Feedforward Carrier Recovery For Polarization Demultiplexed Signals With Unequal Signal To Noise Ratios.

We investigate feedforward carrier recovery (FFCR) in coherent polarization diversity receivers where the signal to noise ratio (SNR) of polarization demultiplexed signals can be unequal, such as in polarization-dependent loss impaired systems. A joint-polarization FFCR mechanism for estimating the carrier phase noise based on samples from both polarizations is proposed and compared with three other plausible alternatives. We evaluated each architecture using Monte Carlo simulations and observed that the joint-polarization FFCR yields a 1.1 dB SNR penalty for a given laser linewidth x baud rate product, while the other three architectures offer 1.8 dB, 2.0 dB and 3.9 dB, for QPSK at BER = 10(-3) and 3 dB SNR imbalance.177958-6

An Insight into the Total Cost of Ownership of 5G Fronthauling

This paper provides an assessment of the total cost of ownership (TCO) of a number of 5G fronthauling solutions based on digital and analog radio-over-fiber (RoF) architectures in cloud radio access network (C-RAN). We computed the capital and operational expenditures (CAPEX, OPEX) in the case of an optical fiber aggregation network based on a ring topology. Three different RoF architectures were considered: intermediate frequency analog RoF (IF-A-RoF), digital signal processing assisted analog RoF (DSP-A-RoF), and digital RoF (D-RoF) based on the common public radio interface (CPRI). A greenfield scenario considering both fiber deployment and fiber leasing was analyzed. The results presented in the paper show how the TCO changes with the number of aggregated carriers for the considered RoF architectures and fiber deployment strategy. They also reveal the impact that each cost category has on the overall CAPEX and OPEX value

Transmission of CE-OFDM signals over MMF links using directly modulated 850-nm VCSELs

We report the experimental transmission of constant-envelope orthogonal frequency division multiplexing (CE-OFDM) signals over short-reach multimode fiber links. Error-free transmission of 2.2 Gb/s over a 300-m OM-3 fiber link, using a directly modulated 850-nm vertical-cavity surface emitting laser and direct detection, is achieved. The results confirm the CE-OFDM modulation format as a low peak-to-average power ratio alternative for low-cost data-center interconnects273315318CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPFUNDAÇÃO DE AMPARO À PESQUISA E INOVAÇÃO DO ESPÍRITO SANTO - FAPES307470/2012-1; 474947/2013-0376/14Sem informação48508560/200

Parameter selection in optical networks with variable-code-rate superchannels

Future flexible transceivers will be able to adjust modulation format, number of subcarriers, symbol rate, and forward error correction (FEC) scheme, according to channel and network conditions. This paper uses a combination of theoretical derivations and experimental results to recommend the best set of parameters to satisfy a specific demand to be routed along the network. In particular, for a given required transparent reach and desired net bit rate, and assuming an FEC scheme with a constant gap to capacity, the paper provides a set of modulation format, number of subcarriers, symbol rate, and code rate, which requires minimum bandwidth, while offering a conveniently low bit error rate (in optical systems, typically 10(-15)). We observed that optimum operating points required FEC schemes with overheads ranging from almost 0 to 145%, which is an important guideline for future flexible optical communications systems87A152A161FINANCIADORA DE ESTUDOS E PROJETOS - FINEPFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPnão temnão te