Thesis (M.S.)--University of Texas at Dallas, 2008. / Includes vita. Includes bibliographical references (leaves 57-60)

M.Comm. / Most modern and even not so modern businesses are currently investing in the hire or purchase of private access branch exchange (PABX) equipment. Usually the main concern is one of reduced costs to the company, since the internal calls between users on the same PABX are not routed via the public telecommunications operator (Telkom) and therefore free of charge [ James, 1997: 17 ]. Larger companies are experiencing the problem that their offices are distributed countrywide. They can install PABX equipment at each regional office, but this will only allow the employees within the regional office to communicate via internal calls. These organisationssoon realise the need for a voice network that provide them with the capability to communicate internally on a country-wide and in some cases, even a worldwide scale. A private voice network can be established by following two routes. If the company is relatively small and cannot afford its own transmission infrastructure in the form of openwire routes. coaxial cables. microwave routes, satellite routes and the associated multiplexers and flexible multiplexers. then they can lease transmission infrastructure from the public telecommunications operator (Telkom) and pay rental and other associated charges for usage thereof If the company can afford the capital investment in its own transmission infrastructure, it will be capable of communicating on a countrywide basis without relying on the service provided by the public telecommunications operator. In most cases, however, the latter option is illegal, due to regulatory protection of the national telecommunications operator. as stipulated by the telecommunications act (103/1996). In some cases, like the Transnet group, legislation requires the use of a private telecommunications network. The reason for this was that a major catastrophe in the transport industry might result due to problems with the telecommunications facilities. In that case, the public telecommunications operator would not accept any responsibility for the consequences of the break in communications. Transtel is the business unit that acts as a "private telecommunications operator" for the Transnet group . Transtel provides both voice and data communications to its clients within the Transnet group . In this case the main concern is not one of reduced costs, and therefore Transtel is implementing a tariff structure similar to that of the public telecommunications operator. The problem of providing voice communications between geographically distributed offices must be solved reliably and efficiently by the private voice network implemented by Transtel to serve the Transnet group. This implies that Transtel have the challenging responsibility to implement a managed voice network, in order to ensure better service levels than can be obtained from Telkom. The next problem that faces the private telecommunications operators for organisations with several business units and a plethora of departments, is that the costs for telecommunications facilities must be broken down into separate amounts per business unit and per department. This breakdown of costs must also reflect actual usage of the communications network and the billing systems must have the capability to generate detailed reports on network usage, as requested. In organisations like Transnet, where lower costs were not the primary objective of the private communications network, usage of the private network as well as usage of a combination of the private and public network, is being billed back to the department that uses the service. In short, the private telecommunications operator must rely on highly efficient and reliable billing systems to keep track of network costs and clients, since it operates as a separate business unit within the group and have to show a return on the investment on network technology [ Wasnick, 1998 : 26 ]. Inevitably, the private communications operator will need to ensure its clients of superior telecommunications services, and in many cases formal service level agreements will define the acceptable service level from the client's point of view. In order to place the private operator in a position to honour the service level agreements, its networks and especially its voice network must be managed by a global, integrated network management system. The network management system must be global in the sense that it manages all the resources in the voice network as well as resources in other networks that are utilised by the voice network. In order to facilitate optimal service levels, the network management system must be fully integrated with the rest of the operator's information technology infrastructure. It is, however, not enough to have a network management system in place that can cater for all the technical network management needs of the organisation. The organisational structure, management philosophies and business processes must also be adapted, in order to fully utilise the potential benefit of the technical network management functionality [ Sutherland, 1998 : 8 ]. A multi-faceted approach to voice network management will ensure that bi-directional information flow and a balance is established between the technical network side, the business side and the organisational structure, as depicted in Figure 1.1. A major disadvantage will be overcome by focusing on the total telecommunications environment, rather than emphasising the business environment, the technical environment or the organisation. No modern telecommunications operator will be able to survive in the highly competitive environment without a strong business focus integrated with technical excellence and supported by an appropriate organisation structure.

For integration between application-systems in a global context, interoperability needs to be established on a global level; global interoperability, in turn, is based on a global common application-interface. This is achieved through resolving differences in, inter alia, protocol profiles, among participants in the global network. ebXML is used as the point of departure. A messaging framework, which is based on existing Web technology and standards, is proposed. Certain security and Web service standards are examined to determine specific parameters for an interoperable secure messaging environment. A security based framework comprising a predefined message format and architecture is investigated for a secure interoperable global electronic marketspace.

Research shows how M-Commerce has managed to find its way to previously inaccessible parts of the world as a major Information and Communication Technologies (ICT) tool for development due to widespread introduction of mobile phones in remote areas. M-Commerce has offered valuable advantages: anytime, anywhere, more personal, more location-aware, more context-aware, more age aware, always online and instant connectivity. But this is not without its problems, of which security is high on the list. The security issues span the whole M-Commerce spectrum, from the top to the bottom layer of the OSI network protocol stack, from machines to humans. This research proposes a threat-mitigation modular framework to help address the security issues lurking in M-Commerce systems being used by marginalised rural community members. The research commences with a literature survey carried out to establish security aspects related to M-Commerce and to determine requirements for a security framework. The framework classifies M-Commerce security threat-vulnerability-risks into four levels: human behaviour and mobile device interaction security, mobile device security, M-Commerce access channel security, wireless network access security. This is followed by a review of the supporting structures or related frameworks that the proposed framework could leverage to address security issues on M-Commerce systems as ICT4D initiatives. The proposed security framework based on the requirements discovered is then presented. As a proof-of-concept, a case study was undertaken at the Siyakhula Living Lab at Dwesa in the Eastern Cape province of South Africa in order to validate the components of the proposed framework. Following the application of the framework in a case study, it can be argued that the proposed security framework allows for secure transacting by marginalised users using M-Commerce initiatives. The security framework is therefore useful in addressing the identified security requirements of M-Commerce in ICT4D contexts.

M.Ing. (Electrical and Electronic Engineering) / Since the beginning of telecommunications. more than 100 years ago, systems have been developed through a constant interaction between technical inventions. economic applications and the desire for improved communication facilities to such an extend that there is now a highly efficient communication network whichspans over the entire globe. The still growing demand for data communication. on conventional channels such ascoaxial cables and twisted pairs. made it necessary to develop systems which make use of line codes. In developing countries. like South-Africa. it is not economically feasible to change the existing analog systems to digital systems to enable data communications. In this study. we have done research into the possibility of combining ananalog speech signal with a digital data channel. Ideally the data channel should make use of line codes with low power contents at low frequencies. so that an analog speech channel can be inserted. Different coding methods were used to construct simple encoders and decoders which generate sequences with low power content at low frequencies. The experimental setup used in this thesis. showed that these new line codes exhibit low frequency suppression to such an extend that an analog speech channel can be inserted without the one interfering with the another.

This paper is a description of the analysis and testing of a method to estimate noise mixed in with a desired signal and to then subtract out the estimated noise. The paper documents the situation in which noise becomes a problem, the method of noise elimination, the mathematics used to analyze the noise eliminator, a digital/analog hybrid simulation of a system utilizing the techniques described, and comparative results between expected performance and actual system performance. Also described is the practicality of the system, the limitations of the system and its unique capabilities. Since the system is a totally new concept, it was being developed for the writing of this thesis. Therefore many changes were implemented with respect to the original design. These modifications are documented along with the reasons for the deviations from the original idea. Conclusions and a summary are provided. Several suggestions as to where the system would be beneficial are also supplied.

A technique for terminal communication through transmission links established across a wireless sensor network is developed and tested. Using protocols established for conventional wireless communication networks as a guiding principle, different methodologies for link management, and segmentation and reassembly of information are explored. A protocol for sensor network encapsulation was designed and implemented across a network of terminals and wireless sensor motes. The study concludes with a discussion of the capabilities and limitations of this technique supported by results obtained through experiments under various scenarios. / Singapore Army author.

by T.S. Chew. / Thesis (M.Sc.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references. / Chapter Chapter 1 --- Introduction / Chapter Chapter 2 --- Network Planning / Chapter 2.1 --- Routing Planning / Chapter 2.2 --- Junction Circuit Planning / Chapter 2.3 --- Signalling Network Planning / Chapter Chapter 3 --- System Architecture / Chapter 3.1 --- User Interface / Chapter 3.2 --- Control / Chapter 3.3 --- Design / Chapter Chapter 4 --- Network Creation / Chapter 4.1 --- Network Compilation / Chapter 4.2 --- Traffic Characteristics / Chapter Chapter 5 --- Network Design / Chapter 5.1 --- Routing Design / Chapter 5.2 --- Junction Circuit Design / Chapter 5.3 --- Signalling Network Design / Chapter Chapter 6 --- Program Description / Chapter Chapter 7 --- Design Example / Chapter Chapter 8 --- Conclusions / References / Chapter Appendix 1 - --- Erlang B Formula / Chapter Appendix 2 - --- Program Listing of NETPLAN / Chapter Appendix 3 - --- Design Example Results / Chapter 3.1 - --- Network Objects / Chapter 3.2 - --- Network Configuration / Chapter 3.3 - --- Network Design Result with No. of Paths =1

Lu Guowei. / "January 2005." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

This thesis reports on an investigation into the teletraffic modelling and performance of layered cellular networks that use overflow for new call and handover attempts in order to improve system performance It addresses the important problems how to model and analyse overflow in large cellular networks so that the overall impact across the network can be evaluated, the overflow policies that can be used with new calls and handovers to improve network performance and how these policies perform under a range of conditions. The general problem of modelling overflow in cellular networks is considered at length and from this it is concluded that the use of overflow in existing schemes such as directed retry, reuse partitioning and overlaid cells can also be described by the simple concepts of intra and inter layer overflow Using these concepts the author formulates the problem of overflow in layered networks as a subset of the general problem of overflow with multiple overflow routes and restricted overflow. This leads to the derivation of the mean and variance of the overflow traffic from a cell with multiple handover routes and restricted handover from the two-dimensional birth death model of the system. These expressions for the mean and variance are used in conjunction with the Equivalent Random Theory and splitting formulae in the development of the Splitting Formula Method or SF Method. The accuracy of three splitting formulae and a simple Poisson approximation are investigated and compared with simulation. From this we conclude that the splitting formulae of Akimaru and Takahashi and Wallstrom provide the best overall result. This method is used to solve the general problem of multiple user classes for an example two layer network. This leads to conclusions on the complex relationship between cell capacity, the proportion of uses that can access the microcells and the proportion of users that can overflow from the microcell to the macrocell. The Modified Splitting Formula Method is an extension of the SF Method that includes handovers and overflow for handovers. A user perceived measure of the effect of new call and handover blocking described by the probability of call failure augments the Modified SF method. This is then used to analyse five new call overflow policies for a three layer network under conditions of extended handover, restrictions on handover for calls in cells at the edge of layers and spatial offset between the peak of the traffic demand and the cell layout. The results give new and valuable insight into the behaviour of layered cellular networks with overflow and the trade-offs in performance that exist when designing and operating these networks.