CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O uso de dispositivos multi-interface, tais como smart phones, tem crescido ao mesmo tempo que as demandas por melhores serviÃos de mobilidade em redes heterogÃneas. Neste cenÃrio, a ideia da continuidade de serviÃos tornou-se um requisito crucial. Para atender essas demandas, esquemas eficientes de handover devem ser desenvolvidos com o objetivo de alcanÃar o chamado Handover Transparente, que significa a mudanÃa de domÃnios de rede de uma forma transparente e sem a descontinuidade dos serviÃos para o usuÃrio final. Atualmente, existem diferentes esquemas de handover e alguns deles podem envolver diferentes tecnologias de acesso (Handover Vertical). Entretanto, o tempo de interrupÃÃo do serviÃo ainda à um problema a ser resolvido. A principal proposta deste trabalho à uma melhoria para Handovers Verticais utilizando mobilidade IP, objetivando o tÃo desejado Handover Transparente. Neste trabalho, fez-se uso do framework MIH (Media Independent Handover) fornecido pelo padrÃo IEEE 802.21 para habilitar o handover vertical em redes heterogÃneas. AlÃm disso, propÃe-se uma extensÃo do protocolo FMIPv6 (Fast Handovers for Mobile IPv6), o FaHMA (Fast Handovers using Multicast Addressing), utilizando endereÃamento multicast para gerenciar a mobilidade nesses tipos de rede. Para fazer a anÃlise de desempenho, simulaÃÃes foram utilizadas considerando-se mÃtricas tais com o atraso do handover e a perda de pacotes como os critÃrios mais importantes para avaliar a efetividade da soluÃÃo. Os resultados destas simulaÃÃes mostraram que o FaHMA obtÃm melhores resultados que o FMIPv6, inclusive em relaÃÃo aos fatores que determinam a qualidade do funcionamento de aplicaÃÃes multimÃdias em rede. / The use of multi-interface devices such as smart phones has grown at the same time as the demands for efficient mobility services in heterogeneous networks. In this scenario, the idea of service continuity has become a crucial requirement. To achieve these demands, efficient handover schemes should be developed aiming to achieve Seamless Handover, which means the change of network domains in a transparent way and without services discontinuity to the end user. Currently, there are different schemes for handover and some of them may be used between different access technologies (Vertical Handover). However, the service time disruption is still a major problem to be solved. The main purpose of this study is to propose an improvement for Vertical Handovers using IP mobility, aiming at Seamless Handover. In this work, the framework provided by the MIH (Media Independent Handover) IEEE 802.21 is used to enable vertical handover in heterogeneous networks, and propose an extension of FMIPv6 (Fast Handovers for Mobile IPv6) called FaHMA (Fast Handovers using Multicast Addressing), using multicast in order to manage mobility in these types of networks. To make the performance analysis, we decided for simulations and we considerered metrics such as the handover delay and packet loss as the most important criteria for evaluating the effectiveness of our proposal. Simulation results have shown that FaHMA achieve better results than FMIPv6, including factors that determine the quality of operation in networked multimedia applications.

WiMax, the Worldwide Interoperability for Microwave Access is a new technology dealing with provision of data over long distance using wireless communication method in many different ways. Based on IEEE 802.16 WiMax is claimed as an alternative broadband rather than cable and DSL. In our thesis study we will findout the phenomenon and factors involved in WiMax handover and their effect on overall quality of service. We also intend to look into the solutions possible for those problems effecting WiMax QoS in handover. Handover is the main theme of wireless technolgy and it makes interoperability between diffrent network technologies and provides mobility. However there are some problems during handover and the problem in our focus will be handover delay. Handover delay if longer than expected makes the communication faulty and introduces errors and packet loss which in turns degrade QoS in WiMax

MSc, Nursing, Faculty of Health Sciences, University of the Witwatersrand / Handover is an internationally recognised formal procedure, which has become a ritual in daily nursing practice. A structured handover plays an important role in verbal as well as written interdisciplinary communication, decision making and patient treatment, thus ensuring patient safety and maintaining the continuity of care. The purpose of this study was to determine and describe the handover practices as reported by registered nurses working in emergency care units in private sector hospitals. The objectives determined the information content in current handover practices of registered nurses, including the view or opinions of these nurses regarding handover practices. Furthermore, this study indicated were there are differences in handover practices between specialists versus non – specialist nurses. A descriptive, prospective research design was used to collect data from registered nurses working in emergency care units at private sector hospitals (n = 8). All registered nurses (N = 142) who met the inclusion criteria, were invited to participate in the study. Registered nurses who returned completed questionnaires constituted the final sample (n = 117). Data on handover practices were collected by means of a 96 item (17 question / 5 page) self administered questionnaire. This data were analysed using descriptive statistics, Chi2, Bartlett’s test for equal variances, Spearman’s test, Pearson’s r, Fisher’s exact, student T-Test and Cronbach’s Alpha. The level of significance was set at p ≤ 0.05. Epi-Info and STATA version 10 statistical computer packages were used for data analysis. Results indicated that 10.26% of registered nurses working in emergency care units had received formal training regarding handover practices and procedures. In order to solve lack of formal handover training problem, the researcher has established an acronym by using the word “HANDOVER”©, which may aid registered nurses with the handover practices and procedures. Thus, offering the handover structure and more user-friendly format. Use of a handover acronym pocket card was suggested for future formal training purposes.

Handing over objects is the foundation of many human-robot interaction and collaboration tasks. In the scenario where a human is handing over an object to a robot, the human chooses where the object needs to be transferred. The robot needs to accurately predict this point of transfer to reach out proactively, instead of waiting for the final position to be presented. We first conduct a human-to-robot handover motion study to analyze the effect of user height, arm length, position, orientation and robot gaze on the object transfer point. Our study presents new observations on the effect of robot's gaze on the point of object transfer. Next, we present an efficient method for predicting the Object Transfer Point (OTP), which synthesizes (1) an offline OTP calculated based on human preferences observed in the human-robot motion study with (2) a dynamic OTP predicted based on the observed human motion. Our proposed OTP predictor is implemented on a humanoid nursing robot and experimentally validated in human-robot handover tasks. Compared to using only static or dynamic OTP estimators, it has better accuracy at the earlier phase of handover (up to 45% of the handover motion) and can render fluent handovers with a reach-to-grasp response time (about 3.1 secs) close to natural human receiver's response. In addition, the OTP prediction accuracy is maintained across the robot's visible workspace by utilizing a user-adaptive reference frame.

<p>Wireless communication is of great importance for safety and entertainment purposes in vehicular networks. Vehicles on roads are required to share sensor data, road traffic information or digital maps with other vehicles on the road. To be able to do this, vehicles require to either communicate directly with each other or to be connected to a wireless communication-based access points on the road side. These wireless access points support short to medium range wireless communication through the protocol 802.11p. 802.11p is designed specifically for vehicular communication and it is an amended form of the widely used 802.11 protocol suit for wireless local area networks (WLAN). Vehicles are able to be associated with these wireless access points for exchange of information. While vehicles move along the road infrastructure, they change their point of attachment from one wireless access point to another wireless access point. During this process, connectivity to the access point breaks down until the vehicle is connected to a new access point in its area. This disconnection causes an interruption in the data flow. This interruption increases when vehicle requires a new IP address, i.e. when the vehicle is going to attach to an access point which is part of another network. In this thesis report, we give an overview of standard handover methods and their enhancements and propose a fast handover scheme for layer 3 of the communication stack. Based on the assumption that vehicles know their route in advance, we enhance the handover process and improve seamless connectivity. We also discuss different issues which are the cause of delay and how they can be overcome in our proposed solution.</p>

<p>The past few years have seen great increases in the use of portable devices like laptops, palmtops, etc. This has also led to the dramatic increase demand on wireless local area networks (WLAN) due to the flexibility and ease of use that it offers. Mobile IP and handover are important issues to be considered as these devices move within and between different networks and still have to maintain connectivity. It is, therefore, imperative to ensure seamless mobile IP handover for these devices as they move about.</p><p>In this thesis we undertake a survey to describe the real processes involved in mobile IP handover in WLAN environment for different scenarios. Our work also identifies individual sources of delay during the handoff process, the sum total of which makes up the total latency. Other factors that could militate against the aim of having a seamless handoff in an inter-subnet network roaming were also considered as well as some proposed solutions. These factors are security, packet loss and triangle routing.</p>

Wireless communication is of great importance for safety and entertainment purposes in vehicular networks. Vehicles on roads are required to share sensor data, road traffic information or digital maps with other vehicles on the road. To be able to do this, vehicles require to either communicate directly with each other or to be connected to a wireless communication-based access points on the road side. These wireless access points support short to medium range wireless communication through the protocol 802.11p. 802.11p is designed specifically for vehicular communication and it is an amended form of the widely used 802.11 protocol suit for wireless local area networks (WLAN). Vehicles are able to be associated with these wireless access points for exchange of information. While vehicles move along the road infrastructure, they change their point of attachment from one wireless access point to another wireless access point. During this process, connectivity to the access point breaks down until the vehicle is connected to a new access point in its area. This disconnection causes an interruption in the data flow. This interruption increases when vehicle requires a new IP address, i.e. when the vehicle is going to attach to an access point which is part of another network. In this thesis report, we give an overview of standard handover methods and their enhancements and propose a fast handover scheme for layer 3 of the communication stack. Based on the assumption that vehicles know their route in advance, we enhance the handover process and improve seamless connectivity. We also discuss different issues which are the cause of delay and how they can be overcome in our proposed solution.

The past few years have seen great increases in the use of portable devices like laptops, palmtops, etc. This has also led to the dramatic increase demand on wireless local area networks (WLAN) due to the flexibility and ease of use that it offers. Mobile IP and handover are important issues to be considered as these devices move within and between different networks and still have to maintain connectivity. It is, therefore, imperative to ensure seamless mobile IP handover for these devices as they move about. In this thesis we undertake a survey to describe the real processes involved in mobile IP handover in WLAN environment for different scenarios. Our work also identifies individual sources of delay during the handoff process, the sum total of which makes up the total latency. Other factors that could militate against the aim of having a seamless handoff in an inter-subnet network roaming were also considered as well as some proposed solutions. These factors are security, packet loss and triangle routing.

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With the flourishing development of the Internet and progress of science and technology, the wireless network technology is growing up rapidly at present. People can make connections through the Internet whenever and wherever possible. Mobile IPv6 is proposed in order to support mobility in IPv6 network, offers safer and more efficient mobile communication service to users than Mobile IPv4. However, it still suffers long delays and high packet losses. In order to enable smooth handovers, many researches in which use buffering and forwarding methods have been proposed. Although these proposals significantly improve handover performances, they suffer from the out-of-order delivery problem. This paper proposes a scheme which integrates multicast technologies with FMIPv6 for improving the handover performance. By switching between unicast addressing mode and multicast addressing mode, and letting the access router of the new network (NAR) join the multicast group in anticipation during handover, correspondent nodes (CNs) can transmit data packets to the new and old networks of mobile nodes (MNs) directly at the same time. It not only averts the out-of-order delivery problem, but also reduces the effect of the Duplicated Address Detection (DAD) time on the service disruption time.