Browsing by Author "Liang, ST"

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Departure process analysis for earliest-due-date scheduling discipline in ATM switches
(1996-11-01)
Liang, ST
;
Yuang, MC
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
Asynchronous Transfer Mode (ATM) networks are expected to support to diverse mix of traffic sources demanding different Quality Of Service (QOS) guarantees. Regarding the Earliest-Due-Date (EDD) as one of the most promising scheduling disciplines offering delay guarantees in ATM switches, we provided in our previous work a decent queueing analysis for determining the urgency number (D-i) for each service class in an effort to offer 99% delay guarantees for higher delay priority calls under various traffic loads. To further evaluate the end-to-end delay distribution for an observed call, in this paper we present the departure process analysis for the EDD discipline with two urgency numbers D-0 = 0 and D-1 = D associated with two delay-based service classes (class 0 and class 1), respectively. The EDD-based ATM switch is modelled by a discrete-time, single-server queueing system with renewal and non-renewal arrivals. Based on the queueing model, we derive the interdeparture time distribution for the observed traffic stream being multiplexed with other traffic streams. The accuracy of the analysis is confirmed by simulation results. Numerical results demonstrate the characteristic reform of the periodic traffic stream after multiplexing through an EDD-based ATM switch. Since the derived departure process becomes the arrival process of the subsequent ATM switch along the pre-established virtual route, the analysis offers the realization of end-to-end delay computation for ATM networks.
Dynamic video playout smoothing method for multimedia applications
(1996)
Yuang, MC
;
Liang, ST
;
Chen, YG
;
Shen, CL
;
資訊工程學系
Dynamic video playout smoothing method for multimedia applications
(1998-01-01)
Yuang, MC
;
Liang, ST
;
Chen, YG
;
資訊工程學系
;
Department of Computer Science
Multimedia applications including video data require the smoothing of video playout to prevent potential discontinuity. In this paper, we propose a dynamic video playout smoothing method, called the Video Smoother, which dynamically adopts various playout rates in an attempt to compensate for high delay variance of networks. Specifically, if the number of frames in the buffer exceeds a given threshold (TH), the Smoother employs a maximum playout rate. Otherwise, the Smoother uses proportionally reduced rates in an effort to eliminate playout pauses resulting from the emptiness of the playout buffer. To determine THs under various loads, we present an analytic model assuming the interrupted Poisson Process (IPP) arrival. Based on the analytic results, we establish a paradigm of determining THs and playout rates for achieving different playout qualities under various loads of networks. Finally, to demonstrate the viability of the Video Smoother, we have implemented a prototyping system including a multimedia teleconferencing application and the Video Smoother performing as part of the transport layer. The prototyping results show that the Video Smoother achieves smooth playout incurring only unnoticeable delays.
Dynamic video playout smoothing method for multimedia applications
(1998-01-01)
Yuang, MC
;
Liang, ST
;
Chen, YG
;
資訊工程學系
;
Department of Computer Science
Multimedia applications including video data require the smoothing of video playout to prevent potential discontinuity. In this paper, we propose a dynamic video playout smoothing method, called the Video Smoother, which dynamically adopts various playout rates in an attempt to compensate for high delay variance of networks. Specifically, if the number of frames in the buffer exceeds a given threshold (TH), the Smoother employs a maximum playout rate. Otherwise, the Smoother uses proportionally reduced rates in an effort to eliminate playout pauses resulting from the emptiness of the playout buffer. To determine THs under various loads, we present an analytic model assuming the interrupted Poisson Process (IPP) arrival. Based on the analytic results, we establish a paradigm of determining THs and playout rates for achieving different playout qualities under various loads of networks. Finally, to demonstrate the viability of the Video Smoother, we have implemented a prototyping system including a multimedia teleconferencing application and the Video Smoother performing as part of the transport layer. The prototyping results show that the Video Smoother achieves smooth playout incurring only unnoticeable delays.
Intelligent video smoother for multimedia communications
(1997-02-01)
Yuang, MC
;
Tien, PL
;
Liang, ST
;
交大名義發表
;
資訊工程學系
Multimedia communications often require intramedia synchronization for video data to prevent potential playout discontinuity resulting from network delay variation (jitter) while still achieving satisfactory playout throughput. In this paper, we propose a neural network (NN) based intravideo synchronization mechanism, called the intelligent video smoother (IVS), operating at the application layer of the receiving end system. The IVS is composed of an NN traffic predictor, an NN window determinator, and a window-based play out smoothing algorithm, The NN traffic predictor employs an on-line-trained back-propagation neural network (BPNN) to periodically predict the characteristics of traffic modeled by a generic interrupted Bernoulli process (IBP) over a future fixed time period. With the predicted traffic characteristics, the NN window determinator determines the corresponding optimal window by means of an off-line-trained BPNN in an effort to achieve a maximum of the playout quality (Q) value. The window-based playout smoothing algorithm then dynamically adopts various playout rates according to the window and the number of packets in the buffer, Finally, we show that via simulation results and live video scenes, compared to two other playout approaches, IVS achieves high-throughput and low-discontinuity playout under a mixture of IBP arrivals.
Realization of earliest-due-date scheduling discipline for ATM switches
(1998-02-01)
Liang, ST
;
Yuang, MC
;
資訊工程學系
;
Department of Computer Science
Asynchronous Transfer Mode (ATM) networks are expected to support a diverse mix of traffic sources requiring different Quality Of Service (QOS) guarantees. This paper initially examines several existing scheduling disciplines which offer delay guarantees in ATM switches. Among them, the Earliest-Due-Date (EDD) discipline has been regarded as one of the most promising scheduling disciplines. The EDD discipline schedules the departure of a cell belonging to a call based on the delay priority assigned for that call during the call set-up. Supporting n delay-based service classes through the use of n respective urgency numbers D-0 to Dn-1 (D-0 less than or equal to D-1 less than or equal to...less than or equal to Dn-1), EDD allows a class-i cell to precede any class-j (j>i) cell arriving not prior to (D-j - D-i)-slot time. The main goal of the paper is to determine the urgency numbers (D-i's), based on an in-depth queueing analysis, in an attempt to offer ninety-nine percentile delay guarantees for higher priority calls under various traffic loads. In the analysis, we derive system-time distributions for both high-and low-priority cells based on a discrete-time, single-server queueing model assuming renewal and non-renewal arrival processes. The validity of the analysis is justified via simulation. With the urgency numbers (D-i's) determined, we further propose a feasible efficient VLSI implementation architecture for the EDD scheduling discipline, furnishing the realization of QOS guarantees in ATM switches.
Threshold-based intra-video synchronization for multimedia communications
(1998-04-01)
Liang, ST
;
Tien, PL
;
Yuang, MC
;
資訊工程學系
;
Department of Computer Science
Multimedia communications often require intramedia synchronization for video data to prevent potential playout discontinuity while still retaining satisfactory playout throughput. In this paper, we propose a novel intra-video synchronization mechanism, called the Video Smoother, particularly suitable for low-end multimedia applications, such as video conferencing. Generally, the Video Smoother dynamically adopts various playout rates according to the number of frames in the playout buffer in an attempt to compensate for the delay jitter introduced from networks. In essence, if the number of frames in the buffer exceeds a given threshold (TH), the Smoother employs a maximum playout rate. Otherwise, the Smoother employs linearly or exponentially reduced rates to eliminate playout pauses resulting from the emptiness of the playout buffer. To determine optimal TH's achieving a minimum of playout discontinuity and a maximum of playout throughput under various bursty traffic, we propose an analytic model assuming incoming traffic following an Interrupted Bernoulli arrival Process (IBP). As a result, optimal TH's can be analytically determined resulting in superior playout quality under various arrivals and loads of networks. Finally, we display simulation results which demonstrate that, compared to the playout without intra-video synchronization (instant playout), the Video Smoother achieves superior smooth playout and compatible throughput.