The present disclosure relates to a demodulation method, apparatus, and device. Some embodiments of the present disclosure are beneficial to improving demodulation performance.

A symbol-determining device according to an embodiment includes: a transmission line shortening unit that multiplies each symbol value of a symbol array that is part of an input signal by a tap gain of a linear digital filter and outputs a symbol array representing a sum of values acquired through the multiplication; a transmission line estimating unit that estimates a transfer function of a transmission line using an adaptive nonlinear digital filter on the basis of a symbol array representing a state of the transmission line; an addition comparison processing unit that calculates a minimum value of a distance function in a Viterbi algorithm on the basis of a metric that is calculated on the basis of the output of the transmission line shortening unit and the transfer function; and a path tracing-back determination unit that performs symbol determination by tracing back a trellis path in the Viterbi algorithm on the basis of the minimum value of the distance function.

A system that includes a Viterbi Equalizer having adaptive signal levels is disclosed. Each branch metric of the Viterbi Equalizer compares the value of the incoming bit to one of a plurality of different expected signal levels. A set of default signal values may be used by the Viterbi Equalizer. The system is also configured to determine whether these default expected signal levels are acceptable by monitoring the incoming data bits. If it is determined that the actual signal levels of the incoming data bits differ from the default expected signal levels by more than a predetermined amount, the signal levels used by the Viterbi Equalizer may be changed from default signal levels to the adaptive signal levels. The adaptive signal levels may be determined using the synchronization pattern.

The present disclosure provides techniques for bandwidth constrained communication systems with frequency domain information processing. A bandwidth constrained equalized transport (BCET) communication system can include a transmitter, a communication channel, and a receiver. The transmitter can include a pulse-shaping filter that intentionally introduces memory into a signal in the form of inter-symbol interference, an error control code (ECC) encoder, a multidimensional fast Fourier transform (FFT) processing block that processes the signal in the frequency domain, and a first interleaver. The receiver can include an information-retrieving equalizer, a deinterleaver with an ECC decoder, and a second interleaver joined in an iterative ECC decoding loop. The communication system can be bandwidth constrained, and the signal can comprise an information rate that is higher than that of a communication system without intentional introduction of the memory at the transmitter.

The present disclosure relates to a demodulation method, apparatus, and device. Some embodiments of the present disclosure are beneficial to improving demodulation performance.

The present disclosure relates to an encoded signal demodulation method, apparatus, and device. Some embodiments of the present disclosure are beneficial to improving demodulation performance.

Systems and methods for measuring wireless uplink signal quality of a P25 H-CPM uplink waveform are provided. In particular, such systems and methods can include calculating an SINR measurement and/or an FBER measurement for the P25 H-CPM uplink waveform to determine whether P25 user equipment has been successfully deployed.

This application provides an error correction method and apparatus, relates to the field of communications technologies, so as to reduce a bit error rate of a decision feedback equalizer (DFE) and improve equalization performance. The method includes: obtaining a decision signal of a DFE; obtaining at least one of an input signal, an equalized output signal, and a difference of the DFE, where the difference is a difference between a level value of the decision signal and a level value of the equalized output signal; determining a symbol location of an end of burst error of the decision signal based on detection of at least one of the decision signal, the equalized output signal, and the difference; and when the symbol location is detected, performing error correction on the decision signal based on the at least one of the input signal, the equalized output signal, and the difference.

A method for generating a Trellis-Coded Modulation (TCM) scheme for transmitting symbols over a Partial-Response (PR) channel, the method including holding a base TCM scheme including a plurality of states and transitions among the states. Sequences of symbols are produced, and second sequences of symbols are calculated, each second sequence emulating a response of the PR channel to a respective sequence of symbols traversing the PR channel. The TCM scheme is initialized by assigning the sequences to the transitions of the base TCM scheme. One or more transitions are removed so that second sequences corresponding to transitions that were not removed are separated by at least a first distance. One or more additional transitions are further removed from the TCM scheme, so that second sequences corresponding to parallel transitions from a current state to a next state are separated by at least a second distance larger than the first distance.

Methods are disclosed for improving communications on feedback transmission channels, in which there is a possibility of bit errors. The basic solutions to counter those errors are: proper design of the CSI vector quantizer indexing (i.e., the bit representation of centroid indices) in order to minimize impact of index errors, use of error detection techniques to expurgate the erroneous indices and use of other methods to recover correct indices.