Channel Scanning and Access Point Selection Mechanisms for 802.11 Handoff: A Survey

While the cellular technology has been evolving continuously in recent years and client handoffs remain unnoticed, the 802.11 networks still impose an enormous latency issue once the client device decides to roam between the Access Point (AP). This latency is caused by many factors reckoning on scanning the channels and searching for APs with better signal strength. Once data from all the nearby APs has been collected, the client picks the most suitable AP and tries to connect with it. The AP verifies if it has enough capability to serve the client. It also ensures that the client has the required parameters and supported rates to match with the AP. The AP then processes this request, generates a new Association ID and sends it back to the client, thereby granting access to connect. Throughout this re-association process, the client fails to receive or send any data frames and experiences a lag between leaving the old and associating with a new AP. Originally, 802.11 authentication frames were designed for Wired Equivalent Privacy protocol, but later it was found to be insecure and thus got depreciated. Keeping these security aspects concerning shared key authentication in mind, few additional drafts were introduced by IEEE that concerned many key exchanges between the devices. IEEE 802.11r was introduced in 2008 that permits wireless clients to perform faster handoff along with additional data security standards. The key exchange method was redefined and also the new security negotiation protocol started serving wireless devices with a better approach. This enables a client to set up the Quality of Service state and security on an alternative AP before making a transition which ends up in minimal connectivity losses. Although this was an excellent step towards minimizing the service disruption and channel scanning, failure to remain connected with consecutive suitable APs within the minimum time continued to be a challenge. Different manufacturers use their custom-built methodology of handling a client handoff and hence the latency costs differ based on the type of handoff scheme deployed on the device. This thesis focuses on the foremost economical researches throughout recent years which targets minimizing the delays involved with channel scanning and AP selection. A wide sort of enhancements, whether it is on a client device or the AP, has been discussed and compared. Some modifications are associated with enhancing channel scan period or using beacons, and probe requests/responses in an efficient manner. Others concentrate on modifying the device hardware configuration and switching between Network Interfaces. Central controllers are a solution to handoff delays that may track the status of each device within the network and guide them to provide the appropriate Quality of Service to the end-users

Survey and Evaluation of Advanced Mobility Management Schemes in the Host Identity Layer

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A cross-layer mobility management framework for next-generation wireless roaming

Word processed copy.Includes bibliographical references (leaves 62-64).This thesis proposes a mobility management framework that aims to provide a framework for advanced mobility algorithms that allows the challenges of next-generation roaming to be met. The framework features tools that gather context and content information, guarantee low-level QoS, provide security, and offer link and handoff management. The framework aims to be scalable and reliable for all-IP heterogeneous wireless networks whilst conforming to 4G service requirements

A network-based coordination design for seamless handover between heterogeneous wireless networks

Includes bibliographical references (leaves 136-144).The rapid growth of mobile and wireless communication over the last few years has spawned many different wireless networks. These heterogeneous wireless networks are envisioned to interwork over an IP-based infrastructure to realize ubiquitous network service provisioning for mobile users. Moreover, the availability of multiple-interface mobile nodes (MNs) will make it possible to communicate through any of these wireless access networks. This wireless network heterogeneity combined with the availability of multiple-interface MNs creates an environment where handovers between the different wireless access technologies become topical during mobility events. Therefore, operators with multiple interworking heterogeneous wireless networks will need to facilitate seamless vertical handovers among their multiple systems. Seamless vertical handovers ensure ubiquitous continuity to active connections hence satisfy the quality of experience of the mobile users

Supporting group mobility in mission-critical wireless networks for SIP-based applications

Diplomityössä tarkastellaan viiveherkkien SIP-sovellusten verkkoalueiden välistä ryhmäliikkuvuutta langattomissa, IEEE 802.11x -pohjaisissa IPv4/IPv6 verkkoympäristöissä. Nykyaikaisissa kriisinhallintatehtävissä reaaliaikaisen viestinnän merkitys on viime vuosina vahvasti korostunut. Tähän tarkoitukseen käytetyt viestintäjärjestelmät ovat olleet tavallisesti erittäin kalliita. Langattomien teknologioiden nopea kehitys on kuitenkin suunnannut mielenkiinnon edullisiin, kaupallisiin siviilipuolen valmisratkaisuihin. Pitkät yhteydensiirtoviiveet ovat tärkeä ongelma reaaliaikaliikenteen yhteydensiirron kannalta. VoIP-pohjaisen puheliikenteen on todettu kestävän enimmillään suuruusluokkaa 100 ms olevia viiveaikoja palvelunlaadun ratkaisevasti kärsimättä. Linkkitason yhteydensiirron ohella duplikaattiosoitteiden tarkistuksella DHCP-osoitteenhaun aikana ja SIP-yhteyden uudelleenmuodostuksella on saumattoman yhteydensiirron kannalta olennainen merkitys. Ryhmäliikkuvuus on saanut osakseen paljon huomiota ad hoc -verkkojen tutkimuksessa. Työssä tutkitaan mandollisesti saavutettavia hyötyjä, joita ryhmäliikkuvuusmalli pystyisi perinteiseen yhteydensiirtotapaan nähden tuomaan hierarkkisissa infrastruktuurisissa SIP-verkoissa. Sovellustason liikkuvuutta ja signaloinnin tehokkuutta tarkastellaan kaistankäytön ja tietoturvallisuuden näkökulmasta. Kokeellisessa osiossa pyritään mallintamaan ryhmäyhteydensiirtoja yksinkertaisessa, simuloidussa ympäristössä. Päätelmien tueksi yhteydensiirtojen suorituskykyä arvioidaan lisäksi numeerisella analyysilla.This thesis studies the provision of group mobility during inter-domain hand-offs for delay-sensitive SIP applications over wireless IPv4/IPv6 network environment, based on the IEEE 802.11x platform. In contemporary disaster relief operations, the role of real-time communications has been strongly escalating over the recent years. The communication systems used for these ends have been conventionally very expensive. The rapid evolution of wireless technologies has brought the focus of interest to the affordable Common-Off-the-Shelf civilian applications. Long latencies during hand-offs for real-time traffic are a very important problem. As the studies have pointed out, the VoIP-based voice traffic can withstand maximum approximate disruption times of 100 ms, without too high degradation in the quality of service. Along with the link-layer hand-off, the duplicate address detection procedure during DHCP address acquisition and the SIP connection re-establishment both have a major impact on the hand-off latency. The group mobility has gained high attention in the research of ad-hoc networks. The work studies the benefits that this scheme could possibly bring over the conventional hand-offs in hierarchical infrastructured SIP networks. Different approaches to application-level mobility and the signaling efficiency are examined from the viewpoint of bandwidth usage and network security. In the experimental part, group hand-offs are modeled in a simple, simulated environment. In addition, a numerical analysis is used to assess the hand-off performance to support the made conclusions

Remote Control of Unmanned Aerial Vehicles Through the Internet and IEEE 802.11

This dissertation focuses on real-time control of Unmanned Aerial Vehicles (UAVs) through TCP/IP/IEEE 802.11. Using the MAVLink protocol - an open-source protocol for micro air vehicles - a solution that allows the exchange, in real-time, of control messages between a UAV and a remote Control Station was implemented. In order to allow the UAV control by a remote user, the vehicle streams a real-time video feed captured by a video-camera on board. The main challenge of this dissertation is related about the designing and implementation of a fast handover solution that allows an uninterruptible communication

A framework for integrating Mobile Hosts within the Internet

Host mobility and wireless access are two emerging design considerations that pose challenging problems at all layers of the networking protocol stack. This dissertation investigates their impact on the design of link, network, and transport layer protocols. At the network layer, we have designed and implemented a new routing architecture that allows the current set of Internet standards to support routing to mobile hosts. At the link and transport layers, we have designed mechanisms to improve throughput over error-prone wireless channels. At the network layer, the most crucial problem is that of routing. The existing Internet routing mechanisms cannot route packets to hosts whose points of attachment to the network change over time. Exploiting IP's Loose Source Route option, we have designed and implemented a routing scheme which provides location independent network access to TCP/IP compliant mobile hosts. It also allows mobile hosts equipped with multiple network interfaces to dynamically migrate active network sessions from one network interface to another. The proposed scheme only requires the addition of two new entity types, Mobile Routers and Mobile Access Stations. These entities perform all required mobility-aware functions, such as address translation, user tracking and location management. No modifications to existing host or router software are required. Although MobileIP provides continuous network connectivity to mobile hosts, the effects of host movement and wireless medium characteristics are often visible at the transport layer. We consider the effect of wireless medium characteristics on the performance of Transmission Control Protocol (TCP) sessions. Unlike wired networks, packets transmitted on wireless channels are often subject to burst errors which cause back to back packet losses. We show that TCP's error-recovery mechanisms perform poorly when packets from a TCP session are subject to burst errors. Unlike other approaches which require modification to TCP, our solution requires enhancements only at the wireless link layer, thus making it applicable to other transport protocols as well. We use a Channel State Dependent Packet (CSDP) scheduler which takes wireless channel characteristics into consideration in making packet dispatching decisions. Our results show that the CSDP technique provides improved throughput, better channel utilization, and fairness among multiple TCP streams. (Also cross-referenced as UMIACS-TR-95-124

Software Defined Application Delivery Networking

In this thesis we present the architecture, design, and prototype implementation details of AppFabric. AppFabric is a next generation application delivery platform for easily creating, managing and controlling massively distributed and very dynamic application deployments that may span multiple datacenters. Over the last few years, the need for more flexibility, finer control, and automatic management of large (and messy) datacenters has stimulated technologies for virtualizing the infrastructure components and placing them under software-based management and control; generically called Software-defined Infrastructure (SDI). However, current applications are not designed to leverage this dynamism and flexibility offered by SDI and they mostly depend on a mix of different techniques including manual configuration, specialized appliances (middleboxes), and (mostly) proprietary middleware solutions together with a team of extremely conscientious and talented system engineers to get their applications deployed and running. AppFabric, 1) automates the whole control and management stack of application deployment and delivery, 2) allows application architects to define logical workflows consisting of application servers, message-level middleboxes, packet-level middleboxes and network services (both, local and wide-area) composed over application-level routing policies, and 3) provides the abstraction of an application cloud that allows the application to dynamically (and automatically) expand and shrink its distributed footprint across multiple geographically distributed datacenters operated by different cloud providers. The architecture consists of a hierarchical control plane system called Lighthouse and a fully distributed data plane design (with no special hardware components such as service orchestrators, load balancers, message brokers, etc.) called OpenADN . The current implementation (under active development) consists of ~10000 lines of python and C code. AppFabric will allow applications to fully leverage the opportunities provided by modern virtualized Software-Defined Infrastructures. It will serve as the platform for deploying massively distributed, and extremely dynamic next generation application use-cases, including: Internet-of-Things/Cyber-Physical Systems: Through support for managing distributed gather-aggregate topologies common to most Internet-of-Things(IoT) and Cyber-Physical Systems(CPS) use-cases. By their very nature, IoT and CPS use cases are massively distributed and have different levels of computation and storage requirements at different locations. Also, they have variable latency requirements for their different distributed sites. Some services, such as device controllers, in an Iot/CPS application workflow may need to gather, process and forward data under near-real time constraints and hence need to be as close to the device as possible. Other services may need more computation to process aggregated data to drive long term business intelligence functions. AppFabric has been designed to provide support for such very dynamic, highly diversified and massively distributed application use-cases. Network Function Virtualization: Through support for heterogeneous workflows, application-aware networking, and network-aware application deployments, AppFabric will enable new partnerships between Application Service Providers (ASPs) and Network Service Providers (NSPs). An application workflow in AppFabric may comprise of application services, packet and message-level middleboxes, and network transport services chained together over an application-level routing substrate. The Application-level routing substrate allows policy-based service chaining where the application may specify policies for routing their application traffic over different services based on application-level content or context. Virtual worlds/multiplayer games: Through support for creating, managing and controlling dynamic and distributed application clouds needed by these applications. AppFabric allows the application to easily specify policies to dynamically grow and shrink the application\u27s footprint over different geographical sites, on-demand. Mobile Apps: Through support for extremely diversified and very dynamic application contexts typical of such applications. Also, AppFabric provides support for automatically managing massively distributed service deployment and controlling application traffic based on application-level policies. This allows mobile applications to provide the best Quality-of-Experience to its users without This thesis is the first to handle and provide a complete solution for such a complex and relevant architectural problem that is expected to touch each of our lives by enabling exciting new application use-cases that are not possible today. Also, AppFabric is a non-proprietary platform that is expected to spawn lots of innovations both in the design of the platform itself and the features it provides to applications. AppFabric still needs many iterations, both in terms of design and implementation maturity. This thesis is not the end of journey for AppFabric but rather just the beginning

Estudo de mecanismo de mobilidade intra e interdomínio

Mestrado em Engenharia Electrónica e TelecomunicaçõesDesde a invenção da roda e dos sinais de fumo que o Homem tem como umas das suas grandes preocupações o poder mover-se e comunicar. Esta tese vai discutir o que se passa quando o homem quer comunicar em movimento, e falar sobre mobilidade associada ao protocolo IP nas suas duas divisões: intradomínio e inter-domínio focando-se especialmente numa nova proposta para um protocolo de mobilidade, o ESM. ESM, também conhecido por Eppur si muove é uma proposta que pretende ser uma solução completa e eficiente para a mobilidade IP. Abrange mobilidade intra-domino e inter-domínio e é uma arquitectura inteiramente operada pela parte da rede, tem um serviço central de localização em cada domínio o que permite saber onde estão os nós moveis e usa endereçamento não hierárquico que possibilita que possam existir endereços IP com o prefixo diferente do utilizado em determinada localização. Foi por isto tudo que foi escolhido como principal objecto de estudo neste trabalho. Esta tese irá concentrar-se na arquitectura ESM com as suas diferentes opções e novos melhoramentos, incluindo resultados da sua simulação em NS-2 para testar o comportamento do ESM e provar que é um mecanismo rápido e eficiente como se pretende. Irá também apresentar alguns outros protocolos que suportem mobilidade, tal como MIP, CIP, HAWAII, SIP entre outros. ABSTRACT: Since the invention of the wheel and smoke signals that Men has at high concerns the ability to move and communicate. This thesis will discuss what happens when Men want to communicate while is moving and talk about mobility associated with IP protocol in its two divisions, intra-domain and interdomain with a special focus on one new proposal to a mobility protocol, ESM. ESM, also known as, Eppur si muove it’s a proposal that intends to be a complete and efficient solution to mobility using IP. It covers the intra-domain and the inter-domain mobility and it is an architecture entirely operated by the network side, has one central service of location on each domain that allows to know where are the mobile nodes and uses a flat IP that allow to have IP address with prefixes different of the IPs on that location. Was because all this that was chosen as the principal study of this work This thesis will focus on ESM architecture with the different options and new improvement solutions including its simulation and results using NS-2, to test ESM behavior and to prove that it can be a fast and efficient mechanism as it claims to be. It also presents some other mobility protocols like MIP, CIP, HAWAII or SIP among others

Security-centric analysis and performance investigation of IEEE 802.16 WiMAX

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