559 research outputs found
Power Consumption Modeling and Analysis of Integrated Optical-Wireless Access Network
The integration of optical and wireless technologies at access networks are considered as a future solution which provide both high bandwidth and high mobility in an efficient way. GPON is a suitable candidate for optical backhaul due to the combination of higher data rates, greater split ratio and support for triple play services hence it offers maximum flexibility and cost advantages. On the other hand, recent developments of new radio access technologies and introduction of femtocell base stations provide the potential of offering broadband services and applications to everyone and everywhere. However, the power consumption of this network demands a particular attention because access networks are the largest contributor the network related electricity consumption. Therefore, in this paper we evaluate the power consumption of integrated optical-wireless access network which is based on independent ONU-BS architecture. We proposed a power consumption model for such network and the assessment has been done under different simulation scenarios. The constructed model will provide insight of the energy performance of the integrated access network so that in the network design process, focus can be done to the most energy saving strategies
Optical-WiMAX Hybrid Networks
The emergence of bandwidth-intensive Internet services, such ascircuit-quality voice transfer and interactive video gaming, createa high demand for a very qualified next-generation access network.In addition to high bandwidth, these future access networks shouldalso provide improved network availability, flexibility, mobility,reliability, failure protection, quality of service (QoS) supportand cost-effective access. The integration between optical networksand Worldwide Interoperability for Microwave Access (WiMAX) is apromising solution for future access networks. Accordingly, a fewdifferent architectures and MAC protocol components have recentlybeen proposed for the integration between the Ethernet PassiveOptical Network (EPON) and WiMAX. However, the proposedarchitectures contain several drawbacks. Moreover, the EPON-WiMAXhybrid does not yet contain a comprehensive Medium Access Control(MAC) protocol and a mechanism for Quality of Service (QoS) support.Finally, this work introduces the Resilient Packet Ring (RPR)standard, which aims to build high-performance metro edge and metrocore ring networks that interconnect multiple access networks. Theobjective of this thesis is to examine the integration of opticalstandards, such as RPR and EPON, with the WiMAX standard.Subsequently, this integration will be applied to the areas ofarchitecture and MAC Protocol as a promising solution for not onlyaccess networks but also for metro networks.The first part of the thesis examines the EPON-WiMAX integration asa solution for the access network. Specifically, the proposedsolution includes new EPON-WiMAX hybrid network architectures thatare suitable for both urban and rural environment requirements, andit also introduces a joint MAC protocol for these architectures. Theproposed architectures are reliable and provide extended networkcoverage; in particular, reliability is achieved by applying aprotection scheme to the most critical portion of the EPON part ofthe architecture. Additionally, the network coverage of thearchitecture is extended by inserting an intermediate networkbetween the front end and the backhaul network of the traditionalEPON-WiMAX architecture. Subsequently, we propose a comprehensivejoint MAC protocol for the proposed EPON-WiMAX architecture; thisprotocol provides a per-stream quality-of-service guarantee andimproves the network utilization. Also, the proposed joint MACprotocol includes an admission controller, a scheduler and abandwidth allocator.While the first part of the thesis strives to improve the hybridnetwork reliability through protection in the EPON part and extendthe network coverage through innovative methods, the second partattempts to maintain and enhance these objectives by adding areliable technology to the integrated network. Specifically, thissection examines the way in which the RPR network can be integratedwith the proposed EPON-WiMAX architecture to form an RPR-EPON-WiMAXhybrid network, which can be a solution for both access and metronetworks. The proposed architecture is reliable due to thedependability of the RPR standard and the protection mechanismemployed in the EPON network. Moreover, the architecture contains ahigh fault tolerance against node and connection failure. In thesecond part, the joint MAC protocol for the RPR-EPON-WiMAX hybridnetwork includes a multi-level dynamic bandwidth allocationalgorithm, a distributed admission control, a scheduler, and arouting algorithm. This MAC protocol aims to maximize the advantagesof the proposed architecture by distributing its functionalitiesover the parts of the architecture and jointly executing the partsof the MAC protocol
Next Generation Optical Access Networks: from TDM to WDM
Postprint (author’s final draft
Next Generation Optical Access Networks: from TDM to WDM
Postprint (author’s final draft
State-of-the-art in Power Line Communications: from the Applications to the Medium
In recent decades, power line communication has attracted considerable
attention from the research community and industry, as well as from regulatory
and standardization bodies. In this article we provide an overview of both
narrowband and broadband systems, covering potential applications, regulatory
and standardization efforts and recent research advancements in channel
characterization, physical layer performance, medium access and higher layer
specifications and evaluations. We also identify areas of current and further
study that will enable the continued success of power line communication
technology.Comment: 19 pages, 12 figures. Accepted for publication, IEEE Journal on
Selected Areas in Communications. Special Issue on Power Line Communications
and its Integration with the Networking Ecosystem. 201
Otimização do fronthaul ótico para redes de acesso de rádio (baseadas) em computação em nuvem (CC-RANs)
Doutoramento conjunto (MAP-Tele) em Engenharia Eletrotécnica/TelecomunicaçõesA proliferação de diversos tipos de dispositivos moveis, aplicações e serviços
com grande necessidade de largura de banda têm contribuído para o aumento
de ligações de banda larga e ao aumento do volume de trafego das
redes de telecomunicações moveis. Este aumento exponencial tem posto
uma enorme pressão nos mobile operadores de redes móveis (MNOs). Um
dos aspetos principais deste recente desenvolvimento, é a necessidade que as
redes têm de oferecer baixa complexidade nas ligações, como também baixo
consumo energético, muito baixa latência e ao mesmo tempo uma grande
capacidade por baixo usto. De maneira a resolver estas questões, os MNOs
têm focado a sua atenção na redes de acesso por rádio em nuvem (C-RAN)
principalmente devido aos seus benefícios em termos de otimização de performance
e relação qualidade preço. O standard para a distribuição de sinais
sem fios por um fronthaul C-RAN é o common public radio interface (CPRI).
No entanto, ligações óticas baseadas em interfaces CPRI necessitam de uma
grande largura de banda. Estes requerimentos podem também ser atingidos
com uma implementação em ligação free space optical (FSO) que é um sistema
ótico que usa comunicação sem fios. O FSO tem sido uma alternativa
muito apelativa aos sistemas de comunicação rádio (RF) pois combinam a
flexibilidade e mobilidade das redes RF ao mesmo tempo que permitem a
elevada largura de banda permitida pelo sistema ótico. No entanto, as ligações
FSO são suscetíveis a alterações atmosféricas que podem prejudicar
o desempenho do sistema de comunicação. Estas limitações têm evitado o
FSO de ser tornar uma excelente solução para o fronthaul. Uma caracterização
precisa do canal e tecnologias mais avançadas são então necessárias
para uma implementação pratica de ligações FSO. Nesta tese, vamos estudar
uma implementação eficiente para fronthaul baseada em tecnologia
á rádio-sobre-FSO (RoFSO). Propomos expressões em forma fechada para
mitigação das perdas de propagação e para a estimação da capacidade do
canal de maneira a aliviar a complexidade do sistema de comunicação. Simulações
numéricas são também apresentadas para formatos de modulação
adaptativas. São também considerados esquemas como um sistema hibrido
RF/FSO e tecnologias de transmissão apoiadas por retransmissores
que ajudam a alivar os requerimentos impostos por um backhaul/fronthaul
de C-RAN. Os modelos propostos não só reduzem o esforço computacional,
como também têm outros méritos, tais como, uma elevada precisão na estimação
do canal e desempenho, baixo requisitos na capacidade de memória
e uma rápida e estável operação comparativamente com o estado da arte
em sistemas analíticos (PON)-FSO. Este sistema é implementado num recetor
em tempo real que é emulado através de uma field-programmable gate
array (FPGA) comercial. Permitindo assim um sistema aberto, interoperabilidade,
portabilidade e também obedecer a standards de software aberto.
Os esquemas híbridos têm a habilidade de suportar diferentes aplicações,
serviços e múltiplos operadores a partilharem a mesma infraestrutura de
fibra ótica.The proliferation of different mobile devices, bandwidth-intensive applications
and services contribute to the increase in the broadband connections
and the volume of traffic on the mobile networks. This exponential growth
has put considerable pressure on the mobile network operators (MNOs). In
principal, there is a need for networks that not only offer low-complexity,
low-energy consumption, and extremely low-latency but also high-capacity
at relatively low cost. In order to address the demand, MNOs have given significant
attention to the cloud radio access network (C-RAN) due to its beneficial
features in terms of performance optimization and cost-effectiveness.
The de facto standard for distributing wireless signal over the C-RAN fronthaul
is the common public radio interface (CPRI). However, optical links
based on CPRI interfaces requires large bandwidth. Also, the aforementioned
requirements can be realized with the implementation of free space
optical (FSO) link, which is an optical wireless system. The FSO is an appealing
alternative to the radio frequency (RF) communication system that
combines the flexibility and mobility offered by the RF networks with the
high-data rates provided by the optical systems. However, the FSO links are
susceptible to atmospheric impairments which eventually hinder the system
performance. Consequently, these limitations prevent FSO from being an
efficient standalone fronthaul solution. So, precise channel characterizations
and advanced technologies are required for practical FSO link deployment
and operation. In this thesis, we study an efficient fronthaul implementation
that is based on radio-on-FSO (RoFSO) technologies. We propose closedform
expressions for fading-mitigation and for the estimation of channel
capacity so as to alleviate the system complexity. Numerical simulations
are presented for adaptive modulation scheme using advanced modulation
formats. We also consider schemes like hybrid RF/FSO and relay-assisted
transmission technologies that can help in alleviating the stringent requirements
by the C-RAN backhaul/fronthaul. The propose models not only
reduce the computational requirements/efforts, but also have a number of
diverse merits such as high-accuracy, low-memory requirements, fast and
stable operation compared to the current state-of-the-art analytical based
approaches. In addition to the FSO channel characterization, we present
a proof-of-concept experiment in which we study the transmission capabilities
of a hybrid passive optical network (PON)-FSO system. This is
implemented with the real-time receiver that is emulated by a commercial
field-programmable gate array (FPGA). This helps in facilitating an
open system and hence enables interoperability, portability, and open software
standards. The hybrid schemes have the ability to support different
applications, services, and multiple operators over a shared optical fiber
infrastructure
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