Many real-time systems demand effective and efficient delay-guaranteed services to meet timing requirements of their applications. We note that a system provides a delay-guaranteed service if the system can ensure that each task will meet its predefined end-to-end deadline. Admission control plays a critical role in providing delayguaranteed services. The major function of admission control is to determine admissibility of a new task. A new task will be admitted into the system if the deadline of all existing tasks and the new task can be met. Admission control has to be efficient and efficient, meaning that a decision should be made quickly while admitting the maximum number of tasks. In this dissertation, we study a utilization-based admission control mechanism. Utilization-based admission control makes an admission decision based on a simple resource utilization test: A task will be admitted if the resource utilization is lower than a pre-derived safe resource utilization bound. The challenge of obtaining a safe resource utilization bound is how to perform delay analysis offline, which is the main focus of this dissertation. For this, we develop utilization-based delay guarantee techniques to render utilization-based admission control both efficient and effective, which is further confirmed with our data. We develop techniques for several systems that are of practical importance. We first consider wired networks with the Differentiated Services model, which is wellknown as its supporting scalable services in computer networks. We consider both cases of providing deterministic and statistical delay-guaranteed services in wired networks with the Differentiated Services model. We will then extend our work to wireless networks, which have become popular for both civilian and mission critical applications. The variable service capacity of a wireless link presents more of a challenge in providing delay-guaranteed services in wireless networks. Finally, we study ways to provide delayguaranteed services in component-based systems, which now serve as an important platform for developing a new generation of computer software. We show that with our utilization-based delay guarantee technique, component-based systems can provide efficient and effective delay-guaranteed services while maintaining such advantages as the reusability of components.

In this thesis, we proposed a call admission control algorithm (CAC) and an adaptive allocation of resource algorithm (AAR) for 3G wireless multimedia data transmission. The proposed CAC algorithm uses a measurement-based method by measuring real-time network load to modulate the parameters of the CAC algorithm and to decide whether to accept a call or not. When a call is admitted, the proposed AAR algorithm uses a low complexity algorithm to adaptively allocate bandwidth for the call to improve resource utilization. Taking advantages of the proposed CAC and AAR algorithms, the desired quality of service (QoS) can be maintained, the call forced termination probabilities can be reduced, and the call completion probabilities can be increased. In addition, there are a variety of types of data in 3G wireless communication networks. To set a proper priority for different data to maintain a desired QoS is important. Therefore, we also proposed a scheme to set priority for each call. On the basis of this scheme, simulation results show that the proposed CAC algorithm and the AAR algorithm can forward the call with higher priority to get relative higher QoS, and guarantee that an emergency call can go through and complete at any time in a normal situation.

M. Tech. Public Management / Granting admission to students using various entrance requirements in Further Education and Training (FET) colleges presents a huge challenge. The criteria have proved to be inadequate to meet this challenge. According to the Department of Higher Education and Training, the aim is to develop economies of scale and create capacity within colleges, to reach more students and offer a wide range of programmes, thereby positioning them to meet social and economic demands. However, the challenge still exists. The demand to produce skilled youth is escalating rapidly, hence some students opt to further their studies at FET colleges even if they have completed grade 12 and when, on completion, they will receive the same National Qualification Framework (NQF) level 4 certificates. The study is aimed at investigating the effects of using various admission requirements at FET Colleges, as well as to recommend measures which could be taken to overcome the challenges.

published_or_final_version / Language Studies / Master / Master of Arts

No description available.

In recent years, wireless mesh networking has attracted a growing interest due to its inherent flexibility, scalability, and reliability. The IEEE 802.16 standard, commonly known as worldwide interoperability for microwave access (WiMAX), is the latest technology that enables broadband wireless access over long distances. WiMAX, which emerges as a wireless alternative to cable and digital subscriber line (DSL), is an ideal candidate to serve as the infrastructure for large scale wireless mesh networks. This thesis focuses on the quality of service (QoS) provisioning techniques in WiMAX-based metropolitan area mesh networks. We study the connection admission control (CAC) and routing issues in the design and operation of wireless multihop mesh networks. We propose a joint CAC and routing scheme for multiple service classes with the objective to maximize the overall revenue from all carried connections. Connection-level QoS constraints such as handoff connection dropping probability can be guaranteed within a threshold. Multiple service classes can be prioritized by imposing different reward rates. We apply optimization techniques to obtain the optimal CAC policies. The optimality criterion is the long-run average reward. We demonstrate that the proposed scheme can the maximum revenue obtainable by the system under QoS constraints. We show that the optimal joint policy is a randomized policy, i.e., connections are admitted to the system with some probabilities when the system is in certain states. Simulation results illustrate that the proposed scheme meets our design goals and outperforms the existing scheme.

To meet growing demand for wireless access to multimedia traffic, future generations of wireless networks need to provide heterogenous services with high data rate and guaranteed quality-of-service (QoS). Many enabling technologies to ensure QoS have been investigated, including cross-layer admission control (AC), error control and congestion control. In this thesis, we study the cross-layer AC problem. While previous research focuses on single-antenna systems, which does not capitalize on the significant benefits provided by multiple antenna systems, in this thesis we investigate cross-layer AC policy for a code-division-multiple-access (CDMA) system with antenna arrays at the base station (BS). Automatic retransmission request (ARQ) schemes are also exploited to further improve the spectral efficiency. In the first part, a circuit-switched network is considered and an exact outage probability is developed, which is then employed to derive the optimal call admission control (CAC) policy by formulating a constrained semi-Markov decision process (SMDP). The derived optimal policy can maximize the system throughput with guaranteed QoS requirements in both physical and network layers. In the second part, a suboptimal low-complexity CAC policy is proposed based on an approximate power control feasibility condition (PCFC) and a reduced-outage-probability algorithm. Comparison between optimal and suboptimal CAC policies shows that the suboptimal CAC policy can significantly reduce the computational complexity at a cost of degraded performance. In the third part, we extend the above research to packet-switched networks. A novel SMDP is formulated by incorporating ARQ protocols. Packet-level AC policies are then proposed. The proposed policies exploit the error control capability provided by ARQ schemes, while simultaneously guaranteeing QoS requirements in the physical and packet levels. In the fourth part, we propose a connection admission control policy in a connection-oriented packet-switched network, which can guarantee QoS requirements in physical, packet and connection levels. By considering joint optimization across different layers, the proposed optimal policy provides a flexible way to handle multiple QoS requirements, while at the same time, maximizing the overall system throughput. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2008-08-05 16:21:40.431

The purpose of this study was to explore the experiences and needs of families during the admission of a child to a paediatric ward in an acute care hospital. Qualitative research methods were used to access the caregivers' and professionals' perceptions of the culture that families experience in a paediatric in-patient setting. For this project, data collection methods included a review of the literature in the area, individual interviews with caregivers, and focus groups with paediatric health care professionals. / In the study, both parents and paediatric professionals described a multitude of experiences and needs of families during a child's admission to a paediatric ward in an acute care setting. Understanding the experiences and needs of families is important for professionals. The information collected in this study provides some insight into the culture that families experience when their child is admitted to a paediatric ward in an acute care hospital.

A common feature of colleges of education in Transkei in the early nineties was the crisis during the admissions period. This study investigated the extent to which factors such as nepotism, political interference, ethnicity and others affected admissions to colleges of education in Transkei in 1995. Random samples of student-teachers, lecturers, rectors and community members of selected colleges of education were drawn from target populations of all Course I student-teachers, all lecturers of 14 colleges, all rectors of colleges of education, and communities of all 14 colleges of education in Transkei. Thus, samples of 313 student teachers, 100 lecturers, 35 members of community and all seven rectors of colleges were studied. Both quantitative and qualitative research techniques were used to collect data. In this study questionnaires were used to collect information from student teachers and lecturers, interviews were conducted with rectors and community members to obtain the necessary data. Data analysis, using the Statistical Analysis System (SAS) computer package revealed the following: 1. It was found that contradictions and ambiguities existed in the admission guidelines and procedures. It was also discovered that there were discrepancies between guidelines and practices in admission to colleges of education. These could be avoided if all stakeholders were involved in policy formulation thereby ensuring that no one member could be accused for admission problems. 2. The applicants and communities perceived that the right to demand access to colleges of education also contributed to the problem of admissions. 3. It was found that the automatic bursary allocation to student teachers greatly contributed to the admission crisis. 4. Factors such as nepotism, ethnicity and bribery also contributed to the crisis. 5. Other findings related to the perception that teaching was an easier option than other careers, and this also contributed to the crisis. 6. A surprising finding was that respondents did not perceive political influence to have significantly affected the admission procedures in colleges of education in Transkei. From the findings, a conclusion was drawn that the problems of admissions and registration in colleges of education were aggravated by the contradictory policies of the Affiliated Colleges Board (ACB) and the Department malpractices by college authorities, and by community pressure. Thus, the major stakeholders in the colleges, namely, rectors, lecturers and prospective student-teachers were to blame for the crisis. Based on the above conclusion, recommendations were given as follows : 1. Community members, student-teachers, lecturers and rectors should be involved in policy formulation concerning admissions. 2. The autonomy for colleges of education can be the aim so as to avoid dual control on crucial matters of college governance, such as student admission and registration. 3. Admission requirements should be upgraded to ensure that only adequately qualified candidates apply for admission. 4. Central admission be utilised in order to minimize corruption in the students' admission and registration processes. 5. In view of the finding that availability of funding through the bursary scheme influenced potential trainees to seek admission to colleges of education, the bursary system, as was in force in 1995, be phased out in favour of a loan scheme. The rationale for this being that only candidates who have an interest in a teaching career would apply for admission. 6. A recommendation for further research is that a similar study should be conducted in other parts of South Africa in order to determine how other colleges conducted their admissions and avoided the problems identified in this study. / Thesis (M.Ed) - University of Natal, Pietermaritzburg, 1997.

In recent years, wireless mesh networking has attracted a growing interest due to its inherent flexibility, scalability, and reliability. The IEEE 802.16 standard, commonly known as worldwide interoperability for microwave access (WiMAX), is the latest technology that enables broadband wireless access over long distances. WiMAX, which emerges as a wireless alternative to cable and digital subscriber line (DSL), is an ideal candidate to serve as the infrastructure for large scale wireless mesh networks. This thesis focuses on the quality of service (QoS) provisioning techniques in WiMAX-based metropolitan area mesh networks. We study the connection admission control (CAC) and routing issues in the design and operation of wireless multihop mesh networks. We propose a joint CAC and routing scheme for multiple service classes with the objective to maximize the overall revenue from all carried connections. Connection-level QoS constraints such as handoff connection dropping probability can be guaranteed within a threshold. Multiple service classes can be prioritized by imposing different reward rates. We apply optimization techniques to obtain the optimal CAC policies. The optimality criterion is the long-run average reward. We demonstrate that the proposed scheme can the maximum revenue obtainable by the system under QoS constraints. We show that the optimal joint policy is a randomized policy, i.e., connections are admitted to the system with some probabilities when the system is in certain states. Simulation results illustrate that the proposed scheme meets our design goals and outperforms the existing scheme.