Abstract: A coherent optical data receiver having a digital signal processor (DSP) capable of mitigating equalization-enhanced phase noise (EEPN). In an example embodiment, the DSP mitigates EEPN by applying individual phase adjustments to different spectral slices of a digital stream carrying CD-compensated digital samples of the received optical data signal. In different embodiments, the individual phase adjustments can be dynamically selected based on symbol decisions taken prior to EEPN mitigation, based on transmitted pilot symbols, and/or using moving averages computed for different spectral slices. Some embodiments are suitable for handling polarization-division-multiplexed optical data signals. Some embodiments are advantageously capable of producing an effective SNR gain of approximately 1 dB.

Abstract: Embodiments relate to a method for generating a second data packet for a second network layer from a first data packet including a first header portion with information related to a first network layer higher than the second network layer. The method comprises generating, based on the first header portion, a second header portion including information related to the second network layer and generating a payload portion including the first data packet. The method further comprises generating the second data packet for the second network layer by linking the second header portion and the payload portion.

Abstract: Embodiments relate to an apparatus for a regenerative network node between a first and a second link portion. The apparatus comprises an input configured to receive, from the first link portion, a signal impaired by the first link portion, the signal including a data packet with a Forward Error Correction (FEC) encoded payload portion and a header portion. The apparatus comprises a signal regeneration unit configured to mitigate signal impairments of the first link portion to provide a regenerated FEC encoded payload portion. The apparatus comprises a processing unit configured to extract destination information in the data packet's header portion. If extracted destination information indicates that the data packet's destination is the regenerative network node, the data packet's regenerated FEC encoded payload portion is forwarded to a decoding unit of the regenerative network node. Else, the data packet's regenerated FEC encoded payload portion is forwarded to the second link portion.

Abstract: Embodiments relate to an apparatus for a regenerative network node between a first and a second link portion. The apparatus comprises an input configured to receive, from the first link portion, a signal impaired by the first link portion, the signal including a data packet with a Forward Error Correction (FEC) encoded payload portion and a header portion. The apparatus comprises a signal regeneration unit configured to mitigate signal impairments of the first link portion to provide a regenerated FEC encoded payload portion. The apparatus comprises a processing unit configured to extract destination information in the data packet's header portion. If extracted destination information indicates that the data packet's destination is the regenerative network node, the data packet's regenerated FEC encoded payload portion is forwarded to a decoding unit of the regenerative network node. Else, the data packet's regenerated FEC encoded payload portion is forwarded to the second link portion.

Abstract: Embodiments relate to a method for generating a second data packet for a second network layer from a first data packet including a first header portion with information related to a first network layer higher than the second network layer. The method comprises generating, based on the first header portion, a second header portion including information related to the second network layer and generating a payload portion including the first data packet. The method further comprises generating the second data packet for the second network layer by linking the second header portion and the payload portion.

Abstract: A method, a network controller, a network node and a network for switching an optical signal in an optical flex grid network is disclosed. A first optical signal is allocated to a first spectral slot of the grid at an input port of an optical node, and an output port of the node to which the first optical signal shall be switched at the node is asserted. Allocation status of a second, next neighboring spectral slot at the input port of the node is determined Control instructions request for switching at least the first signal from the input port to the output port at the node by a flex grid WSS via a continuous filter function comprising at least the spectral slices of said first spectral slot. The filter function comprises one or more spectral slices of the second spectral slot in dependence on the determined allocation status.

Abstract: In order to achieve a higher spectral efficiency of OFDM sub-bands, optical signals using orthogonal frequency division multiplexing are transmitted through an optical network in the form of a continuous waveband optical signal. An optical add/drop multiplexer (1) splits the continuous waveband optical signal into an express path and a drop path. A band pass filter (4) is provided in the drop path to extract a sub-band carrying at least one of said OFDM modulated optical signals (DROP). The band pass filter (4) has a filter bandwidth that covers the sub-band to be extracted. A band-stop filter (3) is provided in the express path to remove the sub-band to be extracted from the continuous waveband optical signal (IN). The band stop filter (3) has a filter bandwidth which is narrower than the band pass filter (4). An OFDM modulated optical add signal (ADD) can be added into the wavelength gap created through the band stop filter (3).

Abstract: The present invention provides a method and system for transmitting data over an optical channel using OFDM with a variable transmission rate. Such method and system feeds an essentially constant transmission power over a predetermined OFDM bandwidth into the optical channel. In an embodiment, at least two OFDM subcarriers may be modulated with signal information derived from a single word of an OFDM symbol. Further thereto, the frequency spacing between the transmitted OFDM subcarriers may be changed.

Abstract: In order to achieve a higher spectral efficiency of OFDM sub-bands, optical signals using orthogonal frequency division multiplexing are transmitted through an optical network in the form of a continuous waveband optical signal. An optical add/drop multiplexer (1) splits the continuous waveband optical signal into an express path and a drop path. A band pass filter (4) is provided in the drop path to extract a sub-band carrying at least one of said OFDM modulated optical signals (DROP). The band pass filter (4) has a filter bandwidth that covers the sub-band to be extracted. A band-stop filter (3) is provided in the express path to remove the sub-band to be extracted from the continuous waveband optical signal (IN). The band stop filter (3) has a filter bandwidth which is narrower than the band pass filter (4). An OFDM modulated optical add signal (ADD) can be added into the wavelength gap created through the band stop filter (3).

Abstract: A receiver device for optical data signals, in particular optical data signals in the Gb/s range, comprising an opto-electrical conversion unit, a frequency multiplicator unit (24) for frequency-multiplying the converted electrical data signal, and a clock recovery unit is characterized in that the frequency multiplicator unit (24) performs a frequency multiplication by a factor of n, with n being a natural number larger than 2. The receiver device has an improved tolerance on dispersion as far as generating a clock line is concerned.

Abstract: System, apparatus and method of optical communication are provided for performing efficient channel estimation for a CO-OFDM link utilizing an intra-symbol frequency-domain averaging (ISFA) to compensate for transmission impairments. An exemplary method includes receiving a pair of training symbols in an optical orthogonal frequency-division multiplexed (OFDM) signal, performing channel estimation to obtain a first estimated channel matrix for each of a plurality of subcarriers of the OFDM signal; and averaging the first estimated channel matrix of a first subcarrier with the first estimated channel matrix of others of the subcarriers to obtain a second estimated channel matrix for the first subcarrier. The second estimated channel matrix may be an average or weighted average. Prior to the averaging, compensation of chromatic dispersion may be performed. Channel compensation is performed based on the second estimated channel matrix for the first subcarrier of the OFDM signal and symbols then decoded.

Abstract: A polarization mode dispersion (PMD) controller device for controlling the state of polarization of an optical light wave comprising a dispersion compensation unit (2; 25; 40) and an adaptation control unit (6; 28; 44), wherein the dispersion compensation unit (2; 25; 40) comprises a multitude of compensation stages processing the optical light wave, and wherein the adaptation control unit (6; 28; 44) controls the dispersion compensation unit (2; 25; 40) is characterized in that at least one feed-forward signal tap (4; 26a-26c, 73a-73c) is provided tapping the optical light wave inserted into one of the compensation stages, that the feed-forward signal(s) is(are) fed into a distortion analyzer unit (5; 27; 66) and that the distortion analyzer unit (5; 27; 66) provides the adaptation control unit (6; 28; 44) with information about the incoming optical light wave. It accelerates the adaptation speed and lowers the costs of a high-speed PMD controller device.

Abstract: A method for transmitting a modulated optical signal (S) comprising a carrier and at least two sidebands (LSB, USB) which are arranged symmetrically to a carrier wavelength (AC) from a transmitter (2) to a receiver (3) via an optical transmission link (4, 4?, 4?) comprises the steps of: separating the optical signal (S) into two optical single sideband signals (SB1, SB2) symmetrically to the carrier wavelength (?C), mirroring one of the two sideband signals (SB2) to the spectral location of the other single sideband signal (SB1), and combining both sideband signals (SB1, SB2) prior to optical-electrical conversion at the receiver (3). To this end and according to another aspect of the invention, a signal processing unit (5) comprises a wavelength mirror (7) that mirrors one of the sidebands (SB2) of the transmitted signal (S) onto the other (SB1).

Abstract: A device for receiving a distorted signal, in particular an optical signal converted by an opto/electrical converter, comprises an analog/digital converter (1) with adjustable thresholds and a Viterbi equalizer (10). The device further comprises a histogram estimator (13) for determining a probability density function of the distorted signal and a threshold estimator (4) for dynamically adjusting at least one threshold of the analog/digital converter (1) in an overlap region of a first signal amplitude attributed to a first symbol (?10, X10) and a second signal amplitude attributed to a second symbol (?11, X11) of the probability density function.

Abstract: A device (1) for receiving a distorted signal, in particular an optical signal converted by an opto/electrical converter (2), comprises an electrical low-pass filter (3), an analog/digital converter (4), and a Viterbi equalizer (5). The bandwidth of the electrical low-pass filter (3) and the sampling rate of the device (1) are set such that a noise sample at an actual sampling time is correlated to one or more noise samples at one or more adjacent sampling times and the Viterbi equalizer (5) comprises a means (5a) for mitigating inter-symbol interference by taking into account correlation of the different noise samples at the actual sampling time and one or more adjacent sampling times.

Abstract: A process is proposed for recovering disturbed digital signals, wherein the electrical signals pass through a feedback equalizer and an analogue control of the setting parameters of the equalizers is performed. A pseudo-error monitor, which facilitates a high-speed adjustment of decision element thresholds, is also provided.

Abstract: A receiver is described for optical or electromagnetic signals comprising a digital equalizer and a Forward Error Correction, said digital equalizer and FEC combined together to obtain an iterative equalization and error-correction loop, plus a method is described for improving the exactness in relating binary data to a digitalized-data transmitting, analog electromagnetic or optical-electrical signal arriving at a receiver, comprising the steps a) transforming the arriving analog signals into analog signals in the form of digital soft data representing interim values, which indicate the value of the amplitude of the analog signal, b) feeding the soft data to a digital equalizer, c) sequential determination of the interim value representing the boundary at which the decision would have to be made whether a ‘0’ or a ‘1’ had to be related to the soft data when transformed to binary data in the digital equalizer, d) feeding the soft-data signal further processed in the way described to a soft-in/soft-out FEC, e)

Abstract: A receiver for optical signals is described, comprising a Viterbi equalizer which comprises an analog electronic equalizer as a filter for the signals before the signals are to be processed by the Viterbi equalizer, and a receiver for optical signals is described, comprising a Viterbi equalizer which comprises a parameter-estimation device for obtaining estimated values indicating the degree of distortion of the optical signal connected with the analog signal path, with the parameter-estimation device connected with the Viterbi equalizer for transmitting the estimated values gained from the analog signal to the Viterbi equalizer, plus a method is described for improving an optical receiver's ability to identify digitalized data transmitted by analog optical signals, comprising the steps of analog filtering of the analog signal, subsequent analog-to-digital conversion of the analog signal into a digital soft-data signal, feeding the digital soft data to a Viterbi equalizer, relating the digital soft data to bi

Abstract: A receiver device for optical data signals, in particular optical data signals in the Gb/s range, comprising an opto-electrical conversion unit, a frequency multiplicator unit (24) for frequency-multiplying the converted electrical data signal, and a clock recovery unit is characterized in that the frequency multiplicator unit (24) performs a frequency multiplication by a factor of n, with n being a natural number larger than 2. The receiver device has an improved tolerance on dispersion as far as generating a clock line is concerned.

Abstract: A polarization mode dispersion (PMD) controller device for controlling the state of polarization of an optical light wave comprising a dispersion compensation unit (2; 25; 40) and an adaptation control unit (6; 28; 44), wherein the dispersion compensation unit (2; 25; 40) comprises a multitude of compensation stages processing the optical light wave, and wherein the adaptation control unit (6; 28; 44) controls the dispersion compensation unit (2; 25; 40) is characterized in that at least one feed-forward signal tap (4; 26a-26c, 73a-73c) is provided tapping the optical light wave inserted into one of the compensation stages, that the feed-forward signal(s) is(are) fed into a distortion analyzer unit (5; 27; 66) and that the distortion analyzer unit (5; 27; 66) provides the adaptation control unit (6; 28; 44) with information about the incoming optical light wave. It accelerates the adaptation speed and lowers the costs of a high-speed PMD controller device.