58 research outputs found
A QoS Aware Vertical Handover In Mobile Network
The convergence of heterogeneous wireless access technologies characterizes the 4G wireless networks. In such converged systems, the seamless and efficient handoff between different access technologies (vertical handoff) is essential and remains a challenging problem. The heterogeneous co-existence of access technologies with largely different characteristics creates a decision problem of determining the “best” available network at “best” time to reduce the unnecessary handoffs. This project proposes a dynamic decision model to decide the “best” network at “best” time moment to handoffs. The proposed dynamic decision model make the right vertical handoff decisions by determining the “best” network at “best” time among available networks based on, dynamic factors such as “Received Signal Strength(RSS)” of network and SNR(Signal-to-Noise Ratio), Link capacity(offered bandwidth) and power consumption. This model not only meets the individual user needs but also improves the whole system performance by reducing the unnecessary handoffs
Security and mobility in 802.11 structured networks
Mestrado em Engenharia Electrónica e TelecomunicaçõesNesta tese é apresentado um protocolo que permite handovers rápidos e seguros
em redes estruturadas 802.11. Este protocolo recupera o paradigma
original do 802.11: autenticar primeiro, reassociar depois. Partindo deste
paradigma, apresentamos duas novas operações 802.11 de autenticação e
(re)associacão, que permitem que uma estacão móvel realize reautenticacões
e reassociações com as mesmas funcionalidades do 802.1X. Esta nova
aproxiamação requer pouca mudança na arquitectura da rede, nomeadamente
só necessita de um novo Servidor de Reautenticação, para armazenar os dados
usados pelas estações móveis durante as reautenticações. Nesta tese é
também apresentada uma extensão do nosso protocolo, de maneira a permitir
uma migração rápida e segura entre ESS usando Mobile IP.
ABSTRACT: This thesis presents a fast, secure handover protocol that recovers the original
802.11 paradigm: authenticate first, reassociate next. Following this paradigm,
we present two new 802.11 authentication and (re)association operations which
allow a mobile station to perform network reauthentications and reassociations
with the same functionality of a complete 802.1X authentication. This new approach
requires very little from the environment, namely it only requires a new,
central network Reauthentication Service, for storing data used in the reauthentication
of stations. This thesis also presents a layer 3 extension of our protocol,
to support fast, secure transitions between ESS using Mobile IP
Design and Experimental Evaluation of a Route Optimisation Solution for NEMO
An important requirement for Internet protocol (IP)
networks to achieve the aim of ubiquitous connectivity is network
mobility (NEMO). With NEMO support we can provide Internet
access from mobile platforms, such as public transportation vehicles,
to normal nodes that do not need to implement any special
mobility protocol. The NEMO basic support protocol has been
proposed in the IETF as a first solution to this problem, but this
solution has severe performance limitations. This paper presents
MIRON: Mobile IPv6 route optimization for NEMO, an approach
to the problem of NEMO support that overcomes the limitations
of the basic solution by combining two different modes of operation:
a Proxy-MR and an address delegation with built-in routing
mechanisms. This paper describes the design and rationale of the
solution, with an experimental validation and performance evaluation
based on an implementation.Publicad
Multichannel Virtual Access Points for Seamless Handoffs in IEEE 802.11 Wireless Networks
Session: Handoff and Mobility Management 2International audienceWithin IEEE 802.11 Wireless Local Area Networks (WLANs), client stations can move freely, but because of the short range of their Access Points (APs), they usually need to reassociate with different APs to continue to communicate. When changing APs, a client station starts a process known as a handoff that can take up to 2 seconds, which is too long for real-time applications such as Voice over IP (VoIP). Various solutions have been proposed to change or improve the client behaviour when doing a handoff. Previously, we proposed the idea of Virtual Access Points (VAP) implemented on APs in which a client station changes APs without disrupting its current communication. Based on this new concept, we have developed a solution called Multichannel Virtual Access Points (mVAP) to take advantage of APs operating on multiple channels. We have implemented mVAP using PACMAP, a tool for packet manipulation, and evaluated its performance. Our results show that mVAP is a new efficient technique for seamless handoffs without performance degradation
Controlo de mobilidade com segurança em redes estruturadas 802.11
Mestrado em Engenharia ElectrĂłnica e TelecomunicaçõesEsta dissertação aborda o problema da gestĂŁo da mobilidade com segurança em redes 802.11. Assim, começa por apresentar um estudo detalhado do protocolo 802.11, do handoff de dispositivos mĂłveis entre pontos de acesso e de soluções apresentadas por diversos autores com o objectivo de reduzir o tempo dispendido neste processo, com e sem segurança associada. Seguidamente, sĂŁo apresentadas mĂ©tricas e atributos de rede que podem ser considerados no estabelecimento de polĂticas de mobilidade que gerem as transições de AP que cada dispositivo mĂłvel efectua. Uma vez feito este estudo inicial, Ă© apresentada uma solução que potencĂa handoffs rápidos e seguros em redes estruturadas 802.11 e que minimiza o tempo da sua preparação. Este novo protocolo representa uma evolução do trabalho desenvolvido por Rodolphe Marques no trabalho intitulado “Segurança e Mobilidade em Redes Estruturadas 802.11” referenciado em [1]; a sua novidade consiste em usar tramas 802.11 de reconhecimento da rede (Probe Request/Response) para difundir associações de segurança com os pontos de acesso ao alcance de cada dispositivo mĂłvel. A nova abordagem implica mudanças reduzidas na arquitectura de rede considerada em [1] e permite que, no âmbito das operações de reconhecimento de pontos de acesso, que sĂŁo comuns e necessárias, um equipamento mĂłvel instale paralelamente associações de segurança nos APs que poderá vir a usar num futuro prĂłximo, ou seja, todos os que estĂŁo ao seu alcance.
ABSTRACT: This thesis handles the problem of mobility management with security in 802.11 networks. Therefore it begins by presenting a detailed study of the 802.11 protocol, the handoff process of roaming mobile nodes between access points and solutions presented by many authors with the common goal of reducing the time spent in this process, with and without associated security. After this we present metrics and attributes of the network that may be considered on the establishment of mobility policies that handle the AP transitions made by every mobile node. Once finished this initial study we present a solution that enhances fast and secure handoffs in structured 802.11 networks and minimizes the time spent in its setting. This new protocol represents an evolution on the work developed by the author Rodolphe Marques in his work named “Security and Mobility in 802.11 Structured Networks” referred in [1]; its new feature consists in using 802.11 network scanning frames (Probe Request/Response) to distribute security associations to all access points in range of each mobile node. This new approach implies some changes on the architecture proposed in [1] and allows a mobile node to install security associations simultaneously while browsing the neighborhood for access points that may be used in a near future
Hierarchical Group Based Mutual Authentication and Key Agreement for Machine Type Communication in LTE and Future 5G Networks
In view of the exponential growth in the volume of wireless data communication among heterogeneous devices ranging from smart phones to tiny sensors across a wide range of applications, 3GPP LTE-A has standardized Machine Type Communication (MTC) which allows communication between entities without any human intervention. The future 5G cellular networks also envisage massive deployment of MTC Devices (MTCDs) which will increase the total number of connected devices hundredfold. This poses a huge challenge to the traditional cellular system processes, especially the traditional Mutual Authentication and Key Agreement (AKA) mechanism currently used in LTE systems, as the signaling load caused by the increasingly large number of devices may have an adverse effect on the regular Human to Human (H2H) traffic. A solution in the literature has been the use of group based architecture which, while addressing the authentication traffic, has their share of issues. This paper introduces Hierarchical Group based Mutual Authentication and Key Agreement (HGMAKA) protocol to address those issues and also enables the small cell heterogeneous architecture in line with 5G networks to support MTC services. The aggregate Message Authentication Code based approach has been shown to be lightweight and significantly efficient in terms of resource usage compared to the existing protocols, while being robust to authentication message failures, and scalable to heterogeneous network architectures
Application of the DQCA protocol to the optimization of wireless communications systems in cellular environments
This final career thesis (Master thesis) is a contribution on the enhancement of
wireless communications, specifically WLAN multi-cell systems based on the
IEEE 802.11 standard. The objectives were to propose and study different
Cross-Layer AP selection mechanisms that include single, dual and multiple
metric based criteria using PHY-MAC interactions. These mechanisms are
designed in order to improve system efficiency through the increase of the
utilization of the available transmission resources. The key idea of these
mechanisms is to make use of certain PHY and MAC parameters, other than
the traditional RSSI measurements, in order to optimize the association to the
best AP, specially focusing on the innovative use of MAC level state metrics. In
this regard, of special interest is the inclusion of MAC level AP traffic load
estimations within these association decisions.
All the proposals are based on the use of a high-performance MAC protocol
called DQCA (Distributed Queueing Collision Avoidance), which is specially
fitted to include the proposed techniques. Computer simulations have been
carried out to evaluate and quantify the benefits of the proposed mechanisms
and techniques in representative scenarios. Moreover, a completely new
handoff procedure has been designed for the DQCA muti-cell operation. This
handoff process allows implementing each of the proposed AP selection
mechanisms.
Furthermore, the interaction between a Cross-Layer scheduling technique at
the MAC level and two proposed AP selection mechanisms has also been
studied. The performance of these techniques has also been assessed by
means of computer simulations.
The analysis of the obtained results show that the proposed mechanisms
perform differently under the considered scenarios. However, the main
conclusion that can be drawn is that AP selection mechanisms that are based
on joint multiple metrics considerations (SNR, AP load, delay, etc.) perform
significantly better than those that use only single or dual metric based
mechanisms.
After the study, we can conclude that the proposed techniques and
mechanisms provide significant efficiency enhancements for DQCA-based
WLAN multi-cell systems so that all of them may be taken into account in future
wireless networks
- …