Oliver Wellnitz

A mobile gaming platform for the IMS

Mobile devices offer the opportunity to play games nearly everywhere. Moreover, networked games allow individual players to interact with other people and to participate in a larger gaming world, which also provides for new business opportunities. Hence, we currently see an increased interest from game developers, providers and players in mobile games. In this paper we propose a novel architecture and platform for games on the IMS. This allows games to utilize the features and capabilities that are inherent to the IMS. At the same time existing games can be flexibly adapted to this new type of network and have the possibility to reserve network resources for game data transmission, thus improving the experience of players.

Real-time service provisioning for mobile and wireless networks

As mobile devices and wireless networks are becoming ubiquitous, the interest of users to deploy real-time applications, e.g. online gaming or Voice-over-IP in such environments is also increasing. Due to the difference between traditional and wireless networks, in particular in terms of available bandwidth and network structure, the concepts used for supporting real-time applications in both networks are different. This paper gives an overview of the key technical challenges that are fundamental and need to be solved in order to easily support real-time applications in wireless and mobile environments. In a first step, issues related to service provisioning in mobile networks are discussed. This is followed by a look at the Quality of Service supported by wireless networks and possible techniques for improving it. Finally, concepts for securing the communication between the users of real-time applications in wireless and mobile networks are presented. For each of these issues, we provide a detailed analysis and an overview of the state-of-the-art. Moreover, we illustrate the main points using distributed online games as an example.

QoS Extensions to Mobile Ad Hoc Routing Supporting Real-Time Applications

The increasing number and diversity of wireless mobile devices are driving a revolutionary change in the way users are accessing and using services and resources. Mobile ad hoc networks (MANETs), temporarily created by mobile devices, offer opportunities for sharing services and resources made available by member nodes. Especially, real-time applications have great potentials in mobile ad hoc environments as MANETs form an ideal technological basis for ad hoc real-time interaction among people. However, real-time applications require low latency connections with a minimum of jitter and packet loss rate from the underlying network. To meet these demands is a challenging task in mobile ad hoc networks due to the high level of node mobility, properties of the wireless communication channel and the lack of central administration. In this paper, via a simulation study we analyze and evaluate some Quality of Service (QoS) extensions, like priority queuing or rate control policies, to ad hoc routing in IEEE 802.11 wireless mobile ad hoc networks from the aspects of real-time applications. We show how these QoS extensions can improve the performance of AODV routing protocol and why we selected AODV as the starting point of our work.

Performance Control in Wireless Sensor Networks

Most of the currently deployed wireless sensor networks applications do not require performance control. The goal of the GINSENG project is sensor networks that meet application-specific performance targets, in particular with respect to latency and reliability. We present scenarios within the GALP oil reÂ?nery where the system will be deployed and some initial technical insights with respect to deterministic communication.

Networked mobile gaming for 3G-networks

Mobile devices offer the opportunity to play games nearly everywhere. Moreover, networked games allow individual players to interact with other people and to participate in a larger gaming world, which also provides for new business opportunities. Hence, we currently see an increased interest from game developers, providers and players in mobile games. However, due to the inherent nature of wireless networks, many challenges have to be addressed. 3G technology combines two of the world’s most powerful innovations, wireless communications and the Internet. This paper proposes an architecture for multiplayer games in 3G networks. It uses the capabilities and functionality provided by the IP Multimedia Subsystem (IMS). A prototype implementation demonstrates the feasibility of our approach.

QoS-AODV6E: An energy-balancing QoS routing scheme for WSNs

Wireless Sensor Networks (WSN) now advance into areas where new scenarios and applications require WSNs to meet certain Quality of Service (QoS) requirements. To tackle these challenges, a routing approach has to consider limited energy supply of sensor nodes, dynamic network conditions as well as node mobility. This paper presents QoS-AODV6E, a routing scheme based on the Ad-hoc On-Demand Distance Vector (AODV) routing protocol, which encompasses QoS and Energy-Awareness for mobile WSNs. Based on the reactive AODV routing protocol, QoS-AODV6E allows applications to specify QoS parameters and finds suitable routes that support their requirements. In order to prolong the lifetime of the network, QoS-AODV6E balances the energy consumption between different paths through the network based on the weakest node. We evaluate our implementation of QoS-AODV6E in Contiki using simulation and measurements.

Assigning game server roles in mobile ad-hoc networks

Over the last couple of years, multi-player games have become more and more popular. Additionally, new mobile devices now have sufficient resources to play these multi-player games in mobile and wireless networks. As the classic centralised game server design is unsuited for mobile ad-hoc networks, a group of nodes can take the role of a distributed game server. This group of nodes can provide the necessary redundancy which is needed in the dynamic environment of a mobile ad-hoc network. In this paper we present a modified dominating set algorithm for server selection which uses local information to determine well-suited nodes from the group of players. Our algorithm uses three phases (discovery, determination and marking) to calculate an initial server set and adjusts to network changes during the game. We implemented our server selection algorithm in NS-2 and evaluated its behaviour in two different realistic scenarios for mobile games (schoolyard and train) as well as in an artificial stress scenario.

Bringing AgentX Subagents to the Operating System Kernel Space

SNMP agents on conventional operating system platforms are mostly monolithic and implement Managed Objects in a single program. The concept of subagents makes it possible to delegate the implementation of Managed Objects to several subagents located close to the managed subsystems. All subagents are managed by a master agent. While this concept is well accepted for hardware subsystems of modular devices and for host services running in the user space, it is not yet applied for components of conventional operating systems.