Multimedia broadcast multicast service (MBMS) with inherently low requirement for network resources has been proposed as a candidate solution for using such resources in a more efficient manner. On the other hand, the Next Generation Mobile Network (NGMN) combines multiple radio access technologies (RATs) to optimize overall network performance. Handover performance is becoming a vital indicator of the quality experience of mobile user equipment (UE). In contrast to the conventional vertical handover issue, the problem we are facing is how to seamlessly transmit broadcast/multicast sessions among heterogeneous networks. In this paper, we propose a new network entity, media independent broadcast multicast service center (MIBM-SC), to provide seamless handover for broadcast/multicast sessions over heterogeneous networks, by extensions and enhancements of MBMS and media independent information service (MIIS) architectures. Additionally, a network selection scheme and a cell transmission mode selection scheme are proposed for selecting the best target network and best transmission mode. Both schemes are based on a load-aware network capacity estimation algorithm. Simulation results show that the proposed approach has the capability to provide MBMS over heterogeneous networks, with improved handover performance in terms of packet loss rate, throughput, handover delay, cell load, bandwidth usage, and the peak signal-to-noise ratio (PSNR).

This paper investigates the impact of multiple BER requirements on resource allocation for orthogonal frequency division multiple access (OFDMA) downlink systems. Max-total capacity (MTC) and proportional fairness (PF) problems are considered. With the goal of maximizing either the instantaneous or long-term network capacity, we propose BER-driven resource allocation (BRA) schemes which exploit both channel state information (CSI) and target BER of each traffic flow. Simulations results show that the average spectral efficiency of the BRA-like schemes is superior to that of the conventional schemes which only consider one BER constraint and thus the chosen BER constraint has to be the strictest one out of multiple BER requirements. The performance gap between these schemes increases when the average signal-to-ratio (SNR) increases. Besides that, the average spectral efficiency increases when the target BER ratio of one user to the other users increases. In other words, our proposed methods enhance wireless resource utilization.

We tackle the problem of video multicast over mobile ad hoc networks in this paper using multiple trees multicast routing protocol. More specifically, we propose an extension to the Multicast Ad Hoc On-Demand Distance Vector (MAODV) to construct two highly-disjoint trees in a single routine; we called it Multiple-Tree Multicast Ad Hoc On-Demand Distance Vector (MT-MAODV) routing protocol. By using Multiple Description Coding (MDC) scheme for video coding, the video is divided into two independent sub-streams and is transmitted separately along these trees. This technique is believed to improve the overall quality for best-effort video. Preliminary simulation shows that the proposed MT- MAODV routing protocol provides better video quality as compared to the conventional video multicast using single tree.

Supporting video applications over infrastructureless mobile ad hoc networks is more challenging than over any other networks due to the absence of fixed infrastructure and rapid changes in network topology. In this paper, we tackle this problem by adopting the concept of multipoint-to-point (M2P) video transmission together with multiple description coding (MDC) scheme. Some modifications have been introduced considering the differences between wired and wireless networks and the dynamic source routing (DSR) protocol is extended accordingly to support M2P video transmission. Simulation study is carried out using NS-2 to demonstrate the performance of the proposed mechanism as compared to point-to-point transmission and the original dynamic source routing protocol. We show that the proposed mechanism outperforms the conventional point-to-point transmission, especially at high mobility

In this paper, we are studying the capacity dimensioning of virtual private networks (VPN) access-links for elastic traffic, such as the Web or ftp. Under the assumption that the core-VPN network is provisioned with sufficient large capacity, the capacity management of the VPN access link is a matter of bandwidth-sharing for elastic traffic of the two bottleneck links, the ingress and egress access links, the processor -sharing model gives a simple formulae of mean transfer time, but in our case, the value may be less than the actual transfer time. In contrast, max-min fair sharing provides an accurate sharing model which is similar to the TCP, but it is difficult to obtain a closed form of performance statistics. We propose a closed form approximation for a max-min fair sharing model, in a specific but realistic topology, by investigating the difference between the max-min and the processor sharing model. Using the approximation, we are performing the capacity dimensioning of VPN access links.

In this demonstration, we present IP network designer: interfaces for IP network simulation. The IP network designer consists of two subsystems: the IP network design workbench and a 3D simulator. IP network design workbench is intended to support a collaborative design and simulation of an IP network by a group of network designers and their customers. This system is based on a tangible user interface platform called "sensetable" and allows users to directly manipulate network topologies. Users can control parameters of nodes and links using physical pucks on the sensing table and simultaneously see the simulation results projected onto the table. 3D simulator provides a 3D view of simulation results. Users can see traffic packets flow as if they are inside the network. This system allows users to understand network behavior intuitively.

A mechanism is proposed for managing distributed applications (DAPs) in environment having multiple object request brokers (ORBs). The mechanism ensures the normal-state functioning of DAPs composed of servers. It facilitates DAP management including fault, performance, and configuration management throughout the DAP lifecycle. The mechanism includes three kinds of key components. The first is a domain manager which is responsible for fault and configuration management of DAPs. The second is a server manager, which is responsible for fault and configuration management for servers that make up DAPs. The third is a monitor that manages the performance and normal/abnormal state of servers. The common interface for monitors functioning on different kinds of DAP platforms facilitates managing DAPs over multiple ORBs. The prototype of the proposed mechanism functions properly and performs well when used with a CORBA-2.0-compliant ORE.

Undoubtedly, users' requirements and engineering constraints will influence the future information environment. The authors have started a project named CUE (Coordinating Users' requirements and Engineering constraints). The project uses an efficient ultra-multiprocessing capability with overload tolerance and maintainability/expandability, incorporating run-time reconfiguration as essential requirements to realize distributed networking systems such as TINA, which is aimed at the interoperability, reusability and transparency of application software. To satisfy these requirements from engineering viewpoints, the CUE project proposes applying to the network systems an autonomous decentralized data-driven processor which adopts an autonomous execution control scheme in which data packets passing through the pipeline achieve all data transfer, processing and storing/buffering functions in a completely decentralized manner. The processor can therefore perform high flow-rate multimedia streams with considerable flow fluctuations and act as a functional module flexibly adding to/removing from the system at run-time without any overheads. The essential requirements to realize a distributed networking environment such as TINA are first discussed. The applicability of our data-driven processor is shown through actual performance evaluations by the latest VLSI systems. An autonomous run-time reconfiguration scheme in a multiprocessor system is proposed to demonstrate the potential of the data-driven processor. Finally, the current status and future directions of the CUE project are briefly addressed.

If a service extends over multiple networks, network operators of these networks should be able to negotiate service provision and contract establishment with each other. We have developed a support environment allowing such negotiation for a target service of network management of an ATM virtual path network. Network resource information of each network is protected against other network operators' tampering by classifying it according to the level of access permission. User friendly graphical objects in this environment facilitate the use of underlying management functions to manipulate the networks. A videoconferencing system is attached to the environment to help interaction among the operators. With all these features, this environment enables network providers to cooperate with each other to set up VP trails in quick response to customer's demands.

We describe the evolution of the novel shared drawing medium ClearBoard which was designed to seamlessly integrate an interpersonal space and a shared workspace. ClearBoard permits coworkers in two locations to draw with color markers or with electronic pens and software tools while maintaining direct eye contact and the ability to employ natural gestures. The ClearBoard design is based on the key metaphor of “talking through and drawing on a transparent glass window.” We describe the evolution from ClearBoard-1 (which enables shared video drawing) to ClearBoard-2 (which incorporates TeamPaint, a multiuser paint editor). Initial observations and findings gained through the experimental use of the prototype, including the feature of “gaze awareness,” are discussed. Further experiments are conducted with ClearBoard-0 (a simple mockup), ClearBoard-1, and an actual desktop as a control. In the settings we examined, the ClearBoard environment led to more eye contact and potential awareness of collaborator's gaze direction over the traditional desktop environment.

This paper introduces a novel shared drawing medium called ClearBoard. It realizes (1) a seamless shared drawing space and (2) eye contact to support realtime and remote collaboration by two users. We devised the key metaphor: “talking through and drawing on a transparent glass window” to design ClearBoard. A prototype of ClearBoard is implemented based on the “Drafter-Mirror” architecture. This paper first reviews previous work on shared drawing support to clarify the design goals. We then examine three methaphors that fulfill these goals. The design requirements and the two possible system architectures of ClearBoard are described. Finally, some findings gained through the experimental use of the prototype, including the feature of “gaze awareness”, are discussed.

Article Integration of inter-personal space and shared workspace: ClearBoard design and experiments Share on Authors: Hiroshi Ishii View Profile , Minoru Kobayashi View Profile , Jonathan Grudin View Profile Authors Info & Claims CSCW '92: Proceedings of the 1992 ACM conference on Computer-supported cooperative workDecember 1992 Pages 33–42https://doi.org/10.1145/143457.143459Online:01 December 1992Publication History 92citation1,201DownloadsMetricsTotal Citations92Total Downloads1,201Last 12 Months10Last 6 weeks2 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access

This paper introduces TeamWorkStation (TWS), a new desktop real-time shared workspace characterized by reduced cognitive seams. TWS integrates two existing kinds of individual workspaces, computers and desktops, to create a virtual shared workspace. The key ideas are the overlay of individual workspace images in a virtual shared workspace and the creation of a shared drawing surface. Because each co-worker can continue to use his/her favorite application programs or manual tools in the virtual shared workspace, the cognitive discontinuity (seam) between the individual and shared workspaces is greatly reduced, and users can shuttle smoothly between these two workspaces.