Network access selection in heterogeneous wireless networks

In heterogeneous wireless networks (HWNs), both single-homed and multi-homed terminals are supported to provide connectivity to users. A multiservice single-homed multi-mode terminal can support multiple types of services, such as voice call, file download and video streaming simultaneously on any one of the available radio access technologies (RATs) such as Wireless Local Area Network (WLAN), and Long Term Evolution (LTE). Consequently, a single-homed multi-mode terminal having multiple on-going calls may need to perform a vertical handover from one RAT to another. One of the major issues in HWNs is how to select the most suitable RAT for multiple handoff calls, and the selection of a suitable RAT for multiple-calls from a single-homed multi-mode terminal in HWNs is a group decision problem. This is because a single-homed multi-mode terminal can connect to only one RAT at a time, and therefore multiple handoff calls from the terminal have to be handed over to the same RAT. In making group decision for multiple-calls, the quality of service (QoS) requirements for individual calls needs to be considered. Thus, the RAT that most satisfies the QoS requirements of individual calls is selected as the most suitable RAT for the multiple-calls. Whereas most research efforts in HWNs have concentrated on developing vertical handoff decision schemes for a single call from a multi-mode terminal, not much has been reported in the literature on RAT-selection for multiple-calls from a single-homed multi-mode terminal in next generation wireless networks (NGWNs). In addition, not much has been done to investigate the sensitivity of RAT-selection criteria for multiple-calls in NGWNs. Therefore, this dissertation addresses these issues by focusing on following two main aspects: (1) comparative analysis of four candidate multi-criteria group decision-making (MCGDM) schemes that could be adapted for making RAT-selection decisions for multiple-calls, and (2) development of a new RAT-selection scheme named the consensus RAT-selection model. In comparative analysis of the candidate RAT-selection schemes, four MCGDM schemes namely: distance to the ideal alternative-group decision making (DIA-GDM), multiplicative exponent weighting-group decision making (MEW-GDM), simply additive weighting-group decision making (SAW-GDM), technique for order preference by similarity to Ideal solution-group decision making (TOPSIS-GDM) are considered. The performance of the multiple-calls RAT-selection schemes is evaluated using the MATLAB simulation tool. The results show that DIA-GDM and TOPSIS-GDM schemes are more suitable for multiple handoff calls than SAW-GDM and MEW-GDM schemes. This is because they are consistent and less-sensitive in making RAT-selection decision than the other two schemes, with regards to RAT-selection criteria (service price, data rate, security, battery power consumption and network delay) in HWNs. In addition, the newly developed RAT-selection scheme incorporates RAT-consensus level for improving RAT-selection decisions for multiple-calls. Numerical results conducted in MATLAB validate the effectiveness and performance of the newly proposed RAT-selection scheme for multiple-calls in HWNs

Decisão no handoff vertical ciente da confidencialidade das redes de acesso

Orientador : Prof. Aldri Luiz dos SantosCo-orientadora : Profª. Michele Nogueira LimaDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Informática. Defesa: Curitiba, 31/08/2015Inclui referências : f. 63-70Resumo: A diversidade das tecnologias de comunicação sem fio existentes e o constante aumento do número de pontos de acessos resultaram em ambientes repletos de redes sem fio com diferentes características de desempenho e segurança. Estes avanços, em conjunto com o desenvolvimento de dispositivos móveis com mais de uma interface para comunicação sem fio e a proliferação do uso da comunicação no dia a dia das pessoas, instigaram o de-senvolvimento da interoperabilidade entre as diferentes tecnologias. A interoperabilidade tem como objetivo alcançar maiores áreas de cobertura, melhorar a qualidade dos serviços oferecidos para o usuário, bem como mantê-lo conectado em todo lugar e a todo momento, resultando no paradigma das redes heterogêneas. Este novo paradigma demanda o gerenciamento da mobilidade do usuário para manter a sua conectividade, transferindo a conexão do dispositivo móvel quando necessário e sem perdas nos serviços. Este processo e chamado de handoff em redes heterogêneas e depende da escolha automática de um ponto de acesso adequado as necessidades do usuário móvel. Com esta finalidade, vários métodos de decisão propostos na literatura avaliam as características de desempenho, qualidade de serviço e segurança das redes de acesso para classificá-las de acordo com estes conjuntos de propriedades. Entretanto, os métodos encontrados na literatura analisam a segurança de maneira genérica, ignorando os aspectos distintos de suas propriedades de confidencialidade, integridade e disponibilidade. Este problema pode gerar decisões inadequadas e que colocam o usuário em risco, como quando o dispositivo requer confidencialidade nas transmissões e o processo de decisão seleciona uma rede cuja à segurança se refere a disponibilidade das transmissões, conectando-o a uma rede inadequada. Alem disso, nenhum método considera a falta de informações a respeito dos critérios de comparação na escolha dos pontos de acesso, o que diminui a precisão das decisões, levando a escolhas inadequadas ou ate falhas do processo de transição. Portanto, este trabalho apresenta um método de decisão, chamado SDHet, que seleciona a rede de acesso com base no seu nível de confidencialidade. Ele e inspirado na teoria da prospecção, que modela a tomada de decisão por seres humanos quando em risco e falta de informações, para selecionar as redes quando nestas situações. O SDHet foi avaliado através de simulações e os resultados mostram a sua eficácia em escolher as redes considerando o nível de confidencialidade e a falta de informações dos critérios de comparação. Alem disso, a utilização do método não interfere de maneira significativa no desempenho do processo de transição. Palavras-chave: Redes Heterogeneas, handoff, método de decisão, teoria da prospecção, analise de risco, confidencialidade.Abstract: The diversity of wireless communication technologies and the steady increase in the num-ber of access points resulted in full of wireless networks with different performance cha-racteristics and safety environments. This advances, together with the development of mobile devices with more than one interface for wireless communication and the proli-feration of the use of communication in day-to-day lives instigated the development of interoperability between different technologies. The interoperabolity aims to achieve gre-ater coverage areas, improve the quality of services offered to the user, as well as keep him connected everywhere and at all times resulting in the paradigm of heterogeneous networks. This new paradigm provides the mobility management for the user to maintain its connectivity, transferring the mobile connection when required and no with loss in service. This process is called vertical handoff and depends on the automated choice of a suitable access point for user needs. To this end, various decision methods proposed in the literature evaluate performance characteristics, quality of service and safety of access networks to classify them according to these sets of properties. However, the methods in the literature analyze the safety of the networks in a generic way, ignoring the different aspects of their confidentiality, integrity and availability properties. This problem can lead to inappropriate decisions and put the user at risk, such as when the device requires confidentiality in transmissions and the decision making process selects a network whose security criteria refers to the availability of transmissions. Furthermore, no method con-siders the absence of information about the comparison criteria in the choice of access points, which decreases the accuracy of the decisions, leading to inappropriate choices or to the transition faults. Therefore, this paper presents a decision method, called SDHet, which selects the access network based on their level of confidentiality. He is inspired by the prospect theory, modeling decision making by humans when at risk and lack of information, to select the networks on these situations. The SDHet method was evaluated through simulation and the results shows its effectiveness in choosing the networks consi-dering the level of confidentiality and the lack of information of the comparison criteria. Furthermore, the use of the method does not interfere significantly the performance of the transition. Keywords: Heterogeneous networks, handoff, decision method, prospect theory, risk analysis, confidentiality