A Real-Time Communication Framework for Wireless Sensor Networks

Recent advances in miniaturization and low power design have led to a flurry of activity in wireless sensor networks. Sensor networks have different constraints than traditional wired networks. A wireless sensor network is a special network with large numbers of nodes equipped with embedded processors, sensors, and radios. These nodes collaborate to accomplish a common task such as environment monitoring or asset tracking. In many applications, sensor nodes will be deployed in an ad-hoc fashion without careful planning. They must organize themselves to form a multihop, wireless communication network. In sensor network environments, much research has been conducted in areas such as power consumption, self-organisation techniques, routing between the sensors, and the communication between the sensor and the sink. On the other hand, real-time communication with the Quality of Service (QoS) concept in wireless sensor networks is still an open research field. Most protocols either ignore real time or simply attempt to process as fast as possible and hope that this speed is sufficient to meet the deadline. However, the introduction of real-time communication has created additional challenges in this area. The sensor node spends most of its life routing packets from one node to another until the packet reaches the sink; therefore, the node functions as a small router most of the time. Since sensor networks deal with time-critical applications, it is often necessary for communication to meet real time constraints. However, research that deals with providing QoS guarantees for real-time traffic in sensor networks is still in its infancy.This thesis presents a real-time communication framework to provide quality of service in sensor networks environments. The proposed framework consists of four components: First, present an analytical model for implementing Priority Queuing (PQ) in a sensor node to calculate the queuing delay. The exact packet delay for corresponding classes is calculated. Further, the analytical results are validated through an extensive simulation study. Second, report on a novel analytical model based on a limited service polling discipline. The model is based on an M/D/1 queuing system (a special class of M/G/1 queuing systems), which takes into account two different classes of traffic in a sensor node. The proposed model implements two queues in a sensor node that are served in a round robin fashion. The exact queuing delay in a sensor node for corresponding classes is calculated. Then, the analytical results are validated through an extensive simulation study. Third, exhibit a novel packet delivery mechanism, namely the Multiple Level Stateless Protocol (MLSP), as a real-time protocol for sensor networks to guarantee the traffic in wireless sensor networks. MLSP improves the packet loss rate and the handling of holes in sensor network much better than its counterpart, MMSPEED. It also introduces the k-limited polling model for the first time. In addition, the whole sending packets dropped significantly compared to MMSPEED, which it leads to decrease the consumption power. Fourth, explain a new framework for moving data from the sink to the user, at a low cost and low power, using the Universal Mobile Telecommunication System (UMTS), which is standard for the Third Generation Mobile System (3G). The integration of sensor networks with the 3G mobile network infrastructure will reduce the cost of building new infrastructures and enable the large-scale deployment of sensor network

A Unified Mobility Management Architecture for Interworked Heterogeneous Mobile Networks

The buzzword of this decade has been convergence: the convergence of telecommunications, Internet, entertainment, and information technologies for the seamless provisioning of multimedia services across different network types. Thus the future Next Generation Mobile Network (NGMN) can be envisioned as a group of co-existing heterogeneous mobile data networking technologies sharing a common Internet Protocol (IP) based backbone. In such all-IP based heterogeneous networking environments, ongoing sessions from roaming users are subjected to frequent vertical handoffs across network boundaries. Therefore, ensuring uninterrupted service continuity during session handoffs requires successful mobility and session management mechanisms to be implemented in these participating access networks. Therefore, it is essential for a common interworking framework to be in place for ensuring seamless service continuity over dissimilar networks to enable a potential user to freely roam from one network to another. For the best of our knowledge, the need for a suitable unified mobility and session management framework for the NGMN has not been successfully addressed as yet. This can be seen as the primary motivation of this research. Therefore, the key objectives of this thesis can be stated as: To propose a mobility-aware novel architecture for interworking between heterogeneous mobile data networks To propose a framework for facilitating unified real-time session management (inclusive of session establishment and seamless session handoff) across these different networks. In order to achieve the above goals, an interworking architecture is designed by incorporating the IP Multimedia Subsystem (IMS) as the coupling mediator between dissipate mobile data networking technologies. Subsequently, two different mobility management frameworks are proposed and implemented over the initial interworking architectural design. The first mobility management framework is fully handled by the IMS at the Application Layer. This framework is primarily dependant on the IMS’s default session management protocol, which is the Session Initiation Protocol (SIP). The second framework is a combined method based on SIP and the Mobile IP (MIP) protocols, which is essentially operated at the Network Layer. An analytical model is derived for evaluating the proposed scheme for analyzing the network Quality of Service (QoS) metrics and measures involved in session mobility management for the proposed mobility management frameworks. More precisely, these analyzed QoS metrics include vertical handoff delay, transient packet loss, jitter, and signaling overhead/cost. The results of the QoS analysis indicates that a MIP-SIP based mobility management framework performs better than its predecessor, the Pure-SIP based mobility management method. Also, the analysis results indicate that the QoS performances for the investigated parameters are within acceptable levels for real-time VoIP conversations. An OPNET based simulation platform is also used for modeling the proposed mobility management frameworks. All simulated scenarios prove to be capable of performing successful VoIP session handoffs between dissimilar networks whilst maintaining acceptable QoS levels. Lastly, based on the findings, the contributions made by this thesis can be summarized as: The development of a novel framework for interworked heterogeneous mobile data networks in a NGMN environment. The final design conveniently enables 3G cellular technologies (such as the Universal Mobile Telecommunications Systems (UMTS) or Code Division Multiple Access 2000 (CDMA2000) type systems), Wireless Local Area Networking (WLAN) technologies, and Wireless Metropolitan Area Networking (WMAN) technologies (e.g., Broadband Wireless Access (BWA) systems such as WiMAX) to interwork under a common signaling platform. The introduction of a novel unified/centralized mobility and session management platform by exploiting the IMS as a universal coupling mediator for real-time session negotiation and management. This enables a roaming user to seamlessly handoff sessions between different heterogeneous networks. As secondary outcomes of this thesis, an analytical framework and an OPNET simulation framework are developed for analyzing vertical handoff performance. This OPNET simulation platform is suitable for commercial use

An investigation into the use of B-Nodes and state models for computer network technology and education

This thesis consists of a series of internationally published, peer reviewed, conference research papers and one journal paper. The papers evaluate and further develop two modelling methods for use in Information Technology (IT) design and for the educational and training needs of students within the area of computer and network technology. The IT age requires technical talent to fill positions such as network managers, web administrators, e-commerce consultants and network security experts as IT is changing rapidly, and this is placing considerable demands on higher educational institutions, both within Australia and internationally, to respond to these changes

Satellite Networks: Architectures, Applications, and Technologies

Since global satellite networks are moving to the forefront in enhancing the national and global information infrastructures due to communication satellites' unique networking characteristics, a workshop was organized to assess the progress made to date and chart the future. This workshop provided the forum to assess the current state-of-the-art, identify key issues, and highlight the emerging trends in the next-generation architectures, data protocol development, communication interoperability, and applications. Presentations on overview, state-of-the-art in research, development, deployment and applications and future trends on satellite networks are assembled

Models of Emergency Departments for Reducing Patient Waiting Times

In this paper, we apply both agent-based models and queuing models to investigate patient access and patient flow through emergency departments. The objective of this work is to gain insights into the comparative contributions and limitations of these complementary techniques, in their ability to contribute empirical input into healthcare policy and practice guidelines. The models were developed independently, with a view to compare their suitability to emergency department simulation. The current models implement relatively simple general scenarios, and rely on a combination of simulated and real data to simulate patient flow in a single emergency department or in multiple interacting emergency departments. In addition, several concepts from telecommunications engineering are translated into this modeling context. The framework of multiple-priority queue systems and the genetic programming paradigm of evolutionary machine learning are applied as a means of forecasting patient wait times and as a means of evolving healthcare policy, respectively. The models' utility lies in their ability to provide qualitative insights into the relative sensitivities and impacts of model input parameters, to illuminate scenarios worthy of more complex investigation, and to iteratively validate the models as they continue to be refined and extended. The paper discusses future efforts to refine, extend, and validate the models with more data and real data relative to physical (spatial–topographical) and social inputs (staffing, patient care models, etc.). Real data obtained through proximity location and tracking system technologies is one example discussed

WLAN Protocol and Network Architecture Identification for Service Mix Applications

This paper proposes an algorithm approach to examine the impact of using different application services with various IEEE technologies in order to identify the optimum technology among different network architectures;Basic Service Set (BSS), Extended Service Set (ESS), and the Independent Basic Service Set (IBSS).Specifically, we utilize an algorithmic and mathematical scheme to allow user/client to analyse the optimum WLAN technology and network architecture‟s performance to be used for a given mix of internet applications configured across three spatial distributions (circular, uniform, random).Moreover, the proposed algorithm considers multi-criteria access network selection such as spatial distribution and number of nodes, hence to facilitate the provision of the best overall network performance and high-quality services. For further throughput enhancement, we adopt the Quality of Service (QoS) metrics for each application to develop a computational algorithm model to provide precise numerical results used to rank and identify the optimum overall performance‟s technologies. Our numerical results corroborate the analytical framework results and demonstrate the strength of the proposed algorithm

Virtualization of network I/O on modern operating systems

Network I/O of modern operating systems is incomplete. In this networkage, users and their applications are still unable to control theirown traffic, even on their local host. Network I/O is a sharedresource of a host machine, and traditionally, to address problemswith a shared resource, system research has virtualized the resource.Therefore, it is reasonable to ask if the virtualization can providesolutions to problems in network I/O of modern operating systems, inthe same way as the other components of computer systems, such asmemory and CPU. With the aim of establishing the virtualization ofnetwork I/O as a design principle of operating systems, thisdissertation first presents a virtualization model, hierarchicalvirtualization of network interface. Systematic evaluation illustratesthat the virtualization model possesses desirable properties forvirtualization of network I/O, namely flexible control granularity,resource protection, partitioning of resource consumption, properaccess control and generality as a control model. The implementedprototype exhibits practical performance with expected functionality,and allowed flexible and dynamic network control by users andapplications, unlike existing systems designed solely for systemadministrators. However, because the implementation was hardcoded inkernel source code, the prototype was not perfect in its functionalcoverage and flexibility. Accordingly, this dissertation investigatedhow to decouple OS kernels and packet processing code throughvirtualization, and studied three degrees of code virtualization,namely, limited virtualization, partial virtualization, and completevirtualization. In this process, a novel programming model waspresented, based on embedded Java technology, and the prototypeimplementation exhibited the following characteristics, which aredesirable for network code virtualization. First, users program inJava to carry out safe and simple programming for packetprocessing. Second, anyone, even untrusted applications, can performinjection of packet processing code in the kernel, due to isolation ofcode execution. Third, the prototype implementation empirically provedthat such a virtualization does not jeopardize system performance.These cases illustrate advantages of virtualization, and suggest thatthe hierarchical virtualization of network interfaces can be aneffective solution to problems in network I/O of modern operatingsystems, both in the control model and in implementation

Improvement of outpatient service processes based on BRP theory and information technology: a case study of the University of Hong Kong-Shenzhen Hospital

JEL Classification: M15 – IT Management, I12 – Health ProductionCurrently, due to some irrational allocation of medical and healthcare resources, a considerable proportion of state-of-the-art medical equipment and talented medical personnel are concentrated in large urban hospitals. This situation is particularly common in 3A hospitals (3A hospitals are hospitals which are equipped with more than 501 beds, can provide medical and healthcare services with high-level specialty to various regions and with scores higher than 900 according to the grading standard), which are often crowded with patients. According to the normal outpatient process, patients need to undergo a prolonged procedure from registration, treatment, laboratory test, diagnosis to drug dispensing. Often patients have to spend a long time waiting for treatment, receiving tests and paying for medical care. The congestion of patients at certain time-consuming processes allows doctors little time to check and treat patients thoroughly. As a result, doctors are often unable to make accurate and comprehensive diagnosis. Considered the window of a hospital, outpatient service is extremely important. Whether the design of its process is reasonable and whether its management is able to maximize interests for patients will directly affect the hospital’s medical level, and even its social benefits and reputation. Therefore, it has become a major issue for a hospital achieves to optimize the business process of its outpatient service. Outpatient process, as a core business process of a hospital, is critical to improving the quality of its medical service, upgrading its performance and minimizing its operating costs. Therefore, re-designing the outpatient process of a hospital can help enhance its comprehensive strength by endowing it with a core competence. In addition, the hospital will be impelled to provide patients with more convenient medical services with higher quality and lower price. This work conducts a case study on The University of Hong Kong-Shenzhen Hospital (HKU-SZH), which was the first to implement an outpatient appointment registration system. This thesis gives an anatomy of the outpatient process of the hospital through various methods and theories, such as literature review, field research, expert consultation, Business Process Reengineering Theory and Information technology, aiming to identify objectives and strategies of the case hospital in improving its outpatient process. The study consists of: - An investigation into the current situation of HKU-SZH’s outpatient registration process: through questionnaires and structured interviews, the defects and weak links in the hospital’s appointment registration model were analyzed. A structural equation model for existing outpatient processes was established and the influence of different variables on patients’ satisfaction level as well as the correlation between these variables was analyzed by means of a simulation model. - Research on outpatient process reengineering: with the needs and satisfaction of patients as a goal, this thesis reexamines the strategic goals and internal and external environment of HKU-SZH on the basis of Business Process Reengineering Theory, Queuing Theory, Six Sigma Theory and Information technology. This thesis improves HKU-SZH’s registration process, using methods of order modification, integration, simplification and automation and materializes the process by network technology and outpatient information system. - An empirical study on outpatient process: this thesis conducts a systemic and empirical analysis in a functional integration of registration and payment, process reengineering research through information technology (development of new functions of appointment system) and an empirical study on queuing theory. - Research on local adaptation of outpatient process: this thesis explores solutions and suggestions for HKU-SZH with the objective of optimize its outpatient process through the perspectives of hospital organizational structure, information technology, human resources, building of outpatient culture and optimization of waiting cost. By means of outpatient process reengineering, this thesis aim to increase the case hospital’s efficiency and raise its patients’ satisfaction so that the hospital may enhance its comprehensive competence. In addition, an effective and operable methodology will be generated, which is expected to serve as a reference for other hospitals to improve their operation and their management.Atualmente, devido a alguma atribuição irracional dos recursos médicos e de saúde, uma proporção considerável de modernos equipamentos médicos e pessoal médico talentoso estão concentrados em grandes hospitais urbanos. Esta situação é particularmente comum em hospitais 3A (hospitais 3A são os hospitais que estão equipados com mais de 501 camas, e que podem fornecer serviços médicos e de saúde com alto nível de especialidade para diversas regiões e com pontuações superiores a 900 de acordo com o padrão de classificação), que são frequentemente sobrelotados com pacientes. De acordo com o processo ambulatório normal, os pacientes precisam passar por um procedimento prolongado desde o registo, tratamento, análise laboratorial, diagnóstico, até à distribuição de medicamentos. Muitas vezes os pacientes têm de passar um longo tempo de espera para tratamento, para receber testes e para pagar por cuidados médicos. O congestionamento de pacientes em determinados processos demorados, leva a que os médicos tenham pouco tempo para verificar e tratar os pacientes completamente. Como resultado, os médicos são muitas vezes incapazes de fazer um diagnóstico preciso e abrangente. Considerado a montra de um hospital, o serviço ambulatório é extremamente importante. Se o desenho do seu processo é razoável e se a sua gestão é capaz de maximizar os interesses dos pacientes, irá afetar diretamente o nível médico do hospital, e até mesmo os seus benefícios sociais e reputação. Portanto, tornou-se um importante problema para um hospital conseguir otimizar o processo do seu serviço ambulatório. O processo ambulatório, como um processo de negócio nuclear de um hospital, é fundamental para melhorar a qualidade do seu serviço médico, aumentar o seu desempenho e minimizar seus custos operacionais. Portanto, reprojetar o processo ambulatório de um hospital pode ajudar a aumentar a sua força global dotando-o de uma competência essencial. Além disso, o hospital será impelido a oferecer aos pacientes serviços médicos mais convenientes com maior qualidade e menor preço. Este trabalho apresenta um estudo de caso sobre o Hospital da Universidade de Hong Kong-Shenzhen (HKU-SZH), que foi o primeiro a implementar um sistema de registo de consulta externa. Esta tese apresenta uma análise do processo ambulatório do hospital através de vários métodos e teorias, como a revisão de literatura, pesquisa de campo, consultas a especialistas, teoria da reengenharia de processos e tecnologias da informação, com o objetivo de identificar os objetivos e estratégias do hospital na melhoria do seu serviço ambulatório. O estudo consiste em: - Investigação sobre a situação atual do processo de registo ambulatório de HKU-SZH. Através de questionários e entrevistas estruturadas, foram analisados os defeitos e pontos fracos no modelo de registro de consultas do hospital. Um modelo de equações estruturais para os processos ambulatórios existentes foi estabelecido, e a influência de diferentes variáveis sobre o nível de satisfação dos pacientes, bem como a correlação entre essas variáveis foi analisada por meio de um modelo de simulação. - Investigação sobre a reengenharia do processo ambulatório. Tendo as necessidades e satisfação dos pacientes como objetivo, esta tese reexamina as metas estratégicas e o ambiente interno e externo de HKU-SZH com base na Teoria da Reengenharia de Processos, Teoria das Filas, Teoria Six Sigmae Tecnologias da Informação. Esta tese melhora o processo de registro de HKU-SZH, usando métodos de modificação, integração, simplificação e automação e materializa o processo através de tecnologias de rede e um sistema de informação para o processo ambulatório. - Estudo empírico sobre o processo ambulatório. Esta tese conduz uma análise sistémica e empírica sobre a integração funcional de inscrições e pagamentos, a pesquisa de reengenharia de processos através de tecnologias da informação (desenvolvimento de novas funções do sistema de consultas) e um estudo empírico sobre a teoria das filas. - Investigação sobre a adaptação local do processo ambulatório. Esta tese explora soluções e sugestões para o HKU-SZH para otimizar seu processo ambulatório através das perspetivas de estrutura hospitalar organizacional, tecnologias da informação, recursos humanos, construção da cultura do ambulatório e otimização do custo de espera. Por meio do processo de reengenharia do serviço de ambulatório, esta tese visa aumentar a eficiência do processo de internamento e aumentar a satisfação dos seus pacientes para que o hospital possa aumentar a sua capacidade global. Além disso, foi gerada uma metodologia eficiente e operacionalizavel, a qual se espera possa servir como referência para outros hospitais, para melhorar o seu funcionamento e a sua gestão