Existing ABR algorithms face a significant challenge in estimating future capacity: capacity can vary widely over time, a phenomenon commonly observed in commercial services. In this work, we suggest an alternative approach: rather than presuming that capacity estimation is required, it is perhaps better to begin by using only the buffer, and then ask when capacity estimation is needed. We test the viability of this approach through a series of experiments spanning millions of real users in a commercial service. We start with a simple design which directly chooses the video rate based on the current buffer occupancy. Our own investigation reveals that capacity estimation is unnecessary in steady state; however using simple capacity estimation (based on immediate past throughput) is important during the startup phase, when the buffer itself is growing from empty. This approach allows us to reduce the rebuffer rate by 10-20% compared to Netflix's then-default ABR algorithm, while delivering a similar average video rate, and a higher video rate in steady state.

/pdf/a-buffer-based-approach-to-rate-adaptation-evidence-from-a-42j7jpd30s.pdf

A buffer-based approach to rate adaptation: evidence from a large video streaming service

Digital Control Of Dynamic Systems This well-respected, market-leading text discusses the use of digital computers in the real-time control of dynamic systems. The emphasis is on the design of digital controls that achieve good dynamic response and small errors while using signals that are sampled in time and quantized in amplitude. Digital Control of Dynamic Systems (3rd Edition): Franklin ... This well-respected, market-leading text discusses the use of digital computers in the real-time control of dynamic systems. The emphasis is on the design of digital controls that achieve good dynamic response and small errors while using signals that are sampled in time and quantized in amplitude. Digital Control of Dynamic Systems: Gene F. Franklin ... Digital Control of Dynamic Systems, 2nd Edition. Gene F. Franklin, Stanford University. J. David Powell, Stanford University Digital Control of Dynamic Systems, 2nd Edition Pearson This well-respected work discusses the use of digital computers in the real-time control of dynamic systems. The emphasis is on the design of digital controls that achieve good dynamic response and small errors while using signals that are sampled in time and quantized in amplitude. MATLAB statements and problems are thoroughly and carefully integrated throughout the book to offer readers a complete design picture. Digital Control of Dynamic Systems, 3rd Edition ... Digital control of dynamic systems | Gene F. Franklin, J. David Powell, Michael L. Workman | download | B–OK. Download books for free. Find books Digital control of dynamic systems | Gene F. Franklin, J ... Abstract This well-respected work discusses the use of digital computers in the real-time control of dynamic systems. The emphasis is on the design of digital controls that achieve good dynamic... (PDF) Digital Control of Dynamic Systems Digital Control of Dynamic Systems, Addison.pdf There is document Digital Control of Dynamic Systems, Addison.pdfavailable here for reading and downloading. Use the download button below or simple online reader. The file extension PDFand ranks to the Documentscategory. Digital Control of Dynamic Systems, Addison.pdf Download ... Automatic control is the science that develops techniques to steer, guide, control dynamic systems. These systems are built by humans and must perform a specific task. Examples of such dynamic systems are found in biology, physics, robotics, finance, etc. Digital Control means that the control laws are implemented in a digital device, such as a microcontroller or a microprocessor. Introduction to Digital Control of Dynamic Systems And ... The discussions are clear, nomenclature is not hard to follow and there are plenty of worked examples. The book covers discretization effects and design by emulation (i.e. design of continuous-time control system followed by discretization before implementation) which are not to be found on every book on digital control. Amazon.com: Customer reviews: Digital Control of Dynamic ... Find helpful customer reviews and review ratings for Digital Control of Dynamic Systems (3rd Edition) at Amazon.com. Read honest and unbiased product reviews from our users. Amazon.com: Customer reviews: Digital Control of Dynamic ... 1.1.2 Digital control Digital control systems employ a computer as a fundamental component in the controller. The computer typically receives a measurement of the controlled variable, also often receives the reference input, and produces its output using an algorithm. Introduction to Applied Digital Control From the Back Cover This well-respected, marketleading text discusses the use of digital computers in the real-time control of dynamic systems. The emphasis is on the design of digital controls that achieve good dynamic response and small errors while using signals that are sampled in time and quantized in amplitude. Digital Control of Dynamic Systems (3rd Edition) Test Bank `Among the advantages of digital logic for control are the increased flexibility `of the control programs and the decision-making or logic capability of digital `systems, which can be combined with the dynamic control function to meet `other system requirements. `The digital controls studied in this book are for closed-loop (feedback) Every day, eBookDaily adds three new free Kindle books to several different genres, such as Nonfiction, Business & Investing, Mystery & Thriller, Romance, Teens & Young Adult, Children's Books, and others.

http://ieeexplore.ieee.org/iel6/29/26151/01163502.pdf

Digital control of dynamic systems

User-perceived quality-of-experience (QoE) is critical in Internet video applications as it impacts revenues for content providers and delivery systems. Given that there is little support in the network for optimizing such measures, bottlenecks could occur anywhere in the delivery system. Consequently, a robust bitrate adaptation algorithm in client-side players is critical to ensure good user experience. Previous studies have shown key limitations of state-of-art commercial solutions and proposed a range of heuristic fixes. Despite the emergence of several proposals, there is still a distinct lack of consensus on: (1) How best to design this client-side bitrate adaptation logic (e.g., use rate estimates vs. buffer occupancy); (2) How well specific classes of approaches will perform under diverse operating regimes (e.g., high throughput variability); or (3) How do they actually balance different QoE objectives (e.g., startup delay vs. rebuffering). To this end, this paper makes three key technical contributions. First, to bring some rigor to this space, we develop a principled control-theoretic model to reason about a broad spectrum of strategies. Second, we propose a novel model predictive control algorithm that can optimally combine throughput and buffer occupancy information to outperform traditional approaches. Third, we present a practical implementation in a reference video player to validate our approach using realistic trace-driven emulations.

/pdf/a-control-theoretic-approach-for-dynamic-adaptive-video-1mmix9lrz0.pdf

A Control-Theoretic Approach for Dynamic Adaptive Video Streaming over HTTP

Many commercial video players rely on bitrate adaptation logic to adapt the bitrate in response to changing network conditions. Past measurement studies have identified issues with today's commercial players with respect to three key metrics---efficiency, fairness, and stability---when multiple bitrate-adaptive players share a bottleneck link. Unfortunately, our current understanding of why these effects occur and how they can be mitigated is quite limited.In this paper, we present a principled understanding of bitrate adaptation and analyze several commercial players through the lens of an abstract player model. Through this framework, we identify the root causes of several undesirable interactions that arise as a consequence of overlaying the video bitrate adaptation over HTTP. Building on these insights, we develop a suite of techniques that can systematically guide the tradeoffs between stability, fairness and efficiency and thus lead to a general framework for robust video adaptation. We pick one concrete instance from this design space and show that it significantly outperforms today's commercial players on all three key metrics across a range of experimental scenarios.

/pdf/improving-fairness-efficiency-and-stability-in-http-based-18w53mubp1.pdf

Improving fairness, efficiency, and stability in HTTP-based adaptive video streaming with FESTIVE

Changing network conditions pose severe problems to video streaming in the Internet. HTTP adaptive streaming (HAS) is a technology employed by numerous video services that relieves these issues by adapting the video to the current network conditions. It enables service providers to improve resource utilization and Quality of Experience (QoE) by incorporating information from different layers in order to deliver and adapt a video in its best possible quality. Thereby, it allows taking into account end user device capabilities, available video quality levels, current network conditions, and current server load. For end users, the major benefits of HAS compared to classical HTTP video streaming are reduced interruptions of the video playback and higher bandwidth utilization, which both generally result in a higher QoE. Adaptation is possible by changing the frame rate, resolution, or quantization of the video, which can be done with various adaptation strategies and related client- and server-side actions. The technical development of HAS, existing open standardized solutions, but also proprietary solutions are reviewed in this paper as fundamental to derive the QoE influence factors that emerge as a result of adaptation. The main contribution is a comprehensive survey of QoE related works from human computer interaction and networking domains, which are structured according to the QoE impact of video adaptation. To be more precise, subjective studies that cover QoE aspects of adaptation dimensions and strategies are revisited. As a result, QoE influence factors of HAS and corresponding QoE models are identified, but also open issues and conflicting results are discussed. Furthermore, technical influence factors, which are often ignored in the context of HAS, affect perceptual QoE influence factors and are consequently analyzed. This survey gives the reader an overview of the current state of the art and recent developments. At the same time, it targets networking researchers who develop new solutions for HTTP video streaming or assess video streaming from a user centric point of view. Therefore, this paper is a major step toward truly improving HAS.

A Survey on Quality of Experience of HTTP Adaptive Streaming

Real-time media communication requires not only congestion control, but also minimization of queuing delays to provide interactivity. In this work we consider the case of real-time communication between web browsers (WebRTC) and we focus on the interplay of an end-to-end delay-based congestion control algorithm, i.e. the Google congestion control (GCC), with two delay-based AQM algorithms, namely CoDel and PIE, and two flow queuing schedulers, i.e. SFQ and Fq_Codel. Experimental investigations show that, when only GCC flows are considered, the end-to-end algorithm is able to contain queuing delays without AQMs. Moreover the interplay of GCC flows with PIE or CoDel leads to higher packet losses with respect to the case of a DropTail queue. In the presence of concurrent TCP traffic, PIE and CoDel reduce the queuing delays with respect to DropTail at the cost of increased packet losses. In this scenario flow queuing schedulers offer a better solution.

Controlling queuing delays for real-time communication: the interplay of E2E and AQM algorithms

The use of control‐theoretic solutions to detect attacks against cyber‐physical industrial systems is a growing area of research. Traditional literature proposes the use of control strateg...

/pdf/adaptive-control-theoretic-detection-of-integrity-attacks-cx9afuf5mj.pdf

Adaptive control‐theoretic detection of integrity attacks against cyber‐physical industrial systems

We address detection of attacks against cyber-physical systems. Cyber-physical systems are industrial control systems upgraded with novel computing, communication and interconnection capabilities. In this paper we reexamine the security of a detection scheme proposed by Mo and Sinopoli (2009) and Mo et al. (2015). The approach complements the use of Kalman filters and linear quadratic regulators, by adding an authentication watermark signal for the detection of integrity attacks. We show that the approach only detects cyber adversaries, i.e., attackers with the ability to eavesdrop information from the system, but that do not attempt to acquire any knowledge about the system model itself. The detector fails at covering cyber-physical adversaries, i.e., attackers that, in addition to the capabilities of the cyber adversary, are also able to infer the system model to evade the detection. We discuss an enhanced scheme, based on a multi-watermark authentication signal, that properly detects the two adversary models.

/pdf/revisiting-a-watermark-based-detection-scheme-to-handle-3dp8ee6nmo.pdf

Revisiting a Watermark-Based Detection Scheme to Handle Cyber-Physical Attacks

The optimization of massive video delivery, with the purpose of improving user engagement by delivering the maximum available quality of experience (QoE) to users, is a hot topic In this paper we propose a Network Control Plane (NCP) for video streaming aimed at jointly maximizing users QoE and network utilization by reserving bandwidth on a per-flow basis The NCP is placed on top of the controlled network and cooperates with distributed buffer-based adaptation techniques implemented at the client It is specifically designed to take into account scalability and adaptivity issues No communication with external entities involved in the delivery process, such as other networks or the streaming server, is required We provide a reference implementation and a performance evaluation through simulations

/pdf/a-control-architecture-for-massive-adaptive-video-streaming-1t4yzvk8pi.pdf

A Control Architecture for Massive Adaptive Video Streaming Delivery

The WebRTC initiative has achieved impressive results in terms of the gained industrial interest, the penetration of the technology in end-user devices, and the ever growing community of developers. WebRTC is today supported by major mobile platforms and Internet browsers, allowing potentially billions of users to seamlessly establish real-time communication sessions. Among all the functionalities that must be implemented by WebRTC devices, congestion control is particularly important to ensure that the network operates properly while providing a satisfactory user experience. A working group that is focusing on this issue is the IETF RTP Media Congestion Avoidance Techniques (RMCAT), which aims at defining the requirements and designing congestion control algorithms to be used for the transport of real-time media flows over RTP. This article overviews the status of the standardization efforts that are taking place in the RMCAT working group. We discuss the choices involved in the design of media congestion control, the proposed algorithms, and the issues that are considered still open.

Luca De Cicco

Papers

Controlling queuing delays for real-time communication: the interplay of E2E and AQM algorithms

Adaptive control‐theoretic detection of integrity attacks against cyber‐physical industrial systems

Revisiting a Watermark-Based Detection Scheme to Handle Cyber-Physical Attacks

A Control Architecture for Massive Adaptive Video Streaming Delivery

Congestion Control for WebRTC: Standardization Status and Open Issues