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Distributed, highly coordinated activities for learning are becoming more and more important as we move further into the world of pervasive mobile computing. These activities can be explored and developed using GroupScribbles, a system to allow the easy creation and exchange of shared information. However, to have confidence in the efficacy of shared activities for learning at scale, we need to be able to model the relationship between the rules and tasks as communicated to the group, and individual behaviour and experience. Trace Theory is a formal modelling language that allows us to do this. We show how Trace Theory and GroupScribbles can be used to model and test different ways a jigsaw pattern of engagement can be implemented, with implications both for the design of emergent pervasive technologies and for acute thought about coordination and collaborative learning.

In this paper we explain the design of t-Frame, a hardware/software architecture that allows the implementation of multiuser interactive wall. t-Frame brings multi-touch sensing to a generic display by means of low cost digital video cameras. The design of t-Frame is illustrated in detail, together with a prototype installation. We show how t-Frame differs from other approaches and discuss our findings, together with a plan of future research and improvements.

This paper proposes the design of virtual teaching environments using the combination of VRML, Java and JavaScript languages for the construction of highly interactive and immersive 3D worlds, whose behaviour is real-time modified by users actions. A number of users involved in the animations are present in the classroom (their presence is captured by a camera or other kind of sensors) and for the rest they are remote internet students. In both cases they are represented within a VRML world as avatars into a virtual classroom designed to be available in an immersive way by everybody. They interact with each other through a Java program that is able to process and generate events determining the behaviour of scene elements. In particular, Java application establishes the communication among users and VRML environment and updates parameters stored in a MySQL database. The database, resident into the server, is necessary to share information among the clients and to guarantee real time changes in the virtual representation.

Game users can behave co-operatively or competitively. An experiment was performed to test the hypothesis that a shared social space (SSS) with continuous and ‘rich’ communication possibilities leads to an increase in forming coalitions. The DOOM game provides a test environment. Two samples of 12 players each were tested playing DOOM: one with the SSS conditions (continuous communication mode, small physical distance among players) and another under the condition of separation during the game (discontinuous communication mode, large physical distance). During a break all players had have the chance to discuss the outcome of the first trial (group process feedback). The SSS conditions led to a significantly increased amount of coalitions between players. Group process feedback also had a positive effect on the extent of coalitions among players. Finally, design recommendations for networked multi-user games are provided.

In this paper, a novel multi-antenna and multi-user system concept featuring combined application of joint detection and OFDM is introduced. To the well known advantages of OFDM as far as high bit rate communications are concerned, the elimination of multiple access interference offered by joint detection is added, rendering the proposed system highly suitable for beyond 3G communication systems. The air interface is described, and the transmission and detection models are derived. Moreover, some first results are presented, demonstrating the system performance in comparison to a reference detection case.

Recently, researches for wireless ATM system are the progress effectively in order to extend broadband communication network to wireless area. In wireless ATM environment, the multimedia multi-user communication applications such as multimedia conferences will be requested a lot in the future, and it requests more complex communication service than an unique media point to point communication. In this paper, in order to implement the multimedia multi-user communication service in wireless ATM system environment, we introduce a multi-point communication method that is effective for using network resources, easy to guarantee Quality of Service (QoS), and effective to prepare for the changes those are caused by handover in the communication environment. Furthermore, this paper introduces an algorithm to find an anchor switch quickly and easily and effective for use of the network resources. The anchor switch controls multipoint communication services in this method. And, this paper also analyzes the effect of QoS for the multi-point communication method.

Based on a fifteen month investigation of post production facilities for both the entertainment and broadcast industries, we identified a number of challenges that arise when designing a server in support of multiple editing stations. These include how to: share the same content among multiple editors; support continuous display of the edited content for each editor; support complex editing operations; compute the set of changes (deltas) proposed by an editor; and to compare the deltas proposed by multiple editors. It is beyond the focus of this paper to report on each challenge and its related solutions. Instead, we focus on one challenge and the physical design of the system that addresses this issue.

We present a novel algorithm for paging multiple mobile users in cellular networks, the Round-Robin with Adaptive Multiplicity Paging (RAMP) policy. RAMP seeks to increase the number of paging requests (PRs) successfully served without incurring high delays. RAMP adjusts adaptively the paging multiplicity such that in low backlogs a request is paged in several cells simultaneously decreasing the location discovery delay, while in high backlogs the request is only paged in a few or one cells at a time, increasing the mobile discovery rate. Unlike paging policies proposed in the past, the mobile location distribution is not necessary for the implementation of RAMP, while the achievable throughput is higher. Analytic results for the achievable throughput are provided and evaluation of the delay characteristics are shown through simulations. Furthermore it is shown that the proposed policy is independent of the cell ordering in which paging is performed. The location distribution vector that provides maximum throughput for this policy is also identified. The proposed policy is of very low computational complexity and is fully compatible with existing registration schemes.

This paper focuses on the application control functionality required for future interactive multi-user, multimedia applications. Accordingly a new service control reference model is described which is part of a more general Multimedia Reference Model. This service control reference model introduces application building blocks that facilitate application creation and management in all kinds of multi-user, multi-point and multi-channel environments in interactive video and other multimedia broadband networks. The Multimedia Reference Model is derived by applying the conceptual modelling technique standardized for Intelligent Networks by ITU-T. Based on the service control reference model, a distributed functional architecture is developed which contains — among others — the functionality for application control, session management, and security handling. The functional design of the architecture enables it to be mapped in various ways onto the physical network components, for example, in a set-top box/video server configuration. The new Multimedia Reference Model is applied to an interactive multi-user video games environment.

We describe how WorldNet, a software toolkit for networked virtual worlds, solves the problem of scaling up to support large numbers of simultaneous virtual world users. The two key ideas behind our approach are to partition virtual world users into groups and to use Group Dead-Reckoning technique. These two techniques combined together reduce the total network bandwidth required as well as the computation power required at the virtual world client to retrieve and process network messages.

A novel and efficient adaptive implementation of the multi-user decorrelating detector for the uplink in a CDMA mobile communications system is presented. Further, decision feedback is incorporated into this structure to yield a detector with improved performance. Receiver performance evaluation is conducted for some multi-user scenarios to substantiate the potential of this structure for real-time operation.