Ognjen Dobrijevic

Application-Level QoS Negotiation and Signaling for Advanced Multimedia Services in the IMS

The IP multimedia subsystem (IMS) has been recognized as a reference next-generation network architecture for offering multimedia services over an Internet Protocol (IP)-based infrastructure. One of the key benefits of the IMS is efficient and flexible introduction of new services and access to third-party application providers, thanks to standard interfaces and standardized service capabilities. To support novel media-rich applications across a wide range of user devices and access networks, IMS must support negotiable quality of service (QoS) for IP multimedia sessions. In this article, we describe the application-level QoS signaling as specified by the 3GPP and propose some enhancements based on advanced QoS parameter matching and optimization functionality to be included along the signaling path. We outline various signaling flow scenarios and discuss them in the context of a case study involving an IMS-supported 3D virtual environment, featuring a treasure-hunt-like game.

MMORPG Player actions: Network performance, session patterns and latency requirements analysis

Providing Massively Multiplayer Online Role-Playing Games (MMORPGs) is a big challenge for future mobile, IP-based networks. Understanding how the players’ actions affect the network parameters, the game platform, and the overall perceived quality is highly relevant for the purposes of game design, as well as for the networking infrastructure and network support for games. We break player actions down into discrete categories, and show that each category is distinct in terms of several key metrics. We discuss which categories of actions could be supported on current mobile devices, and present evidence in form of a user survey demonstrating the demand for such services. The starting points into the discussion include the networking, session and latency requirements for particular player actions on one side, and the players’ interest on the other. The Blizzard Entertainment’s World of Warcraft (WoW) is used as a case study.

Action specific Massive Multiplayer Online Role Playing Games traffic analysis: case study of World of Warcraft

In Massive Multiplayer Online Role Playing Games (MMORPGs) players can perform various actions in the virtual world. We try to answer the question how is generated network traffic, and to what extent, dependent of the action that player performs and overall context/situation in the virtual world. We have divided action types in four major categories: questing, trading, raiding, and player versus player (PvP) combat. We have carried out action-specific measurements of the network traffic for the World of Warcraft (WoW) game and gathered 1.28 GB of data on which the analysis was performed. The traffic analysis included network bandwidth usage, packet payload size, percentage of data packets in the total traffic, packet rate, and packet interarrival and interdeparture times. While the category of PvP combat has highest overall demands on the client side traffic, raiding imposes highest demands on the server side. Trading showed lowest demands on the both sides in almost all categories of the analysis.

Hack, Slash, and Chat: A study of players' behavior and communication in MMORPGs

This paper presents an analysis of player behavior in a Massively Multiplayer Online Role-Playing Game (MMORPG). We examine player behavior in terms of when, how much, and what they do in the virtual world. Player behavior is described through previously defined action categories for MMORPGs (Trading, Questing, Dungeons, Raiding, and Player versus Player (PvP) Combat) with addition of a new category for text and voice communication within a session. We conduct a player survey and perform measurements on the client side for a group of 104 players of a popular MMORPG - World of Warcraft (WoW), and discover that there are significant patterns in player behavior. Additionally we examine the importance of both voice and textual (chat) communication in MMORPGs, and note that communication makes a significant portion of average players playtime and that voice communication is used by a large portion of players. We believe that the results of this study may be used for improving the existing and design of new MMORPGs (e.g., building better load balancing algorithms, addition of content that is more interesting for players) with more emphasis on both old and new communication aspects of the game (e.g., inbuilt voice clients, new ways of connecting the players). This work also serves as a starting point for better insight into networking requirements for such applications, which may be useful for service and network providers.

Ant colony optimization for QoE-centric flow routing in software-defined networks

We present design, implementation, and an evaluation of an ant colony optimization (ACO) approach to flow routing in software-defined networking (SDN) environments. While exploiting a global network view and configuration flexibility provided by SDN, the approach also utilizes quality of experience (QoE) estimation models and seeks to maximize the user QoE for multimedia services. As network metrics (e.g., packet loss) influence QoE for such services differently, based on the service type and its integral media flows, the goal of our ACO-based heuristic algorithm is to calculate QoE-aware paths that conform to traffic demands and network limitations. A Java implementation of the algorithm is integrated into SDN controller OpenDaylight so as to program the path selections. The evaluation results indicate promising QoE improvements of our approach over shortest path routing, as well as low running time.

Open Diameter conformance testing

The diameter base protocol, originally developed by the Internet Engineering Task Force (IETF), provides the authentication, authorization and accounting (AAA) functionality needed for network access and mobility in IP-based networks. Diameter has also been adopted by the Third Generation Partnership Project (3GPP) and other standards bodies as an AAA framework in the IP multimedia subsystem (IMS). With the growing interest in diameter, there is an ongoing effort to develop an open source diameter implementation under the open diameter project (http://www.opendiameter.org/). This paper presents the results of conformance testing of open diameter release 1.0.7-i. We describe the test cases, our laboratory environment and test results, with the goal to provide a neutral evaluation of this implementation to the open diameter community, as well as to potential future diameter application testers and developers.

Towards a Framework for Comparing Application-Network Interaction Mechanisms

Multimedia services, such as HTTP adaptive streaming (HAS) and audio conferencing, hold a dominant share in Internet traffic and are critical to end-user quality of experience (QoE). Since a distributed, application-level adaptation to the available network resources may not result in an optimal and fair QoE among heterogeneous clients, there is the need for a coordinated application-network interaction (App-Net), which includes exchange of monitoring and control information between the involved entities. Numerous App-Net approaches have been proposed, but typically for very specific use cases. A systematic comparison of such solutions, which would identify their pros and cons, as well as potential application scenarios, is missing. Our paper addresses this gap by providing an overview of QoE-centric App-Net mechanisms and deducing an abstract interaction model. In order to evaluate a trade-off between QoE gains and the messaging overhead, we use the latter model to compare two App-Net mechanisms for HAS against a baseline HAS implementation.

Q-POINT: QoE-Driven Path Optimization Model for Multimedia Services

When delivering multimedia services over Internet, different media types are impacted by resource limitations in a different way. While an interactive audio service calls for low-latency communication, video streams should be routed over network paths with sufficient capacity. However, in current networks flows towards the same destination follow the same path, which may lead to a suboptimal resource utilization that effectively penalizes end-users’ quality of experience (QoE). This paper proposes Q-POINT, a QoE-driven path optimization model to fairly maximize aggregated end-user QoE for competing clients’ service flows by calculating the best path for each flow, subject to resource constraints. We formulate the problem as a mixed integer linear program integrating QoE models for audio, video and data transfer. Such an approach can be leveraged within the software-defined networking paradigm, which provides a control plane to orchestrate path set-up. We evaluate our model and illustrate its benefits over shortest path selection.

Towards Evaluating the Quality of Experience of Remote Patient Monitoring Services: A Study Considering Usability Aspects

The applicability of advanced mobile technologies in the m-Health domain has led to a number of studies and (limited) commercial products supporting delivery of health services to remote users. A key issue regarding successful delivery and acceptance of such services is meeting their Quality of Service (QoS) and Quality of Experience (QoE) requirements, focusing on technical aspects and end user perceived quality, respectively. In this paper, the authors address the topic of evaluating QoE for non-emergency remote patient monitoring services. They identify relevant QoE influence factors and metrics, and present the results of a QoE evaluation study, whereby they focus on usability aspects. The study involves 26 users testing a prototype version of the Ericsson Mobile Health service, which is based on a smartphone application and measurement of vital signs via medical sensors. The results show a strong correlation between QoE and: perceived effectiveness of the mobile interface (regarding both adequacy of smartphone screen size and smartphone application navigational support), perceived ease of conducting a blood pressure measurement task, and user motivation for service usage.

On the approximation of ISP and user utilities from quality of experience

While the network quality research has been oscillating between user- and technology-driven viewpoints, the evolution of a utility-centric perspective is still a good way off. Today, not only insufficient data exists on network quality market figures, but also on the users usage appreciation across service types and test ranges. Filling those research gaps, the present work presents a novel model, mainly constructed around existing empirical Quality of Experience (QoE) materials, which approximates both ISP and user utilities. A focus is set on the case of controlled quality and service degradations that intelligently adapt services upon resource shortages. In a case study, this model is applied to the case of Video on Demand services.