This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for demodulation reference signal (DMRS) precoding in high-Doppler scenarios. In some aspects, communicating devices may support different precodings for different portions of a signal, such as for a DMRS portion and an information portion. For example, a device may receive a signal including an orthogonal time-frequency space (OTFS) precoded first waveform portion carrying DMRS symbols and an orthogonal frequency division multiplexing (OFDM) precoded second waveform portion carrying information symbols. The device may transform the OTFS precoded DMRS symbols from a time-frequency domain to a delay-Doppler domain, may use the DMRS symbols to estimate a delay-Doppler channel, and may use the delay-Doppler channel estimate to measure an inter-carrier interference (ICI). The receiving device may use the ICI measurement to receive the information symbols carried by the OFDM precoded second waveform portion.

A method for user localization in a cellular network includes receiving, by a receiver unit, Orthogonal Time Frequency Space (OTFS) modulated Constant-Amplitude-Zero-Autocorrelation (CAZAC) sequences generated and transmitted in a Doppler-delay domain by a transmitter unit. The method further includes estimating, by the receiver unit, Doppler shift and/or relative speed between the transmitter unit and the receiver unit by filtering the received OTFS modulated CAZAC sequences.

Wireless communication transmission and reception techniques are described. At transmitter, source data bits are modulated into a number Nd of constellation symbols. An invertible transform is applied to the constellation symbols, thereby resulting in mapping the transformed symbols into Nd elements in the time-frequency grid. A signal resulting from the invertible transform is transmitted over a communication channel.

Systems and methods for transmitting data using various Modulation on Zeros schemes are described. In many embodiments, a communication system is utilized that includes a transmitter having a modulator that modulates a plurality of information bits to encode the bits in the zeros of the z-transform of a discrete-time baseband signal. In addition, the communication system includes a receiver having a decoder configured to decode a plurality of bits of information from the samples of a received signal by: determining a plurality of zeros of a z-transform of a received discrete-time baseband signal based upon samples from a received continuous-time signal, identifying zeros that encode the plurality of information bits, and outputting a plurality of decoded information bits based upon the identified zeros.

A method comprising receiving a modulated radio signal transmitting coded information bits, performing demodulating on the modulated radio signal, wherein demodulating comprises performing orthogonal time frequency space demodulation, performing equalization on the demodulated radio signal to obtain equalized symbols, obtaining log-likelihood ratios for the coded information bits from the equalized symbols using a trained machine learning model, and reconstructing the coded information bits.

A communication frame for an OTFS transmission system includes at least one first-type and at least one second-type block. At least the first-type block includes data signals two-dimensionally arranged along the delay domain and the Doppler domain of which at least one has a superimposed pilot signal. The second-type block includes data signals two-dimensionally arranged along the delay domain and the Doppler domain which may or may not have superimposed pilot signals. At least one second-type block is preceded and followed, in the delay-domain, by first-type blocks, the first-type blocks preceding and following a second-type block having at least one identical data symbol and associated superimposed identical pilot symbol at an identical location in the two-dimensional arrangement. An OTFS transmitter generates and transmits the communication frame, and a receiver uses its properties for compensating oscillator frequency offset and channel estimation.

Device, methods and systems for implementing aspects of orthogonal time frequency space (OTFS) modulation in wireless systems are described. In an aspect, the device may include a surface of an object for receiving an electromagnetic signal. The surface may be structured to perform a non-electrical function for the object. The surface may generate an electrical signal from an electromagnetic signal. The electromagnetic signal may be received from a transmitter. The transmitter may map digital data to a digital amplitude modulation constellation in a time-frequency space. The digital amplitude modulation constellation may be mapped to a delay-Doppler domain and the transmitter may transmit to the surface according to an orthogonal time frequency space modulation signal scheme. The apparatus may further include a demodulator to demodulate the electrical signal to determine digital data.

Methods and systems for modulating and demodulating data in systems. Bits can be converted into complex-valued symbols. An Inverse Fast Fourier Transform (FFT) can be applied to the complex-valued symbols that represent the bit groups. An FFT time window can be replaced with a time window and a frequency window. A signal comprising the time window and the frequency window can be transmitted. The signal can be converted into a complex-valued symbol. The complex-valued symbols can be converted into bits.

A method for modulating data for transmission within a communication system. The method includes establishing a time-frequency shifting matrix of dimension N×N, wherein N is greater than one. The method further includes combining the time-frequency shifting matrix with a data frame to provide an intermediate data frame. A transformed data matrix is provided by permuting elements of the intermediate data frame. A modulated signal is generated in accordance with elements of the transformed data matrix.

An electronic device and communication method are disclosed. The electronic device comprises a processing circuit configured to perform a pre-processing operation on a first one-dimensional sequence of modulation symbols, the pre-processing operation including: performing a dimension-increasing conversion to convert the first one-dimensional sequence of modulation symbols into a first multi-dimensional modulation symbol block; transforming the first multi-dimensional modulation symbol block into a second multi-dimensional modulation symbol block with a first transformation, wherein the first transformation couples each symbol in the first multi-dimensional modulation symbol block with each other; and performing a dimension-decreasing conversion to convert the second multi-dimensional modulation symbol block into a second one-dimensional sequence of modulation symbols, wherein the dimension-decreasing conversion is an inverse process of the dimension-increasing conversion. The processing circuit is also configured to transmit the second one-dimensional sequence of modulation symbols.