QoE-centric management of advanced multimedia services

Over the last years, multimedia content has become more prominent than ever. Particularly, video streaming is responsible for more than a half of the total global bandwidth consumption on the Internet. As the original Internet was not designed to deliver such real-time, bandwidth-consuming applications, a serious challenge is posed on how to efficiently provide the best service to the users. This requires a shift in the classical approach used to deliver multimedia content, from a pure Quality of Service (QoS) to a full Quality of Experience (QoE) perspective. While QoS parameters are mainly related to low-level network aspects, the QoE reflects how the end-users perceive a particular multimedia service. As the relationship between QoS parameters and QoE is far from linear, a classical QoS-centric delivery is not able to fully optimize the quality as perceived by the users. This paper provides an overview of the main challenges this PhD aims to tackle in the field of end-to-end QoE optimization of video streaming services and, more precisely, of HTTP Adaptive Streaming (HAS) solutions, which are quickly becoming the de facto standard for video delivery over the Internet

Applicability of group communication for increased scalability in MMOGs

Massive multiplayer online games (MMOGs) are today the driving factor for the development of distributed interactive applications, and they are increasing in size and complex-ity. Even a small MMOG supports thousands of players, the biggest support hundreds of thousands of concurrent players. Since they are typically built as strict client-server systems, they suffer from the inherent scalability problem of the architecture. Computing power and bandwidth limita-tions close to the server limit the possible number of players. Also, the latency of communication between players through the server will be higher than using direct communication. In the paper, we address these issues and investigate im-provement options. A typical MMOG consists of a virtual world with a con-cept of time and space that is similar to the real world. In it, players are represented by avatars. Only subsets of these avatars interact with each other at any given time. This allows us to divide them into groups, and communication among group members becomes a multi-party communica-tion problem. Thus, to reduce resource consumption, we compare the performance of several algorithms for group communication with the current central server approach. We use overlay multicast as the means of providing group communication, and research algorithms for creating short-est path trees, spanning trees, delay-bounded spanning trees and, more specific, applying Steiner tree heuristics. Our experimental results indicate that different approaches are useful to reduce resource consumption while achieving a good perceived quality under varying conditions, such as frequent changes in group membership and the demand for low latency. 1

Latency and player actions in online games

The growth and penetration of broadband access networks to the home has fueled the growth of online games played over the Internet. As we write this article, it is 5am on a typical weekday morning and Gamespy Arcade 1 reports more than 250,000 players online playing about 75,000 games! This proliferation of online games has been matched by an equivalent growth in both th

Multicast QoS Routing Using Collaborative Path Exploration

Quality of Service (QoS) is one of the most active research areas in networking. The most fundamental requirement for QoS routing is the ability to find and maintain a network path that provides the required network resources between two or more nodes. In this paper, we present a distributed collaborative multicast QoS routing architecture that uses a semi-greedy probing heuristic to quickly find a QoS path between a joining node and the multicast tree. The proposed architecture will enable the routers along the path to intelligently and dynamically discover a QoS path. Any router that receives a probe will only know its neighbours and it will create a link to the previous router from where the probe comes from. The proposed architecture is a tree-initiated QoS search and the first QoS packet to reach the joining node will be used as the QoS path. Analysis of this method shows that the path search time and message overhead is lower than other similar schemes

An approach to implementing dynamic adaptation in c

This paper describes TRAP/C++, a software tool that enables new adaptable behavior to be added to existing C++ programs in a transparent fashion. In previous investigations, we used an aspectoriented approach to manually define aspects for adaptation infrastructure, which were woven into the original application code at compile time. In follow-on work, we developed TRAP, a transparent shaping technique for automatically generating adaptation aspects, where TRAP/J is a specific instantiation of TRAP. This paper presents our work into building TRAP/C++, which was intended to be a port of TRAP/J into C++. Designing TRAP/C++ required us to overcome two major hurdles: lack of reflection in C++ and the incompatibility between the management of objects in C++ and the aspect weaving technique used in TRAP/J. We used generative programming methods to produce two tools, TrapGen and TrapCC, that work together to produce the desired TRAP/C++ functionality. Details of the TRAP/C++ architecture and operation are presented, which we illustrate with a description of a case study that adds dynamic auditing capabilities to an existing distributed C++ application

Investigating the Network Characteristics of Two Popular Web-Based Video Streaming Sites

The determinants of the strategies to be employed by video streaming sites are application (mobile devices or web browsers) and container of the video application. They affect video streaming network characteristics, which is often the traffic flow, and its quality. It is against this background that studies on streaming strategies suggested the need to investigate and identify the relationship between buffer time, video stream protocol, packet speed and size, upload time, and waiting period, specifically to aid network administrative support in case of network traffic bottlenecks. In view of this, this study investigates the network characteristics of YouTube and Vimeo, using experimental methodology, and involving WireShark as network analyzer. Google Chrome and Firefox are the web browsers employed, while packet size, protocols, packet interval, TCP window size and accumulation ratio are the metrics. Short ON-OFF, Long ON-OFF, and No ON-OFF cycles are the three streaming strategies identified. It is further shown that both Vimeo and YouTube employ these strategies but the choice depends on the container of the video streamed