In-Band Asymmetry Compensation for Accurate Time/Phase Transport over Optical Transport Network

The demands of precise time/phase synchronization have been increasing recently due to the next generation of telecommunication synchronization. This paper studies the issues that are relevant to distributing accurate time/phase over optical transport network (OTN). Each node and link can introduce asymmetry, which affects the adequate time/phase accuracy over the networks. In order to achieve better accuracy, protocol level full timing support is used (e.g., Telecom-Boundary clock). Due to chromatic dispersion, the use of different wavelengths consequently causes fiber link delay asymmetry. The analytical result indicates that it introduces significant time error (i.e., phase offset) within 0.3397 ns/km in C-band or 0.3943 ns/km in L-band depending on the wavelength spacing. With the proposed scheme in this paper, the fiber link delay asymmetry can be compensated relying on the estimated mean fiber link delay by the Telecom-Boundary clock, while the OTN control plane is responsible for processing the fiber link delay asymmetry to determine the asymmetry compensation in the timing chain

Interoperability experiments at obsea

Peer Reviewe

Interoperability experiments at OBSEA

Peer ReviewedPostprint (published version

Fronthaul C-RAN baseado em ethernet

For the last decade mobile data traffic has been increasing at impressive rates. The proliferation of mobile devices together with high-bandwidth services like video and music streaming, social media and other cloud services have increased the load on top of the mobile network infrastructure. In order to support this massive increase in both users and bandwidth the next generation of mobile telecommunications network - 5G - explores new approaches, like the utilization of new frequency bands and the densification of base stations. This kind of requirements along with the inefficiency of the co-location of base band processing near the radio units encourages a rethink of traditional radio access networks. In this scenario emerges the C-RAN paradigm that intend to centralize all the base band processing (BBU) and replace current base stations for simpler, more efficient and compact solutions that only incorporate the radio front-end and respective radio processing (RRH). In addition to these benefits, centralized processing facilitates virtualization and resource sharing, interference management and cooperative processing technologies. This split of functions brings however, some challenges in respect to the data rates, bandwidth and latency in the link that connects BBUs and RRHs - the fronthaul. Today’s existing standards like CPRI weren’t originally designed for such applications and present some intrinsic bandwidth and flexibility limitations. It’s considered that another approach, based on packet switching, could mitigate some of these problems in addition to bring some advantages such as statistical multiplexing, flexible routing and compatibility with current widespread packet switching networks. They do however, present a number of challenges regarding latency and synchronization. This dissertation work focuses on the study and development of a fronthaul solution based in 10 Gigabit Ethernet over optical fiber. Development is done on top of two development kits based in Field Programmable Gate Array (FPGA) and implemented in an already operational C-RAN test-bed - currently with CPRI based fronthaul - at the Instituto de Telecomunicações - Aveiro.Durante a última década o tráfego de dados móveis tem aumentado a um ritmo impressionante. A proliferação de dispositivos móveis juntamente com serviços consumidores de grande largura de banda como streaming de vídeo e música, redes sociais e serviços na cloud têm colocado grande pressão na infraestrutura da rede móvel. Para suportar este aumento massivo de utilizadores e largura de banda a próxima geração de telecomunicações móveis – o 5G – explora novos conceitos, entre eles a utilização de bandas de frequências mais elevadas e a massificação das estações base. A este tipo de requisitos junta-se o facto da ineficiência da co-localização do processamento junto da unidade de rádio que incentiva a uma restruturação da arquitectura tradicional das redes móveis. Neste cenário surge o paradigma C-RAN, que pretende centralizar todo o processamento em banda base (BBU) e substituir as base stations atuais por soluções mais simples, eficientes e compactas que englobam apenas o processamento da parte de rádio e respetivo front-end de rádio frequência (RRH). Para além destes beneficios, a centralização do processamento facilita a virtualização e partilha de recursos, a gestão da interferência e tecnologias de processamento cooperativo. Esta divisão de funções traz no entanto alguns desafios no que diz respeito a largura de banda, taxas de dados e latências na interligação entre BBUs e RRHs – o fronthaul. Standards atualmente utilizados no link de fronthaul como o CPRI não foram originalmente desenhados para aplicações desta dimensão e apresentam algumas limitações, sendo intrinsecamente pouco flexíveis e eficientes. Acredita-se que outro tipo de abordagem, baseada em comutação de pacotes, poderia mitigar alguns destes problemas para além de trazer vantagens como a multiplexagem estatística, routing flexível e compatibilidade com redes de comutação de pacotes actuais. Apresentam no entanto vários desafios a nível de latência e sincronização associados. Este trabalho de dissertação foca-se então no estudo e desenvolvimento de uma solução para o fronthaul baseada em 10 Gigabit Ethernet sobre fibra ótica. O desenvolvimento será feito em dois kits de desenvolvimento baseados em Field Programmable Gate Array (FPGA) e implementado num demonstrador C-RAN já operacional - com fronthaul atualmente baseado em CPRI - no Instituto de Telecomunicações de Aveiro.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

Beam steering in millimeter wave radio links for small cell mobile backhaul

Mobiiliverkkojen dataliikenne kasvaa jatkuvasti. Tulevaisuuden mobiiliverkot kohtaavat uusia haasteita täyttääkseen jatkuvan kasvun asettamat vaatimukset. Yksi mahdollinen tapa parantaa mobiiliverkkojen suorituskykyä on piensoluverkkojen hyödyntäminen, joissa tukiasemat sijaitsevat lähellä toisiaan. Piensoluverkkojen tukiasemat asennetaan epätavallisiin sijainteihin kuten katuvaloihin ja rakennusten seiniin. Piensoluverkkojen tukiasemien epätyypilliset sijainnit asettavat uusia haasteita verkon runkokytkennän toteuttamiselle. Potentiaalinen ratkaisu piensoluverkkojen runkokytkennän toteuttamiseksi on millimetrialueen taajuuksien hyödyntäminen. Millimetrialueen taajuuksilla tarkoitetaan tässä yhteydessä 60 ja 70/80 GHz taajuuksia jotka tarjoavat usean gigahertsin lisensoimatonta ja kevyesti lisensoitua taajuuskaistaa. Millimetrialueen taajuuksilla on korkeat signaalivaimennukset. Teknologiat näillä taajuuksilla tarvitsevat korkean antennivahvistuksen vaimennusten kompensoimiseen. Tämä tarkoittaa sitä että antennin keilanleveys on erittäin kapea. Kapeat antennikeilat tarvitsevat antennikeilan ohjausmenetelmiä muun muassa tuulesta aiheutuvan vibraation kompensoimiseen ja yhteyden muodostamiseen automaattisesti toisen kapeakeilaisen laitteen kanssa, jotta radiolinkkiä ei tarvitse kohdistaa manuaalisesti. Tämän opinnäytetyön päätavoite on kehittää antennikeilan ohjausmenetelmiä Nokia Solutions and Networksin kehittämään millimetrialueen taajuuksilla toimivalle piensoluverkon runkokytkentälaitteelle. Työn tulokset vahvistivat konseptin toimivuuden ja antoivat lupaavia tuloksia antennikeilan ohjausmenetelmien jatkokehitykselle.The mobile data volumes are constantly increasing setting new challenges for the networks to keep up with the demand. One source of improved network performance comes with the extreme cell densification also known as small cells. The small cell deployment creates new challenges for the backhaul. As the small cells are located in city areas of high demand in unconventional installation sites such as lamp posts and building walls; the provisioning of the conventional wired backhaul might be unreasonable. Potential solutions for the small cell backhaul are technologies utilizing millimeter-wave frequencies on 60, 70/80 GHz providing several gigahertz of low cost spectrum. The millimeter-wave frequencies need narrow antenna beams, less than a few degrees, to compensate the high signal attenuations on these frequencies. The narrow beam radio links need vibration compensation mechanisms to compensate the sways and twist of the installation structure caused by wind. Additionally, the narrow beam radio links should automatically establish the connection to avoid time consuming and expensive manual link alignment. Therefore, beam steering is needed denoting that the device can switch the direction of the antenna beam. The main scope of this master’s thesis is to identify the possibilities, challenges and limitations of the potential beam steering methods. The practical part of this thesis included implementation of the beam steering functionalities to a proof-of-concept millimeter-wave small cell backhaul system developed by Nokia Solutions and Networks. The author’s conducted tests confirmed the functionality of the methods and provided suggestions for the future development of the system

A Modular Approach to Adaptive Reactive Streaming Systems

The latest generations of FPGA devices offer large resource counts that provide the headroom to implement large-scale and complex systems. However, there are increasing challenges for the designer, not just because of pure size and complexity, but also in harnessing effectively the flexibility and programmability of the FPGA. A central issue is the need to integrate modules from diverse sources to promote modular design and reuse. Further, the capability to perform dynamic partial reconfiguration (DPR) of FPGA devices means that implemented systems can be made reconfigurable, allowing components to be changed during operation. However, use of DPR typically requires low-level planning of the system implementation, adding to the design challenge. This dissertation presents ReShape: a high-level approach for designing systems by interconnecting modules, which gives a ‘plug and play’ look and feel to the designer, is supported by tools that carry out implementation and verification functions, and is carried through to support system reconfiguration during operation. The emphasis is on the inter-module connections and abstracting the communication patterns that are typical between modules – for example, the streaming of data that is common in many FPGA-based systems, or the reading and writing of data to and from memory modules. ShapeUp is also presented as the static precursor to ReShape. In both, the details of wiring and signaling are hidden from view, via metadata associated with individual modules. ReShape allows system reconfiguration at the module level, by supporting type checking of replacement modules and by managing the overall system implementation, via metadata associated with its FPGA floorplan. The methodology and tools have been implemented in a prototype for a broad domain-specific setting – networking systems – and have been validated on real telecommunications design projects

Journal of Telecommunications and Information Technology, nr 4

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