The invention relates to a technique for controlling in an envelope tracking amplification stage, comprising: determining a representation of the output signal of the amplifier; determining a representation of the input signal of the amplifier; adjusting the determined representation of the input signal according to a target characteristic of the amplifier; comparing the adjusted input and determined representation of the output; and generating a control signal in dependence on the comparison.

A receiver includes an analog-to-digital converter (ADC) module that receives a test signal via a transmission channel and provides a time domain representation of the test signal as received by the receiver, and a processor that determines a time domain representation of an impedance of the transmission channel based on the time domain representation of the test signal.

Various communication systems may benefit from improved radio signaling. For example, communication systems may benefit from selective or partial filtering of a radio signal. A method, in certain embodiments, may include analyze at a network entity a radio signal comprising a plurality of orthogonal frequency division multiplexing symbols. The radio signal comprises at least one point of discontinuity between the plurality of symbols. The method may also include filtering a select time domain sample of the radio signal in the plurality of symbols. The select sample surrounds the at least one point of discontinuity. In addition, the method may include replacing the select time domain sample surrounding the at least one point of discontinuity of the radio signal with the filtered sample in the plurality of symbols.

Systems and methods are directed to phase modulation of polar coordinates in a transmitter of wireless signals, to achieve high transmit power levels while meeting spectral mask and EVM requirements. An input signal is mapped to a sequence of modulation frequency (e.g., O-QPSK to MSK) to generate a mapped signal. A digital frequency shaping filter is applied to the mapped signal to generate a shaped signal. An adaptive rounding algorithm is applied to the shaped signal to generate a reduced bit-width signal. A digital frequency synthesizer is applied to the reduced bit-width signal to generate an analog waveform for transmission.

Embodiments of the present disclosure relate to systems and methods to generate a signal in a communication network. The method comprises filtering a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) data signal, and one of a DFT-S-OFDM and orthogonal frequency division multiplexing (OFDM) reference signal (RS) using a data filter and a RS filter respectively, to produce filtered data signal and filtered RS. The RS filter has one to one relationship with the data filter. Thereafter, port mapping the filtered RS to a corresponding port assigned to the transmitter to obtain port mapped filtered RS, wherein the port mapped filtered RS comprises a first subset of non-zero locations comprising of the filtered RS values and a second subset of zero locations comprising of zero values.

A method of connecting devices to a network is provided. The method includes providing base stations connected to a network, and at each of the base stations, receiving probe signals from terminal devices. For each of the terminal devices, the base station calculates a signature waveform based on a time-reversed waveform of a channel response signal derived from the corresponding probe signal. For each of the terminal devices, the base station determines a downlink transmit signal for the terminal device based on the downlink data and the corresponding signature waveform, and transmits the downlink signals to the terminal devices. Several base stations have overlapping broadcast regions, several terminal devices are located within the overlapped broadcast regions, the base stations transmit the downlink signals using a same frequency band, and some downlink signals transmitted by base stations having overlapping broadcast regions also overlap in time.

Provided is a digital filter implementing a function by using circular convolution of a digital input signal and a unit pulse response of the digital filter in applying a filter to the digital signal. In addition, a configuration sequence change of an output signal, which occurs as a result of digital filtering according to the present invention, in comparison to an input signal, is corrected by inversely performing circular shifting in a transmitter by amount of the configuration sequence change, or by reconstructing a signal after making synchronization and acquiring the signal previous to a time point of the synchronization by amount of the configuration sequence change, in a receiver.

A Faster-Than-Nyquist (FTN) signal transmission apparatus and method thereof. The signal transmission apparatus includes a pilot interference estimator and compensator configured to estimate interference on pilot symbols by a Faster-Than-Nyquist (FTN) signal generated by FTN modulating a sequence of data symbols, and generate a compensated pilot symbol sequence to cancel the estimated interference; a pilot FTN modulator configured to generate an FTN pilot signal in which inter-pilot symbol interference does not occur, by performing FTN pulse-shaping on the compensated pilot symbol sequence; and a transmitter configured to transmit an FTN data signal and the FTN pilot signal.

A method implemented by a transmitter, comprising encoding digital in-phase and quadrature-phase (IQ) data associated with a plurality of analog signals according to a first multi-level modulation format to produce a modulated IQ signal, encoding control information associated with the plurality of analog signals according to a second multi-level modulation format that is different from the first multi-level modulation format to produce a modulated control signal, aggregating the modulated IQ signal and the modulated control signal via time-division multiplexing (TDM) to produce an aggregated TDM signal, and transmitting the aggregated TDM signal over a communication channel.

The embodiments described herein include amplifiers configured for use in radio frequency (RF) applications. In accordance with these embodiments, the amplifiers are implemented to generate a shaped envelope signal, and to apply the shaped envelope signal to transistor gate(s) of the amplifier to provide gate bias modulation. So configured, the shaped envelope signal may facilitate high linearity in the amplifier.