Methods and apparatuses for direct sequence detection can receive an input signal over a communication channel. Next, the input signal can be sampled based on a clock signal to obtain a sampled voltage. A set of reference voltages can be generated based on a main cursor, a set of pre-cursors, and a set of post-cursors associated with the communication channel. Each generated reference voltage in the set of reference voltages can correspond to a particular sequence of symbols. A sequence corresponding to the sampled voltage can be selected based on comparing the sampled voltage with the set of reference voltages.

A communication method, a communications apparatus, and a storage medium are disclosed, to reduce a probability that consecutive bit errors occur in a communications system. A received to-be-sent signal is modulated to obtain a modulated signal, and N rounds of operations are further performed on the modulated signal to obtain an encoded signal. An output of the 1.sup.st-round operation in the N rounds of operations is determined based on the modulated signal and an output that is of the N.sup.th-round operation and that is processed by a first delay circuit, and an output of the i.sup.th-round operation in the N rounds of operations is determined based on an output of the (i1).sup.th-round operation and an output that is of the N.sup.th-round operation and that is processed by a second delay circuit, where i is an integer greater than 1 and less than or equal to N.

A reception device 20 is configured to include a separation means 21 and a plurality of optical reception means 22. Each optical reception means 22 further includes an optical/electrical conversion means 23, a reception coefficient computation means 24, and a band restoration means 25. The separation means 21 separates a multiplexed signal into which signals of respective channels to which spectral shaping that narrows bandwidth to less than or equal to a baud rate is applied as band narrowing filter processing on the transmission side, based on characteristics of a transmission line are multiplexed at spacings less than or equal to the baud rate. Each band restoration means 25 applies processing having inverse characteristics to those of the band narrowing filter processing to a reception signal, based on the band narrowing parameter acquired by the reception coefficient computation means 24 and thereby restores the band of the reception signal.

Certain aspects of the disclosure are directed to a method for communicating data from a transmitting circuit to a receiving circuit over a noisy channel. The method can be performed by logic circuitry, and can include encoding data, for transmission over the noisy channel. The data can be encoded, as a shaped-coded modulation signal by shaping the signal based on an amplitude selection algorithm that leads to a symmetrical input and by constructing a trellis having a bounded-energy sequence of amplitude values selected by computing and storing a plurality of channel-related energy constraints based on use of a nonlinear-estimation process, and therein providing an index for the bounded-energy sequence of amplitudes. The method can also include receiving over the noisy channel, the shaped-coded modulation signal, and decoding the data from the shaped-coded modulation signal by using the index to reconstruct the bounded-energy sequence of amplitudes.

Certain aspects of the disclosure are directed to a method for communicating data from a transmitting circuit to a receiving circuit over a noisy channel. The method can be performed by logic circuitry, and can include encoding data, for transmission over the noisy channel. The data can be encoded, as a shaped-coded modulation signal by shaping the signal based on an amplitude selection algorithm that leads to a symmetrical input and by constructing a trellis having a bounded-energy sequence of amplitude values selected by computing and storing a plurality of channel-related energy constraints based on use of a nonlinear-estimation process, and therein providing an index for the bounded-energy sequence of amplitudes. The method can also include receiving over the noisy channel, the shaped-coded modulation signal, and decoding the data from the shaped-coded modulation signal by using the index to reconstruct the bounded-energy sequence of amplitudes.

Embodiments can provide a coding method, a coding apparatus, and a communications apparatus. The method includes: determining N to-be-coded bits, where N is a positive integer; obtaining a first sequence that includes N polar channel sequence numbers; determining a location of an information bit in the N to-be-coded bits based on the first sequence; and performing polar coding on the N to-be-coded bits to obtain coded bits. The location of the information bit in the to-be-coded bits is determined based on the obtained first sequence that includes N polar channel sequence numbers, so that performance of a polar code can be improved.

An iterative two dimension equalizer usable in a receiver of orthogonal time frequency space (OTFS) modulated signals is described. In one configuration of the equalizer, a forward path generates, from received time-frequency domain samples and a channel estimate, estimates of data bits and likelihood numbers associated with the estimates of data bits, generated by delay-Doppler domain processing. In the feedback direction, the estimates of data bits are used to generate symbol estimates and autocorrelation matrix estimate in the time domain. In another configuration, a soft symbol mapper is used in the feedback direction for directly generating the feedback input symbol estimate without having to generate estimates of data bits.

There is described a method for communicating data, the method comprising: receiving an incomplete data stream, wherein the incomplete data stream comprises a plurality of sequences of data points having respective values and a plurality of sequences of missing data points; receiving a missing data model; determining values for each of the plurality of sequences of missing data points, comprising: selecting a sequence of missing data points that has not previously been processed, wherein the sequence of missing data points to be processed is selected as a smallest sequence of missing data points of the plurality of sequences of missing data points that have not previously been processed; processing the incomplete data stream to determine values for the selected sequence of missing data points based upon the missing data model; updating the incomplete data stream to include the determined values for the selected sequence of missing data points; and wherein values for subsequent sequences of missing data points are generated based upon the updated data stream; and outputting a corrected data stream comprising the determined values for each of the plurality of sequences of missing data points.

A method includes: generating a trellis; generating one or more predicted symbols using a first non-linear model; computing and saving two or more branch metrics using a priori log-likelihood ratio (LLR) information, a channel observation, and the one or more predicted symbols; if alpha forward recursion has not yet completed, generating alpha forward recursion state metrics using a second non-linear model; if beta backward recursion has not yet completed, generating beta backward recursion state metrics using a third non-linear model; if sigma forward recursion has not yet completed, generating sigma forward recursion state metrics using the branch metrics, the alpha state metrics, and the beta backward recursion state metrics; generating extrinsic information comprising a difference of a posteriori LLR information and the a priori LLR information; computing and feeding back the a priori LLR information; and calculating the a posteriori LLR information.

The present application discloses a forward and backward smooth decoding method and device suitable for an OvXDM system, and a system. Importance weights of particles in a particle set corresponding to a symbol are calculated by using a forward process and a backward process, and screening is performed with reference to forward importance weights of particles and backward importance weights of particles, to output a final decoding sequence.