High levels of interference between satellite constellation systems, fading and shadowing are a major problem for the successful performance of communication systems using the allocated L/S frequency bands for Non-Geostationary Earth Orbit (NGEO) satellites. As free spectrum is nonexistent, new systems wishing to operate in this band must co-exist with other users, both satellite and terrestrial. This research is mainly concerned with two subjects. Firstly, band sharing between different systems Code Division Multiple Access (CDMA) and Time Division Multiple Access (TDMA) has been evaluated for maximizing capacity and optimising efficiency of using the spectrum available. For the case of widened channel bandwidth of the CDMA channel, the overlapping was tested under different degrees of channel overlap and different orders of filters. The best result shows that at the optimum degree of channel overlap, capacity increases by up to 21%. For the case of fixed channel bandwidth, the optimum overlapping between CDMA systems depends on the filtering Roll-off factor and achieves an improvement of the spectrum efficiency of up to 13.4%. Also, for a number of narrowband signal users sharing a CDMA channel, the best location of narrowband signals to share spectrum with a CDMA system was found to be at the edge of the CDMA channel. Simulation models have been constructed and developed which show the combination of DS- CDMA techniques, forward error correction (FEC) code techniques and satellite diversity with Rake receiver for improving performance of interference, fading and shadowing under different environments. Voice activity factor has been considered to reduce the effect of multiple access interference (MAI). The results have shown that satellite diversity has a significant effect on the system performance and satellite diversity gain achieves an improvement up to 6dB. Further improvements have been achieved by including concatenated codes to provide different BER for different services. Sharing the frequency band between a number of Low Earth Orbit (LEO) satellite constellation systems is feasible and very useful but only for a limited number of LEOS satellite CDMA based constellations. Furthermore, satellite diversity is an essential factor to achieve a satisfactory level of service availability, especially for urban and suburban environments.

Adaptive antenna array technology will undoubtedly form a vital part of third generation cellular systems owing to not only confining the radiated energy associated with a mobile to a small volume on the downlink but also reducing the interference due to cochannel users on the uplink. The objective of this thesis is to develop signal enhancement schemes for adaptive antenna arrays for the purpose of enhancing the quality and capacity of direct sequence code division multiple access (DS-CDMA) systems. Firstly, The signal enhancement scheme using a real symmetric array covariance matrix (RSACM) method was proposed. This proposed scheme is composed of a unitary and persymmetric transformation methods. A real symmetric array covariance matrix has the same Toeplitz-plus-Hankel matrix structure that is produced by almost total noiseless data sequence. The second proposed signal enhancement scheme consists of the rotation of signal subspace (RSS) and Toeplitz matrix approximation (TMA) methods. This proposed scheme improved the system performance by reducing the interference- plus-noise effect from the complex array covariance matrix of the pre-correlation received signal vector. The third proposed signal enhancement scheme is a modified linear signal estimator (MLSE) which involves the rank N approximation by reducing total noise eigenvalues (RANE) and TMA methods. The aim of this proposed scheme is to improve the system performance by effectively reducing the interference-plus-noise effect from the post-correlation received signal. Secondly, the computational complexity and the performance for all proposed signal enhancement schemes in this thesis are investigated and compared. The signal enhancement scheme using the RSS+TMA and MLSE methods was also proposed for a multi-rate and multicell DS-CDMA systems. The relative other-cell interference factor was analysed for a multicell condition. Finally, the performance of all proposed signal enhancement schemes is shown to be much better than that of no signal enhancement method under a single cell, multicell, single rate, and multirate conditions.

The access control mechanisms used in traditional security infrastructures, such as ACL and password applications, have been proven inadequate, inflexible, and difficult to apply in the Internet due to the incredible magnitude of today's Internet. Recently, research for expressing trust information in the digital world has been explored to be complementary to security mechanisms. This thesis deals with the access control for the resources provided over the Internet. On line digital content service is exemplary of such an application. In this work, we have concentrated on the idea of a trust management system, which was first proposed by Blaze et a1 in 1996, and we have proposed a general-purpose, application-independent Dynamic Distributed Trust Model (DDTM). In our DDTM, access rights are directly associated with a trust value. The trust values in this thesis are further classified into direct trust values, indirect trust values and trust authorization levels. We have calculated and expressed each type of the trust values as explicit numerical values. The core of this model is the recommendation-based trust model, organized as a Trust Delegation Tree (TDT), and the authorization delegation realized by delegation certificate chains. Moreover, the DDTM provides a distributed key-oriented certificate-issuing mechanism with no centralized global authority. A Dynamic Distributed Trust Protocol (DDTP) was developed as a general protocol for establishing and managing the trust relationship in a TDT structure. The protocol was verified by means of the verification tool, SPIN, and was prototyped to simulate communication and behaviors among the certificate issuer nodes on a TDT.

Master of Regional and Community Planning / Department of Landscape Architecture/Regional and Community Planning / Gregory L. Newmark / At Kansas State University, there is not an issue of opposition to public bus services. Instead, there is a perception that taking the bus is too complicated to figure out or cannot appropriately serve the community’s needs. This, combined with dependence and attachment to the automobile, caused local buses to become unpopular mode choices. Since the service is still relatively new, it has not been engrained into campus culture and ridership is very low. This study looked at the local bus system, ATA bus, used to access the Manhattan, KS campus of Kansas State University (KSU). According to the ATA Annual Report from 2014, 75% of off-campus students at KSU and 35% of employees live within five minutes of ATA city-wide routes (FHATA 2014). Ideally, all those students and employees would take the bus to class or work, but in reality, most walk or drive. A very small minority of students use the fixed route service, and many are unfamiliar with how the system works. A campus access survey distributed in March 2017 to the KSU community aimed to ascertain familiarity with the system, current level of use, as well as attitudes towards the existing public transportation system. The data recovered from the survey contradicts the hypothesis that the disuse of the bus system was due to an active opposition to public buses. Conversely, it pointed to the conclusion that disuse resulted from a lack of information about the bus service and a deep-set attachment to private automobiles. This research aimed to increase ridership by identifying attitudes towards transit among the KSU community and suggesting strategies for improving service.

M.Com. (Computer Auditing) / The management and control of modern day computer systems are becoming more and more trying due to the complexity of systems. This renders the traditional approach to evaluating controls in complex computer systems, inadequate and heightens the need for an alternative audit approach. The complex SAP R/3 environment will be evaluated in terms of security and validity of users and processes. This will be achieved through the use of an alternative audit approach namely, the application of the Access Path and Path Context Models (Boshoff 1985, 1990). The research methodology used during this research may indicate universal application implications for similar complex environments, although this has not yet been proved. The research showed that there are many control features available in the different software c.omponents of the SAP R/3 environment, that can be applied to control access and validity of users and processes. The duplication of control features provided by the software components, requires a global approach to security inthe defined environment. Only when evaluating the environment as a whole, will it be able to make the most effective security decisions. The use of the control matrices developed during this research will ease the global evaluation of the SAP R/3 environment. Although further research is required, the above has proven the usefulness of both the research methodology and the resultant model and matrices.

D.Phil. (Computer Science) / Security needs have changed considerably in the past decade as the economics of computer usage necessitates increased business reliance on computers. As more individuals need computers to perform their jobs, more detailed security controls are needed to offset the risk inherent in granting more people access to computer systems. Traditionally, computer security administrators have been tasked with configuring' , security systems by setting controls on the actions of users. This basically entails the compilation of access rules (contained in security profiles), which state who can access what resources in what way. The task of building these rules is of considerable magnitude and is in general not well understood. Adhoc approaches, characterized by exhaustive interviewing and endless printouts of organizational data repositories, are usually followed. In the end, too much is left to the discretion of the security administrators...

M.Comm.

Approved for public release; distribution is unlimited. / The Wideband Code Division Multiple Access is a third generation air interface, initiated in European Union research projects at the start of the 1990s. The standard emerged by the end of 1999 as part of the 3GPP standardization process. It was designed to support multiple simultaneous services with high quality services through an increased data rate. This research examines the properties and parameters of the WCDMA system to determine the feasibility of intercepting and exploiting this technology with known assets. It explores this possibility by looking at link analysis, adaptive antennas and co-channel interference canceling techniques to determine if the interception of WCDMA signals is possible. / Lieutenant Junior Grade, Hellenic Navy

In today’s business world, information has become the driving force of organizations. With organizations transmitting large amounts of information to various geographical locations, it is imperative that organizations ensure the protection of their valuable commodity. Organizations should ensure that only authorized individuals receive, view and alter the information. This is also true to Higher Education Institutions (HEIs), which need to protect its examination papers, amongst other valuable information. With various threats waiting to take advantage of the examination papers, HEIs need to be prepared by equipping themselves with an information security management system (ISMS), in order to ensure that the process of setting examination papers is secure, and protects the examination papers within the process. An ISMS will ensure that all information security aspects are considered and addressed in order to provide appropriate and adequate protection for the examination papers. With the assistance of information security concepts and information security principles, the ISMS can be developed, in order to secure the process of preparing examination papers; in order to protect the examination papers from potential risks. Risk assessment form part of the ISMS, and is at the centre of any security effort; reason being that to secure an information environment, knowing and understanding the risks is imperative. Risks pertaining to that particular environment need to be assessed in order to deal with those appropriately. In addition, very important to any security effort is ensuring that employees working with the valuable information are made aware of these risks, and can be able to protect the information. Therefore, the role players (within the examination paper preparation process (EPPP)) who handle the examination papers on a daily basis have to be equipped with means of handling valuable information in a secure manner. Some of the role players’ behaviour and practices while handling the information could be seen as vulnerabilities that could be exploited by threats, resulting in the compromise in the CIA of the information. Therefore, it is imperative that role players are made aware of their practices and iv behaviour that could result in a negative impact for the institution. This awareness forms part and is addressed in the ISMS.

Today, one is expected to remember multiple user names and passwords for different domains when one wants to access on the Internet. Identity management seeks to solve this problem through creating a digital identity that is exchangeable across organisational boundaries. Through the setup of collaboration agreements between multiple domains, users can easily switch across domains without being required to sign in again. However, use of this technology comes with risks of user identity and personal information being compromised. Criminals make use of spoofed websites and social engineering techniques to gain illegal access to user information. Due to this, the need for users to be protected from online threats has increased. Two processes are required to protect the user login information at the time of sign-on. Firstly, user’s information must be protected at the time of sign-on, and secondly, a simple method for the identification of the website is required by the user. This treatise looks at the process for identifying and verifying user information, and how the user can verify the system at sign-in. Three models for identity management are analysed, namely the Microsoft .NET Passport, Liberty Alliance Federated Identity for Single Sign-on and the Mozilla TrustBar for system authentication.