Navegando por Assunto "Cloud-RAN (Cloud radio acess network)"

Agora exibindo 1 - 2 de 2

Acesso aberto (Open Access)
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.
Acesso aberto (Open Access)
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.