Abstract: Disclosed herein is a method for transmitting digital data in a super channel, in which a set of carriers are packed in a predetermined bandwidth. The set of carriers comprises higher and lower edge carriers having the highest and lowest wavelengths, respectively, among said set of earners, wherein data is transmitted via the higher and lower edge carriers using a corresponding modulation format, each modulation format using a constellation diagram comprising a number of symbols, wherein a binary address is associated with each symbol.

Abstract: Disclosed herein is a decoder 10 for decoding a family of L rate compatible parity check codes, said family of parity check codes comprising a first code that can be represented by a bipartite graph having variable nodes, check nodes, and edges, and L?1 codes of increasingly lower code rate, among which the i-th code can be represented by a bipartite graph corresponding to the bipartite graph representing the (i?1)-th code, to which an equal number of n1 variable nodes and check nodes are added, wherein the added check nodes are connected via edges with selected ones of the variable nodes included in said i-th code, while the added variable nodes are connected via edges with selected added check nodes only. The decoder comprising L check node processing units 14, among which the i-th check node processing unit processes only the check nodes added in the i-th code over the (i?1)-th code, wherein said L check node processing units 14 are configured to operate in parallel.

Abstract: Disclosed herein is a dual parallel Mach-Zehnder-modulator (DPMZM) device comprising a DPMZM 10 having first and second inner MZMs arranged parallel to each other. The first inner MZM generates an in-phase component EI of an optical signal in response to a first driving voltage VI, and the second inner MZM generates a quadrature component EQ of said optical signal in response to a second driving voltage VQ. Further disclosed is a calculation unit 52 configured for receiving an in-phase component yI and a quadrature component yQ_ of a desired base-band signal, and for calculating pre-distorted first and second driving voltages VI, VQ. The calculation of the pre-distorted first and second driving voltages VI, VQ is based on a model of said DPMZM 10 accounting for I-Q cross-talk, and using an algorithm that determines said first and second driving voltages VI, VQ each as a function of both of said in-phase and quadrature components yI, yQ of said base-band signal.

Abstract: An encoder encodes digital data, said encoder includes one or more component encoders, one or more interconnections between component encoders, one or more inputs and one or more outputs. The encoder is configured to carry out the following steps: combining internal input bits received via an interconnection and external input bits received via a corresponding input, to assemble a local information word, encoding the local information word such as to generate a local code word, outputting a reduced local code word and handling the same reduced local code word over to the interconnect for forwarding the same reduced local code word to another component encoder or to itself, wherein the encoder is configured to forward on each interconnect the bits of the reduced local code in parallel but with delays that are mutually different for at least a subset of the reduced local code word bits.

Abstract: Disclosed is a method for decoding an optical data signal. Said optical data signal is phase and amplitude modulated according to a constellation diagram with at least eight constellation points representing non-binary symbols. Said decoding method comprises the following steps: —carrying out a carrier phase recovery of a received signal ignoring the possible occurrence of phase slips, —decoding said signal after phase recovery, wherein in said decoding, possible cycle slips occurring during phase recovery are modelled as virtual input to an equivalent encoder assumed by the decoding scheme. Further disclosed are a related encoding method as well as a receiver and a transmitter.

Abstract: Enclosed herewith is a method for protecting a link in an optical network configured for transmitting digital data employing a predetermined modulation format which comprises a number of symbols in a constellation diagram. A binary address is associated with each symbol. The modulation format allows for a constellation distortion, according to which the relative positions of constellation points in the constellation diagram are varied in a predetermined way by a predetermined degree.

Abstract: The present invention relates to performing chromatic dispersion estimation in a receiver of an optical communication system. Here, the signal received by the receiver includes frames, each comprising a training portion and a data portion. The training portion comprises a plurality of identical pattern sequences. Different settings are applied to an equalizer to generate a plurality of equalized signals from at least one of the received frames. Then, at least one correlation value is calculated between a first pattern sequence and a second pattern sequence of the equalized signals and a final correlation value is derived from the respective correlation values. The setting of the equalizer corresponding to the equalized signal providing the highest final correlation value is selected to provide the chromatic dispersion estimation.

Abstract: Disclosed herein is a modulator (50) for polarization-division multiplexing (PDM) transmission. The modulator (50) comprises first and second DP-MZMs (12, 28) associated with first and second polarizations, each DP-MZM (12, 28) having an input for an in-phase and a quadrature driving signal for modulating the in-phase and quadrature components of an optical signal according to respective transfer functions, and a detector (58) suitable for detecting light comprising at least a portion of the light outputted by the first DP-MZM (12) and a portion of the light outputted by the second DP-MZM (28). The modulator (50) is adapted to superimpose a first pilot signal on one of the in-phase and quadrature driving signals of the first DP-MZM (12) and on one of the in-phase and quadrature driving signals of the second DP-MZM (28), and a second pilot signal on the respective other of the in-phase and quadrature driving signals of the first and second DP-MZMs (12, 28).

Abstract: The present invention relates to signal processing in an optical receiver, in particular to equalization performed in coherent optical receivers. A multiple-input multiple-output (MIMO) equalizer receives and equalizes a plurality of real value signals, for example four sampled electrical baseband tributaries (HI, HQ, VI, VQ). The outputs of the multiple-input multiple-output (MIMO) equalizer provide equalized real or imaginary components of complex signals. The complex signals including the real and imaginary components are then each and individually equalized to remove chromatic dispersion.

Abstract: Disclosed herein is an encoder for encoding digital data, said encoder comprising one or more component encoders, one or more interconnections between component encoders, one or more inputs and one or more outputs. The encoder is configured to carry out the following steps:—combining internal input bits received via an interconnection and external input bits received via a corresponding input, to assemble a local information word,—encoding the local information word such as to generate a local code word,—outputting a reduced local code word and handing the same reduced local code word over to said interconnect for forwarding said same reduced local code word via said interconnect to another component encoder or to itself, wherein said encoder is configured to forward on each interconnect the bits of the reduced local code in parallel but with delays that are mutually different for at least a subset of the reduced local code word bits.

Abstract: The present invention relates to performing chromatic dispersion estimation in a receiver of an optical communication system. Here, the signal received by the receiver includes frames, each comprising a training portion and a data portion. The training portion comprises a plurality of identical pattern sequences. Different settings are applied to an equalizer to generate a plurality of equalized signals from at least one of the received frames. Then, at least one correlation value is calculated between a first pattern sequence and a second pattern sequence of the equalized signals and a final correlation value is derived from the respective correlation values. The setting of the equalizer corresponding to the equalized signal providing the highest final correlation value is selected to provide the chromatic dispersion estimation.

Abstract: Disclosed herein is a modulator (50) for polarization-division multiplexing (PDM) transmission. The modulator (50) comprises first and second DP-MZMs (12, 28) associated with first and second polarizations, each DP-MZM (12, 28) having an input for an in-phase and a quadrature driving signal for modulating the in-phase and quadrature components of an optical signal according to respective transfer functions, and a detector (58) suitable for detecting light comprising at least a portion of the light outputted by the first DP-MZM (12) and a portion of the light outputted by the second DP-MZM (28). The modulator (50) is adapted to superimpose a first pilot signal on one of the in-phase and quadrature driving signals of the first DP-MZM (12) and on one of the in-phase and quadrature driving signals of the second DP-MZM (28), and a second pilot signal on the respective other of the in-phase and quadrature driving signals of the first and second DP-MZMs (12, 28).

Abstract: Disclosed is a method for decoding an optical data signal. Said optical data signal is phase and amplitude modulated according to a constellation diagram with at least eight constellation points representing non-binary symbols. Said decoding method comprises the following steps: —carrying out a carrier phase recovery of a received signal ignoring the possible occurrence of phase slips, —decoding said signal after phase recovery, wherein in said decoding, possible cycle slips occurring during phase recovery are modelled as virtual input to an equivalent encoder assumed by the decoding scheme. Further disclosed are a related encoding method as well as a receiver and a transmitter.

Abstract: A received POLMUX signal is rotated by fixed rotation parameters (Rot0, Rot1, Rot2) and the rotated POLMUX signal with optimal signal performance is selected and phase information is derived from both polarities. A pre-filter improves the timing accuracy.

Abstract: Disclosed herein is a dual parallel Mach-Zehnder-modulator (DPMZM) device comprising a DPMZM 10 having first and second inner MZMs arranged parallel to each other. The first inner MZM generates an in-phase component EI of an optical signal in response to a first driving voltage VI, and the second inner MZM generates a quadrature component EQ of said optical signal in response to a second driving voltage VQ. Further disclosed is a calculation unit 52 configured for receiving an in-phase component yI and a quadrature component yQ_ of a desired base-band signal, and for calculating pre-distorted first and second driving voltages VI, VQ. The calculation of the pre-distorted first and second driving voltages VI, VQ is based on a model of said DPMZM 10 accounting for I-Q cross-talk, and using an algorithm that determines said first and second driving voltages VI, VQ each as a function of both of said in-phase and quadrature components yI, yQ of said base-band signal.

Abstract: A method for phase recovery in a system that includes a clock recovery unit and an estimation unit. The clock recovery unit of the system has a first phase detector unit. The estimation unit has a second phase detector unit and it is configured to estimate a gain of the second phase detector unit. The estimation unit and the clock recovery unit are configured to operate in parallel.

Abstract: An apparatus for optical communication and optical communication method are provided, the method comprising the steps of generating an optical signal for transmitting the sequence of information data, transmitting the sequence of information data as a sequence of transmit matrices, S(k) being the k-th transmit matrix and k being a positive integer, and wherein the sequence of transmit matrices is transmitted through an optical channel characterized by a unitary channel matrix H, receiving a sequence of receive matrices, the k-th receive matrix R(k) being expressed as: R(k)=H·S(k)+N(k) wherein k is a positive integer and N(k) is a complex matrix of noise samples and providing a sequence of decision matrices, the k-th decision matrix D(k) being expressed as: D(k)=RH(k?1)R(k).

Abstract: A first optical data signal is transmitted on a first data carrier from a first network element. First service information is transmitted from a first service by means of a first optical service signal on a first service carrier. A second optical data signal is transmitted on a second data carrier from a second network element, and second service information is transmitted by a second optical service signal on a second service carrier. An offset between a frequency of the first data carrier and a frequency of the first service carrier is substantially equal to an offset between a frequency of the second data carrier and a frequency of the second service carrier.

Abstract: A method and a device for processing a signal determine a timing phase over an observation interval of an input signal. A frequency estimation is determined based on the timing phase. A phase correction is determined for the observation interval based on the timing phase and the frequency offset. Then the phase correction is used to adjust the timing of the input signal. Also, a communication system with at least one such device is described.

Abstract: A received POLMUX signal is rotated by fixed rotation parameters (Rot0, Rot1, Rot2) and the rotated POLMUX signal with optimal signal performance is selected and phase information is derived from both polarities. A pre-filter improves the timing accuracy.