Lien Deboosere

A hybrid thin-client protocol for multimedia streaming and interactive gaming applications

Despite the growing popularity and advantages of thin-client systems, they still have some important shortcomings. Current thin-client systems are ideally suited to be used with classic office-applications but as soon as multimedia and 3D gaming applications are used they require a large amount of bandwidth and processing power. Furthermore, most of these applications heavily rely on the Graphical Processing Unit (GPU). Due to the architectural design of thin-client systems, they cannot profit from the GPU resulting in slow performance and bad image quality. In this paper, we propose a thin-client system which addresses these problems: we introduce a realtime desktopstreamer using a videocodec to stream the graphical output of applications after GPU-processing to a thin-client device, capable of decoding a videostream. We compare this approach to a number of popular classic thin-client systems in terms of bandwidth, delay and image quality. The outcome is an architecture for a hybrid protocol, which can dynamically switch between a classic thin-client protocol and realtime desktopstreaming.

Design and implementation of a hybrid remote display protocol to optimize multimedia experience on thin client devices

In a thin client computing architecture, application processing is delegated to a remote server rather than running the application locally. User input is forwarded to the server, and the rendered images are relayed through a dedicated remote display protocol to the users device. Existing remote display protocols have been successfully optimized for applications with only minor and low-frequent screen updates, such as a spreadsheet or a text editor. However, they are not designed to cope with the fine-grained and complex color patterns of multimedia applications, leading to high bandwidth requirements and an irresponsive user interface. In this article, a hybrid remote display protocol approach is presented. The existing Remote FrameBuffer protocol of Virtual Network Computing (VNC-RFB) protocol is leveraged with a video streaming mode to transport the rendered images of multimedia applications to the client. Dependent on the amount of motion in the images to be presented, the images are relayed to the client either through the VNC-RFB protocol or through video streaming in the H.264 format. The architecture of this hybrid image renderer is presented and the implementation is detailed. Furthermore, the decision heuristic to switch between the VNC-RFB and the streaming mode is discussed. Experimental results clearly show the advantage of the hybrid approach in terms of client CPU and bandwidth requirements.

Cloud-Based Desktop Services for Thin Clients

Cloud computing and ubiquitous network availability have renewed peoples interest in the thin client concept. By executing applications in virtual desktops on cloud servers, users can access any application from any location with any device. For this to be a successful alternative to traditional offline applications, however, researchers must overcome important challenges. The thin client protocol must display audiovisual output fluidly, and the server executing the virtual desktop should have sufficient resources and ideally be close to the users current location to limit network delay. From a service provider viewpoint, cost reduction is also an important issue.

Efficient resource management for virtual desktop cloud computing

In virtual desktop cloud computing, user applications are executed in virtual desktops on remote servers. This offers great advantages in terms of usability and resource utilization; however, handling a large amount of clients in the most efficient manner poses important challenges. Especially deciding how many clients to handle on one server, and where to execute the user applications at each time is important. Assigning too many users to one server leads to customer dissatisfaction, while assigning too little leads to higher investments costs. We study different aspects to optimize the resource usage and customer satisfaction. The results of the paper indicate that the resource utilization can increase with 29% by applying the proposed optimizations. Up to 36.6% energy can be saved when the size of the online server pool is adapted to the system load by putting redundant hosts into sleep mode.

Thin Client Computing Solutions in Low- and High-Motion Scenarios

The centralized thin client computing environment offers a solution to the vulnerability of desktops to viruses, trojan horses and worms. It also releases the user from regular software and hardware updates. One of the major barriers for the proliferation of thin clients in public wide-area networks is the hampering presentation of multimedia applications. While the existing remote display protocols offer a good user experience for office applications, most protocols cannot deal with swift display updates, like video playback, or hardware-accelerated 3D-graphics as in games. In this paper, a wide range of well-known and widely used thin client protocols are tested in both low-motion and high-motion scenarios. It is shown that additional functionality is required to offer a satisfying multimedia experience.

Power efficiency of thin clients

Worldwide, awareness for energy consumption is rising because of global energy production limits as well as because of environmental concerns. As the energy fraction currently consumed by ICT-related equipment is substantial (about 8 per cent of electricity consumption worldwide in the use phase) and the growth rate in this particular sector is spectacular, in the ICT sector, adequate solutions are needed to allow sustainable growth. In this paper we aim at reducing power consumption of desktop applications by applying a thin client approach and we analyse the conditions necessary. To this end, estimates on power consumptions in typical desktop scenarios and analogous thin client settings are made and analysed. The paper concludes with an experimental study on currently available equipment, to translate the generic conclusions into their current implications and trade-offs. Copyright

Bandwidth Optimization for Mobile Thin Client Computing through Graphical Update Caching

This paper presents graphical update caching as a mechanism to reduce the network load generated by thin client computing systems. In such system, the user interaction and processing are separated by a network. User input such as keystrokes and mouse clicks are sent to the server over the network and graphical updates are transported the reverse way. The cache proposed in this article is static, meaning that it is composed before the thin client computing session starts and that the cache does not change during the session. Through experiments with an implementation of the cache, we show that graphical update caching effectively reduces the network load generated by thin client computing.

Cross-Layer Optimization of Radio Sleep Intervals to Increase Thin Client Energy Efficiency

Thin client computing trades local processing for network bandwidth consumption by offloading application logic to remote servers. User input and display updates are exchanged between client and server through a thin client protocol. This thin client protocol traffic can lead to a significantly higher power consumption of the radio interface of the wireless device. In this contribution, we present a cross-layer algorithm that exploits thin client protocol layer information to determine intervals where no traffic from the server is expected. During these intervals, the wireless network interface card (WNIC) is instructed to enter the energy conserving sleep mode. Using this algorithm for a remote text editor, WNIC energy consumption reductions of 21-52% can be achieved.

Optimization models for application migration to support mobile thin clients

Thin clients are lightweight devices from which all hardware, not related to input and output, is removed. Applications are executed on remote servers that render the graphical output and send it back to the client. As the reaction on user events can appear on the screen only after a two-way path delay, thin client computing can suffer from a high latency that degrades the user experience. We therefore propose that the application follows the user through the network by migrating to a server near enough to the user. In this paper, a theoretical model and heuristics are presented to efficiently select servers for mobile users, in order to minimize the number of migrations and the corresponding application downtime. A sample scenario is presented, which clearly exposes the trade-off between the number of migrations and the average client-server latency. We then detail a theoretical model to determine the optimal allocation of applications to servers, in order to minimize the number of handovers. This model is based on the knowledge of the exact user movements and is only useful in an off-line setting. As this is impossible in real-time, several heuristics are presented. Their performance is compared and validated against the theoretical model.

Characterization of power consumption in thin clients due to protocol data transmission over IEEE 802.11

In thin client computing, applications are executed on a network server instead of on the user terminal. Since the amount of processing at the terminal is reduced, thin clients are potentially energy efficient devices. However, a network connection between client and server is required for the transmission of user input and display updates. The energy needed for this intense network communication might undo or even exceed the power savings achieved by the reduction in client-side processing. In this paper, we present experimental results on power efficiency of the wireless platform on the thin client in case of thin client traffic. The discussion is focused on VNC-RFB, a widespread thin client protocol, over an IEEE 802.11 link in three typical user scenarios. The results indicate that a cross-layer approach between application and wireless link layer could potentially lead to important power savings.