Methods, systems, and devices for wireless communications are described. A first device and a second device may communicate via a channel. The first device may generate and transmit a reference signal, which may be a distortion probing reference signal with a high peak to average power ratio. In one implementation, the first device may use the reference signal as an input for a neural network model to learn a nonlinear response of the second device transmission components. In another implementation, the second device may sample the generated reference signal, and use the samples as inputs for a neural network model to learn the nonlinear response. The first device and the second device may exchange signaling based on learning the nonlinear response, and each device may compensate for the nonlinear response when communicating via the channel.

A method of transmitting, by a transmitting device, an orthogonal frequency division multiplexing (OFDM) signal in a wireless communication system, the method including: generating, by a digital module of the transmitting device, a frequency-shifted OFDM baseband signal by performing frequency up-shift of a first signal by a difference between a carrier frequency f.sub.0 and a first frequency f.sub.base, wherein the first frequency f.sub.base is among frequencies corresponding to integer multiples of 128Δf closest to the carrier frequency f.sub.0, and wherein Δf is an OFDM subcarrier spacing; up-converting, by an analog oscillator of the transmitting device, the frequency-shifted OFDM baseband signal by the first frequency f.sub.base to generate an OFDM symbol signal at the carrier frequency f.sub.0; and transmitting the OFDM symbol signal at the carrier frequency f.sub.0.

This disclosure provides methods, devices and systems for pre-compensation of downlink communication based on a transmission of a request for the pre-compensation from a user equipment (UE). For example, the UE may determine an impairment at the UE that has a greater severity (a greater impact on downlink communication) or is associated with a greater amount of resources for processing relative to a remainder of a set of impairments that is experienced at the UE and the UE may transmit a request for pre-compensation of the impairment by a base station. The base station may transmit feedback to the UE indicating a confirmation of pre-compensation for the impairment by the base station or to deferment of compensation for the impairment back to the UE. If the base station acknowledges pre-compensation for the impairment, the base station may pre-compensate a downlink transmission to the UE for the impairment.

An OAM multiplexing communication system uses one or more OAM modes and multiplexes signals of one or more sequences for each OAM mode. A transmitting station includes a transmitting antenna using an M-UCA, and an OAM mode generation unit that simultaneously generates one or more OAM modes from each UCA. A receiving station includes a receiving antenna equivalent to the M-UCA, an OAM mode separation unit that separates signals received by each UCA for each OAM mode, and a received signal processing unit that estimates channel information for each OAM mode and performs an equalization process for each OAM mode by using a receiving weight calculated from the channel information. The received signal processing unit is configured to estimate, for each OAM mode, channel information of another OAM mode causing interference and calculate the receiving weight of a subject OAM mode by using the channel information of the subject OAM mode and said another OAM mode.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a network entity, a reference signal. The UE may transmit, to the network entity and via a feedback channel, digital pre-distortion (DPD) information that is based at least in part on the reference signal, wherein the DPD information indicates an estimate of non-linearities of a power amplifier at the network entity based at least in part on the reference signal. Numerous other aspects are described.

A method of signal communication is disclosed comprising providing source data having a predetermined signal power; mapping the source data onto a first modulation scheme to obtain a first set of complex symbols; mapping the source data onto at least one further modulation scheme to obtain at least one further set of complex symbols; combining the first set of complex symbols and the at least one further set of complex signals to form a modulated signal to be forwarded along a communications channel. Beneficially, the predetermined signal power of the source data is split between the first modulation scheme and the at least one further modulation scheme.

Techniques are presented for mapping a digital data sequence into a signal point sequence for transmission. The signal point sequence belongs to a set of possible signal point sequences. In one example, a digital data sequence is received. Forbidden branch flags that forbid certain signal points in the possible signal points sequences are applied. The signal point sequence is selected from a subset of all the possible signal point sequences based on the digital data sequence. The subset is defined by the forbidden branch flags.

A demodulation method and apparatus is disclosed that is for use on a modulated communication signal. The method includes receiving the modulated signal including a first set of complex symbols and at least one further set of complex symbols; applying a Forward Error Correction (FEC) decoding technique; applying a first phase estimation technique to the first set of symbols; applying a second phase estimation technique to the further set of symbols to determine phase information for the modulation signal using a first phase estimation means; and repeating in part using at least one further phase estimation means to identify the presence of phase rotation. Beneficially the method enables the use of large block sizes in the FEC technique.

Transmitters and methods of transmitting a polar-modulated signal include a driver to output a polar-modulated signal according to a phase-modulation signal and an amplitude-modulation signal. A voltage regulator is connected to the driver, with the amplitude-modulation signal controlling an input of the voltage regulator and with the amplitude-modulation signal further being combined with an output of the voltage regulator to control an amplitude of the output of the driver to compensate for bandwidth cutoff noise in the voltage regulator.

Disclosed is a method for communication by a base station in a wireless communication system, including transmitting, to a user equipment (UE), downlink control information (DCI) including information on a modulation and coding scheme (MCS) for processing downlink data using an MCS table among a plurality of tables, and transmitting, to the UE, the downlink data, wherein each of the plurality of MCS tables indicates modulation orders and code rates, wherein the plurality of MCS tables comprises a first MCS table which supports 256 quadrature amplitude modulation (QAM) and a second MCS table which does not support 256 QAM, and wherein a number of MCS indexes in the first MCS table is equal to a number of MCS indexes in the second MCS table.