A flexible medium access control framework for multimedia application support in wireless ATM

Includes bibliographical references.The field of wireless communications has seen phenomenal development over the last decade. With the current abundance of applications that use broadband multimedia over wired networks it is logical that users will want to have access to these same multimedia streams [rom a mobile terminal. Wireless solutions for connectivity to networks such as Ethernet networks already exist, however, a method of supporting access to an ATM network from a mobile terminal has not yet been standardised. Transporting ATM data over the wireless medium poses a number of problems. The Medium Access Control (MAC) layer of any proposed wireless ATM network would be responsible for resolving many of these problems. Unfortunately, research into MAC layers is hampered by the fact that most existing MAC layers cannot be modified in order to experiment with the effectiveness of the many MAC protocol techniques that exist

Improving VBR voice performance in integrated services broadband wireless networks

The integration of multimedia applications into future wireless networks is expected to accelerate the demand for incorporating broadband infrastructure into wireless arena. Providing an efficient broadband wireless infrastructure capable to carry a mixture of different services brings a large set of new technical challenges. The current wireless networks that have been designed to carry low bit-rate voice and data are not able to carry bandwidth consuming and delay sensitive multimedia traffic. Consequently fundamental changes at different layers of current technology used in wireless networks are required. In this thesis we focus on Medium Access Control protocols (MAC) suitable for broadband wireless networks. Wireless ATM (WATM) has been considered in this work. This is mainly because it is widely accepted that ATM is the foundation of future broadband networks and integrating ATM into wireless networks provides a seamless interface between wired and wireless environments. We investigate the major recent proposals for MAC protocols for broadband wireless networks and propose a new reservation mechanism for the reservation part of a FDD-based MAC protocol. This novel mechanism is called “Dynamic Hybrid Partitioning with Adjustable Repeat” which helps to improve the performance of the Variable Bit Rate (VBR) voice traffic in a broadband wireless network with integrated traffic. Through a number of simulation experiments based on AKAROA2 [Ewi99J, we analyze the different aspects of our proposed mechanism and show how it improves the performance of the VBR voice traffic sources in a network with different classes of traffic

Improving VBR voice performance in integrated services broadband wireless networks

The integration of multimedia applications into future wireless networks is expected to accelerate the demand for incorporating broadband infrastructure into wireless arena. Providing an efficient broadband wireless infrastructure capable to carry a mixture of different services brings a large set of new technical challenges. The current wireless networks that have been designed to carry low bit-rate voice and data are not able to carry bandwidth consuming and delay sensitive multimedia traffic. Consequently fundamental changes at different layers of current technology used in wireless networks are required. In this thesis we focus on Medium Access Control protocols (MAC) suitable for broadband wireless networks. Wireless ATM (WATM) has been considered in this work. This is mainly because it is widely accepted that ATM is the foundation of future broadband networks and integrating ATM into wireless networks provides a seamless interface between wired and wireless environments. We investigate the major recent proposals for MAC protocols for broadband wireless networks and propose a new reservation mechanism for the reservation part of a FDD-based MAC protocol. This novel mechanism is called “Dynamic Hybrid Partitioning with Adjustable Repeat” which helps to improve the performance of the Variable Bit Rate (VBR) voice traffic in a broadband wireless network with integrated traffic. Through a number of simulation experiments based on AKAROA2 [Ewi99J, we analyze the different aspects of our proposed mechanism and show how it improves the performance of the VBR voice traffic sources in a network with different classes of traffic

WiMAX (IEEE 802.16)-profıbus arabağlaşım elemanının petri ağlarla modellenmesi ve performans analizi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Endüstriyel kontrol uygulamalarında saha seviyesindeki dağıtık kontrolör cihazların haberleşmesinde sahayolu ağları kullanılmaktadır. PROFIBUS (PROcess FIeld BUS) uluslararası standartlarla (IEC61158, EN50170) tanımlanmış en popüler sahayoludur. Üretim (fabrika), süreç ve bina otomasyon uygulamalarında yaygın olarak kullanılan PROFIBUS, 100 m ile 1200 m mesafede 9.6 kbps ile 12 Mbps arasındaki iletişim hızlarını desteklemektedir. Bu durum, PROFIBUS'ın daha geniş kapsama alanları ve yüksek hızlarda kullanılabilmesi için omurga teknolojisine sahip arabağlaşım elemanlarının kullanımını gerektirir.Arabağlaşım için kullanılan omurga protokolü gereksinimleri gelişen teknolojilerle birlikte değişmektedir. Günümüzde, kurulum kolaylığı ve hareketlilik avantajlarından dolayı kablolu omurga çözümlerine karşılık, kablosuz omurga çözümleri de kullanılmaya başlanmış ve hızla yaygınlaşmaktadır. Kablosuz genişbant omurga teknolojisi olan IEEE 802.16-WiMAX, görüş hattında 50 km'lik bir kapsama alanı, 120 Mbps veri transfer hızı ve farklı servis sınıflarında (UGS, rtPS, nrtPS, BE, ErtPS) hizmet kalitesi sunan bir protokoldür.Bu çalışmada, farklı lokasyonlardaki PROFIBUS segmentlerini IEEE 802.16-WiMAX kablosuz omurga teknolojisi üzerinden UGS servis sınıfı kullanarak birbirine bağlayan bir arabağlaşım birimi önerilmektedir. Bu birimin, senkronizasyon, koşutzamanlılık, kilitlenmeyi önleyebilme, üstel dağılım ve sabit zaman gecikme özellikleri olan Genelleştirilmiş Stokastik Petri Ağlar modeli sunulmaktadır. Ayrıca, model içerisinde PROFIBUS paketlerinin IEEE 802.16 paketleri içerisine kapsüllendiği önerilmektedir.Tasarlanan PROFIBUS/IEEE 802.16-WiMAX arabağlaşım birimi, geçit çıkış tampon boyutu, geçit giriş tampon boyutu, master istasyon jeton tutma süresi ve geçit PROFIBUS ayağı jeton tutma süresi parametrelerine bakılarak değerlendirilmiştir. Benzetimlerden alınan sonuçlar, arabağlaşım biriminin, farklı yükler altında yeterli bir hizmet sağladığını ve fiziksel gerçeklemesini yapacak olan kişiler için de başarımı ölçülebilir bir tasarım modeli sunduğunu göstermektedir.In the application of industrial controlling, fieldbuses are used in the communication of distributed controller devices at field layer. PROFIBUS (PROcess FIeld BUS) which is defined with the international standards (IEC61158, EN50170) is the most popular fieldbus. PROFIBUS which is used frequently in manufacturing (factory), process and building automations, provides datarates from 9.6 kbps to 12 Mbps at distance from 100 to 1200 meters. This situation requires using of internetworking units which has backbone technology, for using PROFIBUS at more coverage area and high datarates.The requirements of a backbone protocol used for internetworking, are changed by the development in technology. Nowadays, because of advantages of easiness in installation and mobility, in addition to the wired backbone solutions, wireless backbone solutions began to be used and rapidly became common. As a wireless broadband backbone technology, IEEE 802.16-WiMAX is a protocol that can serve a 50 km coverage area, a 120 Mbps datarate and a QoS at different service classes (UGS, rtPS, nrtPS, BE, ErtPS) in line-of-sight.In this study, an internetworking unit is proposed that interconnects PROFIBUS segments placed at different locations through a wireless backbone technology of IEEE 802.16-WiMAX by using UGS service class. By the features of synchronization, concurrent, deadlock avoidance, exponential distribution and constant time delay, Generalized Stochastic Petri Nets model of the unit is done. Also in the model, it is proposed that PROFIBUS packets are encapsulated into IEEE 802.16 packets.The designed PROFIBUS/IEEE 802.16-WiMAX internetworking unit is analyzed according to gateway output buffer size, gateway input buffer size, master station token holding time and gateway PROFIBUS side token holding time parameters. The outputs of simulations show that internetworking unit can support a sufficient service under different loads and present a designed model with a measurable performance for the people who want to implement it physically

Evolution of NOMA Toward Next Generation Multiple Access (NGMA) for 6G

Due to the explosive growth in the number of wireless devices and diverse wireless services, such as virtual/augmented reality and Internet-of-Everything, next generation wireless networks face unprecedented challenges caused by heterogeneous data traffic, massive connectivity, and ultra-high bandwidth efficiency and ultra-low latency requirements. To address these challenges, advanced multiple access schemes are expected to be developed, namely next generation multiple access (NGMA), which are capable of supporting massive numbers of users in a more resource- and complexity-efficient manner than existing multiple access schemes. As the research on NGMA is in a very early stage, in this paper, we explore the evolution of NGMA with a particular focus on non-orthogonal multiple access (NOMA), i.e., the transition from NOMA to NGMA. In particular, we first review the fundamental capacity limits of NOMA, elaborate on the new requirements for NGMA, and discuss several possible candidate techniques. Moreover, given the high compatibility and flexibility of NOMA, we provide an overview of current research efforts on multi-antenna techniques for NOMA, promising future application scenarios of NOMA, and the interplay between NOMA and other emerging physical layer techniques. Furthermore, we discuss advanced mathematical tools for facilitating the design of NOMA communication systems, including conventional optimization approaches and new machine learning techniques. Next, we propose a unified framework for NGMA based on multiple antennas and NOMA, where both downlink and uplink transmissions are considered, thus setting the foundation for this emerging research area. Finally, several practical implementation challenges for NGMA are highlighted as motivation for future work.Comment: 34 pages, 10 figures, a survey paper accepted by the IEEE JSAC special issue on Next Generation Multiple Acces

Nonorthogonal Multiple Access for 5G and Beyond

This work was supported in part by the U.K. Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/N029720/1 and Grant EP/N029720/2. The work of L. Hanzo was supported by the ERC Advanced Fellow Grant Beam-me-up

Acesso local sem fios em redes de comunicação: escalonamento de tráfego de tempo real em sistemas de aquisição de dados e controlo

Este trabalho propõe soluções destinadas a optimizar o transporte do tráfego de sistemas de aquisição de dados e controlo, utilizando redes de comunicação sem fios para a interligação de unidades remotas a uma unidade central. O tráfego gerado por estes sistemas normalmente possui requisitos de tempo real, pelo que a rede sem fios utilizada deve ser capaz de suportar os requisitos de qualidade de serviço (QoS) das aplicações. No entanto, apesar de dar prioridade ao transporte de tráfego com requisitos de tempo real (isócrono), o sistema proposto admite também a transmissão, em simultâneo, de tráfego assíncrono, de forma a permitir a integração de serviços de natureza diferente sobre a mesma plataforma de comunicação. A largura de banda disponível para operação das redes sem fios é escassa, e tem que ser partilhada por todas as unidades. Além disso, a taxa de erros no canal costuma ser bem mais elevada e variável do que nas redes cabladas. Devido a esses problemas, os mecanismos de controlo de acesso ao meio, controlo de erros e escalonamento de tráfego implementados pela rede sem fios utilizada no sistema devem ser optimizados para garantir a qualidade de serviço das aplicações. Efectuado um estudo preliminar das tecnologias de redes sem fios disponíveis, de forma a seleccionar aquelas que apresentam as características mais adequadas para servir de base ao sistema proposto, a escolha recaiu sobre as redes HIPERLAN/2 e IEEE 802.11. Não sendo viável o recurso à utilização de sistemas reais, foi desenvolvido e implementado um modelo de simulação detalhado para cada uma destas redes de acordo com as respectivas normas. Com base nestes modelos, propõem-se algoritmosde escalonamento do tráfego de dados e controlo que fornecem garantias de qualidade de serviço ao tráfego isócrono, ao mesmo tempo que permitem o transporte de tráfego assíncrono no sistema. Os resultados obtidos nas simulações permitem avaliar o desempenho do sistema, mesmo quando este é sujeito a erros no canal, e comparar a qualidade de serviço da rede HIPERLAN/2 com a da rede IEEE 802.11. A tese inicia-se com a introdução dos conceitos fundamentais à compreensão do trabalho apresentado, à qual se segue a descrição das diversas tecnologias de redes sem fios existentes, realçando as normas HIPERLAN/2 e IEEE 802.11. Após a descrição dos modelos de simulação e algoritmos desenvolvidos, apresentam-se os resultados obtidos com os dois sistemas propostosThis work proposes solutions intended to optimize the transmission of traffic on data acquisition and control systems using wireless networks to interconnect remote units to a central unit. The traffic generated by such systems normally is subject to real time constraints, so the wireless network must be able to support the quality of service (QoS) requirements of the applications. Although the priority is given to the transportation of real time (isochronous) traffic, the proposed system also allows the transmission of asynchronous data simultaneously, in order to enable the integration of different services under the same communication platform. The bandwidth available to the operation of wireless networks is scarce, and has to be shared among all the units. Moreover, the channel error rate tends to be higher and more variable than on wired networks. Due to such problems, the medium access control, error control and traffic scheduling mechanisms implemented by the wireless network that is used by the system must be optimized in order to guarantee the quality of service required by the applications. After a preliminary study of the available wireless networks in order to select those who present the most appropriate characteristics to serve as the basis of the proposed system, the HIPERLAN/2 and IEEE 802.11 networks were chosen. As the utilization of real systems was not viable, a detailed simulation model for each of the chosen networks was developed and implemented, according to the respective standards. Based on these models, this thesis proposes scheduling algorithms comprising the data and control traffic, which provide quality of service guarantees to the isochronous traffic and allow the transportation of asynchronous traffic on the system at the same time. The results obtained with the simulations allow the evaluation of the performance of the system, even when it is subject to channel errors, and to compare the quality of service of the HIPERLAN/2 network with that of the IEEE 802.11 network. At the start of this thesis, the fundamental concepts related to the presented work are introduced, followed by the description of the different existing wireless networks technologies, with emphasis on the HIPERLAN/2 and IEEE 802.11 standards. After the description of the developed simulation models and algorithms, the results achieved with both proposed systems are presented.PRODEP - 4/5.3/PRODEP/2000

Performance evaluation of a 40 GHz broadband cellular system

Doutoramento em Engenharia ElectrónicaO trabalho apresentado nesta tese enquadra-se na área das comunicações móveis celulares e tem subjacente a utilização de um protótipo de um sistema de comunicações móveis de banda larga desenvolvido no âmbito do projecto Europeu SAMBA. Este protótipo apresenta como principais características inovadoras as taxas de transmissão, a frequência de operação, a mobilidade e os protocolos de handover rádio. Inicialmente são descritos aspectos relacionados com a evolução das comunicações móveis ao longo do tempo e apresentados conceitos teóricos fundamentais para compreender o comportamento do canal rádio móvel e os mecanismos de propagação. São identificados os tipos de desvanecimento e descritos os vários parâmetros que permitem caracterizar o canal rádio. A descrição do impacto do desvanecimento e as formas de o mitigar são apresentadas para contextualizar o trabalho desenvolvido em termos da especificação do protótipo e as opções escolhidas. As características globais do protótipo são apresentadas o que inclui a descrição do interface rádio, da arquitectura, dos módulos de RF, dos módulos de processamento de banda base, protocolos e algoritmo de transferência rádio. O protótipo foi avaliado em vários cenários com diferentes características. No cenário exterior foi analisada uma rua urbana típica do tipo canyon. Em termos de configuração do sistema foram consideradas e analisadas várias alturas da Estação Base, anglos de inclinação das antenas, várias velocidades da Terminal Móvel, operação com e sem linha de vista e a penetração do sinal rádio em ruas transversais. No cenário interior foram realizados testes similares e medidas relativas às transferências que só foram executadas para este cenário por questões logísticas. Numa primeira abordagem foi analisada a cobertura oferecida por cada célula e posteriormente activada a funcionalidade de transferência. Foram também efectuados estudos com uma única Estação Base cobrindo toda a área. Em termos de caracterização do canal rádio em banda larga são apresentadas medidas da resposta impulsiva para dois cenários interiores e complementados por outros estudos via simulação utilizando uma ferramenta de ray tracing. Nas medidas foi utilizado um método de medição do canal no domínio da frequência. A relação entre o Espalhamento do Atraso e a Banda de Coerência em diferentes cenários foi analisada em detalhe e feita a verificação em termos da violação do limite teórico de Fleury. Como consequência dos tópicos abordados, esta tese apresenta um estudo abrangente de aspectos relacionados com o comportamento do canal rádio na faixa dos 40 GHz e a análise das opções técnicas do protótipo em termos do seu desempenho no âmbito dos sistemas de comunicações móveis 4G.The work presented in this thesis addresses the area of mobile cellular broadband communications and encompasses the utilization of a prototype developed in the framework of the European project SAMBA. This prototype has as main innovative characteristics the transmission rates, the frequency band of operation, the mobility and the radio handover protocols. Initially are described aspects related with the historical evolution of the mobile communications and presented fundamental theoretical concepts to understand the behaviour of the radio channel and the propagation mechanisms. The different types of fading are identified as well as the various parameters that allow the characterisation of the radio channel. The fading impact and its mitigation techniques are presented to contextualise the work developed in terms of the specification of the features implemented in the prototype and the options available. The global characteristic of the prototype are presented namely the radio interface, the architecture, the RF modules, the baseband modules, protocols and the algorithm for the radio handover. The prototype was evaluated in various scenarios with different characteristics. In the outdoor scenario a canyon type street was analysed. Several heights of the Base Station, antenna tilting angles, Mobile Terminal velocities, operation in line-of-sight and non line-of-sight and the penetration of the signal in a transversal street. In the indoor scenario similar measurements were performed. The handover feature was analysed just for this scenario due to logistic reasons. In a first phase the coverage provided by each Base Station was analysed and subsequently activated the handover functionality. Studies using a single Base Station to cover the whole pavilion were also performed. In terms of broadband analysis, channel impulse response measurements were performed using a frequency domain technique in two scenarios and complemented by others analysed only using a ray tracing simulation tool. The relationship between the radio channel Delay Spread and the Coherence Bandwidth was analysed in different scenarios and the possible violation of the Fleury lower bond checked. As a consequence of the several topics covered in this thesis, a deep study of the aspects related with the behaviour of the radio channel in the 40 GHz band and the performance of the technical options implemented in the prototype is presented in the framework of 4G mobile communication systems

Journal of Telecommunications and Information Technology, 2004, nr 4

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