Abstract: A random noise generator for generating a plurality of random noise samples per clock cycle, the noise samples having a distribution. The random noise generator comprises at least a first comparator unit and a second comparator unit, the first comparator unit configured to generate a first plurality of samples representing a high-probability part of the distribution and the second comparator unit configured to generate a second plurality of samples representing a low-probability part of the distribution; and a random selection unit connected to at least the first comparator unit and the second comparator unit. The random selection unit is configured to receive the first plurality of samples generated by the first comparator unit and the second plurality of samples generated by the second comparator unit, to output a random selection of samples from the first plurality of samples and the second plurality of samples.

Abstract: A random noise generator for generating a plurality of random noise samples per clock cycle, the noise samples having a distribution. The random noise generator comprises at least a first comparator unit and a second comparator unit, the first comparator unit configured to generate a first plurality of samples representing a high-probability part of the distribution and the second comparator unit configured to generate a second plurality of samples representing a low-probability part of the distribution; and a random selection unit connected to at least the first comparator unit and the second comparator unit. The random selection unit is configured to receive the first plurality of samples generated by the first comparator unit and the second plurality of samples generated by the second comparator unit, to output a random selection of samples from the first plurality of samples and the second plurality of samples.

Abstract: Techniques herein support enhanced multi-rate encoding and decoding of signals in multiple formats. In one embodiment, input data is received at a first device at one of a plurality of data rates. Encoder units are activated to produce streams of encoded input data. The encoder units are configured to operate at the same data rate. Differential encoding operations are performed to produce an encoded output stream. The encoded output stream is modulated for transmission to a second device. In another embodiment, a first device receives an encoded data stream that is transmitted from a second device. The modulated data stream includes encoded data at one of a plurality of data rates. Differential decoding is performed on the encoded data by activating one or more of a plurality of decoder units, where each of the plurality of decoder units is configured to operate at the same rate.

Abstract: A device receives signals over a communication medium and uses a low density parity check decoder to decode data in the signals. A number of unsatisfied parity checks are counted prior to a first decoding iteration of the low density parity check decoder on a basis of log likelihood ratios computed from the signals. An operational characteristic of the low density parity check decoder is computed based on an accumulated number of unsatisfied parity checks.

Abstract: A method for encoding bits according to a convolutional code. Bits to be encoded with the convolutional code are obtained for transmission over a communication channel. The bits are encoded according to the convolutional code with an encoder having an M-bit memory and a plurality of logic gates so as to separate trellis segments of the convolutional code into trellis sub-segments having a reduced number of branches per state than that of the trellis segments.

Abstract: A forward error correction and differentially encoded signal obtained via a communication channel is supplied to a soft-input soft-output (SISO) differential decoder that is bi-directionally coupled to a SISO forward error correction decoder. Over a first portion of a plurality of decoding iterations of the differentially encoded signal, the SISO differential decoder and the SISO forward error correction decoder are operated in a turbo decoding mode in which decoded messages generated by the SISO differential decoder are supplied to the SISO forward error correction decoder and forward error correction messages are supplied to the differential decoder. Over a second portion of the plurality of decoding iterations of the differentially encoded signal, the SISO forward error correction decoder is operated in a non-turbo decoding mode without any messages passing to and from the SISO differential decoder. Decoder output is obtained from the SISO forward error correction decoder.

Abstract: Techniques herein support enhanced multi-rate encoding and decoding of signals in multiple formats. In one embodiment, input data is received at a first device at one of a plurality of data rates. Encoder units are activated to produce streams of encoded input data. The encoder units are configured to operate at the same data rate. Differential encoding operations are performed to produce an encoded output stream. The encoded output stream is modulated for transmission to a second device. In another embodiment, a first device receives an encoded data stream that is transmitted from a second device. The modulated data stream includes encoded data at one of a plurality of data rates. Differential decoding is performed on the encoded data by activating one or more of a plurality of decoder units, where each of the plurality of decoder units is configured to operate at the same rate.

Abstract: Techniques herein support enhanced multi-rate encoding and decoding of signals in multiple formats. In one embodiment, input data is received at a first device at one of a plurality of data rates. Encoder units are activated to produce streams of encoded input data. The encoder units are configured to operate at the same data rate. Differential encoding operations are performed to produce an encoded output stream. The encoded output stream is modulated for transmission to a second device. In another embodiment, a first device receives an encoded data stream that is transmitted from a second device. The modulated data stream includes encoded data at one of a plurality of data rates. Differential decoding is performed on the encoded data by activating one or more of a plurality of decoder units, where each of the plurality of decoder units is configured to operate at the same rate.

Abstract: A method for encoding bits according to a convolutional code. Bits to be encoded with the convolutional code are obtained for transmission over a communication channel. The bits are encoded according to the convolutional code with an encoder having an M-bit memory and a plurality of logic gates so as to separate trellis segments of the convolutional code into trellis sub-segments having a reduced number of branches per state than that of the trellis segments.

Abstract: A forward error correction and differentially encoded signal obtained via a communication channel is supplied to a soft-input soft-output (SISO) differential decoder that is bi-directionally coupled to a SISO forward error correction decoder. Over a first portion of a plurality of decoding iterations of the differentially encoded signal, the SISO differential decoder and the SISO forward error correction decoder are operated in a turbo decoding mode in which decoded messages generated by the SISO differential decoder are supplied to the SISO forward error correction decoder and forward error correction messages are supplied to the differential decoder. Over a second portion of the plurality of decoding iterations of the differentially encoded signal, the SISO forward error correction decoder is operated in a non-turbo decoding mode without any messages passing to and from the SISO differential decoder. Decoder output is obtained from the SISO forward error correction decoder.

Abstract: A forward error correction and differentially encoded signal obtained via a communication channel is supplied to a soft-input soft-output (SISO) differential decoder that is bi-directionally coupled to a SISO forward error correction decoder. Over a first portion of a plurality of decoding iterations of the differentially encoded signal, the SISO differential decoder and the SISO forward error correction decoder are operated in a turbo decoding mode in which decoded messages generated by the SISO differential decoder are supplied to the SISO forward error correction decoder and forward error correction messages are supplied to the differential decoder. Over a second portion of the plurality of decoding iterations of the differentially encoded signal, the SISO forward error correction decoder is operated in a non-turbo decoding mode without any messages passing to and from the SISO differential decoder. Decoder output is obtained from the SISO forward error correction decoder.

Abstract: Techniques herein support enhanced multi-rate encoding and decoding of signals in multiple formats. In one embodiment, input data is received at a first device at one of a plurality of data rates. Encoder units are activated to produce streams of encoded input data. The encoder units are configured to operate at the same data rate. Differential encoding operations are performed to produce an encoded output stream. The encoded output stream is modulated for transmission to a second device. In another embodiment, a first device receives an encoded data stream that is transmitted from a second device. The modulated data stream includes encoded data at one of a plurality of data rates. Differential decoding is performed on the encoded data by activating one or more of a plurality of decoder units, where each of the plurality of decoder units is configured to operate at the same rate.

Abstract: Techniques herein support enhanced multi-rate encoding and decoding of signals in multiple formats. In one embodiment, input data is received at a first device at one of a plurality of data rates. Encoder units are activated to produce streams of encoded input data. The encoder units are configured to operate at the same data rate. Differential encoding operations are performed to produce an encoded output stream. The encoded output stream is modulated for transmission to a second device. In another embodiment, a first device receives an encoded data stream that is transmitted from a second device. The modulated data stream includes encoded data at one of a plurality of data rates. Differential decoding is performed on the encoded data by activating one or more of a plurality of decoder units, where each of the plurality of decoder units is configured to operate at the same rate.

Abstract: Presented herein are sub-sampled carrier phase recovery techniques. In accordance with one example, a plurality of consecutive symbols associated with a received optical signal is obtained. Carrier phase recovery of the optical signal is performed using one or more carrier phase estimation stages. At each of the one or more carrier phase estimation stages, a subset of the plurality of consecutive symbols is selected for use in carrier phase estimation. The subset of symbols selected for use in carrier phase estimation at each of the one or more stages comprises symbols that provide the most phase recovery information for each of the one or more stages.

Abstract: A device receives signals over a communication medium and uses a low density parity check decoder to decode data in the signals. A number of unsatisfied parity checks are counted prior to a first decoding iteration of the low density parity check decoder on a basis of log likelihood ratios computed from the signals. An operational characteristic of the low density parity check decoder is computed based on an accumulated number of unsatisfied parity checks.

Abstract: A forward error correction and differentially encoded signal obtained via a communication channel is supplied to a soft-input soft-output (SISO) differential decoder that is bi-directionally coupled to a SISO forward error correction decoder. Over a first portion of a plurality of decoding iterations of the differentially encoded signal, the SISO differential decoder and the SISO forward error correction decoder are operated in a turbo decoding mode in which decoded messages generated by the SISO differential decoder are supplied to the SISO forward error correction decoder and forward error correction messages are supplied to the differential decoder. Over a second portion of the plurality of decoding iterations of the differentially encoded signal, the SISO forward error correction decoder is operated in a non-turbo decoding mode without any messages passing to and from the SISO differential decoder. Decoder output is obtained from the SISO forward error correction decoder.

Abstract: Techniques herein support enhanced multi-rate encoding and decoding of signals in multiple formats. In one embodiment, input data is received at a first device at one of a plurality of data rates. Encoder units are activated to produce streams of encoded input data. The encoder units are configured to operate at the same data rate. Differential encoding operations are performed to produce an encoded output stream. The encoded output stream is modulated for transmission to a second device. In another embodiment, a first device receives an encoded data stream that is transmitted from a second device. The modulated data stream includes encoded data at one of a plurality of data rates. Differential decoding is performed on the encoded data by activating one or more of a plurality of decoder units, where each of the plurality of decoder units is configured to operate at the same rate.

Abstract: Presented herein are sub-sampled carrier phase recovery techniques. In accordance with one example, a plurality of consecutive symbols associated with a received optical signal is obtained. Carrier phase recovery of the optical signal is performed using one or more carrier phase estimation stages. At each of the one or more carrier phase estimation stages, a subset of the plurality of consecutive symbols is selected for use in carrier phase estimation. The subset of symbols selected for use in carrier phase estimation at each of the one or more stages comprises symbols that provide the most phase recovery information for each of the one or more stages.

Abstract: Carrier phase estimation techniques are provided for processing a received optical signal having a carrier modulated according to a modulation scheme. First and second carrier phase estimation operations are performed on a digital signal derived from an optical carrier obtained from the received optical signal using coherent optical reception. The first carrier phase estimation operation tracks relatively fast phase variations of the optical carrier of the received optical signal to produce a first carrier phase estimation and the second carrier phase estimation operation tracks relatively slow phase variations of the optical carrier of the received optical signal to produce a second carrier phase estimation. A difference between the first and second carrier phase estimations is computed. Occurrence of a cycle slip is determined when the difference is greater than a threshold. A correction is applied to the first carrier phase estimation when the low pass filtered difference exceeds the threshold.

Abstract: Carrier phase estimation techniques are provided for processing a received optical signal having a carrier modulated according to a modulation scheme. First and second carrier phase estimation operations are performed on a digital signal derived from an optical carrier obtained from the received optical signal using coherent optical reception. The first carrier phase estimation operation tracks relatively fast phase variations of the optical carrier of the received optical signal to produce a first carrier phase estimation and the second carrier phase estimation operation tracks relatively slow phase variations of the optical carrier of the received optical signal to produce a second carrier phase estimation. A difference between the first and second carrier phase estimations is computed. Occurrence of a cycle slip is determined when the difference is greater than a threshold. A correction is applied to the first carrier phase estimation when the low pass filtered difference exceeds the threshold.