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Navegando por Assunto "Fronthaul"

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    Análise de desempenho de redes de acesso G.mgfast e fronthaul 5G baseado em cabos coaxiais
    (Universidade Federal do Pará, 2019-05-27) FREITAS, Marx Miguel Miranda de; NUNES, Diogo Lobato Acatauassú; http://lattes.cnpq.br/1972007941497086; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434
    This work explores two possibilities of harnessing mature cabling technologies used in broadband networks of 4th generation systems in emerging next generation applications. Specifically, two proposals for using the cabling structure of Hybrid Fiber Coax and SAT TV (Satellite Television) systems are evaluated. The first one, as support in 5G network analog transport networks (fronthaul). The second evaluates the use of coaxial cables in access networks G.mgfast (Multi Gigabit G.fast). In the firs one, It is shown the relationships between the data rates and the number of antennas reached by the coaxial cable RG06, under a fixed power level and a target signal noise condition, considering different distances and two configurations of radio signals. It is shown that in the 5G analogue fronthaul analyzed, rates higher than 40 Gbps can be obtained in a RG06 coaxial cable, giving support to 140 antennas, meeting 3GPP transmission criteria. The second solution proposes a process to reduce power consumption in the network, by adapting the transmission power in the coaxial network, with higher bit load in the initial frequencies of the spectrum. Links with RG59, RG06 and RG11 coaxial cables are analyzed, considering rates ranging from 5 Gbps to 10 Gbps and two types of bit loading algorithms. It is shown that with these procedures the power saving obtained in single link with 100 m coaxial cable can be used to power another 28 cables of 50 m. On the other hand, it is shown that the power reduction is not relevant, from the point of view of redistribution, in cables whose length is less than or equal to 25 m.
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    Uma análise técnico-econômica para implantação de arquiteturas centralizadas de redes de telefonia móveis
    (Universidade Federal do Pará, 2018-03-06) SOUZA, Daniel da Silva; CARDOSO, Diego Lisboa; http://lattes.cnpq.br/0507944343674734
    Upon the the challenges proposed by the fifth generation of mobile networks, the architecture of C-RAN (Centralized Radio Acess Network) has gained space by supporting high-capacity ultra-densas networks of next generation and offering economies. This dissertation proposes a TCO (Total Cost of Ownership) for C-RAN, CAPEX (Capital Expenditure), OPEX (Operational Expenditure) and these are the fundamental criteria in the field of investment assessment and projection. It is soon presented with a higher level of detailing as to the investment aspects, which are of great relevance to the architectural landscape of mobile communication networks. In this way, this work is conducted in order to evaluate the economic context of the implementation of a centralized architecture, based mainly on the financial aspects that service operators need to plan before deploying a new Mobile Access Network. The proposed model is used in a case study where the total cost of implementation and operation of the distributed and centralized architectures is compared taking into account several specific scenarios. The results point to an economy in the centralized scenarios and highlight the most relevant economic aspects in the planning of C-RAN.
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    Avaliação de técnicas de compressão de sinais Para o fronthaul
    (Universidade Federal do Pará, 2019-11-27) BRITO, Flávio Mendes de; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284
    The growing data demand of mobile networks has motivated the creation and evolution of architectures aiming to supply such transfer requirements. To meet these requirements, a number of challenges need to be met, including data transfer at the link between the Base Station Unit (BBU) and the Remote Radio Head (RRH). Known as fronthaul, this link requires high speed information transfer and one method that allows to tranfer more data using the same rate is data compression. Therefore, this study aimed to evaluate different techniques used in fronthaul data compression. Initially, the efficiency of some quantizers such as the scalar quantizer (SQ), twodimensional vector (VQ) and the Trellis Coded Quantization (TCQ) was verified. The analysis consists of combining these quantizers with resampling, Block Scaling and Huffman coding. In both analyzes, it was found that the system using TCQ as quantizer obtained the best relationship between Error Vector Magnitude (EVM) and computational cost, offering an EVM lower than the scalar quantizer and a computational cost lower than the vector quantizer.
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    Avaliação técnico econômica de alternativas backhaul e fronthaul para arquiteturas de rádio centralizado em cenários 5G indoor
    (Universidade Federal do Pará, 2019-05-28) FERNANDES, André Lucas Pinho; FARIAS, Fabrício de Souza; http://lattes.cnpq.br/1521079293982268; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434
    The transport networks have a key role fifth in the support of demands of any telecommunications system. The fifth generation of mobile communication systems, the 5G, seeks to support a highly digitalized society, which has high operational demands. CRA (Centralized radio architecture) are emerging as a technically capable transport alternative to support 5G. Such solution divides the transport network into two sections, backhaul and fronthaul, which can be subdivided into several levels of links, whether optical, metallic or based on microwave. The viability of any technology to support the 5G does not only depend of technical requirements, whether traffic, coverage, availability or others, but also of the installation and operation economic aspects of the technologies. In this context, this work performs an technical and economic analysis for CRAs attending the indoor environment in the 5G context. To this end, a reference traffic forecast model is utilized and a set of models for dimensioning, predicting fault behavior and costs have been proposed and developed, which are generic and can be applied to different types of networks configurations or environments, whether indoor or outdoor, in a way that the two last mentioned models are based on a Markovian model solved by simulation. The analysis focused on CRAs installed in the indoor environment, where users spend most of their time, considering a high-density urban scenario, fronthaul with optical and metallic link levels or only metallic, as well PON (Passive Optical Network) based backhaul. The considered fronthaul alternatives were optical-metallic hybrid using 10 and 32 Gbps bidirectional transceivers, as well as all-metallic using the standard G.(mg)fast, making use or not of the phantom mode transmission, which is a technique to create virtual differential channels from real twisted pairs, resulting in increased capacity for metallic cables. The PON considered standards for the backhaul are 40 Gigabit PON and wavelength division multiplexing PON. The considered protection topologies against equipment failures for the PON backhaul are basic (unprotected), protected at the feeder level, protected at the feeder level and optical line terminal, and protected at the optical line terminal and at both levels feeder and distribution). The obtained results indicates that the best fronthaul alternative for CRA, supporting a average building of a high density urban scenario, is the all metallic using the standard G.(mg)fast with phantom mode transmission. In addition, they also indicate that PONs can be viable as backhaul 5G if protection schemes are used, and that in a dense urban setting, the 40 Gigabit PON standard is technically and economically the most viable for CRAs backhaul.
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    Compressão de CSI para MIMO distribuído com processamento centralizado
    (Universidade Federal do Pará, 2024-06-18) SILVA, Marcos Davi Lima da; RAMALHO, Leonardo Lira; http://lattes.cnpq.br/7565458988876048; https://orcid.org/0000-0003-3165-1941
    In Distributed-MIMO (D-MIMO), a large number of distributed Antenna Points (APs) are coordinated by a Central Unit (CU) to serve a limited number of users with the same time/frequency resources, which brings improvements in spectral efficiency. The success of D-MIMO depends on precoding and power allocation, which can be performed completely centrally on the CU or distributed across APs. The centralized approach has greater spectral efficiency than the distributed implementation, but requires a significant spike in fronthaul traffic due to the exchange of Channel State Information (CSI) between APs and CU. In this work, CSI compression schemes are proposed to enable practical and centralized implementation of D-MIMO. It is shown that depending on the compression configuration, the spectral efficiency can be as good as in the case without compression. Furthermore, this work explores the implementation of multiple-input multiple-output (MIMO) within the framework of the New Radio (NR) architecture. The study evaluates a distributed MIMO deployment using NR signals with compression and evaluates its performance compared to the uncompressed scenario. Through simulations using the NR physical layer, the results also show that the spectral efficiency can be as good as in the uncompressed case depending on the compression configuration. Finally, the simulations with NR signals highlight important practical aspects and the feasibility of implementing D-MIMO in the 5G architecture and beyond 5G.
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    Compressão de sinais em sistemas de rádio sobre fibra digital para redes fronthaul
    (Universidade Federal do Pará, 2019-07-23) MATE, Dércio Manuel; TEIXEIRA, António Luis de Jesus; OLIVEIRA, Rosinei de Sousa; http://lattes.cnpq.br/3853897074036715; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434
    The introduction of technologies such as Carrier Aggregation (CA), Massive Multiple Input Multiple Output (MIMO) and Coordinated Multipoint (CoMP), aiming to improve the performance of LTE and LTE-A systems, increases the challenge for deploying Mobile Fronthaul due to the network capacity limitation to support higher transmission rates. An approach to deal with Frontahul’s capacity limitation is data compression. Several techniques have been developed for signal compression in fronthaul, and most of these techniques compress the signal transmitted in baseband. In this work, a compression technique is developed for specific scenarios of Digital Radio-over-Fiber systems, transmitting the signal in intermediate frequency (IF). This technique uses the radio channel state information (CSI) to control signal compression in the fronthaul. The simulation results with the developed technique demonstrate its ability to reduce the data transmitted onthe network by 45.05%. In addition, this technique allows the transmission of 64 QAM modulated signals using a lower quantizer resolution, e.g., 4 bits per sample, maintaining the EVM below 3GPP recommended threshold (8%). Finally, the performance of the fronthaul network is evaluated experimentally in an optical link of 20-km, considering scenarios with and without signal compression.
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    FPGA implementation and evaluation of synchronization architectures for ethernet-based cloud-ran fronthaul
    (Universidade Federal do Pará, 2016-01-18) FREIRE, Igor Antonio Auad; KLAUTAU JÚNIOR, Aldebaro Barreto da Rocha; http://lattes.cnpq.br/1596629769697284
    The use of Ethernet infrastructure available in most commercial buildings can alleviate the costs involved with fronthaul provisioning in cloud radio access networks. However, current fronthaul specifications rely on dedicated synchronous links, which natively support features such as accurate synchronization across radio devices. In this context, a cost-effective and backwardscompatible solution is to adapt standard fronthaul interfaces (e.g. CPRI) to asynchronous networks by using endpoint equipments capable of meeting synchronization requirements over legacy Ethernet. This dissertation proposes design considerations for synchronization of radio over Ethernet and evaluates the feasibility of synchronization architectures by developing an FPGA-based hardware testbed. It contrasts two solutions, a simplistic approach that employs elastic buffering for recovering frequency and an end-to-end IEEE 1588 Precision Time Protocol solution for time and frequency alignment. Results suggest that the scheme with PTP solely at the endpoints can comply with time and frequency alignment requirements of current mobile standards if packet delay variation is treated with sound algorithms.
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    Impacto de não-uniformidades em cabos de pares trançados na transmissão em modo fantasma
    (Universidade Federal do Pará, 2017-09-25) OHASHI, Aline Ayako; RODRIGUES, Roberto Menezes; http://lattes.cnpq.br/0848357090195263; COSTA, João Crisóstomo Weyl Albuquerque; http://lattes.cnpq.br/9622051867672434
    In the next years, a dramatic increase in traffic demands for mobile – communication systems is expected. To support such demands, the new generation of communication, called 5G, is being developed to allow a wide range of new applications. The key point to the future success of 5G networks is the adopted fronthaul solution. In general, optical and microwave links are suitable alternatives for fronthaul. However, copper is still a viable option in some situations, mainly due to reduced cost and the application of techniques to boost the copper performance, such as the phantom mode. Such technique includes extra channels over the ordinary differential ones for the same copper system, increasing its aggregated data rate. For this purpose, the channels called “phantom” use signaling in common mode, over ordinary channels (differentials). Ideally, there is no leakage between differential channels to the phantom one. However, copper cables have non-uniformities that are the source of the signal leakage into the pairs, especially for frequencies of the order of hundreds of MHz. It is not fully understood how the cable non-uniformities affect the crosstalk from the differential to phantom mode transmission, and viceversa. In this work, effect of cable non-uniformities on the attenuation of differential and phantom channels, as well as on the crosstalk among them, is studied. To enable phantom transmission, a simulator developed by Stanford University was adapted. Three types of non-uniformities were simulated: variation in the distance between the center of pairs, pigtail and non-uniform twisted pairs, for frequencies range from DC to 500 MHz, using cable length from 10 to 100 m. The results showed: phantom mode aggregate data rate for uniform scenarios with 61.94% of contribution. Moreover, considering the same length cable, variation in the distance between the center of pairs had a big impact in the reduction of phantom channel contribution with just 24.02 %, more impact than others studied, whereas the non-uniform twists had negligible impact on channel aggregated data rate, with phantom contribution of 61.93 %. Besides that, it is shown that pigtail has impact just to short length cables.
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