An Optimum Vertical Handoff Decision Algorithm for UMTS-WLAN

The integration of diverse but complementary cellular and wireless technologies in the next generation of wireless communication systems requires the design of intelligent vertical handoff decision algorithms to enable mobile users to seamlessly switch network access and experience uninterrupted service continuity anywhere and anytime. This paper provides an adaptive multiple attribute vertical handoff decision algorithm that enables wireless access network selection at a mobile terminal using fuzzy logic concepts and a genetic algorithm. A performance study using the integration of wireless wide area networks (WWANs) and wireless metropolitan area networks (WMANs) as an example shows that our proposed vertical handoff decision algorithm is able to determine when a handoff is required, and selects the best access network that is optimized to network conditions, quality of service requirements, mobile terminal conditions, user preferences, and service cost

Enhanced Handover Mechanism in Long Term Evolution (LTE) Networks

Femtocell is a low power base station, wireless access point designed especially for homes and small organizations. It is promising technology for operators to improve their capacity and for users to give indoor coverage. As mobile users are increasing day by day so the legacy system is unable to provide such a high data rates to all these users. In this case femtocells play a key role to offload the data traffic from macro base station. The implementation of femtocell has posed so many challenges like interference, localization, access control and mobility management. The aim of this paper is to present an enhanced algorithm for handover in Hand-In scenario. In already existing algorithms handover is decided on the basis of a single parameter but here we have simulated an algorithm that considers multiple parameters instead of a single parameter for handover. Through this algorithm, the most suitable femtocell will be selected for handover, hence number of handovers will be decreased. Simulation results show that the system performance has been improved.

Principais características do handoff da camada 3 em redes sem fio

Initially mobility was possible only between similar networks. With the arrival of new devices that offer several types of wireless network interfaces, this mobility was extended which brought new problems, such as slow and loss of connection during the transition between networks. This transition, known as handoff, can be especially complex because of the peculiarities of the various interfaces. Thus, in this work a bibliographical revision of this situation is presented and of the several proposals presents in the literature with subjects that permeate the several nets Wireless, being analyzed among others: some important concepts for the understanding and discussing with larger emphasis the problems and the improvements presented recently in the studies of Handoff, and more specifically, what includes the handoff of the layer 3 of OSI model.Inicialmente a mobilidade era possível apenas entre as redes semelhantes. Com a chegada dos novos dispositivos, que agora disponibilizavam vários tipos de interfaces de rede sem fio, esta mobilidade foi estendida trazendo novos problemas de lentidão e desconexão durante a transição entre as redes. Esta transição, conhecida como handoff, pode ser complexa principalmente devido às particularidades existentes nas diferentes interfaces dos dispositivos. Assim sendo, neste trabalho é apresentada uma revisão bibliográfica desta situação e das várias propostas presentes na literatura com questões que permeiam as diversas redes Wireless, sendo analisado entre outros: alguns conceitos importantes para o entendimento e discutindo com maior ênfase os problemas e as melhorias apresentadas recentemente nos estudos do handoff, e mais especificamente, o que abrange o handoff da camada 3 do modelo OSI

A Unified Mobility Management Architecture for Interworked Heterogeneous Mobile Networks

The buzzword of this decade has been convergence: the convergence of telecommunications, Internet, entertainment, and information technologies for the seamless provisioning of multimedia services across different network types. Thus the future Next Generation Mobile Network (NGMN) can be envisioned as a group of co-existing heterogeneous mobile data networking technologies sharing a common Internet Protocol (IP) based backbone. In such all-IP based heterogeneous networking environments, ongoing sessions from roaming users are subjected to frequent vertical handoffs across network boundaries. Therefore, ensuring uninterrupted service continuity during session handoffs requires successful mobility and session management mechanisms to be implemented in these participating access networks. Therefore, it is essential for a common interworking framework to be in place for ensuring seamless service continuity over dissimilar networks to enable a potential user to freely roam from one network to another. For the best of our knowledge, the need for a suitable unified mobility and session management framework for the NGMN has not been successfully addressed as yet. This can be seen as the primary motivation of this research. Therefore, the key objectives of this thesis can be stated as: To propose a mobility-aware novel architecture for interworking between heterogeneous mobile data networks To propose a framework for facilitating unified real-time session management (inclusive of session establishment and seamless session handoff) across these different networks. In order to achieve the above goals, an interworking architecture is designed by incorporating the IP Multimedia Subsystem (IMS) as the coupling mediator between dissipate mobile data networking technologies. Subsequently, two different mobility management frameworks are proposed and implemented over the initial interworking architectural design. The first mobility management framework is fully handled by the IMS at the Application Layer. This framework is primarily dependant on the IMS’s default session management protocol, which is the Session Initiation Protocol (SIP). The second framework is a combined method based on SIP and the Mobile IP (MIP) protocols, which is essentially operated at the Network Layer. An analytical model is derived for evaluating the proposed scheme for analyzing the network Quality of Service (QoS) metrics and measures involved in session mobility management for the proposed mobility management frameworks. More precisely, these analyzed QoS metrics include vertical handoff delay, transient packet loss, jitter, and signaling overhead/cost. The results of the QoS analysis indicates that a MIP-SIP based mobility management framework performs better than its predecessor, the Pure-SIP based mobility management method. Also, the analysis results indicate that the QoS performances for the investigated parameters are within acceptable levels for real-time VoIP conversations. An OPNET based simulation platform is also used for modeling the proposed mobility management frameworks. All simulated scenarios prove to be capable of performing successful VoIP session handoffs between dissimilar networks whilst maintaining acceptable QoS levels. Lastly, based on the findings, the contributions made by this thesis can be summarized as: The development of a novel framework for interworked heterogeneous mobile data networks in a NGMN environment. The final design conveniently enables 3G cellular technologies (such as the Universal Mobile Telecommunications Systems (UMTS) or Code Division Multiple Access 2000 (CDMA2000) type systems), Wireless Local Area Networking (WLAN) technologies, and Wireless Metropolitan Area Networking (WMAN) technologies (e.g., Broadband Wireless Access (BWA) systems such as WiMAX) to interwork under a common signaling platform. The introduction of a novel unified/centralized mobility and session management platform by exploiting the IMS as a universal coupling mediator for real-time session negotiation and management. This enables a roaming user to seamlessly handoff sessions between different heterogeneous networks. As secondary outcomes of this thesis, an analytical framework and an OPNET simulation framework are developed for analyzing vertical handoff performance. This OPNET simulation platform is suitable for commercial use

An intelligent vertical handoff decision algorithm in next generation wireless networks

Philosophiae Doctor - PhDSeamless mobility is the missing ingredient needed to address the inefficient communication problems faced by the field workforces of service companies that are using field workforce automation solutions to streamline and optimise the operations of their field workforces in an increasingly competitive market place. The key enabling function for achieving seamless mobility and seamless service continuity is seamless handoffs across heterogeneous wireless access networks. A challenging issue in the multi-service next generation wireless network (NGWN) is to design intelligent and optimal vertical handoff decision algorithms, beyond traditional ones that are based on only signal strength, to determine when to perform a handoff and to provide optimal choice of access network technology among all available access networks for users equipped with multimode mobile terminals. The objective of the thesis research is to design such vertical handoff decision algorithms in order for mobile field workers and other mobile users equipped with contemporary multimode mobile devices to communicate seamlessly in the NGWN. In order to tackle this research objective, we used fuzzy logic and fuzzy inference systems to design a suitable handoff initiation algorithm that can handle imprecision and uncertainties in data and process multiple vertical handoff initiation parameters (criteria); used the fuzzy multiple attributes decision making method and context awareness to design a suitable access network selection function that can handle a tradeoff among many handoff metrics including quality of service requirements (such as network conditions and system performance), mobile terminal conditions, power requirements, application types, user preferences, and a price model; used genetic algorithms and simulated annealing to optimise the access network selection function in order to dynamically select the optimal available access network for handoff; and we focused in particular on an interesting use case: vertical handoff decision between mobile WiMAX and UMTS access networks. The implementation of our handoff decision algorithm will provide a network selection mechanism to help mobile users select the best wireless access network among all available wireless access networks, that is, one that provides always best connected services to user

Queueing Networks for Vertical Handover

PhDIt is widely expected that next-generation wireless communication systems will be heterogeneous, integrating a wide variety of wireless access networks. Of particular interest recently is a mix of cellular networks (GSM/GPRS and WCDMA) and wireless local area networks (WLANs) to provide complementary features in terms of coverage, capacity and mobility support. If cellular/ WLAN interworking is to be the basis for a heterogeneous network then the analysis of complex handover traffic rates in the system (especially vertical handover) is one of the most essential issues to be considered. This thesis describes the application of queueing-network theory to the modelling of this heterogeneous wireless overlay system. A network of queues (or queueing network) is a powerful mathematical tool in the performance evaluation of many large-scale engineering systems. It has been used in the modelling of hierarchically structured cellular wireless networks with much success, including queueing network modelling in the study of cellular/ WLAN interworking systems. In the process of queueing network modelling, obtaining the network topology of a system is usually the first step in the construction of a good model, but this topology analysis has never before been used in the handover traffic study in heterogeneous overlay wireless networks. In this thesis, a new topology scheme to facilitate the analysis of handover traffic is proposed. The structural similarity between hierarchical cellular structure and heterogeneous wireless overlay networks is also compared. By replacing the microcells with WLANs in a hierarchical structure, the interworking system is modelled as an open network of Erlang loss systems and with the new topology, the performance measures of blocking probabilities and dropping probabilities can be determined. Both homogeneous and non-homogeneous traffic have been considered, circuit switched and packet-switched. Example scenarios have been used to validate the models, the numerical results showing clear agreement with the known validation scenarios

Network-based IP flow mobility support in 3GPPs evolved packet core

Includes bibliographical references.Mobile data traffic in cellular networks has increased tremendously in the last few years. Due to the costs associated with licensed spectrum, Mobile Network Operators (MNOs) are battling to manage these increased traffic growths. Offloading mobile data traffic to alternative low cost access networks like Wi-Fi has been proposed as a candidate solution to enable MNOs to alleviate congestion from the cellular networks. This dissertation investigates an offloading technique called IP flow mobility within the 3rd Generation Partnership Project (3GPP) all-IP mobile core network, the Evolved Packet Core (EPC). IP flow mobility would enable offloading a subset of the mobile user‟s traffic to an alternative access network while allowing the rest of the end-user‟s traffic to be kept in the cellular access; this way, traffic with stringent quality of service requirements like Voice over Internet Protocol (VoIP) would not experience service disruption or interruption when offloaded. This technique is different from previous offloading techniques where all the end-user‟s traffic is offloaded. IP flow mobility functionality can be realised with either host- or network-based mobility protocols. The recommended IP flow mobility standard of 3GPP is based on the host-based mobility solution, Dual-Stack Mobile IPv6. However, host-based mobility solutions have drawbacks like long handover latencies and produce signaling overhead in the radio access networks, which could be less appealing to MNOs. Network-based mobility solutions, compared to the host-based mobility solutions, have reduced handover latencies with no signaling overhead occurring in the radio access network. Proxy Mobile IPv6 is a networkbased mobility protocol adapted by 3GPP for mobility in the EPC. However, the standardisation of the Proxy Mobile IPv6-based IP flow mobility functionality is still ongoing within 3GPP. A review of related literature and standardisation efforts reveals shortcomings with the Proxy Mobile IPv6 mobility protocol in supporting IP flow mobility. Proxy Mobile IPv6 does not have a mechanism that would ensure session continuity during IP flow handoffs or a mechanism enabling controlling of the forwarding path of a particular IP flow i.e., specifying the access network for the IP flow. The latter mechanism is referred to as IP flow information management and flow-based routing. These mechanisms represent the basis for enabling the IP flow mobility functionality. To address the shortcomings of Proxy Mobile IPv6, this dissertation proposes vi enhancements to the protocol procedures to enable the two mechanisms for IP flow mobility functionality. The proposed enhancements for the session continuity mechanism draw on work in related literature and the proposed enhancements for the IP flow information management and flow-based routing mechanism are based on the concepts used in the Dual- Stack Mobile IPv6 IP flow mobility functionality. Together the two mechanisms allow the end-user to issue requests on what access network a particular IP flow should be routed, and ensure that the IP flows are moved to the particular access network without session discontinuity

Recent Advances in Wireless Communications and Networks

This book focuses on the current hottest issues from the lowest layers to the upper layers of wireless communication networks and provides "real-time" research progress on these issues. The authors have made every effort to systematically organize the information on these topics to make it easily accessible to readers of any level. This book also maintains the balance between current research results and their theoretical support. In this book, a variety of novel techniques in wireless communications and networks are investigated. The authors attempt to present these topics in detail. Insightful and reader-friendly descriptions are presented to nourish readers of any level, from practicing and knowledgeable communication engineers to beginning or professional researchers. All interested readers can easily find noteworthy materials in much greater detail than in previous publications and in the references cited in these chapters

Interface Selection in 5G vehicular networks

ITA Negli ultimi anni, la quantità di dati condivisa nel mondo è aumentata esponenzialmente grazie alle applicazioni innovative che riguardano la sicurezza (e.g. domotica, smart cities, controllo del traffico stradale, veicoli autonomi) e i servizi di intrattenimento (e.g. audio e video streaming, ricerche web, videogiochi online di massa). Per supportare questo trend, le principali compagnie nell’industria delle telecomunicazioni stanno sviluppando nuovi standard che saranno disponibili agli utenti finali nei prossimi anni e che saranno presentati come la Quinta Generazione di Reti Cellulari (5G). Questi standard prevedono miglioramenti ai precedenti standard 4G (e.g. LTE, WiMax, DSRC) e tecnologie completamente nuove (e.g. onde millimetriche, comunicazione con luce visibile) per permettere la diffusione di nuovi servizi che richiedono un throughput estremamente alto e una latency bassa. Nella maggior parte dei casi, queste tecnologie dovranno cooperare per assicurare una rete affidabile e accessibile in ogni situazione. Una delle applicazioni più promettenti di questa nuova generazione di tecnologie sono le reti veicolari, un insieme di servizi che includono la comunicazione con le infrastrutture, come il download di un film da Internet o la ricezione di informazioni riguardanti l’ambiente circostante (e.g. un semaforo manda un messaggio a un veicolo in avvicinamento per farlo fermare), o la comunicazione direttamente tra veicoli, in questo caso il datarate è tipicamente più basso dato che l’uso più tipico sarà, per esempio, mandare informazioni riguardanti le macchine più vicine per fare in modo di diminuore il numero di incidenti stradali o gestire il traffico. Questa tesi è focalizzata sulle applicazioni per reti veicolari, l’obiettivo è di analizzare le prestazioni del protocollo IEEE 802.11p a diversi datarate in un tipico scenario V2V, e di confrontare LTE e mmWaves usando una comunicazione V2I in diverse circostanze, per mostrare come ogni tecnologia offra vantaggi per determinate applicazioni mentre non è adatta per altre. ENG In the last years, the amount of data shared among the world is increased exponentially thanks to the novel applications for security (e.g. home automation, smart cities, traffic control, autonomous vehicles) and infotainment (e.g. audio and video streaming, web browsing, massive online videogames). To support this trend, the major companies in the telecommunication industry are developing new standards that will be available to the final users in the next years and that will be presented as the Fifth Generation of Cellular Networks (5G). These standards provide improvements to the 4G standards (e.g. LTE, WiMax, DSRC) and brand new technologies (e.g. mmWaves, Visible Light Communication) to enable new services that demand extremely high throughput and low latency. In most cases these technologies will cooperate to ensure a reliable and accessible network in every situation. One of the most promising applications of these new generation technologies is vehicular networks, a set of services that includes the communication with infrastructures, such as the download of a film from the Internet or the reception of information about the surrounding environment (e.g. a traffic light sends a message to an incoming vehicle to make it stop), or the communication between vehicles, in this case the datarate is tipically lower since the typical use will be, for example, to send information about the closest cars in order to decrease the number of accidents or to manage the traffic. This thesis is focalized on the vehicular networks applications, it aims to analyze the performance of IEEE 802.11p protocol at different datarates in a typical V2V scenario, and to compare LTE and mmWaves using a V2I communication in different circumstances to show how each technology offers advantages for some applications while is not suitable for others

Human-in-the-Loop Cyber-Physical-Systems based on Smartphones

Tese de doutoramento em Ciências e Tecnologias da Informação, apresentada ao Departamento de Engenharia Informática da Faculdade de Ciências e Tecnologia da Universidade de CoimbraTechnological devices increasingly become smaller, more mobile, powerful and efficient. However, each time we have to hurdle through unintuitive menus, errors and incompatibilities we become stressed by our technology. As first put forward by the renowned computer scientist Mark Weiser, the ultimate form of computers may be an extension of our subconscious. The ideal computer would be capable of truly understanding people's unconscious actions and desires. Instead of humans adapting to technology and learning how to use it, it would be technology that would adapt to the disposition and uniqueness of each human being. This thesis focuses on the realm of Human-in-the-loop Cyber-Physical Systems (HiTLCPSs). HiTLCPSs infer the users’ intents, psychological states, emotions and actions, using this information to determine the system's behavior. This involves using a large variety of sensors and mobile devices to monitor and evaluate human nature. Therefore, this technology has strong ties with wireless sensor networks, robotics, machine-learning and the Internet of Things. In particular, our work focuses on the usage of smartphones within these systems. It begins by describing a framework to understand the principles and theory of HiTLCPSs. It provides some insights into current research being done on this topic, its challenges, and requirements. Another of the thesis' objectives is to present our innovative taxonomy of human roles, where we attempt to understand how a human may interact with HiTLCPSs and how to best explore this resource. This thesis also describes concrete examples of the practical usage of HiTL paradigms. As such, we included a comprehensive description of our research work and associated prototypes, where the major theoretical concepts behind HiTLCPS were applied and evaluated to specific scenarios. Finally, we discuss our personal view on the future and evolution of these systems.A tecnologia tem vindo a tornar-se cada vez mais pequena, móvel, poderosa e eficiente. No entanto, lidar com menus pouco intuitivos, erros, e incompatibilidades, causa frustração aos seus utilizadores. Segundo o reconhecido cientista Mark Weiser, os computadores do futuro poderão vir a existir como se fossem uma extensão do nosso subconsciente. O computador ideal seria capaz de entender, em toda a sua plenitude, as ações e os desejos inconscientes dos seres humanos. Em vez de serem os humanos a adaptarem-se à tecnologia e a aprender a usá-la, seria a tecnologia a aprender a adaptar-se à disposição e individualidade de cada ser humano. Esta tese foca-se na área dos Human-in-the-loop Cyber-Physical Systems (HiTLCPSs). Os HiTLCPSs inferem as intenções, estados psicológicos, emoções e ações dos seus utilizadores, usando esta informação para determinar o comportamento do sistema ciber-físico. Isto envolve a utilização de uma grande variedade de sensores e dispositivos móveis que monitorizam e avaliam a natureza humana. Assim sendo, esta tecnologia tem fortes ligações com redes de sensores sem fios, robótica, algoritmos de aprendizagem de máquina e a Internet das Coisas. Em particular, o nosso trabalho focou-se na utilização de smartphones dentro destes sistemas. Começamos por descrever uma estrutura para compreender os princípios e teoria associados aos HiTLCPSs. Esta análise permitiu-nos adquirir alguma clareza sobre a investigação a ser feita sobre este tópico, e sobre os seus desafios e requisitos. Outro dos objetivos desta tese é o de apresentar a nossa inovadora taxonomia sobre os papeis do ser humano nos HiTLCPSs, onde tentamos perceber as possíveis interações do ser humano com estes sistemas e as melhores formas de explorar este recurso. Esta tese também descreve exemplos concretos da utilização prática dos paradigmas HiTL. Desta forma, incluímos uma descrição do nosso trabalho experimental e dos protótipos que lhe estão associados, onde os conceitos teóricos dos HiTLCPSs foram aplicados e avaliados em diversos casos de estudo. Por fim, apresentamos a nossa perspetiva pessoal sobre o futuro e evolução destes sistemas.Fundação Luso-Americana para o DesenvolvimentoFP7-ICT-2007-2 GINSENG projectiCIS project (CENTRO-07-ST24-FEDER-002003)SOCIALITE project (PTDC/EEI-SCR/2072/2014