Abstract: An optical transmitter capable of colorless WDM includes a source of optical frequency comb (OFC) light having a plurality of separate optical frequency tones, and a plurality of optical modulators connected in parallel to modulate different parts of the OFC light with corresponding modulating signals, each of the parts including the plurality of separate optical frequency tones. An optical combiner combines the different parts of the OFC light to obtain an output optical signal of the optical transmitter. MIMO processing may be used to recover the modulating signals at an optical receiver using, or to configure the modulating signals at the transmitter so that each of the frequency tones is modulated with a corresponding target data signal.

Abstract: Various example embodiments of a wavelength division multiplexing (WDM) direct detection (DD) system are presented. The WDM DD system may be configured to support WDM within the context of any WDM system supporting communication of wavelength channels based on modulation formats recoverable by direct detection (e.g., based on intensity-modulated (IM) signals within the context of a WDM IM-DD system, single-sideband (SSB) signals within the context of a WDM SSB-DD system, or the like). The WDM DD system may be configured to support WDM within the context of a WDM DD system, based on labeling of the wavelength channels with a set of states of spatial mode and polarization (SoSPs), based on use of an SoSP labeler on the transmit side to associate SoSPs with the wavelength channels and based on use of a receiver on the receive side to detect the SoSPs and recover the wavelength channels based on the SoSPs.

Abstract: An optical data receiver is configured for receiving optical signal comprising spectrally adjacent modulated subcarriers. The optical receiver includes an optical comb generator to output separate frequency tones, and a plurality of optical-to-electrical (OE) converters. The OE converters are configured to mix light of a plurality of the frequency tones with part of the received optical signal, and to output a temporal sequence of measurements of the mixture produced by said mixing. A digital signal processor is configured to recover a data stream carried by one of the subcarriers by performing multi-input multi-output (MIMO) processing using the temporal sequences of measurements output by at least two of the OE converters. The MIMO processing involves performing passband filtering for a passband wherein two of the subcarriers are down-converted by the mixing.

Abstract: An optical transmitter capable of colorless WDM includes a source of optical frequency comb (OFC) light having a plurality of separate optical frequency tones, and a plurality of optical modulators connected in parallel to modulate different parts of the OFC light with corresponding modulating signals, each of the parts including the plurality of separate optical frequency tones. An optical combiner combines the different parts of the OFC light to obtain an output optical signal of the optical transmitter. MIMO processing may be used to recover the modulating signals at an optical receiver using, or to configure the modulating signals at the transmitter so that each of the frequency tones is modulated with a corresponding target data signal.

Abstract: A method for configuring an optical transmitter for transmitting optical signals over a passive optical link. The method includes using a digital processor to generate a target constellation probability distribution (CPD) for a probabilistic constellation encoder (PCE) of the optical transmitter. The target CPD is generated using a system performance optimization algorithm accounting for the transmitter peak power constraint and a peak enhancement property of a drive circuit of the optical transmitter.

Abstract: A method and apparatus are provided for addressing problems in performing FEC decoding in OFDM communication systems, particularly problems associated with SNR fluctuations across the subcarrier frequency band. The disclosed decoding process is based on the use of per-subcarrier SNR values when performing data recovery in a subcarrier group sharing the same modulation format. That is, the bit-wise LLRs created for a given subcarrier are based upon that subcarrier's individual SNR, not an averaged (scalar) SNR used for all subcarriers within a given group.

Abstract: An optical data receiver is configured for receiving optical signal comprising spectrally adjacent modulated subcarriers. The optical receiver includes an optical comb generator to output separate frequency tones, and a plurality of optical-to-electrical (OE) converters. The OE converters are configured to mix light of a plurality of the frequency tones with part of the received optical signal, and to output a temporal sequence of measurements of the mixture produced by said mixing. A digital signal processor is configured to recover a data stream carried by one of the subcarriers by performing multi-input multi-output (MIMO) processing using the temporal sequences of measurements output by at least two of the OE converters. The MIMO processing involves performing passband filtering for a passband wherein two of the subcarriers are down-converted by the mixing.

Abstract: A method and apparatus for processing of signals in a point-to-multipoint (P2MP) network are provided. The processing includes obtaining link conditions, in a spectrum comprising multiple OFDM subcarriers, of a plurality of users at respective user nodes that are in communication with a central node of the network. The processing further includes inputting the link conditions to an entropy loading (EL) algorithm, thereby to determine a modulation format for each of the OFDM subcarriers; optimizing an allocation of OFDM subcarriers to users according to an OFDMA scheme; and for each user, loading data from a bitstream onto the allocated OFDM subcarriers in the respective determined modulation formats.

Abstract: A radio apparatus and system may include a means for modulating and/or demodulating an optical signal for respective transmission and/or reception of the optical signal using an optical channel connected to a remote radio unit. There may also be provided a means for performing, based on one or more pre-trained computational models, one or more operations on a digital signal corresponding to the optical signal for mitigating one or more non-linearities introduced by the optical modulating and/or demodulating means and the optical channel. The one or more pre-trained computational models may be pre-trained based on feedback data indicative of said one or more non-linearities.

Abstract: A radio apparatus and system may include a means for modulating and/or demodulating an optical signal for respective transmission and/or reception of the optical signal using an optical channel connected to a remote radio unit. There may also be provided a means for performing, based on one or more pre-trained computational models, one or more operations on a digital signal corresponding to the optical signal for mitigating one or more non-linearities introduced by the optical modulating and/or demodulating means and the optical channel. The one or more pre-trained computational models may be pre-trained based on feedback data indicative of said one or more non-linearities.