The Session Initiation Protocol (SIP) was first published in 1999, by the Internet Engineering Task Force (IETF), to be the standard for multimedia transfers. SIP is a peer-to-peer signaling protocol that is capable of initiating, modifying, and terminating media sessions. SIP utilizes existing Internet Protocols (IP) such as Domain Name Service (DNS) and the Session Description Protocol (SDP), allowing it to seamlessly integrate into existing IP networks. As SIP has matured and gained acceptance, its deficiencies when functioning as a multipoint communications protocol have become apparent. SIP currently supports two modes of operation referred to as conferencing and multicasting. Conferencing is the unicast transmission of session information between conference members. Multicasting uses IP multicast to distribute session information. This thesis proposes an extension for the Session Initiation Protocol that improves functionality for multipoint communications. When using conferencing, a SIP user-agent has limited information about the conference it is taking part in. This extension increases the awareness of a SIP node by providing it with complete conference membership information, the ability to detect neighboring node failures, and the ability to automatically repair conference partitions. Signaling for conferencing was defined and integrated into a standard SIP implementation where it was used to demonstrate the above capabilities. Using a prototype implementation, the additional functionality was shown to come at the cost of a modest increase in transaction message size and processing complexity. IP multicast has limited deployment in today's networks reducing the usability of this useful feature. Since IP multicast support is not guaranteed, the use of application layer multicast protocols is proposed to replace the use of IP multicast. An efficient means of negotiating an application layer protocol is proposed as well as the ability to provide the protocol with session information to begin operation. A ring protocol was defined and implemented using the proposed extension. Performance testing revealed that the application layer protocol had slightly higher processing complexity than conferencing, but on average had a smaller transaction message size. / Master of Science

CU-SeeMe is a video conferencing software package that was designed and programmed at Cornell University. The program works with the TCP/IP network protocol and allows two or more parties to conduct a real-time video conference with full audio support. In this paper we evaluate CU-SeeMe through the process of Formative Evaluation. [3] [9] [16] [24] We first perform a Critical Review of the software using a subset of the Smith and Mosier Guidelines for HumanComputer Interaction. [23] Next, we empirically review the software interface through a series of benchmark tests [3] that are derived directly from a set of scenarios. The scenarios attempt to model real world situations that might be encountered by an individual in the target user class. Designing benchmark tasks becomes a natural and straightforward process when they are derived from the scenario set. Empirical measures are taken for each task, including completion times and error counts. These measures are accompanied by critical incident analysis [2] [7] [13] which serves to identify problems with the interface and the cognitive roots of those problems. The critical incidents reported by participants are accompanied by explanations of what caused the problem and why. This helps in the process of formulating solutions for observed usability problems. All the testing results are combined in the Appendix in an illustrated partial redesign of the CU-SeeMe interface. / Master of Science

Recent research has suggested that building personal relationships with students and establishing "learning communities" may be one way to encourage students to persist in their studies beyond the first year. Because many institutions require students to complete one or more writing courses early in their careers, first-year composition instructors have the opportunity to interact with students as they first attempt to assimilate into the academic culture. Response activities--one of the key ways writing instructors interact with their students and ask their students to engage with one another--can be a be a way to both facilitate effective revision and foster a sense of community among students. Group conferencing, defined in this study as a meeting between an instructor and a small group of students in which the participants receive feedback on drafts from their group members and instructor simultaneously, is a promising strategy for achieving those goals effectively and efficiently. The purpose of this study was to use a teacher research/participant-observer methodology to examine group conferencing more expansively and thoroughly than previous researchers and depicting a broader range of the behaviors that characterized the conferences and including the students' perception of the activity. In order to achieve these aims, a group of eighteen first-year composition students participated in individual conferences, in-class peer response, and group conferences and completed reflective assignments about each activity's effectiveness. Recordings of the group conferences were reviewed for significant behavioral patterns and the students' written responses were analyzed for indications of positive and negative reactions to group conferencing. The results included many behaviors described by previous researchers as well as several additional behavioral patterns that indicated the activity could be an effective and unique feedback experience. Most notably, working side-by-side with the instructor seemed to enhance the quality of feedback the students were able to offer one another because the instructor was able to demonstrate appropriate response techniques, prompt for more detailed responses from the students, and reinforce the students' helpful contributions. The students' written responses indicated that they saw value in group conferencing and, in some cases, came to prefer it over other feedback activities. Further, the findings of this study suggest that group conferencing may provide opportunities for community-building not afforded by other response strategies.

This dissertation describes the successful implementation of a work group infrastructure to support electronic meetings. An exploratory study was undertaken to observe and document the broad range of activities necessary to implement an infrastructure for work groups in a field setting. Activities falling within the scope of this dissertation include the design of a set of work group software tools, the implementation of that software, the gathering of field data, and the interpretation of those data in reference to the software's impact. The dissertation also reports on the effects of the implementation on work group performance, group characteristics, task characteristics, and the technology itself. The final product of the study is a set of factors critical for the successful implementation of a work group infrastructure, including observations and insights related to facility design, software design, facilitation training, and management involvement.

This dissertation investigated the effects of group size, group member proximity and the interaction of these two variables on the performance of brainstorming groups in a synchronous, computer-mediated environment. A laboratory experiment was employed to manipulate the independent variables group size (4- and 8-member) group member proximity. Group member proximity was manipulated by allowing proximate groups to work in a single meeting room, while members of distributed group worked in separate rooms. The subjects, upper-level, undergraduate business students, were asked to identify and discuss all "people, groups and organizations" that would be affected by a proposed policy to require all undergraduate business students to have individual access to a personal computer. The computer-mediated brainstorming system allowed all group members to enter and share information simultaneously, as all communication was electronic. Group performance was assessed by counting the total number of unique solutions generated and by the sum of expert rated quality scores for each unique solution. Groups in all conditions contributed approximately the same number of comments and felt equally satisfied. Contrary to an ample body of noncomputer-mediated brainstorming research, large groups were more productive than small groups for both idea quantity and quality. Small groups were, however, more productive than large groups on a per person basis, as increased group size yielded diminishing returns. Remote groups were more productive than proximate groups. Group researchers have found that group interaction produces productivity gains and losses, each of which increase in strength as the group size increases. This research found group productivity losses for computer-mediated brainstorming to be relatively constant, as the technology mitigated productivity inhibitors in conditions where prior noncomputer-mediated research has found these losses to increase (i.e., larger groups).

Fu, Zhengjia. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 64-70 ). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Design for group network communication --- p.6 / Chapter 2.1 --- Performance metrics of network Voice Conference: GMOS --- p.7 / Chapter 2.2 --- Conference Leader Selection strategies --- p.11 / Chapter 2.3 --- Experiment Description --- p.14 / Chapter 2.4 --- Data analysis and results --- p.16 / Chapter 2.5 --- Applications of Proposals to Voice Conference --- p.25 / Chapter 3 --- P2P Application Identification --- p.27 / Chapter 3.1 --- Periodic Group Communication Patterns --- p.28 / Chapter 3.1.1 --- Terminology for Behavioral Patterns --- p.29 / Chapter 3.1.2 --- Pattern 1: Gossip of Buffer Maps --- p.30 / Chapter 3.1.3 --- Pattern 2: Content flow control --- p.31 / Chapter 3.1.4 --- Pattern 3: Synchronized Link Activation and Deactivation --- p.32 / Chapter 3.2 --- Identification Based on behavioral signatures --- p.33 / Chapter 3.2.1 --- Algorithm Overview --- p.34 / Chapter 3.2.2 --- Sequence Generation (SG1): Time Series for the Gossip Pattern --- p.36 / Chapter 3.2.3 --- Transform Time-domain Sequence to Frequency-domain Sequence --- p.36 / Chapter 3.2.4 --- Sequence Generation (SG2): Time Series for Content Flow Control Pattern --- p.40 / Chapter 3.2.5 --- Sequence Generation (SG3): Time Series for Synchronized Start and Finish of Flows --- p.41 / Chapter 3.2.6 --- Analyzer step --- p.47 / Chapter 3.3 --- Behavioral signatures of popular P2P applications --- p.47 / Chapter 3.4 --- Experiment Results --- p.49 / Chapter 3.5 --- Discussion --- p.52 / Chapter 4 --- Related Work --- p.58 / Chapter 5 --- Conclusion --- p.62 / Bibliography --- p.64

A long-term care resident sits in front of a TV. With the push of a remote control button she instantly sees and visits with her children and grandchildren over 500 miles away. She last saw them on her 80th birthday, four years ago. She and her family are participants in a social action inquiry that explores video conferencing in order to understand the value of technology enhanced face-to-face interaction in a long-term care home. <p>This research, designed as a compassionate response to the serious problems of isolation, loneliness, helplessness, and boredom in long-term care, set out to determine what video conferencing can mean to long-term care residents and to the people they connect with. The study queried possibilities for improving the quality of social interactions of residents in long-term care facilities with family members living at some considerable distance from them. It involved setup of technical equipment, then three residents in a long-term care facility in western Canada were introduced to the practice of video conferencing with their families. Each conferencing event was supported with volunteers for a three-four month exploration period. <p>The research was intended to contribute to knowledge about learning in later life, to promote a way of increasing communication between the elderly and younger generations, and to address issues associated with elderly long-term care residents access to video conferencing technology. <p>Data collected through memory logs, observations, and interviews indicates that all study participants, including residents, family, and volunteers, responded favourably to the video conferencing experience. This study supports the claims that video conferencing can increase the frequency of contact between long-term residents and family members, and that the quality of this contact is enhanced through the visual presence and engagement of participants, through use of video conferencing technology. The video conferencing enabled family members separated by distance and unable to visit frequently to take on a "regular visitor role" and for residents to go visiting. The visually enhanced communication / visits transformed the otherwise limited audio interaction of phone calls or no interaction into socially substantive experiences of connectedness, inclusion about which residents reported feeling excited and connected with something to look forward to. <p>This suggests video conferencing could contribute to a good quality of life for residents. Future communications infrastructures should seriously consider inclusion strategies and availability of effective applications to long-term care residents.

A long-term care resident sits in front of a TV. With the push of a remote control button she instantly sees and visits with her children and grandchildren over 500 miles away. She last saw them on her 80th birthday, four years ago. She and her family are participants in a social action inquiry that explores video conferencing in order to understand the value of technology enhanced face-to-face interaction in a long-term care home. <p>This research, designed as a compassionate response to the serious problems of isolation, loneliness, helplessness, and boredom in long-term care, set out to determine what video conferencing can mean to long-term care residents and to the people they connect with. The study queried possibilities for improving the quality of social interactions of residents in long-term care facilities with family members living at some considerable distance from them. It involved setup of technical equipment, then three residents in a long-term care facility in western Canada were introduced to the practice of video conferencing with their families. Each conferencing event was supported with volunteers for a three-four month exploration period. <p>The research was intended to contribute to knowledge about learning in later life, to promote a way of increasing communication between the elderly and younger generations, and to address issues associated with elderly long-term care residents access to video conferencing technology. <p>Data collected through memory logs, observations, and interviews indicates that all study participants, including residents, family, and volunteers, responded favourably to the video conferencing experience. This study supports the claims that video conferencing can increase the frequency of contact between long-term residents and family members, and that the quality of this contact is enhanced through the visual presence and engagement of participants, through use of video conferencing technology. The video conferencing enabled family members separated by distance and unable to visit frequently to take on a "regular visitor role" and for residents to go visiting. The visually enhanced communication / visits transformed the otherwise limited audio interaction of phone calls or no interaction into socially substantive experiences of connectedness, inclusion about which residents reported feeling excited and connected with something to look forward to. <p>This suggests video conferencing could contribute to a good quality of life for residents. Future communications infrastructures should seriously consider inclusion strategies and availability of effective applications to long-term care residents.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 135-142). Available also in a digital version from Dissertation Abstracts.