Electricity generation for Information and Communications Technology (ICT) contributes over 2% of the human-generated CO2 to the atmosphere. Energy costs are rapidly becoming the major operational expense for ICT and may soon dwarf capital expenses as software and hardware continue to drop in price. In this dissertation, three new approaches to achieving energy-proportional operation of network links and data servers are explored. Ethernet is the dominant wireline communications technology for Internet connectivity. IEEE 802.3az Energy Efficient Ethernet (EEE) describes a Low Power Idle (LPI) mechanism for allowing Ethernet links to sleep. A method of coalescing packets to consolidate link idle periods is investigated. It is shown that packet coalescing can result in almost fully energy-proportional behavior of an Ethernet link. Simulation is done at both the queuing and protocol levels for a range of traffic models and system configurations. Analytical modeling is used to gain a deeper general insight into packet coalescing. The architecture of a hybrid web server based on two platforms - a low-power (ARM based) and a high-power (Pentium based) - can be used to achieve step-wise energy-proportional operation and maintain headroom for peak loads. A new method based on Gratuitous ARP for switching between two mirrored platforms is developed, prototyped, and evaluated. Experimental results show that for up to 50 requests per minute, a hybrid server where the Master platform is a 2012 server-grade desktop PC can sleep for 50% of time with no increase in response time. HTTP can be used for redirection in space - a new method for precise redirection in time is proposed and used to schedule requests to a high-power server in a hybrid server. The scheduling method is modeled as a single server queue with vacations where the vacation duration is fixed and the service distribution is directly a function of the request load. This approach is well suited for delay tolerant applications such as application updates and file back-up. Energy-proportional operation is shown to be achievable in a prototype system. A first-order estimation with conservative assumptions on the adoption rate of the methods proposed and studied here shows that these methods can collectively enable energy savings in the order of hundreds of million dollars in the US annually.

<p>Smart scheduling can be used to reduce infrastructure-to-vehicle</p> <p>energy costs in delay tolerant vehicular</p> <p>networks (Hammad et al., 2010).. In this thesis we show that by combining</p> <p>this with vehicle-to-vehicle (V2V) forwarding, energy efficiency can</p> <p>be increased beyond that possible in the single hop case. This is</p> <p>accomplished by having the roadside infrastructure forward packets</p> <p>through vehicles which are in energy favourable locations. We first</p> <p>derive offline bounds on the downlink energy usage for a given input</p> <p>sample function when V2V forwarding is used. Separate bounds are given</p> <p>for the off-channel and in-channel forwarding cases. These bounds are</p> <p>used for comparisons with a variety of proposed online scheduling</p> <p>algorithms. The paper then introduces online algorithms for both</p> <p>fixed bit rate and variable bit rate air interface options. The first</p> <p>algorithm is based on a greedy local optimization (GLOA). A version of</p> <p>this algorithm which uses a minimum cost flow graph scheduler is also</p> <p>introduced. A more sophisticated algorithm is then proposed which is</p> <p>based on a finite window group optimization (FWGO). Versions of these</p> <p>algorithms are also proposed which use in-channel vehicle-to-vehicle</p> <p>scheduling. The proposed algorithms are also adapted to the variable</p> <p>bit rate air interface case. Results from a variety of experiments</p> <p>show that the proposed scheduling algorithms can significantly improve</p> <p>the downlink energy requirements of the roadside unit compared to the</p> <p>case where vehicle-to-vehicle packet forwarding is not used. The</p> <p>performance improvements are especially strong under heavy loading</p> <p>conditions and when the variation in vehicle communication</p> <p>requirements or vehicle speed is high.</p> / Master of Applied Science (MASc)

It is estimated that networked devices consumed about 150 TWh of electricity in 2006 in the U.S. which has cost around $15 billion and contributed about 225 billion lbs of CO 2 to greenhouse gas emissions. About 13.5% of this energy is consumed by network equipment such as switches and routers. This thesis addresses the energy consumption of Ethernet, and designs and evaluates improvements on existing methods to reduce the energy consumption of Ethernet links and switches. Energy Efficient Ethernet (EEE) is an emerging IEEE 802.3 standard which allows Ethernet links to sleep when idle. In this thesis, a performance evaluation of EEE is completed. This evaluation replicates previous work by Reviriego et al. in an independent manner. The performance evaluation shows that EEE overhead results in less energy savings than expected. A new method based on Packet Coalescing is developed and evaluated to improve the energy efficiency of EEE. Packet Coalescing bursts packets such that EEE overhead is minimized. The results show that EEE with Packet Coalescing for 10 Gb/s Ethernet can achieve very close to ideal (or energy proportional) performance at the expense of an insignificant added per packet delay. Periodically Paused Switched Ethernet (PPSE) was previously proposed and prototyped by Blanquicet and Christensen in 2008. PPSE uses periodically sent notification packets to halt packet transmission into a LAN Switch and thus allowing the switch to sleep periodically. In this thesis, a first performance evaluation of PPSE is completed. The evaluation in this thesis shows that a PPSE for 10 Gb/s Ethernet LAN Switches achieves either significant energy savings at the expense of an excessive packet delay, or less than expected savings with a less than human response time added per-packet delay. An improvement to PPSE (Adaptive PPSE) is proposed and developed based on an adaptive policy. The adaptive policy considers past traffic load to determine whether to put the switch to sleep or not. The evaluation shows that Adaptive PPSE can achieve very close to ideal performance at the expense of an added average per packet delay which is less than half of the human response time.

Submitted by camilla martins (camillasmmartins@gmail.com) on 2017-03-06T16:07:10Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_DesigningCost-EfficientTransport.pdf: 2918415 bytes, checksum: 7ca8ff5f47a7eb9fd97957edfcaf7b51 (MD5) / Approved for entry into archive by Edisangela Bastos (edisangela@ufpa.br) on 2017-03-22T13:30:51Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_DesigningCost-EfficientTransport.pdf: 2918415 bytes, checksum: 7ca8ff5f47a7eb9fd97957edfcaf7b51 (MD5) / Made available in DSpace on 2017-03-22T13:30:51Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_DesigningCost-EfficientTransport.pdf: 2918415 bytes, checksum: 7ca8ff5f47a7eb9fd97957edfcaf7b51 (MD5) Previous issue date: 2016-03-03 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / Esta tese se concentra na avaliação técnico econômica de soluções de transporte para acesso banda larga fixa e móvel. Para futuras redes de acesso móvel, propõem-se arquiteturas de backhaul usando fibra e microondas baseado no desenvolvimento de redes de acesso wireless verde e infraestruturas legadas de backhaul baseada em cobre para migração Brownfield, ou seja, usando infraestrutura existente até o limite de capacidade suportada, enquanto para redes de banda larga fixa são propostas implantações de proteção baseadas em esquemas híbridos, ou seja, fiber+wireless. As principais contribuições desta tese estão relacionadas ao campo de pesquisa do custo total de investimento em infraestrutura de transporte banda larga. Em termos de custo total de investimento, são propostos dois conjuntos de modelos para avaliar as despesas de capital e de operação, CAPEX e OPEX respectivamente, de operadoras de redes de acesso banda larga fixa e móvel. Primeiramente, para banda larga móvel, é apresentado um conjunto de modelos condensado em uma metodologia geral que visa fornecer: previsão de tráfego, implantação de rede sem fio, implantação de backhaul móvel e avaliação do custo total. É mostrado que o backhaul baseado em fibra considerando acesso sem fio verde é a opção mais eficiente em termos de energia. Além disso, Brownfield mostra que o backhaul baseado em cobre ainda pode desempenhar um grande papel se utilizado até a exaustão de sua capacidade e reduz drasticamente os custos de investimentos em infraestrutura. Adicionalmente, são apresentadas as principais diferenças de custos e valores de energia entre redes de acesso sem fio verde e Brownfield. Finalmente, para banda larga fixa, é proposta uma metodologia baseada em dimensionamento de rede, custos associados à falha e avaliação do custo total por assinante. Os modelos são utilizados para avaliar cinco modelos que representam diferentes esquemas de proteção para arquiteturas de banda larga fixa. Esta pesquisa revela os benefícios econômicos do uso de esquema de proteção híbrido baseado em arquitetura fiber+wireless comparado com a opção de proteção baseada totalmente em fibra e é também apresentada uma análise de sensibilidade para provar que o investimento adicional em CAPEX para proteger a infraestrutura pode ser recuperado em alguns anos através da economia em OPEX. / This thesis undertakes a techno-economic evaluation of transport solutions for fixed and mobile broadband access. In the case of future mobile access networks, it is proposed to make use of backhaul architectures using fiber and microwave applied to Greenfield deployments and a copper-legacy backhaul infrastructure based on Brownfield migration, i.e. finding a way of using a legacy infrastructure to its full capacity. At the same time, protection deployments based on fiber-wireless schemes are recommended for future fixed broadband. The main contribution made by this thesis is to carry out a research investigation into the total investment cost of the broadband transport infrastructure. This will be determined by employing two sets of models to assess the capital and operational expenditures, (CAPEX and OPEX respectively), of mobile and fixed broadband access network operators. First, this involves a set of models for mobile broadband that are summarized in a general methodology that aims at providing: traffic forecasting, wireless deployment, mobile backhaul deployment and total cost assessment. It was found that, fiber-based backhaul through a Greenfield deployment is the most energy-efficient option. Furthermore, Brownfield reveals that copper-based backhaul can still play a key role if used up to its full capacity and sharply reduces the investment costs in infrastructure. Additionally, there is an examination of the main differences in cost and energy values between Greenfield and Brownfield. Finally, a methodology is employed for fixed broadband based on network dimensioning, failure costs and an assessment of the total cost of ownership. The models are used to assess five architectures that represent different protection schemes for fixed broadband. This research shows the economic benefits of using a hybrid protection scheme based on fiber-wireless architecture rather than fiber-based protection options and a sensitivity analysis is conducted to show that the extra CAPEX invested to protect the infrastructure might be recovered through the OPEX after a number of years. The results obtained in the thesis should be useful for network operators to plan both their fixed and mobile broadband access network infrastructure in the future.

Made available in DSpace on 2015-05-14T12:36:49Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2456764 bytes, checksum: 4ac348983da5718e79b705aa01b9aa0a (MD5) Previous issue date: 2014-08-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This dissertation proposes two new algorithms for routing and wavelength allocation EA-RWA (Energy Aware Routing and Wavelength Assigment) and IEA-RWA (Impairment and Energy Aware Routing and Wavelength Assigment). The algorithms have the characteristic, improve energy efficiency in dynamic transparent optical networks, the first being simpler, because it does not care about the imperfections of the physical layer. The EA-RWA is compared with a traditional RWA / classic that does not take into account at the time of admission of the physical layer connections restrictions nor energy consumption algorithm. Have the IEA-RWA is compared with a RWA algorithm that takes into account the constraints (IA-RWA) physical layer. Numerical simulations show that the IEA-RWA performs better in many aspects / Esta dissertação propõe dois novos algoritmos de roteamento e alocação de comprimento de onda, a saber, o EA-RWA (Energy Aware Routing and Wavelength Assigment) e o IEA-RWA (Impairment and Energy Aware Routing and Wavelength Assigment). Os algoritmos terão como característica, melhorar a eficiência energética em redes ópticas transparentes dinâmicas, sendo o primeiro mais simples, pois não se preocupa com as imperfeições da camada física. O EA-RWA é comparado com um algoritmo RWA tradicional/clássico que não leva em conta, no momento de admissão de conexões, restrições da camada física e nem consumo de energia. Já o IEA-RWA é comparado com um algoritmo RWA que leva em conta restrições da camada física (IA-RWA). As simulações numéricas mostram que o IEA-RWA apresenta melhor desempenho em vários aspectos

Internet traffic is increasing exponentially, driven by new technologies such as Internet of Things (IoT) and rich streaming media. The traditional IP router becomes a bottleneck for further Internet expansion due to its high power consumption and inefficiency in processing the growing traffic. Router bypass has been introduced to overcome capacity limitations and the processing costs of IP routers. With router bypass, a portion of traffic is provisioned to bypass the router and is switched by the transport layer. Router bypass has shown to provide significant savings in network costs. These advantages are limited by a reduction in the statistical multiplexing associated with the subdivision of the available bandwidth typically into bypass and traditional portions thus limiting the interest in bypass techniques. This thesis will explore multiple techniques to enhance the efficiency of router bypass. The main goals are to address the issue of the reduction in statistical multiplexing and to add a dynamic approach to the router bypass mechanism. The recent advancements in the Optical Transport Network (OTN) play a major role in the transport network. This proposal takes full advantage of OTN in the router-bypassing context by applying recent developments such as Hitless Adjustments ODUflex (HAO), which allow the provisioned channels to be adjusted without re-establishing the connections. In addition, it will allow the bypassing mechanism to be flexible enough to meet the traffic behaviour needs of the future. This thesis will study multiple approaches to enhance the router bypass mechanism including: an adaptive provisioning style using various degrees of provisioning granularities and controlling the provisioning based on traffic behaviour. In addition, this thesis will explore the impact of automation in Software-Defined Networking (SDN) on router bypass. The application-driven infrastructure in SDN is moving the network to be more adaptive, which paves the way for an enhanced implementation of router bypass. Many challenges still face the industry to fully integrate the three layers (3, 2, and 1) to transform the current infrastructure into an adaptive application driven network. The IP router (layer 3) provisions and restores the connection regardless of the underlying layers (layer 2 and 1) and the transport layer does the same regardless of the IP layer. Although allowing every layer to develop without being constrained by other layers offers a huge advantage, it renders the transport layer static and not fully aware of the traffic behaviour. It is my hope that this thesis is a step forward in transforming the current network into a dynamic, efficient and responsive network. A simulation has been built to imitate the router bypassing concept and then many measurements have been recorded. / Graduate

Submitted by Irvana Coutinho (irvana@ufpa.br) on 2015-02-13T14:08:11Z No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Dissertacao_GreenMarkovAbordageml.pdf: 1014480 bytes, checksum: 78962cf42379d2207770c49f4976e8ef (MD5) / Approved for entry into archive by Ana Rosa Silva (arosa@ufpa.br) on 2015-02-19T12:02:56Z (GMT) No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Dissertacao_GreenMarkovAbordageml.pdf: 1014480 bytes, checksum: 78962cf42379d2207770c49f4976e8ef (MD5) / Made available in DSpace on 2015-02-19T12:02:56Z (GMT). No. of bitstreams: 2 license_rdf: 22974 bytes, checksum: 99c771d9f0b9c46790009b9874d49253 (MD5) Dissertacao_GreenMarkovAbordageml.pdf: 1014480 bytes, checksum: 78962cf42379d2207770c49f4976e8ef (MD5) Previous issue date: 2014 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O uso da comunicação de voz e dados através de dispositivos móveis vem aumentando significativamente nos últimos anos. Tal expansão traz algumas dificuldades inerentes, tais como: ampliação constante de capacidade das redes e eficiência energética. Neste contexto, vem se consolidando o conceito de Green networks, que se concentra no esforço para economia de energia e redução de CO2. Neste sentido, este trabalho propõe validar um modelo de uma política baseado em processo markoviano de decisão, visando a otimizar o consumo de energia, QoS e QoE, na alocação de usuários em redes macrocell e femtocell. Para isso o modelo foi inserido no simulador NS-2, aliando a solução analítica markoviana à flexibilidade característica da simulação discreta. A partir dos resultados apresentados na simulação, a política obteve uma economia significativa no consumo energético, melhorando a eficiência energética em até 4%, além de melhorar a qualidade de serviço em relação às redes macrocell e femtocell, demonstrando-se eficaz, de modo a alterar diretamente as métricas de QoS e de QoE. / The use of voice and data communication via mobile devices has increased significantly in recent years. This expansion brings some difficulties such as: continuous expansion of network capacity and energy efficiency. In this context, has been consolidating the concept of Green Networks, which focuses on the effort to energy saving and CO2 reduction. Thus, this paper proposes validate a model of a policy based on Markov decision process to optimize energy consumption, QoS and QoE, in the allocation of macrocell and femtocell users in networks. For this the model was inserted into the network simulator NS-2, combining the Markov analytical solution to the characteristic flexibility of discrete simulation. From the results presented in the simulation, the policy obtained significant savings in energy consumption, improving energy efficiency by up to 4%, and improve the quality of service in relation to the macrocell and femtocell networks, demonstrating effective in order to directly change the metrics of QoS and QoE.

The continuous growth of traffic demand driven by the brisk increase in number of Internet users and emerging online services creates new challenges for communication networks. The latest advances in Wavelength Division Multiplexing (WDM) technology make it possible to build Transparent Optical Networks (TONs) which are expected to be able to satisfy this rapidly growing capacity demand. Moreover, with the ability of TONs to transparently carry the optical signal from source to destination, electronic processing of the tremendous amount of data can be avoided and optical-to-electrical-to-optical (O/E/O) conversion at intermediate nodes can be eliminated. Consequently, transparent WDM networks consume relatively low power, compared to their electronic-based IP network counterpart. Furthermore, TONs bring also additional benefits in terms of bit rate, signal format, and protocol transparency. However, the absence of O/E/O processing at intermediate nodes in TONs has also some drawbacks. Without regeneration, the quality of the optical signal transmitted from a source to a destination might be degraded due to the effect of physical-layer impairments induced by the transmission through optical fibers and network components. For this reason, routing approaches specifically tailored to account for the effect of physical-layer impairments are needed to avoid setting up connections that don’t satisfy required signal quality at the receiver. Transparency also makes TONs highly vulnerable to deliberate physical-layer attacks. Malicious attacking signals can cause a severe impact on the traffic and for this reason proactive mechanisms, e.g., network design strategies, able to limit their effect are required. Finally, even though energy consumption of transparent WDM networks is lower than in the case of networks processing the traffic at the nodes in the electronic domain, they have the potential to consume even less power. This can be accomplished by targeting the inefficiencies of the current provisioning strategies applied in WDM networks. The work in this thesis addresses the three important aspects mentioned above. In particular, this thesis focuses on routing and wavelength assignment (RWA) strategies specifically devised to target: (i) the lightpath transmission quality, (ii) the network security (i.e., in terms of vulnerability to physical-layer attacks), and (iii) the reduction of the network energy consumption. Our contributions are summarized below. A number of Impairment Constraint Based Routing (ICBR) algorithms have been proposed in the literature to consider physical-layer impairments during the connection provisioning phase. Their objective is to prevent the selection of optical connections (referred to as lightpaths) with poor signal quality. These ICBR approaches always assign each connection request the least impaired lightpath and support only a single threshold of transmission quality, used for all connection requests. However, next generation networks are expected to support a variety of services with disparate requirements for transmission quality. To address this issue, in this thesis we propose an ICBR algorithm supporting differentiation of services at the Bit Error Rate (BER) level, referred to as ICBR-Diff. Our approach takes into account the effect of physical-layer impairments during the connection provisioning phase where various BER thresholds are considered for accepting/blocking connection requests, depending on the signal quality requirements of the connection requests. We tested the proposed ICBR-Diff approach in different network scenarios, including also a fiber heterogeneity. It is shown that it can achieve a significant improvement of network performance in terms of connection blocking, compared to previously published non-differentiated RWA and ICBR algorithms.  Another important challenge to be considered in TONs is their vulnerability to physical-layer attacks. Deliberate attacking signals, e.g., high-power jamming, can cause severe service disruption or even service denial, due to their ability to propagate in the network. Detecting and locating the source of such attacks is difficult, since monitoring must be done in the optical domain, and it is also very expensive. Several attack-aware RWA algorithms have been proposed in the literature to proactively reduce the disruption caused by high-power jamming attacks. However, even with attack-aware network planning mechanisms, the uncontrollable propagation of the attack still remains an issue. To address this problem, we propose the use of power equalizers inside the network nodes in order to limit the propagation of high-power jamming attacks. Because of the high cost of such equipment, we develop a series of heuristics (incl. Greedy Randomized Adaptive Search Procedure (GRASP)) aiming at minimizing the number of power equalizers needed to reduce the network attack vulnerability to a desired level by optimizing the location of the equalizers. Our simulation results show that the equalizer placement obtained by the proposed GRASP approach allows for 50% reduction of the sites with the power equalizers while offering the same level of attack propagation limitation as it is possible to achieve with all nodes having this additional equipment installed. In turn, this potentially yields a significant cost saving.    Energy consumption in TONs has been the target of several studies focusing on the energy-aware and survivable network design problem for both dedicated and shared path protection. However, survivability and energy efficiency in a dynamic provisioning scenario has not been addressed. To fill this gap, in this thesis we focus on the power consumption of survivable WDM network with dynamically provisioned 1:1 dedicated path protected connections. We first investigate the potential energy savings that are achievable by setting all unused protection resources into a lower-power, stand-by state (or sleep mode) during normal network operations. It is shown that in this way the network power consumption can be significantly reduced. Thus, to optimize the energy savings, we propose and evaluate a series of energy-efficient strategies, specifically tailored around the sleep mode functionality. The performance evaluation results reveal the existence of a trade-off between energy saving and connection blocking. Nonetheless, they also show that with the right provisioning strategy it is possible to save a considerable amount of energy with a negligible impact on the connection blocking probability. In order to evaluate the performance of our proposed ICBR-Diff and energy-aware RWA algorithms, we develop two custom-made discrete-event simulators. In addition, the Matlab program of GRASP approach for power equalization placement problem is implemented. / <p>QC 20120508</p>

With the global population becoming more urban and less rural, increasingly research has argued for concepts such as establish Green Infrastructure (GI) as a tool for enhancing wildlife survival and human’s living quality (e.g. Harrison et al., 1995; Benedict and McMahon, 2006). However, an interdisciplinary planning approach underpinned by ecological and social evidence has not yet been fully developed. This research therefore seeks to integrate an ecological network with a green space planning standard by exploring the use of biotope and sociotope mapping methods. Seeking a comprehensive planning that takes all green resources into account, a green space typology is firstly developed according to Taiwanese contexts for identifying green spaces from land use maps. In order to specify effective features of these green spaces to bird survival and user preferences, an insight was conducted into the relationship of ‘birds and urban habitats’, as well as ‘human preferred urban green spaces’ in Taipei City. Important environmental factors influencing bird distribution and influencing human experiences in urban green spaces are respectively specified and developed into an ecological value index (EVI) to detail potential habitats and a social value index (SVI) to evaluate recreational green space provision. Interestingly, proximity to green space appears to plays a more critical role in human preferences than bird survival in Taipei city; size is important both as a habitat and for creating an attractive green space; and green space quality tends to be a more significant factor than its structure for both wildlife and people. Utilising the bio-sociotope maps, this thesis argues for a number of strategies: conserving, enlarging, or creating large green spaces in green space deficient areas; increasing ecological and recreational value by enhancing green space quality of specific characteristics; and tackling gravity distance by combining green space accessibility and attractiveness in optimising urban green structure. As these suggestions are a challenge to apply in intensively developed urban areas, barriers from land use, political mechanisms, technical shortages, and cultural characteristics are also explored with possible resolutions presented for facilitating implementation. It is clear that optimising a multifunctional GI for both wildlife and people requires interdisciplinary knowledge and cooperation from various fields. The EVI and SVI developed within this thesis create the potential for a more place-specific and quantifiable green spaces strategy to help better link ecological and social functions in urban areas.