A device may receive a PDCCH signal, may decode encoded bits of the PDCCH signal to generate coded bits, may reencode the coded bits, and may calculate a detection error probability of each coded bit at an output of soft demodulation. The device may calculate a channel decoding error probability that cyclic redundancy check bits are still attached to the coded bits, and may calculate an error probability of channel reencoding, of each coded bit, due to error propagation of polar decoding and reencoding. The device may calculate a probability density of a BMR associated with the coded bits, and may calculate a threshold based on the detection error probability, the channel decoding error probability, the error probability of channel reencoding, and the probability density of a BMR. The device may determine that the PDCCH signal is invalid based on the BMR being greater than the threshold.

Aspects of the disclosure are directed to processing signals including data exhibiting characteristics that facilitate assessment of transmission errors. As may be implemented in accordance with one or more embodiments, parameters are generated based signal transmission characteristics and are indicative of a different types of signal characteristics, including an amount of error correction that has been carried out on the signal. Two or more of the parameters are selected based on properties of signal disturbance under different reception conditions for the signal, and a degree of disturbance in the signal is predicted based on the selected parameters and signal conditions for the respective parameters at which the signal cannot be corrected. An output generated with the signal is then controlled, based on the predicted degree of disturbance and a threshold degree of disturbance.

A method of decoding a polar coded signal includes determining channel reliabilities for a plurality of polar coded bit channels in a data communication system including a plurality of frozen bit channels and non-frozen bit channels, selecting a frozen bit channel, calculating a likelihood value for a bit estimate associated with the frozen bit channel, generating a hard decision value for the bit estimate in response to the likelihood value, comparing the hard decision value for the bit estimate to a known value of a frozen bit transmitted on the frozen bit channel, in response to determining that the hard decision value for the bit estimate differs from the known value of the frozen bit transmitted on the frozen bit channel, updating an accumulated uncertainty, comparing the accumulated uncertainty to a threshold, and determining that a decoding error has occurred in response to the comparison.

Systems and methods for estimating a transmit symbol sequence implemented in a coherent receiver include receiving a nominally error-free information bit sequence subsequent to Forward Error Correction (FEC) decoding; determining a nominally error-free estimate of the transmitted bit sequence based on the nominally error-free information bit sequence; and determining a nominally error-free estimate of the transmit symbol sequence by mapping the transmit bit sequence to transmit symbols. The system and methods can further include comparing a transmit optical field based on the transmit symbols to a received optical field for one or more measurements.

An Ethernet transceiver includes physical-layer (PHY) circuitry and a signal-loss detector. The PHY circuitry is configured to receive a signal from a peer transceiver, to process the received signal in a series of digital PHY-level processing operations, and to output the processed signal for Medium Access Control (MAC) processing. The signal-loss detector is configured to receive, from the PHY circuitry, a digital version of the received signal, and to detect a signal-loss event based on an amplitude of the digital version of the received signal.

A digital transmission system includes a transmitter configured to transmit an orthogonal frequency division multiplexing (OFDM) signal along a signal path, a receiver for receiving the OFDM signal from the transmitter and extracting OFDM symbols from the received OFDM signal, and a diagnostic unit configured to (i) demodulate the received OFDM signal to create an ideal signal, (ii) compare the received OFDM signal with the ideal signal to calculate an error signal, (iii) cross-correlate the error signal with the ideal signal, and (iv) determine a level nonlinear distortion from one of the transmitter and the signal path based on the correlation of the error signal with the ideal signal.

A device may receive a PDCCH signal, may decode encoded bits of the PDCCH signal to generate coded bits, may reencode the coded bits, and may calculate a detection error probability of each coded bit at an output of soft demodulation. The device may calculate a channel decoding error probability that cyclic redundancy check bits are still attached to the coded bits, and may calculate an error probability of channel reencoding, of each coded bit, due to error propagation of polar decoding and reencoding. The device may calculate a probability density of a BMR associated with the coded bits, and may calculate a threshold based on the detection error probability, the channel decoding error probability, the error probability of channel reencoding, and the probability density of a BMR. The device may determine that the PDCCH signal is invalid based on the BMR being greater than the threshold.

A digital transmission system includes a transmitter configured to transmit an orthogonal frequency division multiplexing (OFDM) signal along a signal path, a receiver for receiving the OFDM signal from the transmitter and extracting OFDM symbols from the received OFDM signal, and a diagnostic unit configured to (i) demodulate the received OFDM signal to create an ideal signal, (ii) compare the received OFDM signal with the ideal signal to calculate an error signal, (iii) cross-correlate the error signal with the ideal signal, and (iv) determine a level nonlinear distortion from one of the transmitter and the signal path based on the correlation of the error signal with the ideal signal.

The present invention relates to a method and apparatus for channel estimation between a transmitter and a receiver in a wireless communications system. In one arrangement, the method comprises: receiving at the receiver a first sequence of bits representing a first sequence of coded symbols transmitted over the communications channel; decoding the first sequence of coded symbols using maximum-likelihood based decoding including: generating traceback outcomes by tracing backwards the first sequence of bits through a maximum-likelihood based traceback path, the traceback outcomes including a first portion associated with a first traceback depth and a second portion associated with a second traceback depth that is deeper than the first traceback depth; generating a channel estimate of the communications channel based on the first portion of the traceback outcomes; and generating an estimate of at least some information bits coded in the first sequence of coded symbols based on the second portion of the traceback outcomes.

Aspects of the disclosure are directed to processing signals including data exhibiting characteristics that facilitate assessment of transmission errors. As may be implemented in accordance with one or more embodiments, parameters are generated based signal transmission characteristics and are indicative of a different types of signal characteristics, including an amount of error correction that has been carried out on the signal. Two or more of the parameters are selected based on properties of signal disturbance under different reception conditions for the signal, and a degree of disturbance in the signal is predicted based on the selected parameters and signal conditions for the respective parameters at which the signal cannot be corrected. An output generated with the signal is then controlled, based on the predicted degree of disturbance and a threshold degree of disturbance.