Optical Transport Network

About: Optical Transport Network is a research topic. Over the lifetime, 6055 publications have been published within this topic receiving 85783 citations.

Optical network terminator

Abstract: An optical network terminator for terminating and reducing the accumulated noise in optical networks, particularly ring based networks. The terminator eliminates problems of noise accumulation from amplifier spontaneous emission (ASE), thermal noise, etc., while providing bi-directional communications in the optical network. The optical network may have any topology including ring, star, mesh, point-to-point, etc. In the case of an optical ring, the ring is broken and an optical terminator is placed in line therewith. The optical network terminator includes a filer such as an optical demultiplexer/multiplexer or Fiber Bragg Grating (FBG) based filter. Each individual wavelength of light is filtered and a multi-wavelength optical output is generated whereby the noise accumulation is removed. Each channel is adapted to only pass a band-limited signal around the center frequency corresponding to the wavelengths supported by the particular optical ring network. Channel equalization uses variable optical attenuators and monitors in line with each channel. Channels currently not in use may be disconnected from the ring remotely by setting the corresponding optical attenuator to a low enough level.

Multi-channel, multi-mode redundant optical local loop having a bus topology

Abstract: An optical local loop having a bus topology with a pair of optical fibers disposed among a plurality of Optical Network Units (ONUs). A Host Digital Terminal (HDT) is disposed at the head end of the optical local loop for concentrating optical signals for a network. Redundant transceiver banks are provided within the HDT for operating with the optical signals effectuated at a plurality of wavelengths which are multiplexed and de-multiplexed via a pair of Wavelength Division Multiplex (WDM) couplers disposed on corresponding optical fibers. During transmission, the ONUs excite both optical fibers and the received optical signals are monitored in the HDT for quality and integrity of the optical paths. A selectively actuatable mechanism is provided in the HDT to switch downstream transmission to the ONU nodes from one optical path to the other optical path of the local loop based on the path quality and integrity.

A Low-Complexity Three-Error-Correcting BCH Decoder for Optical Transport Network

Abstract: The forward error correction for 100-Gbit/s optical transport network has received much attention recently. Studies showed that product codes that employ three-error-correcting Bose-Chaudhuri-Hocquenghem (BCH) codes can achieve better performance than other BCH or Reed-Solomon codes. For such codes, the Peterson algorithm can be used to compute the error locator polynomial, and its roots can be found directly using a lookup table (LUT). However, the size of the LUT is quite large for finite fields of high order. In this brief, a novel approach is proposed to reduce the LUT size by at least four times through making use of the properties of the error locator polynomial and normal basis representation of finite field elements. Moreover, hybrid representation of finite field elements is adopted to minimize the complexity of the involved computations. For a (1023, 993) BCH decoder over GF(210), the proposed design can lead to at least 28% complexity reduction.

Routing and wavelength assignment over WDM optical networks: a comparison between MOACOs and classical approaches

Abstract: The increasing demand of bandwidth has found an answer in Optical Transport Networks (OTN). To take advantage of the different resources that OTNs offer, several parameters need to be optimized to obtain good performance. Therefore, this work studies the Routing and Wavelength Assignment (RWA) problem in a multiobjective context. MultiObjective Ant Colony Optimization (MOACO) algorithms are implemented to simultaneously optimize the hop count and number of wavelength conversion for a set of unicast demands, considering wavelength conflicts. This way, a set of optimal solutions, known as Pareto Set, is calculated in one run of the proposed algorithm, without a priori restrictions on some objective. The proposed MOACO algorithms were compared to classical RWA heuristics using several performance metrics. Although, there is not a clear superiority, simulation results indicate that considering most of the performance metrics, MOACO algorithms obtain promising results when compared to the classical heuristics.

100km long reach upstream 36Gb/s-OFDMA-PON over a single wavelength with source-free ONUs

Abstract: We experimentally demonstrate 36-Gb/s source-free single-wavelength upstream OFDMA-PON transmission, enabled by ONU carrier suppression and coherent reception at the OLT. A BER ≪10−3 is reported over 100km SSMF and a 1:32 optical split.