Ciena

About: Ciena is a company organization based out in Hanover, Maryland, United States. It is known for research contribution in the topics: Signal & Node (networking). The organization has 1259 authors who have published 1557 publications receiving 25989 citations.

Method and apparatus for expanding the dynamic range of optical amplifiers

Abstract: The dynamic range of an optical amplifier is extended by the addition of a power control circuit. A switch is interposed between a current source and an optical pump supplying pumping light to the gain medium of the optical amplifier. A modulated signal such as a pulse-width modulated signal is used to actuate the switch and control a relative duration of the “on” and “off” periods of the electrical current supplied to the optical pump. Gain latency in the optical amplifier permits a substantially continuous signal to be output from the optical amplifier in response to the switched electrical current supply to the optical pump. A controller may used a feedback signal from the optical pump or from a power monitoring device to control the modulator and, thereby, the switch. A target pump power level, target gain or target amplified signal power level may also be applied in a feedback control loop that controls the modulator and switch. The invention also takes the form of a method that may be used to control a conventional optical amplifier in order to expand the dynamic range, particularly in the low power region.

Use of Extreme Value Statistics to Assess the Performance Implications of Cascaded ROADMs

Abstract: The performance implications of passband impairments and bandwidth narrowing caused by the cascading of optical filters are investigated using a 100 Gb/s dual polarization, quadrature-phase-shift-keyed (DP QPSK) transceiver. The overall responses for cascades of filters are emulated using the combination of a programmable optical filter and variable bandwidth optical filter. The statistical variations in the responses for a cascade are addressed by considering 1000 realizations that result from randomly selected responses for each of the individual filters. To determine the impact on system margins, a methodology based on extreme value statistics is presented. The signal-to-noise ratios (SNRs) that correspond to real-time estimates of the pre-forward error correction bit error ratio (pre-FEC BER) are quantified in terms of the probability that the minimum of $n$ observations of the SNR is less than a specified value (maximum pre-FEC BER exceeds a specified value). This approach improves the reliability of predicting the impact of cascaded filtering on system performance by removing the uncertainty about the underlying statistical distribution of the SNR.

System and method for compensating packet delay variations

Abstract: A system improves reconstruction of real-time data in a packetized network. The system includes the following elements. A play-out buffer (106) receives packets from the network. A playback element (102), coupled with the play-out buffer (106), retrieves packets from the play-out buffer (106) and outputs data for the reconstruction of real-time data. A time adjuster (502) alters the rate at which the data is output in accordance with the availability of the packets.

Method and apparatus for generating massive interrupts in random access memory (RAM)

Abstract: A method and apparatus for generating massive interrupts in random access memory (RAM) are provided, comprising receiving and storing Time Slot network (TS Net) data frames comprising switching event information in a first RAM area. Compare operations are performed among prespecified ones of the TS Net data frames. Unit interrupt bits are set in a corresponding location of a second RAM area in response to detected bit differences resulting from the compare operations. Interrupt status bits are set in a corresponding location of a third RAM area in response to set unit interrupt bits. Massive interrupt signals are generated in response to set unit interrupt bit.

Optical cross connect apparatus and method

Abstract: A new architecture is proposed for making optical cross connect (200) in wavelength division multiplexed networks The value of optical networks incorporating all-optical cross connects (210) is typically associated with being able to selectively route individual channel wavelengths through several network nodes without performing optical-electrical and electrical-optical conversion From a network perspective, most work on the optical cross connect architectures (210, 202, 204, 220) have been concentrated on the highest possible capability for the cross-connect itself The problem with considering optical cross connect architectures (210) in isolation without attention to the rest of the network may lead to unnecessarily complicated hardware In the proposed architecture, considers the network as a whole and significant cost reductions as well as complexity reductions are realized