Gemeinsamer Workshop von Universitaetsrechenzentrum und Professur Rechnernetze und verteilte Systeme (Fakultaet fuer Informatik) der TU Chemnitz. Workshop-Thema: Infrastruktur der ¨Digitalen Universitaet¨ Der Vortrag zeigt Grundlagen und aktuelle Entwicklungen auf dem Gebiet der IP-Telephony sowie Arbeiten des Autors an der TU Darmstadt zu diesem Gebiet.

Thesis (Ph. D.)--School of Electrical and Computer Engineering, Georgia Institute of Technology, 2004. Directed by Mark Clements. / Vita. Includes bibliographical references (leaves 97-100).

With frequency selective fading, the SNRs of each sub-carrier would vary over the time and frequency. It would then cause fluctuations of the effective SNR. As the decision of MeS in LA is based on the effective SNR, the study of the statistical characterization of effective SNR over frequency selective fading channels would be very important, This problem forms the basis of investigation in this thesis. The methodology used in this thesis is generally divided into two parts. The first part is to investigate the method in obtaining the distribution of EESM over frequency selective fading channels. Such approach will be very helpful for the second part of the work which is to obtain the exact distribution of the EESM effective SNR for a specified fading model. In this case, Nakagami-m fading model is used. The choice of this model is based due to its simplicity and experimental consistency. One of the important features of the distribution is that the SNR of a signal under Nakagami fading is gamma distributed. Thus, in performance evaluation involving Nakagami fading, one can often rely on established results (in the statistics literature) of the gamma distribution. An important special case of the Nakagami distribution is the Rayleigh distribution, which arises in the situation of where the line-of-sight (LOS) component between the transmitter and the receiver is absent, i.e., when all of the received power stems from scattered components. The corresponding distribution for the SNR is the exponential distribution. The research in this thesis represents an effort to provide a statistical characterization of EESM effective SNR which has not appeared in any existing literatures. The goals of this thesis is to Characterize the statistics of EESM effective SNR over frequency selective channels. Obtain the distribution of EESM effective SNR over correlated Nakagami-m fading channels. Theoretically analyze the performance (Le. average SNR, outage probability and Symbol Error Rate (SER) etc.) of EESM over correlated Nakagami-m fading channels. Provide simple approximations to the proposed analytical results. Try to find extension and application of the results.

M. Tech. Electrical Engineering. / A virtual Mobile Voice over IP (MVoIP) service can be implemented by a Mobile VoIP Operator (MVoIPO) in conjunction with a Mobile Network Operator (MNO). MVoIPOs do not operate their own mobile network infrastructure. Instead, they use the MNO's packet-based cellular network. However, the coexistence between the MVoIPO and the MNO raises two related problems: first, how to handle interconnection settlements, and second, how to (inter)connect the two operators to make such settlements. This dissertation uses a game-theoretic modelling approach to show that it is mutually beneficial economically if the MNO allows the MVoIPO to operate on its network. Further, a Service Level Agreement (SLA)-based Transparent Settlement Agreement (TSA) model is proposed to solve the first problem. The TSA model algorithm calculates the MVoIPO's throughput distribution at the edge of a UMTS Core Network (CN). This facilitates the determination of levels of conformance to the pre-set throughput thresholds and, subsequently, the issuing of compensation to the MVoIPO by the MNO after generating an economically acceptable volume of traffic. Further, possible network architecture to solve the second problem is suggested, by combining the TSA model algorithm, the UMTS CN, the IP Multimedia Subsystem (IMS), and the Online Charging System (OCS)

M. Tech. Electrical Engineering. / Proposes a voice and video service that uses context-awareness and Semantic Web technologies to restrict network access to non-privileged users during crisis situations. The laboratory tests show how the service takes over call adission control from the SIP server, rejects non-privileged calls and drops non-privileged ongoing call sessions. OPNet simulations further show how to proposed service improves network performance based on performance parameters such as end-to-end delay time and throughput.

Det militära sambandssystemet RA180 börjar bli föråldrat samtidigt som mobiltelefoni utvecklas snabbt. Systemen skiljer sig från varandra ur flera aspekter, men den allmänna färdigheten i att använda mobiltelefoni ger fördelar för militärt samband. Tidigare forskning har visat att det finns en del brister hos mobiltelefoni, men hur dessa brister förhåller sig till ett sambandssystem som redan används av Försvarsmakten finns inte att studera. Den här uppsatsen syftar till att undersöka om det finns någon militär nytta av att använda mobiltelefoni för samband, istället för RA180. För att göra det görs en systemanalys där systemen jämförs och värderas sinsemellan. I uppsatsen framkommer flera av de möjligheter som finns om mobiltelefoni används som sambandssystem och en av de största är att systemet har en högre tillgänglighet tack vare den befintliga infrastrukturen. Mobiltelefoni har en lägre militär nytta än RA180 i ett specifikt scenario, men flera av de anledningar som gjorde den militära nyttan lägre finns det lösningar för. Kryptering är en av dessa och det finns alternativ som skulle höja säkerheten avsevärt hos mobiltelefoni. / The military communication system RA180 is aging while mobile telephony is evolving rapidly. These systems differ from each other in many aspects, but the overall skill in using a mobile phone offers benefits for military communication. Previous research has shown that there are some flaws in mobile telephony, but how these deficiencies relate to a communication system that is already in use by the Armed Forces have not been studied yet. This essay aims to investigate whether there is any military utility of using mobile telephony for the communication instead of RA180. A systems analysis, where the systems are compared and evaluated, will be implemented for this purpose. The essay reveals several opportunities available when mobile telephony is used as communication systems and one of the main potential is that the system has a higher availability due to the existing infrastructure. Mobile telephony has a lower military utility than RA180 in a specific scenario, but for several of the reasons that resulted in a lower military utility there are solutions. Encryption is one of these and there are options that would improve security significantly in mobile telephony.

Thesis (PhD.) -- Bond University, 2007. / "A dissertation submitted in fulfillment of the requirements for the degree of Doctor of Philosophy"-- t.p. Bibliography: leaves 219-242. Also available via the World Wide Web.

Thesis (PhD) - Swinburne University of Technology, Industrial Research Institute Swinburne - 2007. / Submitted for the degree of Doctor of Philosophy at the Industrial Research Institute Swinburne (IRIS), Swinburne University of Technology - 2007. Typescript. "August 2007". Includes bibliographical references (p. 256-270).

Thesis (M.Eng.) - Carleton University, 2005. / Includes bibliographical references (p. 114-118). Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of North Texas, Dec., 2007. / Title from title page display. Includes bibliographical references.