A Web Based Virtual Community: Functionality and Architecture Issues

A Web Based Virtual Community is an example of a Collaborative Virtual Environment, which focalizes in providing collaborative functionalities and both synchronous and asynchronous interaction services. This paper describes a virtual community, which aims to meet the requirements of a virtual collaboration space and support autonomous and collaborative e-learning services. In particular, a web-based platform is described, which is able to support communities whose members are able to interact and form groups based on their common interests. The community provides its members with the ability to communicate through enhanced forums and chats, but also, to interact in the social interaction spaces. The users can arrange events, which occur in virtual meeting centers, where 3D avatars represent the users. In these multi-user spaces, extended functionalities are offered, while system agents assist and consult the users

A Web-Based Virtual Community

This paper describes functionality and architectural issues in the design of a web-based virtual community. This virtual community aims to meet the requirements of a virtual collaboration system with both autonomous and collaborative e-learning services, by supporting communities whose members interact and form groups based on their common interests

Scalable rate control for video transmission over UMTS

This paper proposes a mechanism for the congestion control for video transmission over Universal Mobile Telecommunications System (UMTS). Our scheme is applied when the mobile user experiences real time multimedia content and adopts the theory of a widely accepted rate control method in wired networks, namely equation-based rate control. In this approach, the transmission rate of the multimedia data is determined as a function of the packet loss rate, the round trip time and the packet size and the server explicitly adjusts its sending rate as a function of these parameters. Through a number of simulations and experiments we validate the correctness and measure the performance and efficiency of the mechanism. A first level of evaluation is carried out using the ns-2 simulator. A second level then validates the proposed mechanism in real world traffic scenarios by performing experiments in a commercial UMTS network

Performance Evaluation of TCP over UMTS Transport Channels

Universal Mobile Telecommunications System (UMTS) is a third-generation cellular network that enables high-speed wireless Internet access. It can provide maximum data-rates ranging from 64kb/s to 2Mb/s in different environmental types. UMTS is designed to provide access to the existing Internet services as well as to UMTS specific services. It will augment the existing capabilities of 2G mobile networks and GPRS, and one often envisaged strategy is to offer a richer set of multimedia services. It is widely known that TCP does not perform efficiently in wireless links where the bit error rate is high enough. This paper has as main target to evaluate the performance of TCP data transfer over the UMTS air interface, by means of a rather detailed simulation model. We examine the performance of TCP over UMTS Dedicated Channels (DCHs) with different bit rates and Transmission Time Intervals (TTIs) and we represent some simulation experiments for UMT

MULTIMEDIA TRANSMISSION OVER THIRD GENERATION CELLULAR NETWORKS

The scheme of real time streaming video is one of the newcomers in wireless data communication, raising a number of new requirements in both telecommunication and data communication systems. This scheme applies when the user is experiencing real time multimedia content. This paper has as main target to study the performance of video transmission over the third generation cellular networks. In particular, we examine the performance of UMTS Dedicated Channels (DCHs) for real time MPEG-4 video transmission in Downlink direction. Finally, we examine if real time video transmission in conjunction with Internet traffic is applicable in UMTS radio interface. 1

2005), “Deployment of Broadband Infrastructure in the Region of Western Greece”, Paper presented at 2nd IEEE/Great e-net International workshop on Deployment models and first/last mile Networking

Abstract—This paper presents the work that is taking place in the Region of Western Greece in order to develop state-of-theart broadband infrastructure. The current status of broadband infrastructure in the region is being analyzed and the main principles on which the deployment of the networks will be based on is being described, by presenting the Metropolitan Area Networks and the Wireless access networks that will be developed. Two case studies of such municipal networks are also presented in this paper. Broadband infrastructure, fiber optics, municipal networks, wireless access netrwork I

Performance Evaluation of UMTS for Mobile Internet Access

UMTS constitutes the third generation of cellular wireless networks which aims to provide high-speed data access along with real time voice calls (Holma & Toskala, 2001). Wireless data is one of the major boosters of wireles

A Web-Based Game For Supporting Game-Based Learning

Game-based learning has been recognized as an important alternative or supplement to traditional in-class, face-to-face teaching. It can help both adults and children in learning new concepts, acquiring expertise and practicing knowledge. Although game-based learning has been applied mainly for teaching children, it can be quite helpful for adult vocational or university learning. In this paper, a web-based game is presented, which has been developed for enhancing the learning experience of university students. Its goal is to serve as a complement to classes, although it can be used independently. It provides the students with many ways for communicating (synchronously or asynchronously) and acquiring information. Through the use of the game, the students gain easily new knowledge, since they have to search for it, understand it and use it in discussions with other students, who are members of other teams. The game is played by many users simultaneously. Microsoft's ASP.NET scripting environment was used for creating the game's website. The website utilizes also Macromedia's communication technology (Flash Communication Server MX) for enabling real-time communication by several means (voice, text, etc). Flash was used in the website for building the real-time communication modules as well as for creating a more elegant user interface. The game platform can be used by many teachers simultaneously for running different game themes. It also gives the opportunity to visitors to watch games as spectators