A method for determining a noise shaped quantized parameter contributing to generation of an output signal comprises estimating an error within the output signal using a quantization of the parameter and a quantization of a further parameter contributing to generation of the output signal. The quantization of the parameter is used as the noise shaped quantized parameter according to a selection criterion.

A circuit includes a polar transmitter to generate a radio frequency output from amplitude and phase signal components. The polar transmitter includes an amplifier to combine amplitude and phase signal components. A processor is coupled to the polar transmitter to provide the amplitude and phase signal components. The processor includes: a digital modulation circuit to generate a modulated digital signal including in-phase and quadrature signal components and a correction circuit to calculate and apply a complex digital offset for local oscillator feedthrough of the amplifier. The complex digital offset includes an in-phase offset correction factor and a quadrature offset correction factor.

A circuit includes a polar transmitter to generate a radio frequency output from amplitude and phase signal components. The polar transmitter includes an amplifier to combine amplitude and phase signal components. A processor is coupled to the polar transmitter to provide the amplitude and phase signal components. The processor includes: a digital modulation circuit to generate a modulated digital signal including in-phase and quadrature signal components and a correction circuit to calculate and apply a complex digital offset for local oscillator feedthrough of the amplifier. The complex digital offset includes an in-phase offset correction factor and a quadrature offset correction factor.

A low frequency ultrasonic communication system includes: a low frequency ultrasonic transmitting apparatus configured to transmit data using a low frequency ultrasonic wave; and a low frequency ultrasonic receiving apparatus configured to recover the data by processing a low frequency ultrasonic reception signal transmitted from the low frequency ultrasonic transmitting apparatus. In communication between the transmitting apparatus and the receiving apparatus, modulation is performed using a DPSK scheme, and FEC coding is used to perform channel coding before the modulation.

Embodiments provide a pre-distortion circuit and apparatus, a method and computer program for pre-distorting, a transmitter, a radio transceiver, a communication device, a mobile transceiver, a base station transceiver and a storage. The pre-distortion circuit (10) is configured for a digital quadrature signal. The pre-distortion circuit (10) comprises a first input (12) for an inphase component of the quadrature signal and a second input (14) for a quadrature component of the quadrature signal. The pre-distortion circuit 10 comprises a signal processing circuit (16) configured to determine whether polarities of the inphase component and quadrature component are equal, and to determine pre-distortion coefficients based on the amplitude of the inphase component, the amplitude of the quadrature component, and based on whether the polarities are equal.

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for communicating signals using a multi-dimensional symbol constellation. In one example, a process for modulating a carrier signal includes the actions of mapping data to symbols of a multi-dimensional symbol constellation that includes at least three dimensions, each dimension of the constellation represented by a respective modulation signal. The dimensions of the constellation include first and second dimensions each of which are represented by respective in-phase modulation values and quadrature phase modulation values of a quadrature amplitude modulation (QAM) signal, and a third dimension represented by a transpositional modulation (TM) signal. The method further includes modulating a carrier signal with the TM signal and the QAM signal.

A circuit includes a polar transmitter to generate a radio frequency output from amplitude and phase signal components. The polar transmitter includes an amplifier to combine amplitude and phase signal components. A processor is coupled to the polar transmitter to provide the amplitude and phase signal components. The processor includes: a digital modulation circuit to generate a modulated digital signal including in-phase and quadrature signal components and a correction circuit to calculate and apply a complex digital offset for local oscillator feedthrough of the amplifier. The complex digital offset includes an in-phase offset correction factor and a quadrature offset correction factor.

Embodiments provide a pre-distortion circuit and apparatus, a method and computer program for pre-distorting, a transmitter, a radio transceiver, a communication device, a mobile transceiver, a base station transceiver and a storage. The pre-distortion circuit (10) is configured for a digital quadrature signal. The pre-distortion circuit (10) comprises a first input (12) for an inphase component of the quadrature signal and a second input (14) for a quadrature component of the quadrature signal. The pre-distortion circuit 10 comprises a signal processing circuit (16) configured to determine whether polarities of the inphase component and quadrature component are equal, and to determine pre-distortion coefficients based on the amplitude of the inphase component, the amplitude of the quadrature component, and based on whether the polarities are equal.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive an indication of a demodulation reference signal (DMRS) port to be used by the UE for transmitting a DMRS communication; determine a base sequence based at least in part on the DMRS port; generate a DMRS sequence for the DMRS port based at least in part on the base sequence; and transmit the DMRS communication including the DMRS sequence via the DMRS port. Numerous other aspects are provided.

A transmitter includes a processing circuit to generate I level data and Q level data that, when respectively converted to I baseband input and Q baseband input, cause a carrier signal modulated by the I baseband input and the Q baseband input to have a desired edge shape in the time domain. The edge shape includes a low portion, a high portion, and an edge portion between the low portion and the high portion. The edge portion has a desired edge time compatible with the frequency of the carrier signal. The transmitter further includes a digital-to-analog converter (DAC) to convert the I level data to the I baseband input and the Q level data to the Q baseband input, and an in-phase and quadrature (I/Q) modulator to perform I/Q modulation of the carrier signal according to the I baseband input and the Q baseband input.