WO2023165703A1 - Dispositif et procédé de traitement de signal dans un système optique cohérent multibande numérique -dmb - - Google Patents

Dispositif et procédé de traitement de signal dans un système optique cohérent multibande numérique -dmb - Download PDF

Info

Publication number
WO2023165703A1
WO2023165703A1 PCT/EP2022/055462 EP2022055462W WO2023165703A1 WO 2023165703 A1 WO2023165703 A1 WO 2023165703A1 EP 2022055462 W EP2022055462 W EP 2022055462W WO 2023165703 A1 WO2023165703 A1 WO 2023165703A1
Authority
WO
WIPO (PCT)
Prior art keywords
signal
sideband signal
sideband
samples
filter
Prior art date
Application number
PCT/EP2022/055462
Other languages
English (en)
Inventor
Michael Zarubinsky
Kfir BEZALEL
Igor Levakov
Itzik MALOBANI
Original Assignee
Huawei Technologies Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Huawei Technologies Co., Ltd. filed Critical Huawei Technologies Co., Ltd.
Priority to PCT/EP2022/055462 priority Critical patent/WO2023165703A1/fr
Publication of WO2023165703A1 publication Critical patent/WO2023165703A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/66—Non-coherent receivers, e.g. using direct detection
    • H04B10/67—Optical arrangements in the receiver
    • H04B10/671—Optical arrangements in the receiver for controlling the input optical signal
    • H04B10/675—Optical arrangements in the receiver for controlling the input optical signal for controlling the optical bandwidth of the input signal, e.g. spectral filtering

Definitions

  • the present disclosure generally relates to optical transmission systems, and in particular to Digital Multiband (DMB) transmission systems.
  • DMB Digital Multiband
  • this disclosure proposes an advanced sideband signal precoding and demodulation solution.
  • the disclosure proposes a transmitting device, a receiving device, a system, and corresponding methods for processing a sideband signal of a multiband signal in an optical transmission system.
  • Coherent DMB modulation is a promising technology for signal modulation and demodulation in modem optical fiber networks. It can be used both in short-reach and long- haul optical networks.
  • WSS Wavelength Selective Switches
  • DWDM Dense Wavelength-Division Multiplexing
  • Side bandwidth cutting can reach 50%, especially for large frequency offset.
  • S21 transfer function S-parameter such as S21.
  • BER Bit Error Rate
  • ISI Inter-Symbol Interference
  • OSNR Optical Signal-To-Noise Ratio
  • FIG. 1 shows typical spectral diagrams with sideband cutting.
  • FIG. 1 (a) shows a back-to- back (B2B) test case
  • FIG. 1 (b) shows a WSS graph corresponding to the 10WSS case.
  • the spectrum diagrams are estimated with a simulation platform using the real frequency response of channel filters.
  • a decrease of the total bandwidth can reduce WSS signal damage but leads to an Additive Gaussian White Noise (AWGN) channel penalty.
  • AWGN Additive Gaussian White Noise
  • bit and entropy loading bit and entropy loading
  • power loading power loading
  • FEC Forward Error Correction
  • turbo equalization turbo equalization
  • Another approach to mitigate performance penalty due to bandwidth limitation is to shape the transmitted signal in such a way that ISI caused by band limitation will have minimal impact on performance.
  • the methods used for shaping include duobinary modulation and super-Nyquist modulation.
  • a sideband of the DMB signal comprises a damaged external edge and an undamaged internal edge (see FIG. 1 (a) and FIG. 1 (b)).
  • Symmetric shaping of DMB sidebands causes a significant B2B penalty due to very large signal energy loss on the undamaged sideband edge.
  • the disclosure aims to provide an optimized signal shaping solution.
  • symmetric shaping is not suitable for sidebands of a DMB signal, because only external edges of the sidebands of the DMB signal are damaged but the internal edges are undamaged.
  • An objective is thus to introduce a solution for asymmetric spectrum shaping.
  • the disclosure has the objective to reduce signal energy at the damaged spectrum portion and move signal energy to the undamaged spectrum portion.
  • Another objective is to significantly reduce performance penalties due to limited analog bandwidth and WSS.
  • a first aspect of the disclosure provides a transmitting device for processing a sideband signal of a multiband signal in an optical transmission system, wherein the sideband signal comprises a plurality of samples, each sample comprising an In-phase component (I- component) and a quadrature component (Q-component), the transmitting device being configured to: shape the sideband signal by pre-coding the sideband signal to obtain a shaped sideband signal, upsample the shaped sideband signal by using a pulse shaping filter to obtain an upsampled sideband signal, shift Q-components of samples of the upsampled sideband signal by a half unit interval (UI) time offset, and transmit the shifted sideband signal to a receiving device via a channel.
  • I- component In-phase component
  • Q-component quadrature component
  • This disclosure provides a transmitting device that is capable of pre-coding sideband signals of the multiband signal, thereby realizing an optimized signal shaping.
  • pre-decoding is used for asymmetric spectrum shaping by reducing signal energy at the damaged spectrum portion and moving signal energy to the undamaged spectrum portion. Due to the optimized spectrum shaping, performance penalty due to limited analog bandwidth and WSS can be significantly reduced even for a relatively large one-side cutoff of the bandwidth.
  • the shaped signal is further upsampled and sent to the channel with a 0.5UI time offset of the Q component.
  • the transmitting device before shaping the sideband signal, is further configured to encode the sideband signal by using a Tomlinson-Harashima Pre-coding (THP) encoder.
  • TTP Tomlinson-Harashima Pre-coding
  • this disclosure also proposes using a THP encoder before the signal shaping.
  • the THP encoder is designed to reduce possible error bursts appearing on the receiver side.
  • the THP encoder is also designed to match the transfer function for the shaping.
  • the THP encoder is configured to operate at a rate of one sample per symbol.
  • the transmitting device is further configured to indicate to the receiving device that the sideband signal has been encoded using the THP encoder.
  • shaping the sideband signal comprises shaping the sideband signal using a Generalized Single Side Precoding (GSSP) filter.
  • GSSP Generalized Single Side Precoding
  • This disclosure particularly proposes a GSSP shaping filter for pre-coding sideband signals, thereby realizing the optimized signal shaping.
  • the GSSP filter is based on a transfer function: rF n (z)
  • F / ⁇ 3 (z) represents a transfer function of the I-components of the samples of the input signal of the GSSP filter to Q-components of the samples of the output signal of the GSSP filter
  • FQ/(Z) represents a transfer function of Q-components of the samples of the input signal of the GSSP filter to the Q-components of the samples of the output signal of the GSSP filter
  • FQQ (Z) represents a transfer function of the Q-components of the samples of the input signal of the GSSP filter to the Q-components of the samples of the output signal of the GSSP filter.
  • the GSSP filter may operate at a rate of one sample per symbol.
  • the GSSP filter is a Single Sideband Duobinary (SSDB) filter, and optionally
  • the GSSP filter proposed in this disclosure may be an SSDB filter.
  • the sideband signal may be a right-side sideband signal or a left-side sideband signal.
  • the above-mentioned SSDB filters used on the different sides are different.
  • the transfer functions may be used for the left-side sideband signal, while the transfer functions may be used for the right-side sideband signal.
  • the above-mentioned values for the transfer functions are merely provided as a particular example of the filter.
  • the GSSP filter is a Single Sideband Faster- than-Nyquist-like (FTN-like) filter, and optionally
  • the GSSP filter proposed in this disclosure may be a Single Sideband FTN-like filter.
  • the sideband signal may be a right-side sideband signal or a left-side sideband signal.
  • the above-mentioned Single Sideband FTN-like filters used on the different sides are different.
  • the transfer functions may be used for the left side-sideband signal, while the transfer functions may be used for the right ⁇ side sideband signal. It should also be noted that the above-mentioned values for the transfer functions are merely provided as a particular example of the filter.
  • a second aspect of the disclosure provides a receiving device for processing a sideband signal of a multiband signal of an optical transmission system, wherein the sideband signal comprises a plurality of samples, each sample comprising an I-component and a Q- component, the receiving device being configured to: receive an input sideband signal from a transmitting device over a channel, partially equalize the input sideband signal by using a linear multiple-input multiple-output, MIMO, equalizer to obtain a partially equalized sideband signal, and decode the equalized sideband signal by using a Maximum Likelihood Sequence Estimator (MLSE) decoder to restore an original sideband signal.
  • MIMO linear multiple-input multiple-output
  • MIMO linear multiple-input multiple-output
  • equalizer to obtain a partially equalized sideband signal
  • decode the equalized sideband signal by using a Maximum Likelihood Sequence Estimator (MLSE) decoder to restore an original sideband signal.
  • MIMO linear multiple-input multiple-output
  • This disclosure further provides a receiving device that is capable of performing partial equalization and MLSE-based signal recovery on the receiver side, thereby restoring an original sideband signal.
  • the target constellation of the linear MIMO equalizer in the receiver side corresponds to the signal constellation after the pre-coding performed on the transmitter side, but not to the original constellation before the pre-coding. Due to the optimized spectrum shaping, performance penalty due to limited analog bandwidth and WSS can be significantly reduced even for a relatively large one-side cutoff of the bandwidth.
  • the receiving device is further configured to receive an indication from the transmitting device that a transmitted sideband signal has been encoded using a THP encoder.
  • the transmitting device may use a THP encoder before the signal shaping.
  • the receiving device needs to be informed about the THP encode, and thus be able to operate accordingly.
  • the receiving device after decoding the equalized sideband signal, is further configured to: shape the decoded sideband signal by pre-coding the sideband signal to obtain a shaped sideband signal, and decode the shaped sideband signal by using a THP decoder corresponding to the THP encoder.
  • the THP encoder used in the transmitting device and the THP decoder used in the receiving device are designed to reduce possible error bursts appearing on the receiver side.
  • shaping the decoded sideband signal comprises shaping the decoded sideband signal by using a GSSP filter.
  • an optionally post-MLSE GSSP shaping filter and an optional THP decoder are designed to remove error bursts that may appear on the MLSE output for some types of the shaping filter.
  • the THP decoder is implemented by performing a modulo operation on the THP encoder.
  • equalizing the input sideband signal by using a linear MIMO equalizer comprises: performing linear partial equalization and demultiplexing on I-components and Q-components of samples of the input sideband signal to obtain a first processed signal, shifting the I-components of samples of the first processed signal by a half unit interval time offset to obtain a second processed signal, and downsampling and slicing the second processed signal to obtain the partially equalized sideband signal.
  • a target constellation of the linear MIMO equalizer of the receiving device corresponds to a signal constellation of the shaped sideband signal produced by the transmitting device.
  • the proposed MIMO equalizer performs a partial equalization instead of a so-called full equalization.
  • the equalizer does not target the original constellation but a modified constellation, that is, the signal constellation of the shaped sideband signal. It can be restored very accurately even with the ISI of sidebands. This method is called partial equalization because the original signal will be restored by the MLSE decoder arranged after the linear MIMO equalizer.
  • F / ⁇ 3 (z) represents a transfer function of the I-components of the samples of the input signal of the MLSE decoder to Q-components of the samples of the output signal of the MLSE decoder
  • FQ/(Z) represents a transfer function of Q-components of the samples of the input signal of the MLSE decoder to the Q-components of the samples of the output signal of the MLSE decoder
  • FQQ (Z) represents a transfer function of the Q-components of the samples of the input signal of the MLSE decoder to the Q-components of the samples of the output signal of the MLSE decoder.
  • the MLSE decoder restores the original signal constellation from the signal source.
  • the I/Q filters used in the MLSE decoder match the shaping filter with the transfer function F.
  • a third aspect of the disclosure provides a system comprising a transmitting device according to the first aspect and its implementation forms, and a receiving device according to the second aspect and its implementation forms.
  • a target constellation of the linear MIMO equalizer of the receiving device corresponds to a signal constellation of the shaped sideband signal produced by the transmitting device.
  • a fourth aspect of the disclosure provides a method for a transmitting device processing a sideband signal of a multiband signal in an optical transmission system, wherein the sideband signal comprises a plurality of samples, each sample comprising an Lcomponent and a Q-component, wherein the method comprises: shaping the sideband signal by precoding the sideband signal to obtain a shaped sideband signal, upsampling the shaped sideband signal by using a pulse shaping filter to obtain an upsampled sideband signal, and shifting Q-components of samples of the upsampled sideband signal by a half unit interval time offset, and transmitting the shifted sideband signal to a receiving device via a channel.
  • Implementation forms of the method of the fourth aspect may correspond to the implementation forms of the transmitting device of the first aspect described above.
  • the method of the fourth aspect and its implementation forms achieve the same advantages and effects as described above for the transmitting device of the first aspect and its implementation forms.
  • a fifth aspect of the disclosure provides a method for a receiving device processing a sideband signal of a multiband signal in an optical transmission system, wherein the sideband signal comprises a plurality of samples, each sample comprising an Lcomponent and a Q-component, wherein the method comprises: receiving an input sideband signal from a transmitting device over a channel, partially equalizing the input sideband signal by using a linear MIMO equalizer to obtain a partially equalized sideband signal, and decoding the equalized sideband signal by using an MLSE decoder to restore an original sideband signal.
  • Implementation forms of the method of the fifth aspect may correspond to the implementation forms of the receiving device of the second aspect described above.
  • the method of the fifth aspect and its implementation forms achieve the same advantages and effects as described above for the receiving device of the second aspect and its implementation forms.
  • FIG. 1 shows examples of spectral diagrams of sideband signal
  • FIG. 2 shows a transmitting device according to an embodiment of the disclosure.
  • FIG. 3 shows a receiving device according to an embodiment of the disclosure.
  • FIG. 4 shows a system according to an embodiment of the disclosure.
  • FIG. 5 shows a GSSP shaping or an MLSE filter according to an embodiment of the disclosure.
  • FIG. 6 shows a MIMO equalizer according to an embodiment of the disclosure.
  • FIG. 7 shows a THP encoder according to an embodiment of the disclosure.
  • FIG. 8 shows examples of frequency responses of GSSP filters according to an embodiment of the disclosure.
  • FIG. 9 shows a system according to an embodiment of the disclosure.
  • FIG. 10 shows a GSSP shaping/MLSE filter and a THP encoder according to an embodiment of the disclosure.
  • FIG. 11 shows DMB spectral diagrams according to an embodiment of the disclosure.
  • FIG. 12 shows MIMO output constellations according to an embodiment of the disclosure.
  • FIG. 13 shows a method according to an embodiment of the disclosure.
  • FIG. 14 shows a method according to an embodiment of the disclosure.
  • FIG. 15 shows MIMO output constellations according to an embodiment of the disclosure.
  • FIG. 16 shows performance results according to an embodiment of the disclosure.
  • FIG. 17 shows performance results according to an embodiment of the disclosure.
  • FIG. 18 shows performance results according to an embodiment of the disclosure. DETAILED DESCRIPTION OF EMBODIMENTS
  • an embodiment or example may refer to other embodiments or examples.
  • any description including but not limited to terminology, element, process, explanation and/or technical advantage mentioned in one embodiment or example is applicative to the other embodiments or examples.
  • FIG. 2 shows a transmitting device 200 according to an embodiment of the disclosure.
  • the transmitting device 200 may comprise processing circuitry (not shown) configured to perform, conduct or initiate the various operations of the transmitting device 200 described herein.
  • the processing circuitry may comprise hardware and software.
  • the hardware may comprise analog circuitry or digital circuitry, or both analog and digital circuitry.
  • the digital circuitry may comprise components such as application- specific integrated circuits (ASICs), field-programmable arrays (FPGAs), digital signal processors (DSPs), or multipurpose processors.
  • the processing circuitry comprises one or more processors and a non-transitory memory connected to the one or more processors.
  • the non- transitory memory may carry executable program code which, when executed by the one or more processors, causes the transmitting device 200 to perform, conduct or initiate the operations or methods described herein.
  • the transmitting device 200 is particularly adapted for processing a sideband signal 201 of a multiband signal in an optical transmission system.
  • the sideband signal 201 comprises a plurality of samples. Each sample comprises an I-component and a Q- component.
  • the transmitting device 200 may comprise a number of units or modules, for processing the sideband signal 201.
  • the transmitting device 200 is configured to shape the sideband signal 201 by pre-coding the sideband signal 201 to obtain a shaped sideband signal 202.
  • the transmitting device 200 is further configured to upsample the shaped sideband signal 202 by using a pulse shaping filter 230 to obtain an upsampled sideband signal 203.
  • the transmitting device 200 is configured to shift Q-components of samples of the upsampled sideband signal 203 by a half unit interval time offset.
  • the transmitting device 200 is further configured to transmit the shifted sideband signal 204 to a receiving device 300 via a channel 100.
  • This disclosure provides a transmitting device 200 that is capable of pre-coding sideband signals of the multiband signal, thereby realizing an optimized signal shaping.
  • pre-decoding is used for asymmetric spectrum shaping by reducing signal energy at the damaged spectrum portion and moving signal energy to the undamaged spectrum portion. Due to the optimized spectrum shaping, performance penalty due to limited analog bandwidth and WSS can be significantly reduced even for a relatively large one-side cutoff of the bandwidth.
  • the shaped signal e.g., shaped sideband signal 202, is further upsampled and sent to the channel 100 with a 0.5UI time offset of the Q component.
  • the transmitting device 200 may be further configured to encode the sideband signal 201 by using a THP encoder.
  • the THP encoder may be configured to operate at a rate of one sample per symbol.
  • the THP encoder proposed in this example is designed to reduce possible error bursts appearing on the receiver side.
  • the THP encoder is also designed to match the transfer function for the shaping.
  • the transmitting device 200 should inform the receiving side, e.g., the receiving device 300. Therefore, the receiving device 300 is able to perform the corresponding decoding. Accordingly, the transmitting device 200 may be further configured to indicate to the receiving device 300 that the sideband signal 201 has been encoded using the THP encoder 210.
  • shaping the sideband signal 201 may comprise shaping the sideband signal 201 using a GSSP filter 220.
  • the GSSP filter 220 provides the spectrum shaping on the sideband signal.
  • the GSSP filter 220 may operate at a rate of one sample per symbol according to the following equation:
  • FIG. 3 shows a receiving device 300 according to an embodiment of the disclosure.
  • the receiving device 300 may comprise processing circuitry (not shown) configured to perform, conduct or initiate the various operations of the receiving device 300 described herein.
  • the processing circuitry may comprise hardware and software.
  • the hardware may comprise analog circuitry or digital circuitry, or both analog and digital circuitry.
  • the digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field- programmable arrays (FPGAs), digital signal processors (DSPs), or multi-purpose processors.
  • the processing circuitry comprises one or more processors and a non-transitory memory connected to the one or more processors.
  • the non-transitory memory may carry executable program code which, when executed by the one or more processors, causes the receiving receiver 300 to perform, conduct or initiate the operations or methods described herein.
  • the receiving device 300 is particularly adapted for processing a sideband signal 301 of a multiband signal in an optical transmission system.
  • the sideband signal 301 comprises a plurality of samples. Each sample comprises an I-component and a Q- component.
  • the receiving device 300 may comprise a number of units or modules, for processing the sideband signal 301.
  • the receiving device 300 is configured to receive an input sideband signal 301 from a transmitting device 200 over a channel 100.
  • the receiving device 300 is further configured to partially equalize the input sideband signal 301 by using a linear MIMO equalizer 310 to obtain a partially equalized sideband signal 302.
  • the receiving device 300 is configured to decode the partially equalized sideband signal 302 by using an MLSE decoder 320 to restore an original sideband signal 303.
  • the transmitting device 200 may be the transmitting device shown in FIG. 2.
  • This disclosure further provides a receiving device 300 that is capable of performing partial equalization and MLSE-based signal recovery on the receiver side, thereby restoring an original sideband signal.
  • the target constellation of the linear MIMO equalizer in the receiver side corresponds to the signal constellation after the pre-coding performed on the transmitter side, but not to the original constellation before the pre-coding (at the transmitting side, e.g., transmitting device 200). Due to the optimized spectrum shaping, performance penalty due to limited analog bandwidth and WSS can be significantly reduced even for a relatively large one-side cutoff of the bandwidth.
  • the receiving device 300 may be further configured to receive an indication from the transmitting device 200 that a transmitted sideband signal 204 has been encoded using a THP encoder 210.
  • the transmitting device 200 should inform the receiving side, e.g., the receiving device 300. Therefore, the receiving device 300 is able to perform the corresponding decoding.
  • the receiving device 300 may be further configured to shape the decoded sideband signal by pre-coding the decoded sideband signal to obtain a shaped sideband signal, and decode the shaped sideband signal by using a THP decoder 340 corresponding to the THP encoder 210.
  • the THP encoder 210 used in the transmitting device 200 and the THP decoder 340 used in the receiving device 300 are designed to reduce possible error bursts appearing on the receiver side.
  • the THP decoder 340 may be implemented by performing a modulo operation on the THP encoder 210.
  • shaping the decoded sideband signal may comprise shaping the decoded sideband signal by using a GSSP filter 330.
  • an optionally post-MLSE GSSP shaping filter and an optional THP decoder are designed to remove error bursts, which may appear on the MLSE output for some types of the shaping filter.
  • equalizing the input sideband signal 301 by using a linear MIMO equalizer 310 comprises: performing linear partial equalization and demultiplexing on I-components and Q-components of samples of the input sideband signal 301 to obtain a first processed signal, shifting the I-components of samples of the first processed signal by a half unit interval time offset to obtain a second processed signal, and downsampling and slicing the second processed signal to obtain the partially equalized sideband signal 302.
  • a target constellation of the linear MIMO equalizer 310 of the receiving device 300 corresponds to a signal constellation of the shaped sideband signal 202 produced by the transmitting device 200. It should be noted that the proposed MIMO equalizer 310 performs a partial equalization instead of a so-called full equalization.
  • the MIMO equalizer target corresponds to an original constellation (for example, QPSK). This is called full equalization meaning that the equalizer restores the original signal.
  • the linear MIMO equalizer 310 does not target the original constellation but a modified constellation, that is, the signal constellation of the shaped sideband signal 202. It can be restored very accurately even with the ISI of sidebands.
  • This method is called partial equalization because the original signal will be restored by the MLSE decoder arranged after the linear MIMO equalizer.
  • F/Q (z) represents a transfer function of the I-components of the samples of the input signal of the MLSE decoder 320 to Q-components of the samples of the output signal of the MLSE decoder 320
  • FQ/(Z) represents a transfer function of Q- components of the samples of the input signal of the MLSE decoder 320 to the Q- components of the samples of the output signal of the MLSE decoder 320
  • FQQ (Z) represents a transfer function of the Q-components of the samples of the input signal of the MLSE decoder 320 to the Q-components of the samples of the output signal of the MLSE decoder 320.
  • FIG. 4 shows a system comprising a transmitting device 200 and a receiving device 300 according to an embodiment of the disclosure.
  • the transmitting device 200 may be the transmitting device 200 as illustrated in FIG. 2 or FIG. 3.
  • the receiving device 300 may be the receiving device 300 as illustrated in FIG. 2 or FIG. 3.
  • the dashed blocks e.g., THP encoder, THP decoder
  • THP encoder e.g., THP encoder, THP decoder
  • a sideband signal 201 coming from a source may be first encoded using an optionally THP encoder 210, then being shaped using a GSSP filter 220.
  • a shaped sideband signal 202 is thus obtained.
  • the shaped sideband signal 202 is then going through a pulse shaping filter 230 to obtain an upsampled sideband signal 203. Further, the Q-components of samples of the upsampled sideband signal 203 are shifted by a half UI time offset and then transmitted to a receiving device 300 via a channel 100.
  • the pulse shaping filter 230 may be for example a square root raised cosine filter, which performs upsampling the signal.
  • the time offset block delays the imaginary part by 0.5UI where UI is a symbol duration.
  • the output of the time offset block is then fed to the channel 100.
  • a sideband signal 301 received over the channel 100 is first partially equalized using a linear MIMO equalizer 310, to obtain a partially equalized sideband signal 302.
  • the partially equalized sideband signal 302 is then decoded by using an MLSE decoder 320.
  • a GSSP shaping filter 330 and a THP decoder 340 are further used to restore an original sideband signal 303.
  • the optionally THP encoder 210 when the optionally THP encoder 210 is used in the transmitting device 200, the optionally GSSP shaping filter 330 and the optionally THP decoder 340 should also be used in the receiving device 300. Accordingly, if no THP encoder 210 is used in the transmitting device 200, no GSSP shaping filter 330 and THP decoder 340 need to be used in the receiving device 300.
  • FIG. 5 shows an example GSSP shaping block, e.g., the GSSP filter 220, according to an embodiment of the disclosure.
  • the MLSE block e.g., the MLSE decoder 320
  • the GSSP shaping and MLSE filter shown in FIG. 5 may be the GSSP filter 220 shown in FIG. 4, or the MLSE decoder 320 shown in FIG. 3 or FIG. 4.
  • the GSSP filter 220 provides the spectrum shaping and has the transfer function:
  • the GSSP filter 220 may operate at a rate of one sample per symbol according to the following equation:
  • FIG. 6 shows an example MIMO block diagram according to an embodiment of the disclosure.
  • the MIMO block shown here may be the linear MIMO equalizer 310 shown in FIG. 3 or FIG. 4.
  • the linear MIMO equalizer 310 performs partial equalization and demultiplexing of two polarization signals based on, for example, Least Mean Square (LMS) technique.
  • LMS Least Mean Square
  • the target constellation of the equalizer 310 corresponds to the signal constellation on the output of the GSSP shaping filter 220 in the transmitter side (not to the original signal constellation from the signal source).
  • the offset blocks in the MIMO output delay the real part of the signal by 0.5UI to compensate for the imaginary part offset in the transmitter.
  • the imaginary part offset of 0.5UI is done again in the LMS feedback path.
  • the MLSE decoder 320 shown in FIG. 5 restores the original signal constellation from the signal source.
  • the I/Q filter used in the MLSE matches the shaping filter with transfer function F(z) .
  • the MLSE decoder 320 can provide a hard decision or soft decision.
  • I/Q offset can be implemented in the time or frequency domain. There is no need to implement oversampling with a sampling rate of 2 samples per second (SPS), a sampling rate of 1.25 SPS can also be used.
  • SPS samples per second
  • the additional MIMO complexity is also small according to this disclosure.
  • FIG. 7 shows an example GSSP THP encoder block diagram according to an embodiment of the disclosure.
  • the THP encoder block shown here may be the THP encoder 210 shown in FIG. 4.
  • the THP encoder 210 used in the transmitting device 200 and the THP decoder 340 used in the receiving device 300 are designed to reduce possible error bursts appearing on the receiver side.
  • An optional Post-MLSE GSSP shaping filter 330 with transfer function F(z) may be used together with the THP decoder 340 to remove the error bursts that appear on the MLSE output for some types of the shaping filter.
  • FIG. 8 shows different frequency response examples of the GSSP filter 220 as shown in FIG. 4 or FIG. 5.
  • the GSSP filter 220 may be an SSDB filter.
  • the solution using the SSDB filter may also be referred to as “Variant A” in this application.
  • the transfer functions may be defined as follows:
  • a sideband signal may be a right-side sideband signal or a left-side sideband signal. Accordingly, the SSDB filters used on the different sides are different.
  • the transfer functions may be used for the left-side sideband signal, while the transfer functions may be used for the right-side sideband signal.
  • FIG. 8 (a) The frequency response of the SSDB filter (for the left-side sideband signal) after upsampling is shown in FIG. 8 (a).
  • the transfer functions are shown after upsampling the signal by a factor of 2.
  • the vertical bold lines shown in the figure represent the signal bandwidth.
  • the SSDB filter provides a simple implementation while it still provides very good performance.
  • the GSSP filter 220 may be a Single Sideband FTN-like filter.
  • the solution using the Single Sideband FTN-like filter may also be referred to as “Variant B” in this application.
  • the transfer functions may be defined as follows:
  • the Single Sideband FTN-like filters (for the left-side sideband signal) used on the different sides are different.
  • the transfer functions may be used for the leftside sideband signal, while the transfer functions may be used for the right-side sideband signal.
  • FIG. 8 (b) The frequency response of this Single Sideband FTN-like filter after upsampling is shown in FIG. 8 (b). Similar to FIG. 8 (a), the vertical bold lines shown in the figure represent the signal bandwidth. Notably, this filter has a more flat transfer function in the passband which provides a better B2B performance.
  • FIG. 9 shows a system comprising a transmitting device 200 and a receiving device 300 according to an embodiment of the disclosure.
  • the system shown in FIG. 9 is based on the system shown in FIG. 4.
  • the transmitting device 200 may be the transmitting device 200 as illustrated in FIG. 2 or FIG. 3.
  • the receiving device 300 may be the receiving device 300 as illustrated in FIG. 2 or FIG. 3.
  • the GSSP filter 220 in the transmitting device 200 is particularly an SSDB filter.
  • the optionally GSSP filter 330 in the receiving device 300 is also an SSDB filter.
  • FIG. 10 (a) shows an example SSDB shaping block, e.g., the SSDB filter, used in the system shown in FIG. 9, according to an embodiment of the disclosure.
  • the MLSE block e.g., the MLSE decoder 320
  • the SSDB shaping and MLSE filter shown in FIG. 10 (a) may be the GSSP filter 220 shown in FIG. 4, or the MLSE decoder 320 shown in FIG. 3 or FIG. 4.
  • FIG. 10 (b) shows an example SSDB THP encoder used in the system shown in FIG. 9, according to an embodiment of the disclosure.
  • the SSDB THP encoder shown here may be the SSDB THP encoder 310 shown in FIG. 3 or FIG. 4.
  • FIG. 11 shows target constellations of the MIMO equalizer according to an embodiment of the disclosure.
  • the target constellation of the MIMO LMS equalizer differs from the original signal constellation (for example QPSK or 16QAM).
  • FIG. 11 (a) shows a target constellation for the SSDB shaping filter for a QPSK source
  • FIG. 11 (b) shows a target constellation for the SSDB shaping filter for a 16QAM source.
  • FIG. 12 shows DMB signal spectrums using different solutions (including conventional solutions and the solution proposed in this disclosure). In these figures, the frequency axis is normalized. The sideband curves show the WSS filter responses.
  • FIG. 12 (a) shows a DMB signal spectrum without power loading. It can be seen from this figure that this method provides the best performance for the AW GN channel. However, there is a very large performance loss for bad S21 (i.e., transfer function S-parameter) and WSS with Local Oscillator Frequency Offset (LOFO) cases. The long ISI time response for the sideband causes a big equalizer penalty for WSS cases.
  • S21 i.e., transfer function S-parameter
  • LOFO Local Oscillator Frequency Offset
  • FIG. 12 (b) shows a DMB signal spectrum with conventional power loading. It can be seen from this figure that this method provides a worse AWGN performance due to a large power gap. This solution does not provide an optimal power spreading for S21 and WSS cases, and the long ISI time response for sideband still exists.
  • FIG. 12 (c) shows a DMB signal spectrum with the solution proposed in this disclosure. It can be seen from this figure that the proposed method enables a better AWGN performance due to a smaller power gap. In addition, it offers an optimal power spreading for S21 and WSS cases. Further, a minimal sidebands ISI for better equalization can be achieved.
  • FIG. 13 shows a method 1300 according to an embodiment of the disclosure.
  • the method 1300 is for processing a sideband signal 201 of a multiband signal in an optical transmission system.
  • the sideband signal 201 comprises a plurality of samples, each sample comprising an I-component and a Q-component.
  • the method 1300 may be carried out by the transmitting device 200 shown in FIG. 2 (or FIG. 3, 4 or 9).
  • the method 1300 comprises a step 1301 of shaping the sideband signal 201 by pre-coding the sideband signal 201 to obtain a shaped sideband signal 202, a step 1302 of upsampling the shaped sideband signal 202 by using a pulse shaping filter to obtain an upsampled sideband signal 203, a step 1303 of shifting Q-components of samples of the upsampled sideband signal 203 by a half unit interval time offset, and a step 1304 of transmitting the shifted sideband signal 204 to a receiving device 300 via a channel 100.
  • FIG. 14 shows a method 1400 according to an embodiment of the disclosure.
  • the method 1400 is for processing a sideband signal 201 of a multiband signal in an optical transmission system.
  • the sideband signal 201 comprises a plurality of samples, each sample comprising an I-component and a Q-component.
  • the method 800 may be carried out by the receiving device 200 shown in FIG. 3 (or FIG. 2, 4 or 9).
  • the method 1400 comprises a step 1401 of receiving an input sideband signal 301 from a transmitting device 200 over a channel 100, a step 1402 of partially equalizing the input sideband signal 301 by using a linear MIMO equalizer 310 to obtain a partially equalized sideband signal 302, and a step 1403 of decoding the partially equalized sideband signal 302 by using an MLSE decoder 320 to restore an original sideband signal 303.
  • the MIMO equalizer proposed in this disclosure performs partial equalization to obtain a target constellation that is corresponding to the output of the transmitter shaping filter. Due to partial equalization, the proposed solution can tolerate bandwidth limitation much better than a regular solution.
  • FIG. 15 shows MIMO output constellation examples for a conventional solution (see FIG. 15 (a)) and the proposed SSDB solution (see FIG. 15 (b)) with a 20% bandwidth cutoff and a high OSNR (QPSK, SSDB filter). It can be seen in this figure that the regular solution constellation is very damaged by ISI, while the proposed one is not sensitive to bandwidth cutoff.
  • FIG. 16 to FIG. 18 show performance results as proof of concept for the solutions proposed in this disclosure, respectively.
  • FIG. 16 shows performance results (BER vs. SNR) of comparing conventional schemes and the SSDB filter scheme (Variant A) proposed in this disclosure.
  • FIG. 16 (a) shows performance results for QPSK of comparing conventional schemes and the SSDB filter without implementing THP encoding.
  • FIG. 16 (b) shows performance results for QPSK comparing conventional schemes and the SSDB filter with THP encoding.
  • the gain which can be achieved by implementing the SSDB filter schemes proposed in this disclosure, for a 20% cutoff is about 2 dB.
  • FIG. 17 shows performance results (BER vs. SNR) of comparing conventional schemes and the Single Sideband FTN-like filter scheme (Variant B) proposed in this disclosure. This figure shows performance results for QPSK of comparing conventional schemes and Variant B without THP precoding.
  • the gain for a cutoff of 20% is about 2.2 dB.
  • FIG. 18 performance results (BER vs. SNR) of comparing conventional schemes and both of Variant A and Variant B proposed in this disclosure.
  • FIG. 18 (a) shows performance results for 16QAM of Variant A without implementing THP encoding. The gain for a cutoff of 20% is more than 6 dB.
  • FIG. 18 (b) shows performance results for 16QAM of Variant B without implementing THP encoding. The gain for a cutoff of 20% is also more than 6 dB.
  • the proposed solutions provide a very large performance gain for DMB sideband cutoff of more than 10% which corresponds to the B2B test case. For a cutoff of 20%, the performance gain is 2dB in QPSK mode and more than 6dB in 16QAM mode. That means, the proposed solutions can remove the error floor caused by ISI due to sideband cutoff.
  • a significant gain is achieved also for the simplest GSSP variant, i.e., the SSDB filter scheme.
  • Implementation of the SSDB filter has a very low complexity because the shaping filter and MESE filter are very short and do not require any multiplication operation. Based on the examples discussed in this application, this disclosure allows significant improvement of the performance of DMB systems and reduces performance penalty due to limited channel bandwidth caused by WSS and other channel filters.

Landscapes

  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Dc Digital Transmission (AREA)

Abstract

La présente invention concerne des systèmes de transmission optique, et en particulier des systèmes de transmission DMB. L'invention propose un dispositif de transmission pour traiter un signal de bande latérale d'un signal multibande dans un système de transmission optique, le signal de bande latérale comprenant une pluralité d'échantillons, chaque échantillon comprenant un composant I et un composant Q, le dispositif de transmission étant conçu pour : mettre en forme le signal de bande latérale en pré-codant le signal de bande latérale pour obtenir un signal de bande latérale mis en forme, sur-échantillonner le signal de bande latérale mis en forme à l'aide d'un filtre de mise en forme d'impulsion pour obtenir un signal de bande latérale sur-échantillonné, décaler Q-composantes d'échantillons du signal de bande latérale sur-échantillonné par un décalage temporel de demi-UI, et transmettre le signal de bande latérale décalé à un dispositif de réception par l'intermédiaire d'un canal. L'invention concerne également un dispositif de réception conçu pour recevoir un signal de bande latérale d'entrée provenant d'un dispositif de transmission sur un canal.
PCT/EP2022/055462 2022-03-03 2022-03-03 Dispositif et procédé de traitement de signal dans un système optique cohérent multibande numérique -dmb - WO2023165703A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2022/055462 WO2023165703A1 (fr) 2022-03-03 2022-03-03 Dispositif et procédé de traitement de signal dans un système optique cohérent multibande numérique -dmb -

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2022/055462 WO2023165703A1 (fr) 2022-03-03 2022-03-03 Dispositif et procédé de traitement de signal dans un système optique cohérent multibande numérique -dmb -

Publications (1)

Publication Number Publication Date
WO2023165703A1 true WO2023165703A1 (fr) 2023-09-07

Family

ID=80953558

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2022/055462 WO2023165703A1 (fr) 2022-03-03 2022-03-03 Dispositif et procédé de traitement de signal dans un système optique cohérent multibande numérique -dmb -

Country Status (1)

Country Link
WO (1) WO2023165703A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6792049B1 (en) * 2000-06-15 2004-09-14 Mitsubishi Electric Research Laboratories, Inc. Digital transceiver system with adaptive channel pre-coding in an asymmetrical communications network
WO2013102898A1 (fr) * 2012-01-06 2013-07-11 Multiphy Ltd. Egalisation de mimo adaptatif à symboles espacés pour systèmes de communication optique à débit binaire ultra élevé
WO2015086136A1 (fr) * 2013-12-09 2015-06-18 Telefonaktiebolaget L M Ericsson (Publ) Précodage dans un système de transmission plus rapide qu'un système de nyquist
US20170214485A1 (en) * 2016-01-27 2017-07-27 Zte Corporation Imaging cancellation in high-speed intensity modulation and direct detection system with dual single sideband modulation

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6792049B1 (en) * 2000-06-15 2004-09-14 Mitsubishi Electric Research Laboratories, Inc. Digital transceiver system with adaptive channel pre-coding in an asymmetrical communications network
WO2013102898A1 (fr) * 2012-01-06 2013-07-11 Multiphy Ltd. Egalisation de mimo adaptatif à symboles espacés pour systèmes de communication optique à débit binaire ultra élevé
WO2015086136A1 (fr) * 2013-12-09 2015-06-18 Telefonaktiebolaget L M Ericsson (Publ) Précodage dans un système de transmission plus rapide qu'un système de nyquist
US20170214485A1 (en) * 2016-01-27 2017-07-27 Zte Corporation Imaging cancellation in high-speed intensity modulation and direct detection system with dual single sideband modulation

Similar Documents

Publication Publication Date Title
Faruk et al. Digital signal processing for coherent transceivers employing multilevel formats
US9438371B2 (en) Linear dispersion polarization-time codes and equalization in polarization multiplexed coherent optical system
Spinnler Equalizer design and complexity for digital coherent receivers
US9698914B2 (en) Recovering data from quadrature phase shift keying modulated optical signals
JP5708085B2 (ja) コヒーレント受信装置およびコヒーレント受信方法
EP2883314B1 (fr) Procédés et appareils pour le traitement d'un signal pm-qpsk cohérent et de forme duobinaire
CA3099841A1 (fr) Transformation bidirectionnelle en communication optique
US9225429B2 (en) Recovering data from quadrature phase shift keying modulated optical signals
El Tabach et al. Spatial data multiplexing over OFDM/OQAM modulations
WO2017181269A1 (fr) Système et procédé pour un précodage plus rapide que la signalisation de nyquist
CN107852248B (zh) 光接收器中的信号处理装置和方法
CA3109092C (fr) Pseudo-multiplexage par repartition en frequence
US9819419B2 (en) Maximum likelihood sequence estimation of Quadrature Amplitude Modulated signals
CN113169751B (zh) 用于窄带滤波信号的噪声白化后补偿的高效实现
Zhu et al. Nyquist-WDM with low-complexity joint matched filtering and adaptive equalization
US10505641B2 (en) Clock recovery for band-limited optical channels
Xu et al. Pulse-overlapping super-Nyquist WDM system
Raphaeli A reduced complexity equalizer for OQPSK
WO2023165703A1 (fr) Dispositif et procédé de traitement de signal dans un système optique cohérent multibande numérique -dmb -
Xiang et al. Linewidth-tolerant joint digital signal processing for 16QAM Nyquist WDM superchannel
JP5657168B2 (ja) 偏波推定器、偏波分離器、光受信器、偏波推定方法、および、偏波分離方法
Zhu et al. Low-complexity fractionally-spaced frequency domain equalization with improved channel estimation for long-haul coherent optical systems
EP3078134B1 (fr) Procédé pour une modulation optique cohérente à double polarisation
EP4099584B1 (fr) Atténuation de bruit de phase amélioré par égalisation dans un récepteur optique cohérent
Rozental et al. Time recovery for spectrally-sliced optical receivers

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 22713369

Country of ref document: EP

Kind code of ref document: A1