摘要:
A method of transmitting a data signal using an optical transmitter of an optical communications system. The optical transmitter is configured to modulate an optical carrier in successive signalling intervals to generate an optical signal. A modulation scheme is provided which comprises a multi-dimensional symbol constellation. The modulation scheme is designed such that an average degree of polarization of a modulated optical signal output from the optical transmitter has a first value when averaged across a first signaling interval, and has a second value when averaged across more than one and fewer than 100 signaling intervals. The second value is less than 10 percent of the first value. During run-time, an encoder of the optical transmitter encoding a data signal to be transmitted as symbols of the constellation, and a modulator of the optical transmitter modulating available dimensions of the optical carrier in accordance with the symbols.
摘要:
A receiver of an optical communications system includes a set of two or more analog-to digital A/D converters, a respective transform block connected to an output of each A/D converter, and a summation block. Each A/D converter samples a respective low-bandwidth analog signal comprising a respective portion of a high-bandwidth data signal. Each transform block calculates a set of spectral components of the respective low-bandwidth analog signal. The summation block combines respective spectral components calculated by each transform block to construct spectral terms of a combined signal having a spectrum corresponding to that of the high-bandwidth data signal.
摘要:
A method of transmitting data. The method comprises preliminarily providing a modulation scheme comprising an N-symbol constellation defined in an M-dimensional space, wherein N
摘要:
A frequency decimation block for processing an analog input signal including a high-bandwidth data signal to generate a parallel set of parallel output signals, in which each output signal represents a respective portion of the high-bandwidth data signal. A preamplifier is provided for amplifying the input signal. A frequency domain divider divides the amplified input signal to generate a set of frequency band signals including a low frequency band signal, a mid-frequency band signal, and a high frequency band signal. Each frequency band signal is supplied to at least one signal path. A respective non-linear processor is connected in each of M signal paths processes the input signal using a respective branch signal to yield a corresponding composite signal. A respective Low-Pass Filter (LPF) is connected in each signal path, for low-pass filtering at least the composite signals to generate corresponding ones of the parallel output signals.
摘要:
In a coherent receiver of an optical communication system, a method of processing a detected symbol estimate to determine a most likely value of a corresponding transmitted data word, the transmitted data word comprising one or more data bits encoded in a transmitter using a predetermined constellation of at least two symbols. A set of two or more virtual constellation points are define in a decision region corresponding to a possible value of the data word. The detected symbol estimate is processed to find a most likely virtual constellation point given the detected symbol estimate. The most likely value of the corresponding transmitted data word is determined based on the most likely virtual constellation point.
摘要:
A method performed at an electronic device comprises receiving information bits, a first nub, and a second nub, each nub comprising redundant values; calculating first calculated determiners from first subsets of the information bits along a first dimension; calculating first corrected determiners by applying first FEC decoding to a combination of the first calculated determiners and the first nub; correcting at least one error in the information bits using a difference between the first corrected determiners and the first calculated determiners; calculating second calculated determiners from second subsets of the information bits along a second dimension that differs from the first dimension; calculating second corrected determiners by applying second FEC decoding to a combination of the second calculated determiners and the second nub; and correcting at least one additional error in the information bits using a difference between the second corrected determiners and the second calculated determiners.
摘要:
A receiver apparatus comprises circuitry configured for storing a first sequence of values. At the receiver apparatus, a communications signal is received which conveys a second sequence of values, the second sequence of values being related to the first sequence of values. According to some examples, the second sequence of values is identical to the first sequence of values. At the receiver apparatus, P results are calculated from a cross-correlation of the first sequence of values with at least a portion of a representation of the communications signal, where P is a positive integer. According to some examples, P≥2. An estimate of a phase offset of a continuous clock is calculated as a function of the P results. According to some examples, the function is a non-linear function. The estimate of the clock phase offset may be used to achieve clock recovery at the receiver apparatus.
摘要:
A receiver applies first processing to a digital representation of a received signal to generate a first processed signal having first additive noise and first linear inter-symbol interference (ISI), the first processing comprising a substantially linear operation designed to substantially minimize a sum of variances of the first additive noise and the first linear ISI. The receiver applies second processing to the first processed signal to generate a second processed signal having second additive noise and second linear ISI, the second processing comprising a substantially nonlinear operation designed (i) to make a variance of the second additive noise substantially lower than the variance of the first additive noise, and (ii) to make a sum of the variance of the second additive noise and a variance of the second linear ISI substantially lower than the sum of the variances of the first additive noise and first linear ISI.
摘要:
A method of recovering a value of a symbol received through an optical communications system. A multi-bit estimate of the symbol is subdivided into a first part and a second part, each part including at least one respective bit of the estimate. A most likely value of the first part is detected. The most likely value of the first part is processed using a Forward Error Correction (FEC) decoder to generate a corrected first part value, which is used to detect a most likely value of the second part. The most likely value of the second part is then processed by the FEC decoder to generate a corrected second part, which is combined with the corrected first part to recover the value of the symbol.
摘要:
Client data bits, including first client data bits and second client data bits, are communicated from a transmitter to a receiver. At the transmitter, the first client data bits are processed to generate processed values, where each processed value is more likely to be a first element than a second element. Forward Error Correction ‘FEC’ encoding is applied to the second client data bits to generate FEC-encoded values. Symbols are created by mapping the FEC-encoded values to first positions in the symbols and by mapping the processed values to second positions in the symbols. The symbols are modulated onto a communications channel using a modulation scheme with a code that assigns a lower average energy to symbols containing the first elements in the second positions than to symbols containing the second elements in the second positions. At the receiver, client data bits are decoded using conditional chain decoding.