A device for controlling spectral regrowth includes a transmission signal processor configured to generate a baseband transmission signal and a controller. The controller is configured to adjust delay of an envelope tracking path that provides a supply voltage to an envelope tracking power amplifier included in a transmission path that generates a radio frequency (RF) transmission signal from the baseband transmission signal. The controller may obtain allocation information of resource blocks included in the RF transmission signal from the transmission signal processor and may determine the delay of the envelope tracking path based on the allocation information.

Circuitry, method and computer program for reducing distortions in a plurality of amplified signals to be radiated by a multiple antenna system. The circuitry comprising: a plurality of inputs for receiving digital signals for a plurality of forward data paths; routing circuitry for routing the digital signals received at the plurality of inputs to pre-distortion logic for applying a pre-distortion function to each of the signals, the pre-distortion logic being operable to forward each of the signals towards a digital to radio frequency converter and subsequent amplifier for amplifying the signals prior to the signals being radiated; one or more feedback paths each comprising processing logic for comparing a feedback signal generated from one of the amplified signals with a corresponding signal received at one of the inputs to determine a function to be applied by the pre-distortion logic to the input signal; selecting logic for selecting the input signal to be provided with the feedback.

A method for receiving a broadcast signal by an access network to a plurality of terminals of a two-way wireless communication system. An information signal is formed from the broadcast information destined for the terminals. A pilot signal is formed and a broadcast signal including the information signal SI1 and the pilot signal is transmitted. The information signal and the pilot signal are transmitted on different respective central frequencies having a predefined frequency gap.

Described examples provide for digital communication circuits and systems that implement digital pre-distortion (DPD). In an example, a circuit includes a baseband DPD circuit, up-conversion circuitry, and feedback circuitry. The baseband DPD circuit comprises a baseband signal path and pre-distortion path. The pre-distortion path is configured to generate a pre-distortion signal based on the baseband signal. The baseband DPD circuit includes a first adder configured to add the baseband signal from the baseband signal path and the pre-distortion signal from the pre-distortion path to generate a pre-distorted baseband signal. The up-conversion circuitry is configured to convert the pre-distorted baseband signal to a radio frequency signal. The up-conversion circuitry is configured to be coupled to an input of a cable television (CATV) amplifier. The feedback circuitry comprises a DPD engine configured to determine a configuration of the pre-distortion path based on an output signal on the output of the CATV amplifier.

Various aspects provide for error detection and compensation for a multiplexing transmitter. For example, a system can include an error detector circuit and a duty cycle correction circuit. The error detector circuit is configured to measure duty cycle error for a clock associated with a transmitter to generate error detector output based on a clock pattern for output generated by the transmitter in response to a defined bit pattern. The duty cycle correction circuit is configured to adjust the clock associated with the transmitter based on the error detector output. Additionally or alternatively, the error detector circuit is configured to measure quadrature error between an in-phase clock and a quadrature clock in response to the defined bit pattern. Additionally or alternatively, the system can include a quadrature error correction circuit configured to adjust phase shift between the in-phase clock and the quadrature clock based on quadrature error.

A transmitter includes: a transmission circuit that outputs, via a transmission amplifier, transmission signals of a same frequency band; and a feedback circuit that feeds back, to the transmission circuit, a distortion compensation coefficient that is used to compensate for distortion of the transmission signals. The feedback circuit includes: a delay circuit that delays each of the transmission signals by a different amount of time; a combining unit that combines the delayed transmission signals to generate a combined signal; a signal conversion unit that converts a frequency of the combined signal to a different frequency using a local signal that is common among the transmission signals, and generates a demodulated digital signal from the combined signal of which the frequency has been converted; and a distortion compensation calculation unit that calculates the distortion compensation coefficient based on the demodulated digital signal.

A method and a transmitter arrangement for cancelling cross talk and correcting power amplifier (PA) distortion for a transmitter branch of a multiple-input multiple-output (MIMO) configuration having multiple branches. The method comprises combining an original baseband input signal of a first MIMO transmitter branch with a crosstalk output signal generated from two or more signals associated with two or more respective MIMO branches, the two or more signals used as input to, and processed by, a crosstalk model. The method further comprises processing the combined signal to generate an output signal in order to minimize the error of the original baseband input signal caused by the crosstalk and/or PA distortion.

Techniques are disclosed relating to use of digital predistortion in the context of full-duplex radio. In some embodiments, an apparatus includes one or more antennas and is configured to simultaneously transmit and receive wireless signals via at least partially overlapping frequency resources using the one or more antennas. In some embodiments, the apparatus includes receive chain circuitry that is configured to process both wireless signals transmitted by the apparatus via the one or more antennas and over-the-air wireless signals from one or more other computing devices. In some embodiments, the apparatus includes one or more processing elements configured to determine one or more digital predistortion parameters based on the wireless signals transmitted by the apparatus via the one or more antennas and processed by the receive chain circuitry and apply predistortion to transmitted wireless signals based on the one or more digital predistortion parameters.

An optical transmitter apparatus is disclosed. The apparatus includes a processor, a memory coupled to the processor, and one or more programs configured to be executed by the processor. The programs include instructions for nonlinearity estimation that characterizes nonlinearity in an optical communication and estimates an amount of symbol distortion caused by the nonlinearity, instructions for selecting and mapping symbols to provide, for the nonlinearity estimation, only symbols that meet predetermined nonlinearity criteria, and instructions for storing, in the memory, the amount of symbol distortion to be used for a nonlinearity pre-compensation.

A method for receiving a broadcast signal by an access network to a plurality of terminals of a two-way wireless communication system. An information signal is formed from the broadcast information destined for the terminals. A pilot signal is formed and a broadcast signal including the information signal SI1 and the pilot signal is transmitted. The information signal and the pilot signal are transmitted on different respective central frequencies having a predefined frequency gap.