Descoberta de serviços independentes do acesso para redes heterogéneas

Mestrado em Engenharia de Computadores e TelemáticaA recente proliferação de nós móveis com múltiplas interfaces sem fios e a constituição de ambientes heterogéneos possibilitaram a criação de cenários complexos onde os operadores de rede necessitam de disponibilizar conectividade para diferentes tipos de redes de acesso. Assim, a norma IEEE 802.21 foi especificada de forma a facilitar e optimizar os procedimentos de handover entre diferentes tecnologias de acesso sem perda de conectividade. Para cumprir o seu propósito, a norma disponibiliza serviços chamados Media Independent Handover e que permitem o controlo e a obtenção de informação de diferentes ligações. A configuração estática destes serviços por parte do nó móvel torna-se ineficiente devido aos múltiplos cenários possíveis. Desta forma, o nó móvel deve descobrir nós da rede que providenciem serviços de mobilidade e as suas capacidade de uma forma dinâmica. Nesta dissertação, um conjunto de mecanismos para descoberta de serviços de handover independentes do acesso são analisados, implementados e avaliados em termos de duração e quantidade de informação trocada. Um novo mecanismo de descoberta de entidades locais é também proposto e avaliado, demonstrando que a sua utilização aumenta o desempenho e requer a troca de menos quantidade de informação.The recent proliferation of mobile nodes with multiple wireless interfaces, in addition to the creation of heterogeneous environments, created complex scenarios where network operators need to provide connectivity for di erent kinds of access networks. Therefore, the IEEE 802.21 standard has been speci ed to facilitate and optimize handover procedures between di erent access technologies in a seamless way. To ful l its purpose, it provides Media Independent Handover services which allow the control and gathering of information from di erent links. The static con guration of these services by the MN becomes ine cient due to the amount of possible scenarios. Thus, the MN must discover the network-supporting nodes and their capabilities in a dynamic way. In this work, a series of proposed Media Independent Handover discovery procedures are analyzed, implemented and evaluated in terms of duration and amount of exchanged information. In addition, a novel discovery procedure for local entities is proposed and evaluated, showing that its deployment increases the performance and requires less information exchanged

Architectural and mobility management designs in internet-based infrastructure wireless mesh networks

Wireless mesh networks (WMNs) have recently emerged to be a cost-effective solution to support large-scale wireless Internet access. They have numerous ap- plications, such as broadband Internet access, building automation, and intelligent transportation systems. One research challenge for Internet-based WMNs is to design efficient mobility management techniques for mobile users to achieve seamless roam- ing. Mobility management includes handoff management and location management. The objective of this research is to design new handoff and location management techniques for Internet-based infrastructure WMNs. Handoff management enables a wireless network to maintain active connections as mobile users move into new service areas. Previous solutions on handoff manage- ment in infrastructure WMNs mainly focus on intra-gateway mobility. New handoff issues involved in inter-gateway mobility in WMNs have not been properly addressed. Hence, a new architectural design is proposed to facilitate inter-gateway handoff man- agement in infrastructure WMNs. The proposed architecture is designed to specifi- cally address the special handoff design challenges in Internet-based WMNs. It can facilitate parallel executions of handoffs from multiple layers, in conjunction with a data caching mechanism which guarantees minimum packet loss during handoffs. Based on the proposed architecture, a Quality of Service (QoS) handoff mechanism is also proposed to achieve QoS requirements for both handoff and existing traffic before and after handoffs in the inter-gateway WMN environment. Location management in wireless networks serves the purpose of tracking mobile users and locating them prior to establishing new communications. Existing location management solutions proposed for single-hop wireless networks cannot be directly applied to Internet-based WMNs. Hence, a dynamic location management framework in Internet-based WMNs is proposed that can guarantee the location management performance and also minimize the protocol overhead. In addition, a novel resilient location area design in Internet-based WMNs is also proposed. The formation of the location areas can adapt to the changes of both paging load and service load so that the tradeoff between paging overhead and mobile device power consumption can be balanced, and at the same time, the required QoS performance of existing traffic is maintained. Therefore, together with the proposed handoff management design, efficient mobility management can be realized in Internet-based infrastructure WMNs

Heterogeneous networks using mobile-IP technology

Whenever a mobile user moves between networks a handover must occur. This basically means that a network-layer protocol must handle the moving of the mobile device. In a cellular phone a GSM/UMTS infrastructure performs horizontal handover and the user does not notices any call or ongoing session interruption while roaming. The handover procedure begins when the received signal strength identificator (RSSI) of a mobile device falls below a level, it discovers a neighbour access point with better quality of services (QoS) than its current access point. In heterogeneous wireless networks different portions of RF spectrum are used and is difficult or impossible for a mobile node to concurrently maintain its connectivity without signal interruptions. Thus, the different network environments must be integrated and support a common platform to achieve seamless handover. The seamless or vertical handover's target is to maintain the mobile user's IP address independently of user's location or of the physical parameters the current network is using. A mechanism that keeps a mobile device to an ongoing connection by maintaining its home-location IP address is the Mobile-IP protocol which operates at the network-layer of the Open System Interconnection (OSI) model. In this M.Sc. thesis we perform heterogeneous network scenarios with the Mobile-IP technology. Moreover, we have built the system practically and assist the applicability of such heterogeneous wireless networks through real-side measurements. We used Linux operating system (Ubuntu & Debian) between different network technologies, made at the National Center for Scientific Research (NCSR) ''Demokritos'' institute, in Greece. The required applications for the Mobile-IP and 3G technologies were implemented and configured in a platform of fixed and mobile devices at Demokrito's departmental laboratory. The idea of using the Mobile-IP protocol was to gather information about time differences that occurred in handover delay between different networks.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

IMPLEMENTATION OF WIRELESS LAN IN UTP

This paper, entitled Implementation ofWireless LAN in UTP environment, looks into the way to implement wireless network in UTP. The main objectives ofthis project are to provide mobile network and internet access using university's network system to students and lecturers and to make it easier and convenient for student to download lecture notes and for lecturers to upload them. Currently, there is no wireless LAN access in UTP environment that can be use by students and staff as alternative opportunity to access and share instant information. Therefore, this project research area is to find out the way to implement wireless LAN using secure Wi-Fi in UTP external environment. For this study, the scope is narrow down to the architecture and design ofwireless LAN network and its developing methodology. Anetwork simulation tool called Network Simulator version 2, or simply known as ns-2, is used to test the efficiency and functionality ofthe designed network. The outcome ofthis project is a good network architecture design that will give high network performance to all users in UTP

Enhanced link layer handover based on localization

Includes abstract.Includes bibliographical references (leaves 60-63).Wireless Technologies over the past years have become cheaper and more available to users. In the Infrastructure Mode of operation, when a mobile node moves from the coverage of one Access Point (AP) to the coverage of another AP, it is said to undergo handoffs. The mobile node has to complete a link layer handoffs together with other tasks associated with handoffs in order to effectively have a new wireless link with the new AP. The link layer handoffs currently specified and practiced in IEEE 802.11 is normally carried out in three time steps. These are; the Scanning Phase; the Authentication Phase and the Association Phase. During the three steps the mobile node is unable to send or receive data meaning that packets are lost or delayed causing real-time applications such as video streaming or VoIP, which can only tolerate an end-to-end delay of 50 ms during handoffs, to suffer. The Scanning phase can be done passively or actively. In passive scanning, the mobile node listens on every bandwidth channel for Beacon Frames from the APs. In active scanning, the mobile node sends Probe Requests frames on every channel expecting to receive Probe Responses from the APs operating on each channel. Localization is the process of a node ending its position in space. Localization methods include the Global Positioning Service (GPS), Cricket, Ultrasonic Location and many more. This study investigates how localization can be used to decrease the latency delay experienced at the link layer during wireless handoffs. In our method, a mobile node is given the ability to have knowledge of the APs through an AP-Table server. The mobile node then uses localization to and the closest APs to it and make faster, smarter handoffs. Our simulations are implemented using the NCTUns network simulator and emulator. The simulations comprise of a mobile node undergoing handoffs between APs in the same subnet and APs in different subnets. Added to that, the direction of the mobile node is monitored and used to further assist the handoffs process to alleviate the number of total handoffs. Our research shows the disadvantages and advantages of the proposed system as it integrates localization and direction into WLAN and mobile communication

Software Defined Networks based Smart Grid Communication: A Comprehensive Survey

The current power grid is no longer a feasible solution due to ever-increasing user demand of electricity, old infrastructure, and reliability issues and thus require transformation to a better grid a.k.a., smart grid (SG). The key features that distinguish SG from the conventional electrical power grid are its capability to perform two-way communication, demand side management, and real time pricing. Despite all these advantages that SG will bring, there are certain issues which are specific to SG communication system. For instance, network management of current SG systems is complex, time consuming, and done manually. Moreover, SG communication (SGC) system is built on different vendor specific devices and protocols. Therefore, the current SG systems are not protocol independent, thus leading to interoperability issue. Software defined network (SDN) has been proposed to monitor and manage the communication networks globally. This article serves as a comprehensive survey on SDN-based SGC. In this article, we first discuss taxonomy of advantages of SDNbased SGC.We then discuss SDN-based SGC architectures, along with case studies. Our article provides an in-depth discussion on routing schemes for SDN-based SGC. We also provide detailed survey of security and privacy schemes applied to SDN-based SGC. We furthermore present challenges, open issues, and future research directions related to SDN-based SGC.Comment: Accepte

The U.S. M-Business Market: Fad or the future

M-Business is information available on any device, anywhere and at anytime, offering businesses in any industry the potential to expand markets, improve their services and reduce costs. The U.S. m-business market is still in its infancy and is a few years away from becoming a growth market. This is due to a few reasons, which are the lack of standards for connectivity and service, no real applications to support the market and the lack of strong encryption to support m-business and e-commerce. M-business is not a fad but a potential new channel for business operations. This thesis will address the issues of why the U.S. m-business is slow to mature and what is required for the U.S. m-business to become a growth market

Ubiquitous Computing for Remote Cardiac Patient Monitoring: A Survey

New wireless technologies, such as wireless LAN and sensor networks, for telecardiology purposes give new possibilities for monitoring vital parameters with wearable biomedical sensors, and give patients the freedom to be mobile and still be under continuous monitoring and thereby better quality of patient care. This paper will detail the architecture and quality-of-service (QoS) characteristics in integrated wireless telecardiology platforms. It will also discuss the current promising hardware/software platforms for wireless cardiac monitoring. The design methodology and challenges are provided for realistic implementation