Bandwidth Renegotiation Research Articles

An Empirical Study on Renegotiated CBR for VBR Video Services Based on Network Testbed

For multimedia network services, bandwidth reservation levels for video transmissions are conventionally defined using traffic descriptors that remain static over the entire playback duration of the video transmissions. Aimed at addressing the bandwidth wastefulness of using the static reservation, renegotiated Constant-Bit-Rate (RCBR) mechanism has been proposed to perform dynamic bandwidth allocation with periodical bandwidth renegotiation during any multimedia transmission sessions. However, this mechanism has been only examined via simulations and theoretical analysis previously. In this study, we have conducted rigorous empirical studies on RCBR scheme using a real network testbed to study its performance. Our study reveals interesting results and provides new insight to any practical deployment of RCBR mechanism and service over broadband packet networks. Moreover, a smoothing technique at application layer is proposed and evaluated in RCBR context to maximize the efficiency of RCBR scheme. We present empirical results and analysis, and highlight our observations.

Dynamic bandwidth reservation for label switched paths: An on-line predictive approach

Managing the bandwidth allocated to a Label Switched Path in MPLS networks plays a major role for provisioning of Quality of Service and efficient use of resources. In doing so, two main contrasting factors have to be considered: not only the bandwidth should be adapted to the traffic profile but also the effort for bandwidth renegotiation associated with a variation of the allocated bandwidth should be kept at low levels. In this context, we formulate a problem of optimal LSP bandwidth reservation as the one of minimizing a convex combination of the difference between the assigned bandwidth and the estimated future traffic, and of a measure of the frequency of bandwidth variations. The contribution of this paper is to propose a new method to reserve optimally the bandwidth of an LSP, avoiding an excess of bandwidth renegotiations on the basis of prediction of future traffic, assuming a simple birth-and-death model to describe the traffic dynamics. Whenever the prediction is inaccurate due to unpredictable variations in the characteristics of real traffic, a suitable “emergency procedure” is proposed, which performs a new traffic prediction and a consequent modified bandwidth reservation. Numerical results are presented which show the effectiveness of the method and the achieved performance, both for simulated and real data traffic.

인터넷 상의 가변 비트율 비디오 스트리밍을 위한 적응형 전송 기법

본 논문에서는 인터넷 상의 분산 비디오 스트리밍 서비스에서 저장된 가변 비트율 비디오의 전송에 대해 고려한다. 스트리밍 서비스에서 전송 중에 대역폭 재조정 프로토콜에 따라 대역폭 할당이 줄게 되면 흔히 재생의 끊김 현상이 발생한다. 본 논문에서는 이러한 문제점을 극복할 수 있는 가변 비트율 비디오에 대한 전송 기법을 제안한다. 이 기법에서는 저장된 가변 비트율 비디오에 대한 사전 정보를 사용하여 재생이 끊김없이 이루어질 수 있도록 전송한다. 또한 제안된 전송 기법 하에서의 수용 제어를 위해 버퍼-대역폭 관계를 근사적으로 계산할 수 있는 기법을 제안한다. In this paper, we consider the transmission or variable bit rate (VBR) stored video for the distributed video streaming service over Internet. In streaming service, users often suffer from the discontinuity in playback due to the decrease in bandwidth during transmission according to bandwidth renegotiation protocol. We propose a novel transmission technique to overcome this problem for stored variable bit rate video. This scheme uses a priori information of stored VBR video to continue streaming without playback discontinuity. In addition, an approximation scheme for the buffer-bandwidth relation is proposed in order to facilitate the admission control under the proposed scheme.

04/00575 Strategizing in the deregulating energy markets: two steps forward, one step back, and where next?: Andersen, T. J. and Remedios, A. J. The Electricity Journal, 2003, 16, (7),86–94.

Managing the bandwidth allocated to a Label Switched Path in MPLS networks plays a major role for provisioning of Quality of Service and efficient use of resources. In doing so, two main contrasting factors have to be considered: not only the bandwidth should be adapted to the traffic profile but also the effort for bandwidth renegotiation associated with a variation of the allocated bandwidth should be kept at low levels. In this context, we formulate a problem of optimal LSP bandwidth reservation as the one of minimizing a convex combination of the difference between the assigned bandwidth and the estimated future traffic, and of a measure of the frequency of bandwidth variations. The contribution of this paper is to propose a new method to reserve optimally the bandwidth of an LSP, avoiding an excess of bandwidth renegotiations on the basis of prediction of future traffic, assuming a simple birth-and-death model to describe the traffic dynamics. Whenever the prediction is inaccurate due to unpredictable variations in the characteristics of real traffic, a suitable “emergency procedure” is proposed, which performs a new traffic prediction and a consequent modified bandwidth reservation. Numerical results are presented which show the effectiveness of the method and the achieved performance, both for simulated and real data traffic.

Dynamic Bandwidth Allocation for VBR Video Transmission

To guarantee quality of service (QoS), the requirements for video transmission, such as delay and cell loss rate (CLR), are very stringent. These constraints are difficult to meet if high network utilization is desired. In this paper, dynamic bandwidth allocation algorithms are proposed to improve the bandwidth utilization. The first approach based on scene change identification, in which the bandwidth is allocated based on the maximum and mean bandwidth of the scene, is applicable to delivering pre-recorded videos. The second approach, in which the bandwidth is adjusted based on the current frame size, is on-line and can be used to deliver real-time videos on-line. When the bandwidth deviation is large enough, the bandwidth renegotiation process is triggered. Compared with CBR service, network utilization can be improved significantly for the same CLR. In general, to achieve a very low CLR and high bandwidth utilization, the renegotiation frequency may become high. Algorithms, which are proven to be effective in reducing the renegotiation frequency while keeping the bandwidth utilization at a reasonable level, are also proposed.

Adaptive rate control algorithms for low bit rate video under networks supporting bandwidth renegotiation

This paper presents new adaptive H.263+ rate control algorithms for video streaming and interactive video applications under networks supporting bandwidth renegotiation, which can communicate with end-users to accommodate their time-varying bandwidth requests during the data transmission. That is, the requests of end-users can be supported adaptively according to the availability of the network resources, and thus the overall network utilization can be improved simultaneously. They are especially suitable for the transmission of non-stationary video traffics. The proposed rate control algorithms communicate with the network to renegotiate the required bandwidth for the underlying video which are measured based on the motion change information, and choose their control strategies according to the renegotiation results. Unlike most conventional algorithms that control only the spatial quality by adjusting quantization parameters, the proposed algorithms treat both the spatial and temporal qualities at the same time to enhance human visual perceptual quality. Experimental results are provided to demonstrate that the proposed rate control algorithms can achieve superior performance to the conventional ones with low computational complexity under networks supporting bandwidth renegotiation.

The transportation of VBR-encoded video using deterministic characterization and bandwidth renegotiation

In this paper, a video transmission service using deterministic characterization and bandwidth renegotiation is proposed. In this service, we characterize a video stream at micro-segment and segment levels, and the bandwidth requirement will be determined as a tradeoff between the characterizations at these two levels, under the scaling of a parameter called degree of aggressiveness (DoA). The DoA parameter determines the degree of service robustness to be provided to the connection. Experimental results show that stream segmentation helps to increase the channel utilization, and higher DoA yields better quality of service because of increased level of service robustness.

Real‐time bandwidth renegotiation through learnt behaviour

AbstractIn many cases traffic is aggregated from several sources, or simply has no well‐understood characteristics, and so it is difficult for the user to decide the basis on which bandwidth should be demanded. A strategy is described to determine the optimum way to decide when to renegotiate the traffic capacity provided in ATM and similar systems. The performance of the strategy is evaluated using simulations on traffic with theoretical distributions and also on recorded real traffic. The strategy appears to work and the results give insights into the very limited benefits obtained by increasing the granularity of the rates provided. Copyright © 2001 John Wiley & Sons, Ltd.

Bandwidth renegotiation with traffic smoothing and joint rate control for VBR MPEG video over ATM

Variable bit-rate (VBR) MPEG video traffic is highly bursty due to group of pictures structure, and shows time-variant statistical characteristics due to scene changes. These characteristics make it more difficult to manage network resources, and leads to the significant reduction in network utilization. We deal with the issues related to efficiently transmitting VBR MPEG video traffic over asynchronous transfer mode networks, while maintaining consistent visual quality and improving network utilization on the basis of real-time applications. First, we propose a joint encoder and channel-rate control scheme that comply with not only negotiated traffic parameters, but also constraints imposed by encoder and decoder buffers. Second, we propose a dynamic bandwidth renegotiation method by combining the above scheme with a traffic smoothing method that can make the peak rate close to the sustainable rate. The efficiencies of the proposed methods are compared with a few other competitive schemes such as transmission methods for unconstrained VBR and the constant bit-rate scheme with average bandwidth equal to that of the proposed methods.

Bandwidth renegotiation scheme for VBR video services

The authors show how the existence of long term variability in variable bit rate (VBR) video traffic imposes the need for bandwidth renegotiation. In particular, two simple scenarios with a fixed renegotiation interval are considered. Using a real MPEG trace, the renegotiation scheme is evaluated to prove its benefits in terms of bandwidth gain and quality of service. The problem of renegotiation demonstrates the need for modelling long term variability in VBR traffic.

Soft QoS control in the WATMnet broadband wireless system

A framework for QoS control in broadband wireless networks is presented. The framework allows terminal and network-initiated bandwidth renegotiation to handle wide spatiotemporal traffic dynamics characteristic of mobile multimedia applications. The concept of softness profiles is used to realize soft QoS control at radio access points. An implementation perspective of the framework's protocol and software components within NEC WATMnet/sup TM/ mobile wireless ATM system is given. The principles of traffic management and signaling extensions required for soft QoS control are outlined. The terminal software architecture is described with a focus on APIs and their use within Winsock's generic QoS architecture. The importance of soft QoS control for future broadband mobile network architectures with integrated IP and ATM transport is discussed.

Rate control of MPEG-2 video traffic over ATM DBR service with bandwidth renegotiation

Rate control of MPEG-2 video traffic over ATM DBR service with bandwidth renegotiation

MPEG over ATM DBR service class for high quality transmission and effective bandwidth usage

The highly bursty nature of the moving picture experts group (MPEG) determines the bandwidth when it is applied to the asynchronous transfer mode (ATM) deterministic bit rate (DBR) service class. Furthermore, the MPEG source must declare peak cell rate (PCR), one of the traffic descriptors used in the call admission control (CAC) procedure, before actual transmission in ATM networks. However, the real-time encoding of the MPEG video introduces a difficulty in predicting a maximum picture size of the video, which is necessary to determine PCR. When an MPEG source can be equipped with the capability to adjust the encoding rate to the allocated bandwidth, the burstiness of the MPEG video can be lowered and the uncertainty in predicting PCR is avoided to some extent. In this case, a problem is apparently quality degradation caused by introducing such a rate adaptation mechanism, which is the main subject of this study. For the rate adaptation method, we consider a priority control method, a space reduction method, a time reduction method and a bandwidth renegotiation method. Quality of the video is evaluated and compared in terms of signal-to-noise ratio (SNR) as well as mean opinion score (MOS) because users' perception becomes an important measure of the quality of video transmissions. Through experimental results, it is shown that the space reduction method is useful for real-time transmission, whereas the time reduction method can be applicable if the users' application can tolerate the relatively large delay between source and destination. Furthermore, the applicability of the bandwidth renegotiation method is also validated. © 1997 by John Wiley & Sons, Ltd.

Bandwidth renegotiation for VBR video over ATM networks

A scheme for delivery or variable bit-rate (VBR) video over asynchronous transfer mode (ATM) networks where bandwidth can be renegotiated during the duration of a call between the video source and the network is considered. Renegotiation can be initiated by either the video source or the network. The video bandwidth requirement is characterized by a usage parameter control (UPC) consisting, in general, of peak rate, burst length, and sustained rate. A baseline design is outlined where rate-control adjusts the source's rate while a new UPC is requested from the network. When granted, the new UPC allows the source to maintain its target quantization and delay requirements. Rate control epochs may be extended when the network blocks UPC requests or sets a lower UPC value to temporally deal with congestion. Simulation results are presented for VBR MPEG video. The results show that with a moderate renegotiation rate the scheme tracks the bandwidth requirements of the source. As a result, the video quality and bandwidth efficiency can be maintained.

Internetting LAN's and MAN's to B-ISDN's for connectionless traffic support

One of the challenges in the interconnection of LANs and MANs to asynchronous transfer mode (ATM) networks is the support of connectionless traffic in the ATM network. A commonly proposed strategy consists of maintaining a thin, low bandwidth virtual path (VP) between each pair of gateways and requesting more bandwidth whenever a burst comes in from the LAN or MAN. Unfortunately, this strategy places a heavy burden on the ATM control processors; furthermore, it is overly conservative in the use of bandwidth. An alternative solution is proposed: on the-fly tranmission of bursts without prior bandwidth reservation. The key conditions for this scheme to work are the use of the cell loss priority (CLP) bit in the ATM cell header and the knowledge of available bandwidth on the path through bandwidth advertising. An on-the-fly strategy for connectionless traffic is described and is compared with a bandwidth renegotiation strategy.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>