Network architecture for large-scale distributed virtual environments

Distributed Virtual Environments (DVEs) provide 3D graphical computer generated environments with stereo sound, supporting real-time collaboration between potentially large numbers of users distributed around the world. Early DVEs has been used over local area networks (LANs). Recently with the Internet's development into the most common embedding for DVEs these distributed applications have been moved towards an exploiting IP networks. This has brought the scalability challenges into the DVEs evolution. The network bandwidth resource is the more limited resource of the DVE system and to improve the DVE's scalability it is necessary to manage carefully this resource. To achieve the saving in the network bandwidth the different types of the network traffic that is produced by the DVEs have to be considered. DVE applications demand· exchange of the data that forms different types of traffic such as a computer data type, video and audio, and a 3D data type to keep the consistency of the application's state. The problem is that the meeting of the QoS requirements of both control and continuous media traffic already have been covered by the existing research. But QoS for transfer of the 3D information has not really been considered. The 3D DVE geometry traffic is very bursty in nature and places a high demands on the network for short intervals of time due to the quite large size of the 3D models and the DVE application requirements to transmit a 3D data as quick as possible. The main motivation in carrying out the work presented in this thesis is to find a solution to improve the scalability of the DVE applications by a consideration the QoS requirements of the 3D DVE geometrical data type. In this work we are investigating the possibility to decrease the network bandwidth utilization by the 3D DVE traffic using the level of detail (LOD) concept and the active networking approach. The background work of the thesis surveys the DVE applications and the scalability requirements of the DVE systems. It also discusses the active networks and multiresolution representation and progressive transmission of the 3D data. The new active networking approach to the transmission of the 3D geometry data within the DVE systems is proposed in this thesis. This approach enhances the currently applied peer-to-peer DVE architecture by adding to the peer-to-peer multicast neny_ork layer filtering of the 3D flows an application level filtering on the active intermediate nodes. The active router keeps the application level information about the placements of users. This information is used by active routers to prune more detailed 3D data flows (higher LODs) in the multicast tree arches that are linked to the distance DVE participants. The exploration of possible benefits of exploiting the proposed active approach through the comparison with the non-active approach is carried out using the simulation­based performance modelling approach. Complex interactions between participants in DVE application and a large number of analyzed variables indicate that flexible simulation is more appropriate than mathematical modelling. To build a test bed will not be feasible. Results from the evaluation demonstrate that the proposed active approach shows potential benefits to the improvement of the DVE's scalability but the degree of improvement depends on the users' movement pattern. Therefore, other active networking methods to support the 3D DVE geometry transmission may also be required

The evaluation of an active networking approach for supporting the QOS requirements of distributed virtual environments

This paper describes work that is part of a more general investigation into how Active Network ideas might benefit large scale Distributed-Virtual-Environments (DVEs). Active Network approaches have been shown to offer improved solutions to the Scalable Reliable Multicast problem, and this is in a sense the lowest level at which Active Networks might benefit DVEs in supporting the peer-to-peer architectures considered most promising for large scale DVEs. To go further than this, the key benefit of Active Networking is the ability to take away from the application the need to understand the network topology and delegate the execution of certain actions, for example intelligent message pruning, to the network itself. The need to exchange geometrical information results in a type of traffic that can place occasional, short-lived, but heavy loads on the network. However, the Level of Detail (LoD) concept provides the potential to reduce this loading in certain circumstances. This paper introduces the performance modelling approach being used to evaluate the effectiveness of active network approaches for supporting DVEs and presents an evaluation of messages filtering mechanisms, which are based on the (LoD) concept. It describes the simulation experiment used to carry out the evaluation, presents its results and discusses plans for future work

A control framework to develop smart grid communications : possible pointers from multiservice network research

This paper addresses the challenge of developing an architecture for the Smart Grid with the particular focus to support Smart Grid communication. It considers the Smart Grid system in general to identify the relationship between the power distribution and communication networks, and then focuses mainly on Smart Grid communication requirements. It observes the similarity between the Quality of Service (QoS) requirements for Smart Grid communications and those identified in multiservice networking. It reviews the principles of open communication and introduces architectures for open communication that have been enhanced to meet the requirements of multiservice. It discusses previous research into multiservice with a review into recent work focused on meeting the multiservice requirements of Smart Grid communications. Based on these, the paper presents key specific pointers toward defining a contextual control framework for the data transport system of the Smart Grid

Evaluation of communication latency for future time-critical smart grid measurement and control systems

This paper focuses on the firm real-time requirements of Time-Critical Wide Area Measurement and Control systems for future Smart Grids. It outlines the findings from the first stage in an ongoing body of work aimed at developing models and techniques that will enable the performance evaluation of these systems to take place prior to their implementation. It then discusses the first phase in the second stage of this project that addresses the problem of evaluation in cases where the output from system's devices is variable. It then presents some preliminary findings and outlines the direction for future work

Network level Quality of Service (QoS) challenges for smart grid measurement and control systems

This paper focuses on the firm real-time requirements of Time-Critical Wide Area Measurement and Control systems, that are expected to play a major role in future Smart Grids. It analyses the operation of these systems and identifies their communication traffic characteristics. It shows that these characteristics are significantly different to those of the current near real-time Wide Area Measurement applications that provide visualization to support manual grid control. It then discusses the performance evaluation of these time critical systems and presents the second stage in an ongoing body of work aimed at developing models and techniques to carry out the performance evaluation process. It presents some preliminary results and outlines the direction for future work