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  • 701.
    Bladh, Thomas
    et al.
    Luleå tekniska universitet.
    Carr, David
    Luleå tekniska universitet.
    Scholl, Jeremiah
    Extending tree-maps to three dimensions: a comparative study2004In: Computer Human Interaction: 6th Asia Pacific Conference, APCHI 2004, Rotorua, New Zealand, June 29-July 2, 2004. Proceedings / [ed] M. Masoodian; S. Jones; B. Rogers, Encyclopedia of Global Archaeology/Springer Verlag, 2004, p. 50-59Conference paper (Refereed)
    Abstract [en]

    This paper presents StepTree, an information visualization tool designed for depicting hierarchies, such as directory structures. StepTree is similar to the hierarchy-visualization tool, Treemap, in that it uses a rectangular, space-filling methodology, but differs from Treemap in that it employs three-dimensional space, which is used to more clearly convey the structural relationships of the hierarchy. The paper includes an empirical study comparing typical search and analysis tasks using StepTree and Treemap. The study shows that users perform significantly better on tasks related to interpreting structural relationships when using StepTree. In addition, users achieved the same performance with StepTree and Treemap when doing a range of other common interpretative and navigational tasks.

  • 702.
    Bladh, Thomas
    et al.
    Luleå tekniska universitet.
    Carr, David
    Luleå tekniska universitet.
    Scholl, Jeremiah
    Extending tree-maps to three dimensions: a comparative study2004Report (Other academic)
    Abstract [en]

    This paper presents StepTree, an information visualization tool designed for depicting hierarchies, such as directory structures. StepTree is similar to the hierarchy-visualization tool, Treemap, in that it uses a rectangular, space-filling methodology, but differs from Treemap in that it employs threedimensional space, which is used to more clearly convey the structural relationships of the hierarchy. The paper includes an empirical study comparing typical search and analysis tasks using StepTree and Treemap. The study shows that users perform significantly better on tasks related to interpreting structural relationships when using StepTree. In addition, users achieved the same performance with StepTree and Treemap when doing a range of other common interpretative and navigational tasks.

  • 703. Drugge, Mikael
    et al.
    Nilsson, Marcus
    Luleå tekniska universitet.
    Liljedahl, Urban
    Parviainen, Roland
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Methods for interrupting a wearable computer user2004In: Proceedings: Eighth IEEE International Symposium on Wearable Computers, ISWC 2004 : 31 October - 3 November 2004, Arlington, Virginia, Los Alamitos, Calif: IEEE Communications Society, 2004, p. 150-157Conference paper (Refereed)
    Abstract [en]

    A wearable computer equipped with a head-mounted display allows its user to receive notifications and advice that is readily visible in her field of view. While needless interruption of the user should be avoided, there are times when the information is of such importance that it must demand the user’s attention. As the user is mobile and likely interacts with the real world when these situations occur, it is important to know in what way the user can be notified without increasing her cognitive workload more than necessary. To investigate ways of presenting information without increasing the cognitive workload of the recipient, an experiment was performed testing different approaches. The experiment described in this paper is based on an existing study of interruption of people in human-computer interaction, but our focus is instead on finding out how this applies to wearable computer users engaged in real world tasks.

  • 704.
    DaSilva, Luiz
    et al.
    Virginia Polytechnic Institute and State University.
    Midkiff, Scott
    Virginia Polytechnic Institute and State University.
    Park, Jahng
    Virginia Polytechnic Institute and State University.
    Phanse, Kaustubh
    Lin, Tao
    Virginia Polytechnic Institute and State University.
    Hadjichristofi, George
    Virginia Polytechnic Institute and State University.
    Davis, Davis, Nathaniel
    Virginia Polytechnic Institute and State University.
    Network mobility and protocol interoperability in ad hoc networks2004In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 42, no 11, p. 88-96Article in journal (Refereed)
    Abstract [en]

    The integration of various network-level functions, including routing, management, and security, is critical to the efficient operation of a mobile ad hoc network. In this article we focus on network mobility (rather than node mobility), implying the movement of entire subnetworks with respect to one another, while individual users initially associated with one such subnetwork may also move to other domains. One example is a battlefield network that includes ships, aircraft, and ground troops. In this "network of networks", subnets (e.g. shipboard networks) may be interconnected via a terrestrial mobile wireless network (e.g., between moving ships). We discuss the design and implementation of a new ad hoc routing protocol, a suite of solutions for policy-based network management, and approaches for key management and deployment of IPsec in a MANET. These solutions, in turn, are integrated with real-time middleware, a secure radio link, and a topology monitoring tool. We briefly describe each component of the solution, and focus on the challenges and approaches to integrating these components into a cohesive system to support network mobility. We evaluate the effectiveness of the system through experiments conducted in a wireless ad hoc testbed.

  • 705. Kristiansson, Johan
    et al.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Providing seamless mobility with competition based soft handover management2004In: Management of Multimedia Networks and Services: 7th IFIP/IEEE International Conference, MMNS 2004, San Diego, CA, USA, October 3-6, 2004. Proceedings / [ed] John Vicente; David Hutchison, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2004, p. 295-307Conference paper (Refereed)
    Abstract [en]

    As host mobility and radio interference in wireless networks cause packet losses and delays, it is difficult to develop useful mobile real-time media applications. This paper describes a new handover strategy for end-to-end mobility called Competition based Soft Handover Management (CSHM). During a handover, redundant packet streams are sent through multiple connections which are later merged into one stream when received by the other end-point. As each network connection competes with other connections in contributing to the merged packet stream, the handover process can be viewed as a competition. As a proof of concept, CSHM has been implemented in Resilient Mobile Socket, RMS, an application-layer mobility scheme and used together with Marratech Pro, which is a commercially available e-meeting application. By using this prototype, the paper shows that it is possible to minimize redundant packets as well as decrease packet losses during handovers.

  • 706.
    Elf, Stefan
    et al.
    Luleå tekniska universitet.
    Scholl, Jeremiah
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Schemes for user-interest controlled video bandwidth adaptation in a collaborative workspace environment2004In: 2004 IEEE International Conference on Multimedia and Expo, Piscataway, NJ: IEEE Communications Society, 2004, p. 197-200Conference paper (Refereed)
    Abstract [en]

    In this paper, bandwidth-sharing schemes, controlled by user-interest, are presented as an approach to efficient use of resources in a collaborative workspace environment. Two schemes for group videoconferencing are presented and evaluated. Monitoring of user-behavior and message passing to adapt video bandwidth allocation to user needs are key features of both schemes, in which each user's client reports interest in other users to enable them to determine their relative importance. Experimental results using a prototype implementation to sample user-behavior show that one scheme is better suited for high, and the other for low bandwidth-limit scenarios. Measurements also show that the message passing does not add a substantial amount of bandwidth.

  • 707.
    Nilsson, Marcus
    et al.
    Luleå tekniska universitet.
    Drugge, Mikael
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Sharing experience and knowledge with wearable computers2004Conference paper (Refereed)
    Abstract [en]

    Wearable computer have mostly been looked on when used in isolation. But the wearable computer with Internet connection is a good tool for communication and for sharing knowledge and experience with other people. The unobtrusiveness of this type of equipment makes it easy to communicate at most type of locations and contexts. The wearable computer makes it easy to be a mediator of other people knowledge and becoming a knowledgeable user. This paper describes the experience gained from testing the wearable computer as a communication tool and being the knowledgeable user on different fairs.

  • 708. Parviainen, Roland
    et al.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    The MIM web gateway to IP multicast e-meetings2004In: Multimedia Computing and Networking 2004: 21 - 22 January 2004, San Jose, California, USA ; proceedings of Electronic imaging, science and technology, Bellingham, Wash: SPIE - International Society for Optical Engineering, 2004, p. 225-236Conference paper (Refereed)
    Abstract [en]

    As video conferencing and e-meeting systems are used more and more on the Internet and in businesses it becomes increasingly important to be able to participate from any computer at any location. Often this is impossible, since these systems requires often special software that are not available everywhere or impossible to install for administrative reasons. Many locations also lack the necessary network infrastructure such as IP multicast. This paper presents a WWW gateway system that enables users to participate using only a standard web browser. The design and architecture of the system are described and performance tests that show the scalability of the system are also presented.

  • 709.
    Drugge, Mikael
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Wearable computer interaction issues in mediated human to human communication2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis explores the use of wearable computers as mediators for human to human communication. The user of a wearable computer can deliver live video, audio and commentary from a remote location, allowing local participants to experience it and interact with people on the other side. In this way, knowledge and information can be shared over a distance, passing through the owner of the wearable computer who acts as a mediator. One of the main problems of today is that the virtual world offered by wearable computers can become too immersive, thereby distancing its user from interactions in the real world. At the same time, the very same immersion serves to let the user sense the remote participants as being there, accompanying and communicating through the virtual world. The key here is to get the proper balance between the real and the virtual worlds; remote participants should be able to experience a distant location through the user, while the user should similarly experience their company in the virtual world.

  • 710.
    Åhlund, Christer
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Brännström, Robert
    Zaslavsky, Arkady
    A multihoming approach to mobile IP2003In: Swedish National Computer Networking Workshop - Proceedings: SNCNW 2003, Stockholm, 2003Conference paper (Other academic)
    Abstract [en]

    Mobile IP is the standard for mobility management in IP networks. With today's emerging possibilities within wireless broadband communication, mobility within networks will increase. New applications and protocols will be created and Mobile IP is important to this development, since Mobile IP support can be used to allow mobile hosts to move between networks with maintained connectivity. This article describes multihomed Mobile IP enabling mobile hosts to register multiple care-of addresses at the home agent, to enhance the performance of wireless network connectivity. Flows can be load-balanced between care-of addresses to achieve a more reliable connectivity. A prototype is also described.

  • 711.
    Elf, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Application semantics for cost-effective media distribution2003Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Public use of the Internet increases as wideband connections become pervasive and applications suitable for media distribution grow popular. Group collaboration applications have attracted interest during recent years. Wireless connectivity and business applications also furthers a need for reliable communication protocols. Multicast is a driving force for new applications involving one-to-many as well as many-to-many user scenarios like lecturing, discussions, and collaborative work. In some applications guaranteed delivery of every packet is not crucial, while in other this is a requirement. Error handling in reliable protocols can present a substantial challenge already in a homogeneous environment. Including a plethora of end-user terminal types with widely varying resources it becomes even more challenging. Protocols and applications must therefore be able to handle receiver and network link heterogeneity. The thesis addresses some of the challenges facing the applications in this field, related to multicast and unicast alike. Although the obstacles each of them must overcome may differ, there are similarities with regards to possible solutions with respect to error handling or resource allocation. Error handling protocols are proactive or reactive. Proactive protocols transmit redundant information along with the original information, enabling the receivers to repair lost packets without feedback to the sender. Reactive protocols rely either on positive or negative feedback from the receivers in order to establish reliability. According to a definition of semantic reliability the reliability concept can be interpreted in terms of application semantics. It is proposed to view reliable multicast as a special case of semantically reliable multicast and to implement a dynamically configurable transport layer with an error-handling rule set that can be configured from the application or even from the sender in- session. It is also proposed to make use of the application's knowledge of specific semantics to improve on the recovery of lost packets, congestion handling, or resource allocation. The thesis also presents a bandwidth-sharing scheme for video in group collaboration using application semantics in the form of user hints. The presence of such events is made available to all senders via message passing between session members. As information relating to a user's interest in another user is conveyed, the sender may increase its use of resources on the expense of other senders. A scheme is proposed and a prototype implementation and experimental results are presented.

  • 712.
    Elf, Stefan
    et al.
    Luleå tekniska universitet.
    Scholl, Jeremiah
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Applying user-behavior to bandwidth adaptations in collaborative workspace applications and video conferencing2003Report (Other academic)
    Abstract [en]

    A bandwidth-sharing scheme for group video conferencing is presented in this paper. The key features of the scheme are the monitoring of user behavior and message passing, which are used by each client in order to identify and report their interest in other group members. Each video sender operates on the information about other users ' interest in order to adjust the sender's own frame rate, resolution, and ultimately bandwidth consumption in an attempt to satisfy the current interests of the receivers as well as the overall bandwidth constraints of the session. A general framework, an initial prototype, and a bandwidth allocation algorithm are presented together with experimental results. The experiences from the prototype have prompted refinements to the bandwidth-allocation algorithm that will be important for future implementations. We also conclude that the necessary messaging will not add a significant amount of bandwidth.

  • 713.
    Schefström, Dick
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Distance- Spanning Technology.
    Architecture of a mobile Internet2003In: Proceedings of the 36th Annual Hawaii International Conference on System Sciences: HICSS ´03, IEEE Communications Society, 2003, p. 150-Conference paper (Refereed)
    Abstract [en]

    In this paper, we outline the next major evolution of the Internet architecture, where support for mobility is not the exception but the typical case. We show which parts of the Internet architecture needs to be extended, how they interact, and why they are needed. We point out the suitability of especially license free radio access equipment not only technically, but as a well harmonizing piece in the non-centralized and distributed way that Internet grows. We show that a wired Internet supporting mobility drastically changes the market situation in the mobile and wireless sector, possibly to a level where special mobile operators are not needed. We show that this leads to a situation where wireless and mobile access is just as inexpensive as its wired counterpart

  • 714. Scholl, Jeremiah
    et al.
    Elf, Stefan
    Luleå tekniska universitet.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Efficient workspaces through semantic reliability2003In: 10th International Conference on Telecommunications: ICT 2003, Piscataway, NJ: IEEE Communications Society, 2003, p. 1099-1104Conference paper (Refereed)
    Abstract [en]

    Transport level protocols typically provide “best-effort” data delivery where no attempts are made to recover lost packets, or “reliable” data delivery where techniques are used to ensure that all data sent out eventually reaches the receiver(s). However, it has been suggested that some applications will perform better when using dynamically configurable reliability based on application level semantics. A general framework has been created with the intent of delivering this type of semantic reliability to a wide variety of applications, but to date little research has been done to demonstrate how any applications can benefit from the use of such a framework. This paper addresses this problem in that it discusses semantic reliability in the context of collaborative workspaces.

  • 715. Drugge, Mikael
    et al.
    Nilsson, Marcus
    Luleå tekniska universitet.
    Kristiansson, Johan
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Experiences from mobile e-meetings with the borderland wearable computer2003Report (Other academic)
    Abstract [en]

    People are presented with an increasing number of opportunities to communicate regardless of location as wireless network connectivity becomes more prevalent. Questions that arise are in what form this communication is and what challenges it poses? Can the experience of group communication be enhanced so that a feeling of actual presence can be conveyed? Can we enable participants to experience the world from another person's perspective? We believe so, in this paper we discuss our experiences of group communication when using a wearable computer that is always connected to the network.

  • 716. Drugge, Mikael
    et al.
    Nilsson, Marcus
    Luleå tekniska universitet.
    Kristiansson, Johan
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Experiences of conveying knowledge in borderland2003Report (Other academic)
    Abstract [en]

    One of humankind's most basic needs is that of being able to communicate with other people. As wireless network connectivity becomes more prevalent, factors such as physical location and situation diminish in significance for deciding when and how such communication can take place. What happens when a user is given this freedom to utilize the network regardless of time and place? Questions that arise are how different media can enrich communication and what challenges it poses. Can we enable other users to experience the world from another person's perspective? Can we expand it beyond pure communication and allow other more novel uses to emerge? Can we use this as a way of conveying knowledge in real-time to those in need of it? We believe so, in this paper we discuss our experiences of mobile communication when using a wearable computer that is always connected to the best network available.

  • 717.
    Åhlund, Christer
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Zaslavsky, Arkady
    Extending global IP connectivity for ad hoc networks2003In: Telecommunications Systems, ISSN 1018-4864, E-ISSN 1572-9451, Vol. 24, no 2-4, p. 221-250Article in journal (Refereed)
    Abstract [en]

    Ad hoc networks have thus far been regarded as stand-alone networks without assumed connectivity to wired IP networks and the Internet. With wireless broadband communications and portable devices with appropriate CPU, memory and battery performance, ad hoc connectivity will become more feasible and demand for global connectivity through ad hoc networking is likely to rapidly grow. In this paper we propose an algorithm and describe a developed prototype for connectivity between an ad hoc network running the ad hoc on-demand distance-vector protocol and a wired IP network where mobile IP is used for mobility management. Implementation issues and performance metrics are also discussed.

  • 718.
    Nilsson, Marcus
    et al.
    Luleå tekniska universitet.
    Drugge, Mikael
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    In the borderland between wearable computers and pervasive computing2003Report (Other academic)
    Abstract [en]

    In this paper we will show the ideas that are the foundation for the Borderland architecture. We have looked at two views of how researchers are thinking about computers in the future, wearable computers and pervasive computing. Wearable computers is the view where the user is wearing a computer and by that augment the user's view on his environment with additional digital information. Wearable computers have their strength in that they mostly do not have any requirements on the environment and that the user is in control of his integrity and security. In the pervasive computing view the digital representation of reality is in the physical environment itself. There are few requirements on the user for him to be able to use this digital augmented environment. There is also no restriction of what can be used in this environment as everything can be used for digital representation. We can see that the problems in one view are often the strengths in the other view. We believe that by combining these views into one we can use the strength of both areas and in that solve some of the problems involved in these two research areas. In this paper we present some of the problems we see in this combined view and also some ideas to solutions that we will evaluate in future work.

  • 719.
    Åhlund, Christer
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Zaslavsky, Arkady
    Integration of ad hoc network and IP network capabilities for mobile hosts2003In: 10th International Conference on Telecommunications: ICT 2003 ; February 23 - March 1, 2003, Sofitel Coralia Maeva Beach Hotel, Tahiti, Papeete, French Polynesia, Piscataway, NJ: IEEE Communications Society, 2003, Vol. 1, p. 482-489Conference paper (Refereed)
    Abstract [en]

    Mobility of user devices connecting to the Internet is of major interest in today’s research in networking. Users with portable devices, like laptops and personal digital assistants (PDA), connecting to foreign networks in the Internet want the same functionality as when connected to the home network, as well as accessibility through the home IP address. Ad hoc networking is also of major importance for connectivity between communicating mobile hosts without backbone infrastructure and for connectivity to access points. For the users as well as for the applications, network mobility should be transparent. The usage of the ad hoc network or the wired IP network should also be managed by the networking software and hidden from applications and users. In this paper we propose and describe an integrated connectivity solution and its software implementation between an ad hoc network running the Ad Hoc On- Demand Distance-Vector Protocol and a wired IP network where Mobile IP is used for mobility management. With the usage of ad hoc networking, a mobile host will be able to use multiple foreign networks to enhance the communication performance. A proposal to multihomed Mobile IP is presented to achieve this.

  • 720.
    Synnes, Kåre
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Nord, James
    Luleå tekniska universitet.
    Parnes, Peter
    Location privacy in the Alipes platform2003In: Proceedings of the 36th Annual Hawaii International Conference on System Sciences: : 6 - 9 January 2003, Big Island, Hawaii / [ed] Ralph H. Sprague, Los Alamitos, Calif: IEEE Communications Society, 2003Conference paper (Refereed)
    Abstract [en]

    An increasing number systems use contextual information about their users. Such contextual information can be used to design applications that survey usage and adapt thereafter, or simply just use context information to optimize presentation. Context information could therefore be used to create applications for the benefit of the users of the system, but the same information could cause serious violations of personal integrity if misused. Locality may be the most widely used, but also the most sensitive contextual information. The Alipes platform makes it easy to create location-based services while enforcing user privacy and integrity. The platform handles privacy through rules that describe how and under what circumstances a user’s context may be distributed to other users, for example rules describing limitations concerning the user’s context, a certain time period, the number of queries and the type of applications. This paper presents how location privacy is enforced in the Alipes platform.

  • 721. Parviainen, Roland
    et al.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Mobile instant messaging2003In: 10th International Conference on Telecommunications: ICT 2003 ; February 23 - March 1, 2003, Sofitel Coralia Maeva Beach Hotel, Tahiti, Papeete, French Polynesia, Piscataway, NJ: IEEE Communications Society, 2003, p. 425-430Conference paper (Refereed)
    Abstract [en]

    In this paper we describe a Mobile Instant Messaging system, MIM, designed for mobile environments. During design of mobile applications several new problems and possibilities have to be considered that do not exist with applications targeted at desktop PCs. One example of an application not designed for a mobile environment is current, very popular, instant messaging systems such as ICQ, AIM and MSN messenger. We describe why current systems are not suitable in a mobile environment and present our architecture for a new system, MIM, and show various implementations for different mobile devices such as PDAs, wearable computers and mobile phones.

  • 722. Kristiansson, Johan
    et al.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Mobility support for collaborative real-time applications2003Report (Other academic)
    Abstract [en]

    Today we are approaching a truly connected and wireless world where users can be always connected by switching between different carriers and providers. This paper presents an architecture which enables mobile media applications to operate across a wide range of wireless networks, gracefully handle network failures and share environmental information, such as packet loss-rate or available bandwidth with remote peers. The architecture is evaluated using a commercially available E-meeting application, Marratech Pro by seamlessly switching between three carriers; LAN, WLAN and GRPS.

  • 723.
    Åhlund, Christer
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Zaslavsky, Arkady
    Multihoming with mobile IP2003In: High-Speed Networks and Multimedia Communications: 6th IEEE International Conference ; proceedings / HSNMC 2003, Estoril, Portugal, July 23 - 25, 2003 / [ed] Mário Marques Freire, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2003, p. 235-243Conference paper (Refereed)
    Abstract [en]

    Mobile IP is the standard for mobility management in IP networks. With today’s emerging possibilities within wireless broadband communication, mobility within networks will increase. New applications and protocols will be created and Mobile IP is important to this development, since Mobile IP support is needed to allow mobile hosts to move between networks with maintained connectivity. This article describes multihomed Mobile IP enabling mobile hosts to register multiple care-of addresses at the home agent, to enhance the performance of wireless network connectivity. Flows can be loadbalanced between care-of addresses to achieve a more reliable connectivity. A prototype is also described.

  • 724.
    Scholl, Jeremiah
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Network and user-level traffic adaptation for collaborative-workspace applications2003Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Collaborative workspace applications based on IP-multicast offer a scalable solution for computer supported human-to-human communication. Although Internet-wide multicast access is not a reality, multicast deployment is steadily increasing on subnets, such as corporate and campus networks. Over the past few years this has allowed these applications to begin making headway into work and educational environments. One of the primary drawbacks that the current generation of these applications suffer from is that they generally use simple data transport protocols, which leads to inefficient use of network resources. The primary reason for this is that while a great deal of progress has been made in the area of multicast transport, additional work is needed that can put this research in the context of real-world requirements and usage scenarios, which will enable effective application-level-framing. The work in this thesis focuses on this problem, in that it discusses data transport in the context of a specific industrial collaborative-workspace and shows how improvements can be made in terms of data recovery and bandwidth adaptation, which will save network resources and improve the quality of media reception experienced by users. Thus, an industrial partner, Marratech AB, which specializes in collaborative workspaces, was consulted throughout the work conducted in the thesis and was valuable in helping identify real-world requirements for the protocols and ideas presented. In addition, prototyping relating to the work has been built into Marratech software. The thesis explores the two primary areas of data transport in this context, these being reliability and bandwidth adaptation. In the area of reliability the thesis explores how to generate the necessary feedback for data recovery in a novel and efficient way that does not interfere with calculations for available bandwidth, which is a drawback that many other reliable multicast protocols suffer from. In addition, the thesis explores how to integrate data semantics into the recovery process in order to minimize unnecessary packet retransmissions and control traffic. In the area of bandwidth adaptation, the feedback scheme mentioned above is used in order to adapt the bandwidth consumption of reliable media, such as whiteboards and shared web-browsers, to levels that are ''friendly'' with traditional TCP-based applications. In addition, a bandwidth sharing scheme for the video-streams used in collaborative workspaces is presented that identifies the most important senders in the session and allocates them with a larger share of the session bandwidth.

  • 725.
    Hallberg, Josef
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nilsson, Marcus
    Luleå tekniska universitet.
    Synnes, Kåre
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Positioning with Bluetooth2003In: 10th International Conference on Telecommunications: ICT 2003 ; February 23 - March 1, 2003, Sofitel Coralia Maeva Beach Hotel, Tahiti, Papeete, French Polynesia, Piscataway, NJ: IEEE Communications Society, 2003, p. 954-958Conference paper (Refereed)
    Abstract [en]

    This paper presents an evaluation of Bluetooth positioning in a general positioning platform. Proceeding the evaluation a Bluetooth based positioning system was implemented in order to complement the theoretical evaluation with empirical tests. Three different ways of positioning with Bluetooth have been developed. With a registered positioning service a Bluetooth device has an active role in the positioning task as it sends a position on request. A Bluetooth device can also take a more passive role in a positioning task, where the unique address of the device is used by a connected device to look up respective position in a database. It is also possible to forward a position gained from the positioning platform using the peer to peer characteristics in Bluetooth. This paper does also contain a discussion on the theoretical time requirements for a positioning system based on Bluetooth. Empirical tests show that these requirements hold.

  • 726.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Secure inclusion of phones into online e-meetings2003In: Management of Multimedia Networks and Services: 6th IFIP/IEEE international conference ; proceedings ; [augmented by a Workshop on End-to-End Monitoring Techniques and Services (E2EMON)] / [ed] Alan Marshall, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2003, p. 396-408Conference paper (Refereed)
    Abstract [en]

    Online Internet based e-meetings for synchronous communication is becoming more and more common and the need for secure communication is a strong requirement from both corporate and private users. At the same time not all users can always be available via the Internet and as phones (fixed and mobile) are still the dominant communication method there is a need for general inclusion of phones into online e-meetings, without compromising the security of the online session. This paper presents an architecture supporting three different scenarios for including normal phones into e-meetings, and at the same time keeping the security of the session intact. It is also shows how an e-meeting portal is used for simple inclusion of phones into e-meetings even if the inviting client is behind a NAT gateway or a firewall.

  • 727. Parviainen, Roland
    et al.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Supporting E-meetings on Java capable mobile phones2003Report (Other academic)
    Abstract [en]

    In this paper we discuss different methods for providing group awareness to participants of e-meeting software using small, limited devices connected with limited networks such as a mobile phone. Currently small devices such as mobile phones are getting more advanced and capable of running custom software such as small Java applications while at the same time the available wireless networks are getting more pervasive and faster making it possible to connect to the Internet from anywhere, from almost any device. We describe the limitations of our target devices and methods to overcome these limitations for each media and present an implementation of some of these methods using an existing commercial e-meeting system.

  • 728. Scholl, Jeremiah
    et al.
    Elf, Stefan
    Luleå tekniska universitet.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    User-interest driven video adaptation for collaborative workspace applications2003In: Group Communications and Charges: technology and business models ; 5th COST 264 International Workshop on Networked Group Communications, and 3rd International Workshop on Internet Charging and QoS Technologies, proceedings / [ed] Burkhard Stiller, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2003, p. 3-12Conference paper (Refereed)
    Abstract [en]

    This paper presents a bandwidth sharing scheme for group video conferencing. The key features of the scheme are the monitoring of implicit user-hints and message passing, which are used by each client in order to identify and report their interest in other group members. Information about user interest is then used by each video sender in order to adjust their frame-rate, resolution, and ultimately bandwidth consumption in an attempt to satisfy the current interests of the receivers. A general framework and initial prototype are presented together with experimental results.

  • 729.
    James, Nord
    et al.
    Luleå tekniska universitet.
    Synnes, Kåre
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Parnes, Peter
    An architecture for location aware applications2002In: Proceedings of the 35th Annual Hawaii International Conference on System Sciences: 7 - 10 January 2001 [i.e. 2002], Big Island, Hawaii / [ed] Ralph H. Sprague, Los Alamitos, Calif: IEEE Communications Society, 2002, p. 3805-3810Conference paper (Refereed)
    Abstract [en]

    This paper presents an architecture for location aware applications, where positioning sources such as GPS, WaveLAN and Bluetooth devices can be seamlessly interchanged and combined to achieve a more accurate positioning service with a higher availability. The architecture also supports peer-to-peer communication to allow clients to interchange position information over a network such as Bluetooth or WaveLAN. This enables a user to use other users position sources if their clients are close enough. The position information can be used directly by an application or be combined with habitual and other contextual information to achieve more personalized applications. A generic positioning protocol for interchange of position information between position sources and client applications, and different techniques for merging of position information are presented. The interfaces to the platform are also discussed. The paper finally touches on privacy issues and outlines a schema for handling positioning information by user controlled contracts

  • 730.
    Elf, Stefan
    et al.
    Luleå tekniska universitet.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Applying semantic reliability concepts to multicast information messaging in wireless networks2002In: IRMA Conference Proceedings: Issues & Trends of Information Technology Management in Contemporary Organizations / [ed] M. Khosrowpour, Hershey, Pa: Idea Group Publishing, 2002Conference paper (Refereed)
    Abstract [en]

    Public use of the Internet increases and applications suitable for multicast distribution grow more popular. An increasing percentage of users require wireless connectivity. Multicast solutions must therefore be able to handle receiver and network link heterogeneity. This paper proposes an approach to handle such challenges. According to a definition of semantic reliability, the reliability concept can be interpreted in terms of application semantics. By using semantic reliability traditional reliability constraints can be relaxed. Our approach is to use an application – transport layer communication to implement a dynamically configurable transport layer protocol whose error-handling rule set can be configured from the application or even from the sender in-session. It can also be initiated from the sender when the session starts.

  • 731.
    Nilsson, Marcus
    et al.
    Luleå tekniska universitet.
    Hallberg, Josef
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Synnes, Kåre
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Bluetooth positioning2002In: CSEE 2002: Second Annual Conference on Computer Science and Electrical Engineering, Luleå, Sweden May 27-28: Conference Proceedings, Luleå tekniska universitet, 2002Conference paper (Other academic)
    Abstract [en]

    Research on positioning systems and context-aware applications are being performed in the Alipes project at CDT, Luleå University of Technology, Sweden. An evaluation of Bluetooth as a possible technology for positioning was performed during autumn of 2001 in this project. Proceeding the evaluation a Bluetooth based positioning system was implemented in order to complement the theoretical evaluation with empirical tests. Three different ways of positioning with Bluetooth have been developed for the Alipes project. With a registered positioning service a Bluetooth device has an active role in the positioning task as it sends a position on request. A Bluetooth device can also take a more passive role in a positioning task, which is when the unique address of the device is used by a connected device to look up a position in a database. It is also possible to forward a position gained from a positioning platform like Alipes over Bluetooth. This paper presents a Bluetooth positioning system where the three ways of positioning are implemented. The evaluation and conclusions of Bluetooth as a positioning source and how well Bluetooth performs in such a task are being discussed. To give support to the statements the implementation and tests are also presented.

  • 732.
    Schefström, Dick
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Designing a mobile Internet2002In: Redefining Internet in the Context of Pervasive Computing: Proceedings of ICCC 2002 / [ed] S.V. Raghavan ; Sudhir P Mudur, ICCC Press , 2002, Vol. 2, p. 750-67Conference paper (Refereed)
    Abstract [en]

    This paper outlines the next major evolution of the Internet architecture, where support for mobility is not the exception but the typical case. We show which parts of the Internet architecture needs to be extended, how they interact, and why they are needed. We point out the suitability of especially license free radio access equipment not only technically, but as a well harmonizing piece in the non-centralized and distributed way that Internet grows. We show that a wired Internet supporting mobility drastically changes the market situation in the mobile and wireless sector, possibly to a level where special mobile operators are not needed. We show that this leads to a situation where wireless and mobile access is just as inexpensive as its wired counterpart. The plans outlined here are pursued at the Center for distance-spanning technology within the project called the RadioSphere

  • 733.
    Parnes, Peter
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Nilsson, Marcus
    Device independent user interface description for wearable computers2002Report (Other academic)
    Abstract [en]

    This report discusses the aspect of user interfaces on wearable computers. Today wearable computers can be of very different size and capabilities. The way of communicating with the user also varies for different devices. This paper looks into several different approaches of describing a user interface that is independent of the underlying device and architecture.

  • 734.
    Widen, Johnny
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Bullock, Adrian
    SICS.
    Karlsson, Jan BM
    Umeå university.
    E-meetings to support netlearning2002Conference paper (Other academic)
  • 735. Scholl, Jeremiah
    et al.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Low-weight congestion control for multi-sender applications2002In: Management of Multimedia on the Internet table of contents: 5th IFIP/IEEE International Conference on Management of Multimedia Networks and Services, Santa Barbara, CA USA, October 6 - 9, 2002 ; proceedings / [ed] Kevin C. Almeroth, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2002, p. 315-327Conference paper (Refereed)
    Abstract [en]

    This paper presents a prototype for single-rate reliable multicast congestion control, which has been built into an existing commercial whiteboard. The prototype was developed using a novel scheme that was engineered around conflicting industry provided requirements for collaborative workspaces. This required the scheme to be both low-weight when used with many senders and compatible with NAT, firewalls and reflectors. The key to overcome this conflict was to combine congestion control and recovery feedback. This differs from many current solutions in that they are often designed for use with a wide variety of protocols and thus operate independent of the recovery mechanism. This paper does not go into the detail required to specify a protocol but instead discusses a few important design requirements for multi-sender applications, which are generally not considered by current research, and describes an approach towards meeting these requirements.

  • 736.
    Synnes, Kåre
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    On distributed real-time systems: the mStar environment, net-based learning and context-aware applications2002Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This doctoral thesis presents two frameworks for distributed real-time systems, the mStar environment for Computer Supported Collaborative Work (CSCW) and the Alipes architecture for context-aware applications, from the perspective of distributed teamwork and net-based learning. The mStar environment was designed to be symmetric and fully distributed, which allows all users equal access and thus full interactivity, as well as scalable through the use of IP multicast and a server-less design. The environment makes use of reliable multicast, network resource management and packet loss recovery techniques to increase robustness. Heterogeneous networks and terminals are supported through tunneling and transcoding of media. Asynchronous use of the environment is made possible through support for recording and replay of sessions. It is therefore well equipped to meet the requirements for net-based learning, as the inherent time- and location-independence allows students to follow distributed courses, when otherwise large geographical distances or time restrictions otherwise would limit where and when education could be offered. The student can be anything from a full-time student attending lectures physically at the university, to a part-time student following courses from his home during evenings and weekends. Students will thus have increased possibilities of taking part in education. The Alipes architecture for context-aware applications allows multiple positioning techniques to be seamlessly interchanged and combined, enabling applications to utilize a single interface, yet benefit from several advantages that single positioning techniques cannot offer alone. Add peer-to-peer interchange of position information using ad-hoc networks, and the platform offers a wide variety of techniques to be interchanged or combined, with obvious advantages such as increased coverage and accuracy. Privacy issues are central to managing a user?s context information, for example his position, as that information could cause serious violations of personal integrity if misused. The Alipes architecture handles privacy through general criteria and contracts between users and location servers. Information exchange is typically carried out on a peer-to-peer basis using ad-hoc networks. Integrated examples could be combining locating a nearby tutor with setting up a conference call to initiate a tutoring session, using context information to enhance the perceived feeling of presence within the mStar environment or to optimize network-usage depending on the user?s context. A final conclusion is that systems aiming at enhancing the social aspects of distributed applications by using context information might be important, if not vital, when creating new real-time services for mobile terminals.

  • 737.
    Åhlund, Christer
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Zaslavsky, Arkady
    Software solutions to Internet connectivity in mobile ad hoc networks2002In: Product focused software process improvement: 4th international conference ; proceedings / [ed] Markku Oivo, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2002, p. 559-571Conference paper (Refereed)
    Abstract [en]

    In recent years wireless Internet access and wireless communications between peers have become the focus of intensive research efforts in various areas of information and communication technologies. Mobility aspects, software development and support for mobile users are currently of major interest within this research area. The Mobile IP protocol is deployed for mobility management of hosts moving between networks. Ad hoc routing is also of major importance for connectivity between communicating mobile hosts without backbone infrastructure. In this paper we propose and describe an integrated connectivity solution and its software implementation between an ad hoc network running the Ad Hoc On-Demand Distance-Vector Protocol (AODV) and a wired IP network where Mobile IP is used for mobility management. The article also describes a project called Mobile City in which our software solutions and support infrastructure are tested and validated.

  • 738.
    Åhlund, Christer
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Zaslavsky, Arkady
    Support for wireless connectivity in hot spot areas2002In: MOST: Technology for Mobile Society: MOST International Conference. Proceedings / [ed] Mieczysław R Muraszkiewicz, Warsaw: Most Press , 2002Conference paper (Refereed)
  • 739.
    Åhlund, Christer
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Supporting global connectivity in heterogeneous IP networks2002Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mobility of user devices connecting to the Internet is of major interest in today's research in networking. Users with portable devices, like laptops and personal digital assistants (PDA), connecting to foreign networks in the Internet want the same functionality as when connected to the home network as well as accessibility through the home IP address. For the users as well as for the applications, network mobility should be transparent. To achieve this transparency, the Mobile IP is deployed. Connecting wireless devices through an access point for network access enables mobility. Geographical areas are covered with wireless high bandwidth connections, creating so-called hot spot areas. The access points may have different capabilities, be connected to different networks and be installed by different providers. A mobile host will sense multiple access points in this environment. To make use of the dynamic capability, a device should be able to use the best available connectivity for a network flow and perhaps different connections for different flows. In hot spot areas it may be difficult to cover everything with good radio coverage, and therefore a mobile host may have to use an intermediate, peer mobile host for connectivity to an access point. Also, co-operating mobile users who require connectivity between their devices, should be able to quickly and easily establish a multi-hop ad hoc network between them. This thesis proposes and describes a number of solutions towards enhancing network connectivity in wireless broadband network areas, where the networking software will evaluate and decide which wireless network connections to use. Multi-hop ad hoc connections can be used between peers and in the connecting to access points. Modifications are proposed to Mobile IP to manage multihoming of a mobile host simultaneously connecting it to multiple access points. The connectivity between mobile hosts and access points is evaluated to enable usage of the best connections. The mobile host, the home agent and the correspondent host are able to decide on which network connections to use. A gateway is proposed to enable a reactive ad-hoc routing protocol to interoperate with wired IP networks and to support mobility of hosts between ad hoc networks.

  • 740.
    Åhlund, Christer
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Zaslavsky, Arkady
    Matskin, M.
    Supporting mobile business applications in hot spot areas with pervasive infrastructure2002In: M-business 2002: evolution sceniarios for emerging mobile commerce services ; the 1st International Conference on Mobile Business ; 8 - 9 July 2002, Athens, Greece, Athens, 2002Conference paper (Refereed)
  • 741.
    Elf, Stefan
    et al.
    Luleå tekniska universitet.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    A configurable transport layer as a cure for crying babies2001In: CSEE'2001: Conference Proceedings, Luleå tekniska universitet, 2001Conference paper (Refereed)
    Abstract [en]

    Group collaboration and media distribution ap- plications have attracted more interest during recent years. With an increasing attention to wireless environments and business applications there is a growing need for reliable multicast communication protocols. There have been mainly two approaches, proactive or re- active, to error handling in reliable multicast. Proactive protocols transmit redundant information along with the original information, enabling the receivers to repair lost packets without the necessity of feedback to the sender. Re- active protocols rely either on positive or negative feedback from the receivers. A case of special interest in relation to wireless connec- tivity is where essentially one receiver on a lossy link even- tually will consume most of the error handling resources. This problem has been addressed by some researchers, e.g. by the use of probabilistic methods. We propose to view reliable multicast as a special case of semantically reliable multicast. We propose to make use of the application’s knowledge of its specific semantics to improve e.g. on the problem with single, lossy, links. We suggest the design of a semantic rule set for the transport layer protocol, which can be configured by the application. Using application semantics would allow the application to relax the reliability requirement at the transport level.

  • 742.
    Elf, Stefan
    et al.
    Luleå tekniska universitet.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    A literature review of recent developments in reliable multicast error handling2001Report (Other academic)
    Abstract [en]

    As the number of applications directed towards group collaboration and group media dissemination increases, the interest for multicast protocols has also grown during recent years. Several applications have a need for reliability. This is true for the use of shared network editors, shared white-boards, networked games, etc. An increased popularity of media and application distribution over the Internet and the beginning growth of mobile computing with its inherent inhomogeneity and higher loss-rate, will create a demand for security which will increase the need for reliable transmissions. This paper aims to study reliable multicast protocols from an error correction perspective. During recent years, a number of protocols have been proposed. The reliability properties of these lies partly with error correction measures, but to a great extent also with different topological and timing measures which are aimed at boosting protocol efficiency. As it turns out, there are mainly two groups of error correction measures which are used. They can be divided into reactive measures, and proactive. The development in this field of research is very fast. Although a number of studies have already been done, this paper aims to summarise the most recent developments in the area of reliable multicast. This is a literature study and the sources are mainly English-language references from the INSPEC database and the ACM, IEEE, and IEEE Computer Society's digital libraries, essentially from 1997 until 2000.

  • 743. Bittencourt, Roberto Almeida
    et al.
    Carr, David
    Luleå tekniska universitet.
    A method for asynchronous web-based lecture delivery2001In: Impact on engineering and science education: conference proceedings / FIE 2001, 31st Annual Frontiers in Education Conference, IEEE Communications Society, 2001Conference paper (Refereed)
    Abstract [en]

    Computer-based distance education has been growing enormously in recent years due to advances in key technologies: telecommunications, computer technology, graphical user interfaces, and the Internet. Distance education materials can be presented either synchronously, creating the illusion of a classroom on the computer, or asynchronously, allowing the students access-on-demand. We describe the development of a system to solve part of the asynchronous education problem - delivery of pre-recorded multimedia lectures via a web browser. We built a demonstration system using off-the-shelf technology making it possible to make presentations using commercial tools and to display them on standard systems. We designed the system with lectures composed of "slides" accompanied by audio commentary. These presentations can be delivered via lowspeed modem links - an important consideration in places without a well-developed infrastructure. We also believe that computer-based education is often so complicated to use that operation interferes with education. In order to avoid this, we evaluated a prototype system to obtain feedback about difficulties in operation and to correct them.

  • 744. Parviainen, Roland
    et al.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Large scale distributed watermarking of multicast media through encryption2001In: Proceedings of the International Federation for Information Processing, Communications and Multimedia Security Joint working conference IFIP TC6 and TC11, 2001, p. 149-158Conference paper (Refereed)
    Abstract [en]

    In this paper we describe a scheme in which each receiver of a multicast session receives a stream with a different, unique watermark, while still retaining the scalability of multicast. The watermarked streams can be used to trace those users who make unauthorized copies of a stream. The watermarking is enabled by encryption of two slightly different copies of the original stream with a large set of different keys.

  • 745.
    Synnes, Kåre
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Söderström, Tor
    Luleå tekniska universitet.
    Parnes, Peter
    Learning in desktop video-conferencing environments2001In: WebNet 2001: World Conference on the WWW and Internet ; [Orlando, Florida, October 23 - 27, 2001 / [ed] Wendy Fowler, Norfolk, Va: Association for the Advancement of Computing in Education, 2001Conference paper (Refereed)
    Abstract [en]

    Luleå University of Technology has since 1997 used net-based learning environments based on desktop video-conferencing tools to distribute courses to students. It has been claimed that the environment gives remotely attending students equal possibilities as traditionally attending students to take an active part of a course, as well as enhancing the learning experience for all students. This is in part true, but in reality there are many pedagogical and technical obstacles to overcome before a course can be seen as successful. This paper identifies a number of problems, which will be considered from both a pedagogical and technical perspective.

  • 746.
    Åhlund, Christer
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Zaslavsky, Arkady
    "Mobile city" ad hoc wireless network support for regional communities2001In: Proceedings: The Path to 4G Mobile, 2001Conference paper (Refereed)
  • 747.
    Thakur, Aruna
    et al.
    Luleå tekniska universitet.
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Multi-layered video transmission over Internet2001In: CSEE '2001: Conference Proceedings, Luleå tekniska universitet, 2001Conference paper (Other academic)
  • 748.
    Parviainen, Roland
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    On large scale real time music distribution: security, reliability and heterogeneity2001Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents a system for real-time large scale distributed music distribution, such as radio on the Internet. The existing technologies do not enable the full potential that broadcast media on the Internet can give, such as a very large number of interactive receivers. A technology that can help achieve potential is IP-multicast, which enables broadcast applications to scale to millions of receivers. However, IP-multicast creates new problems that have to be solved for it to be used on the Internet; some of these problems are addressed in this thesis. The system presented in this thesis, mIR - multicast Interactive Radio, has been used as a prototype to implement and examine different solutions to some of the issues of IP-multicast and real time music distribution. These are problems such as heterogeneity, reliability and security. Heterogeneity and reliability are different aspects of the same problem: that IP-multicast is an unreliable Internet transport mechanism. In this thesis different methods for avoiding these problems are described and evaluated. Security in the context of IP-multicast has many aspects. While the problems of confidentiality and authentication have been extensively examined, there are still a few unresolved problems. One of these problems is traitor tracing: how to know the origin of illegal copies of a media object such as a radio transmission. An application of digital watermarking, fingerprinting, can be used to distinguish between different copies of the same media object, but requires that each copy is individually marked. This contradicts the basic property of multicast that ensures its scalability: that everyone receives exactly the same data. We show how we can combine the different goals of fingerprinting and IP-multicast while still maintaining the scalability features of multicast.

  • 749.
    Schefström, Dick
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Distance- Spanning Technology. Mäkitalo Research Centre.
    Saving Mobile Internet2001Report (Other academic)
    Abstract [en]

    In this paper I will point out a number of very serious principal objections on the idea of a Mobile Internet, and why it will not work. At least not as currently planned. Then, I will show how some of the objections - the most serious ones - can be solved by taking a radically different path to the future. A path that is so different that most people hesitate to think about it since it may mean that the role of mobile operators disappears. The resulting project, called The RadioSphere, is run at the Centre for Distance-spanning Technology, CDT, in Sweden.When discussing concrete examples and general market situations I will use Sweden because of its very high penetration of broadband Internet to homes, PC's & mobile phones. It therefore has especially good prerequisites for pioneering the RadioSphere approach.

  • 750.
    Thakur, Aruna
    et al.
    Luleå tekniska universitet.
    Gao, Chaunsi
    Luleå tekniska universitet.
    Larsson, Andreas
    Parnes, Peter
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    The effects of frame-rate and image quality on perceived video quality in videoconferencing2001Report (Other academic)
    Abstract [en]

    This report discusses the effect of frame-rate and image quality on the perceived video quality in a specific videoconferencing application (MarratechPro). Subjects with various videoconferencing experiences took part in four experiments wherein they gave their opinions on the quality of video upon the variations in frame-rate and image quality. The results of the experiments showed that the subjects preferred high frame rate over high image quality, under the condition of limited bandwidth.

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