a CRMA network: a performance analysis

In this paper, we summarise the previous work in the area of modelling variable bit rate (VBR) coded video sources in asynchronous transfer mode (ATM) networks. We verify these models, especially in the area of measuring the quality of their predictions for network performance and the grade of service experienced by a user. In addition to verifying these models, we suggest a new modelling approach of VBR coded video sources. In previous cases, the number of cells generated by the coder for a sequence of video frames are modelled. In the new modelling approach, the number of cells in each type of macroblocks of a frame are modelled. This model is tested by comparing the cell loss rate in simulation of an ATM switch to cell loss rate produced when traces generated by the model were used as source.

This paper presents a systems view of video transport issues in asynchronous transfer mode (ATM) networks. Since video is a critical component of future distributed multimedia applications, we consider technical approaches necessary to realize a flexible, robust, and efficient ATM framework for video delivery. The overall system-design problem is discussed for a general distributed multimedia computing scenario, and key video-related design issues are identified. This is followed by a more detailed discussion of selected ATM video topics, including: (1) variable bit-rate (VBR) statistical multiplexing and dynamic usage parameter control (VBR+), (2) ATM cell-loss concealment in MPEG decoders, and (3) new transport protocols (“MTP”) for video and multimedia. Supporting simulation or experimental results from ongoing research are given where available.