Abstract: An apparatus grouping data units for optical network units into groups of Encapsulation Method, EM, frame(s), wherein a respective group of EM frame(s) include data units addressed to a respective subset of ONUs, generating, based on the groups of EM frame(s), a Framing Sublayer payload including at least one specific frame, wherein, the specific frame includes a length indicator determined in relation to the length of the group(s) of EM frame(s) that is(are) directly following the specific frame and is(are) addressed to at least one subset of ONUs; instructing the ONUs assigned to at least one of said at least one subset to process the EM frame directly following the specific frame, and instructing the ONUs not assigned to the at least one subset to process the EM frame that is indicated by the length indicator of the specific frame; and transmitting the Framing Sublayer payload to the ONUs.

Abstract: A method for transmitting a first segment of a first modulation format, a second segment of a second modulation format and a third segment of a third modulation format, wherein the second segment is transmitted between the first segment and the third segment, wherein the first modulation format includes a first set of constellation points, wherein the second modulation format includes a second set of constellation points, wherein the third modulation format includes a third set of constellation points, wherein the second set is included in an intersection of the first set and the third set, wherein the first set and the third set differ by at least one constellation point.

Abstract: In one embodiment, the apparatus includes at least one memory configured to store instructions; and at least one processor configured to execute the instructions and cause the apparatus to perform, receiving, by a receiver in an Optical Line Terminal, OLT, a burst of an upstream signal transmitted in burst mode, adjusting settings for an analog signal conditioning of the received upstream signal; performing the analog signal conditioning of the received upstream signal based on the adjusted settings such that a first compensated signal is provided, obtaining coefficient(s) for a digital signal conditioning of the first compensated signal; performing the digital signal conditioning of the first compensated signal based on the obtained coefficient(s) such that a second compensated signal is provided.

Abstract: An apparatus including at least one processor configured to execute instructions and cause the apparatus to perform, obtaining for a first possible state (s) of a received sample at the current time step (k), log-likelihood ratio, Ilr, values Ilrold,min, Ilrold,max of a first transmitted bit (bj), wherein, the Ilr values Ilrold,min, Ilrold,max are respectively associated with a most likely state and a less likely state related to a received sample at the previous time step (k?1); determining based on path metrics and branch metrics corresponding to the received sample at the current time step (k); a first parameter (Q) related to a difference between likelihoods of the most likely state and the less likely state; updating magnitude of the Ilr value Ilrold,min at least based on the Ilr value Ilrold,min, the Ilr value Ilrold,max, and the first parameter, to obtain an updated Ilr value Ilrold,updated.

Abstract: An upstream (US) optical line terminal (OLT) for a passive optical network having at least one downstream (DS) optical network unit (ONU). The OLT generates a trigger signal indicating a need to receive at least one US burst having a shortened codeword for a first forward error-correction (FEC) code. Based on the trigger signal, the OLT transmits a DS message instructing the ONU to transmit an US burst having a shortened codeword. The OLT receives and decodes the US burst having the shortened codeword using the first FEC code. During periods of high bit-error rate, the shortened codewords increase the ability of the OLT to decode the US bursts and keep communications from the ONU alive. The OLT can use the decoded US bursts to measure BER and, if appropriate, instruct the ONU to use a different FEC code.

Abstract: The method includes transmitting by a first remote communication unit an upstream symbol with a first structure onto a first communication line at a reference time point trf, wherein the reference time point trf is determined based on a time of reception of a downstream symbol with the first structure tFDX_DS_RX and a first propagation delay over the first communication line tPD1, as trf=tFDX_DS_RX?tPD1; transmitting by a second remote communication unit an upstream symbol with a second structure onto the second communication line at tTDD_US_TX=trf?tPD2 during a time interval assigned for upstream transmission on the second communication line, wherein tPD2 is a second propagation delay over the second communication line, so that the upstream symbol with the second structure transmitted by the second remote communication unit arrives at the access node at the reference time point trf.

Abstract: A digital receiver based on one-dimensional hard demapping of an input symbol stream (FEC encoded) is configured to utilize LLRs created to have bit-specific magnitude values to improve the probability that the included decoder (such as an LDPC decoder) properly recovers each bit from the original stream. The digital receiver may be used with various types of data modulation schemes (e.g., PAM3, PAM4, DSQ8, etc.), with a specific set of LLR magnitudes created for each modulation scheme.

Abstract: The present disclosure relates to an equalizer training unit for deriving equalization parameters for compensating data-dependent distortion in received samples by use of a training sequence including a sequence p>1 times and cyclically comprising N sub-sequences of respective combinations of L time-domain symbols of a modulation scheme, wherein the N sub-sequences are cyclically arranged in a selected order and such that L?1 symbols of a respective sub-sequence overlap with symbols in the preceding and following sub-sequences. The present disclosure further relates to a training sequence generator unit for generative the training sequence and an equalizer employing the equalizer training unit.

Abstract: An apparatus, for use by an Optical Network Unit, performs receiving, from an Optical Line Terminal, a broadcast message including code set information indicating a first code set selected from a plurality of error correction code sets; determining whether the first code set is comprised in a group of code sets supported by the Optical Network Unit, wherein, the group of code sets includes at least one code set of the plurality of error correction code sets; and encoding an upstream transmission with the first code set, in case the first code set is included in the group of code sets.

Abstract: Various example embodiments for supporting forward error correction (FEC) in a communication system are presented. Various example embodiments for supporting FEC in a communication system may include the selection of a FEC setting for a communication channel from a transmitter to a receiver, e.g., the selection of a FEC setting for a communication channel, the selection of a FEC setting for a data burst sent over a communication channel, the selection of a FEC setting for a portion of a data burst sent over a communication channel, switching between FEC settings for different portions of a data burst over a communication channel, or the like, as well as various combinations thereof.

Abstract: An upstream (US) optical line terminal (OLT) for a passive optical network having at least one downstream (DS) optical network unit (ONU). The OLT generates a trigger signal indicating a need to receive at least one US burst having a shortened codeword for a first forward error-correction (FEC) code. Based on the trigger signal, the OLT transmits a DS message instructing the ONU to transmit an US burst having a shortened codeword. The OLT receives and decodes the US burst having the shortened codeword using the first FEC code. During periods of high bit-error rate, the shortened codewords increase the ability of the OLT to decode the US bursts and keep communications from the ONU alive. The OLT can use the decoded US bursts to measure BER and, if appropriate, instruct the ONU to use a different FEC code.

Abstract: In one embodiment, an apparatus is configured to perform mapping an interleaved bit stream into a sequence of 4-level pulse amplitude modulation (PAM4) labels according to a mapping scheme, with a respective PAM4 label including a least significant bit (LSB) and a most significant bit (MSB) respectively corresponding to a bit in the interleaved bit stream; transmitting a sequence of PAM4 symbols generated based on the sequence of PAM4 labels to the ONUs; and wherein, bits from respective one of the N codewords are assigned to LSBs of a first subset of labels, and to MSBs of a second subset of labels, with the first and the second subset of labels being determined based on the interleaving scheme and the mapping scheme and respectively comprising labels located N labels apart in the sequence of PAM4 labels.

Abstract: The method includes sending a first frame of a first modulation format that is suitable for a first group of receivers before sending a second frame of a second modulation format that is suitable for a second group of receivers, wherein the first modulation format is a higher modulation format than the second modulation format, and wherein the method further includes inserting into the first frame at least one symbol of the second modulation format at at least one outer edge of the first frame.

Abstract: Apparatus and method for low density parity check code decoding in a first processing device, wherein the method includes receiving a first bit-word of a first length related to a log-likelihood ratio of a bit of a signal; obtaining a second bit-word of a second length that is shorter than the first length, wherein obtaining the second bit-word comprises applying a correction to the first bit-word; and determining a message depending on a set of second bit-words, wherein the set of second bit-words includes the second bit-word.

Abstract: An apparatus grouping data units for optical network units into groups of Encapsulation Method, EM, frame(s), wherein a respective group of EM frame(s) include data units addressed to a respective subset of ONUs, generating, based on the groups of EM frame(s), a Framing Sublayer payload including at least one specific frame, wherein, the specific frame includes a length indicator determined in relation to the length of the group(s) of EM frame(s) that is(are) directly following the specific frame and is(are) addressed to at least one subset of ONUs; instructing the ONUs assigned to at least one of said at least one subset to process the EM frame directly following the specific frame, and instructing the ONUs not assigned to the at least one subset to process the EM frame that is indicated by the length indicator of the specific frame; and transmitting the Framing Sublayer payload to the ONUs.

Abstract: The present disclosure relates to an equalizer training unit for deriving equalization parameters for compensating data-dependent distortion in received samples by use of a training sequence including a sequence p>1 times and cyclically comprising N sub-sequences of respective combinations of L time-domain symbols of a modulation scheme, wherein the N sub-sequences are cyclically arranged in a selected order and such that L?1 symbols of a respective sub-sequence overlap with symbols in the preceding and following sub-sequences. The present disclosure further relates to a training sequence generator unit for generative the training sequence and an equalizer employing the equalizer training unit.

Abstract: An apparatus, for use by an Optical Network Unit, performs receiving, from an Optical Line Terminal, a broadcast message including code set information indicating a first code set selected from a plurality of error correction code sets; determining whether the first code set is comprised in a group of code sets supported by the Optical Network Unit, wherein, the group of code sets includes at least one code set of the plurality of error correction code sets; and encoding an upstream transmission with the first code set, in case the first code set is included in the group of code sets.

Abstract: An optical network unit (ONU) includes a transmitter and receiver to optically communicate with an optical line terminal (OLT) of a passive optical network. The ONU is configured to send an acknowledgment message to the OLT in response to a burst-profile message unicast by the OLT. The acknowledgement message indicates unsupported forward error correction (FEC) code in response to the burst-profile message identifying an FEC code for upstream transmission and the ONU not supporting the FEC code for upstream transmission to the OLT.

Abstract: According to example embodiments, the OLT includes at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the OLT to perform grouping data units for the ONUs in groups, wherein a group includes data units for a subset of the ONUs, encoding the groups of data units into respective sets of at least one codeword, interleaving the at least one codeword of the respective sets thereby obtaining a stream of codewords, and sequentially transmitting the stream of codewords to the ONUs.

Abstract: Various example embodiments for supporting forward error correction (FEC) in a communication system are presented. Various example embodiments for supporting FEC in a communication system may include the selection of a FEC setting for a communication channel from a transmitter to a receiver, e.g., the selection of a FEC setting for a communication channel, the selection of a FEC setting for a data burst sent over a communication channel, the selection of a FEC setting for a portion of a data burst sent over a communication channel, switching between FEC settings for different portions of a data burst over a communication channel, or the like, as well as various combinations thereof.