A variable bit rate video codec for asynchronous transfer mode networks

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. >

Layered Coding Schemes for Video Transmission on 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 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.

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.

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

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 RITM (real-time integrated traffic management) scheme that can effectively manage VBR (variable bit rate) and ABR (available bit rate) cell services having unpredictable characteristics in ATM (asynchronous transfer mode) networks. In addition to its exact traffic monitoring capability, the proposed scheme intends to efficiently use network resources without any deterioration in QoS (quality of service) of the accepted connections. Specifically, we highlight some functions of resource management, connection admission control that should be integrated to operated correctly in the emerging ATM networks. This enables ATM switch designers to find a suitable buffer design method. An unique feature of this scheme is that it has a special ATM cell control block, which makes it possible to manage ATM traffic in real-time so that the delay incurred to measure the cell arrival rate in existing algorithms is removed. By doing this, we can also save ATM switch buffers fairly, which means that those buffers would be used for more users or ABR services. This property makes the scheme extremely attractive for supporting most delay-sensitive and loss-sensitive applications at the same time without changing the existing ATM environments. The proposed RITM scheme has been verified to reliably monitor incoming traffic and to efficiently manage network resources by simulations.

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 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. The authors propose an explicit rate congestion control mechanism based on the LB scheme. Unlike the conventional LB, the leak rate is controlled using delayed feedback information sent by the network. The results show that cell loss and delay are reduced significantly at the ATM switch node.

The authors present the bit-rate characteristics of variable bit-rate (VBR) MPEG-1 compatible video intended for asynchronous transfer mode (ATM) network applications. The VBR coding mode for MPEG video is of special interest in teleconferencing and workstation multimedia applications requiring constant image quality, low delay, and/or integrated multimedia transport. Simulation data are provided for a 5-10 Mbps CCIR601 VBR MPEG encoder appropriate for standard-quality TV broadcasting or multimedia applications. The results presented include bit-rate traces and signal-to-noise ratio for typical test sequences, along with summary bit-rate statistics. The performance of frame-based peak rate control as a traffic shaping method is studied. Signal-to-noise ratio obtained with VBR and constant bit-rate coding modes operating at the same average bit-rate is also given for purposes of comparison. >

Performance evaluation methods that have been used so far failed to capture the real characteristics of network traffic. This is especially true when the service times are general such as the variable bit rate (VBR) video, which is proven to be self-similar. In the paper, diffusion approximation methods are proposed to analyse a dynamic scheduler for self-similar VBR video traffic in asynchronous transfer mode (ATM) networks. The proposed scheme employs a coupled queueing system that has been used extensively in the modelling of computer and communication systems. Diffusion approximations methods are used to decouple a queueing system which represents an ATM network node into separate G/G/1 queues. Real MPEG video traces are used in the discrete event simulation. Results are compared with the approximation, and are found to work very well under different traffic conditions.

A New Modeling Approach of H.263+ VBR Coded Video Sources in ATM Networks

We present a new approach to modelling variable bit rate (VBR) coded video sources in asynchronous transfer mode (ATM) networks. Unlike the existing methods which model the number of cells generated by the coder for a sequence of video frames, the new approach improves modelling accuracy by considering the characteristics of different cells generated by the coder, and modelling the number of cells in each type of macroblocks of a frame separately. The 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 are used as the source. Comparison with the existing models are performed in the area of measuring the quality of their predictions for network performance and the grade of service experienced by a user.

We present a new approach to modelling variable bit rate (VBR) coded video sources in asynchronous transfer mode (ATM) networks. Unlike the existing methods which model the number of cells generated by the coder for a sequence of video frames, the new approach improves the modelling accuracy by considering the characteristics of different cells generated by the coder, and modelling the number of cells in each type of macroblocks of a frame separately. The model is tested by comparing the autocorrelation function and mean queue size in the buffer by simulation of an ATM switch to the mean queue size produced when traces generated by the model are used as the source. Comparisons with the existing models are performed in the area of measuring the quality of their predictions for the network performance and the grade of service experienced by a user.