3,047 research outputs found
A survey on OFDM-based elastic core optical networking
Orthogonal frequency-division multiplexing (OFDM) is a modulation technology that has been widely adopted in many new and emerging broadband wireless and wireline communication systems. Due to its capability to transmit a high-speed data stream using multiple spectral-overlapped lower-speed subcarriers, OFDM technology offers superior advantages of high spectrum efficiency, robustness against inter-carrier and inter-symbol interference, adaptability to server channel conditions, etc. In recent years, there have been intensive studies on optical OFDM (O-OFDM) transmission technologies, and it is considered a promising technology for future ultra-high-speed optical transmission. Based on O-OFDM technology, a novel elastic optical network architecture with immense flexibility and scalability in spectrum allocation and data rate accommodation could be built to support diverse services and the rapid growth of Internet traffic in the future. In this paper, we present a comprehensive survey on OFDM-based elastic optical network technologies, including basic principles of OFDM, O-OFDM technologies, the architectures of OFDM-based elastic core optical networks, and related key enabling technologies. The main advantages and issues of OFDM-based elastic core optical networks that are under research are also discussed
Design, implementation and experimental evaluation of a network-slicing aware mobile protocol stack
Mención Internacional en el título de doctorWith the arrival of new generation mobile networks, we currently observe a paradigm
shift, where monolithic network functions running on dedicated hardware are now
implemented as software pieces that can be virtualized on general purpose hardware
platforms. This paradigm shift stands on the softwarization of network functions and
the adoption of virtualization techniques. Network Function Virtualization (NFV)
comprises softwarization of network elements and virtualization of these components.
It brings multiple advantages: (i) Flexibility, allowing an easy management of the virtual
network functions (VNFs) (deploy, start, stop or update); (ii) efficiency, resources can be
adequately consumed due to the increased flexibility of the network infrastructure; and
(iii) reduced costs, due to the ability of sharing hardware resources. To this end, multiple
challenges must be addressed to effectively leverage of all these benefits.
Network Function Virtualization envisioned the concept of virtual network, resulting in
a key enabler of 5G networks flexibility, Network Slicing. This new paradigm represents
a new way to operate mobile networks where the underlying infrastructure is "sliced"
into logically separated networks that can be customized to the specific needs of the
tenant. This approach also enables the ability of instantiate VNFs at different locations
of the infrastructure, choosing their optimal placement based on parameters such as the
requirements of the service traversing the slice or the available resources. This decision
process is called orchestration and involves all the VNFs withing the same network slice.
The orchestrator is the entity in charge of managing network slices. Hands-on experiments
on network slicing are essential to understand its benefits and limits, and to validate the
design and deployment choices. While some network slicing prototypes have been built
for Radio Access Networks (RANs), leveraging on the wide availability of radio hardware
and open-source software, there is no currently open-source suite for end-to-end network
slicing available to the research community. Similarly, orchestration mechanisms must
be evaluated as well to properly validate theoretical solutions addressing diverse aspects
such as resource assignment or service composition.
This thesis contributes on the study of the mobile networks evolution regarding its
softwarization and cloudification. We identify software patterns for network function
virtualization, including the definition of a novel mobile architecture that squeezes the virtualization architecture by splitting functionality in atomic functions.
Then, we effectively design, implement and evaluate of an open-source network
slicing implementation. Our results show a per-slice customization without paying the
price in terms of performance, also providing a slicing implementation to the research
community. Moreover, we propose a framework to flexibly re-orchestrate a virtualized
network, allowing on-the-fly re-orchestration without disrupting ongoing services. This
framework can greatly improve performance under changing conditions. We evaluate
the resulting performance in a realistic network slicing setup, showing the feasibility and
advantages of flexible re-orchestration.
Lastly and following the required re-design of network functions envisioned during
the study of the evolution of mobile networks, we present a novel pipeline architecture
specifically engineered for 4G/5G Physical Layers virtualized over clouds. The proposed
design follows two objectives, resiliency upon unpredictable computing and parallelization
to increase efficiency in multi-core clouds. To this end, we employ techniques such as tight
deadline control, jitter-absorbing buffers, predictive Hybrid Automatic Repeat Request,
and congestion control. Our experimental results show that our cloud-native approach
attains > 95% of the theoretical spectrum efficiency in hostile environments where stateof-
the-art architectures collapse.This work has been supported by IMDEA Networks InstitutePrograma de Doctorado en Ingeniería Telemática por la Universidad Carlos III de MadridPresidente: Francisco Valera Pintor.- Secretario: Vincenzo Sciancalepore.- Vocal: Xenofon Fouka
A look at cloud architecture interoperability through standards
Enabling cloud infrastructures to evolve into a transparent platform while preserving integrity raises interoperability issues. How components are connected needs to be addressed. Interoperability requires standard data models and communication encoding technologies compatible with the existing Internet infrastructure. To reduce vendor lock-in situations, cloud computing must implement universal strategies regarding standards, interoperability and portability. Open standards are of critical importance and need to be embedded into interoperability solutions. Interoperability is determined at the data level as well as the service level. Corresponding modelling standards and integration solutions shall be analysed
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