A method for signal distortion mitigation in a communication device with at least one transmitter in a communication system, generating a signal for transmission for each of the at least one transmitter; performing Peak-to-Average Power Ratio (PAPR) reduction and spectrum shaping of each of the generated signal to provide a distorted signal for transmission; determining signal distortions of the distorted signals, and precoding the determined signal distortions. The method further generating a composite signal for transmission based on the precoded determined signal distortions and the generated signal for transmission, to provide a composite signal, and transmitting the composite signal to at least one receiving communication device, wherein the precoding enables mitigating the signal distortion impact on the at least one receiver.

An apparatus, comprising: circuitry configured, in response to receipt of input data, to transmit a stream of symbols of a constellation to a modulator for modulation onto a carrier wherein a frequency of occurrence of symbols in the stream is dependent upon a probability-amplitude distribution for symbols of the constellation, wherein the probability-amplitude distribution has a kurtosis less than a target value and a shape of the probability-amplitude distribution causes low-amplitude symbols to occur more frequently on average in the stream than high-amplitude symbols.

Systems and methods for automatic level control (ALC) are provided. In one embodiment, an ALC system for communications signals comprises: a multi-threshold programmable ALC controller; and at least one signal path that includes: a digital step attenuator configured to receive an analog communications signal and attenuate the analog communications signal in response to an attenuation adjustment signal from the ALC controller; and an analog-to-digital converter configured to receive the analog communications signal as attenuated by the digital step attenuator and generate samples of the attenuated analog communications signal, wherein the ALC controller receives the samples. The ALC controller comprises a plurality of clip detectors that function in parallel. Each of the clip detectors are programmed with a respective amplitude and time threshold. Based on which of the plurality of clip detectors determine that the samples exceed their respective amplitude and time threshold, the ALC controller generates the attenuation adjustment signal.

A system for selecting an equalizer setting of an equalizer to equalize signals received via a communications link. Starting with a first (e.g., minimum) equalizer setting and a threshold voltage near the mid-eye voltage of the equalized output signal, the system estimates the amplitude of the inner eye of the equalized output signal by comparing the equalized output signal to a series of threshold voltages. If the amplitude of the equalized output signal is less than ideal, the system dynamically increases the equalizer setting. The system quickly converges on the equalizer setting for the communication link because, rather than comparing the output signal at every voltage offset using every equalizer setting, the system only evaluates the equalizer settings necessary to select the equalizer setting for the communications link and uses only the voltage offsets necessary to evaluate each equalizer setting.

Provided are a discrete Fourier transform (DFT)-spread orthogonal frequency division multiplexing (OFDM) transmitter and transmission method, and a DFT-spread OFDM receiver and reception method which may receive signals transmitted thereby, in which a constellation rotation angle and a frequency domain spectrum shaping vector are designed such that a PAPR may be easily traded off with frequency efficiency even without inter-symbol interference. The DFT-spread OFDM transmitter includes a constellation rotation unit constellation-rotating a symbol vector including M pulse amplitude modulation (PAM) symbols by a constellation rotation angle to generate a constellation-rotated symbol vector, a pruned DFT-spread unit spreading the constellation-rotated symbol vector by using a pruned DFT matrix to generate a pruned DFT-spread vector, a frequency domain spectrum shaping unit performing a Hadamard product on the pruned DFT-spread vector with a shaping vector to generate a frequency domain spectrum shaped vector, and a subcarrier allocation unit allocating the frequency domain spectrum shaped vector to a subcarrier in an allocated frequency range.

Disclosed is a system and method for transmitting and receiving digital data, wherein (1) a receiving mechanism is configured to receive an incoming stream of digital information carried on at least one incoming line; (2) a weighing mechanism is configured to generate respective weighing factors using the digital information; (3) a signal generation mechanism is configured to generate a plurality of smooth Time-and-Frequency-Bounded functions; and (4) a mapping mechanism is coupled to the signal generation mechanism, wherein the mapping mechanism is configured to apply weighing factors generated by the weighing mechanism to a corresponding Time-and-Frequency-Bounded function, and subsequently summing the weighted Time-and-Frequency-Bounded functions to thereby generate a corresponding plurality of Time-and-Frequency-Bounded packets, the plurality of Time-and-Frequency-Bounded packets comprising a Time-and-Frequency-Bounded information stream, and a transmission mechanism transmits the plurality of Time-and-Frequency-Bounded packets over the transmission medium.

A transmit/receive signal processor for Wireless Local Area Network (WLAN) and Bluetooth has selectable signal processing elements for mixers, Intermediate Frequency (IF) filters, transmit power amplifiers, and clock sources which are suitable for either Bluetooth or WLAN signal processing. The operating mode of the signal processor is selected to be one of Wireless High Performance, Wireless Low Power, Bluetooth High Performance or Bluetooth Low power, and the signal processing modules are selected to provide performance or power requirements using selected modules.

Systems and methods for automatic level control (ALC) are provided. In one embodiment, an ALC system for communications signals comprises: a multi-threshold programmable ALC controller; and at least one signal path that includes: a digital step attenuator configured to receive an analog communications signal and attenuate the analog communications signal in response to an attenuation adjustment signal from the ALC controller; and an analog-to-digital converter configured to receive the analog communications signal as attenuated by the digital step attenuator and generate samples of the attenuated analog communications signal, wherein the ALC controller receives the samples. The ALC controller comprises a plurality of clip detectors that function in parallel. Each of the clip detectors are programmed with a respective amplitude and time threshold. Based on which of the plurality of clip detectors determine that the samples exceed their respective amplitude and time threshold, the ALC controller generates the attenuation adjustment signal.

An adaptive frequency equalizer for wide modulation bandwidth envelope tracking (ET) is provided. In this regard, an ET integrated circuit (ETIC) provides an ET power signal for one or more power amplifiers (PAs). A voltage error can occur in the ET power signal due to variable impedance sources, such as a variable load impedance at the PA and a variable trace inductance between the ETIC and the PA. The adaptive frequency equalizer disclosed herein works to adaptively correct for such voltage errors to provide improved overall power signal tracking at the PA, especially where there is a large trace inductance from the ETIC being located several centimeters (cm) away from the PA. Thus, embodiments of the adaptive frequency equalizer enhance ET performance for radio frequency (RF) systems having a modulation bandwidth of 100 megahertz (MHz) or above.

Apparatus and methods related to multipath bandpass filters with passband notches are provided herein. In certain configurations, a multipath bandpass filter includes multiple filter circuit branches or paths that are electrically connected in parallel with one another between an input terminal and an output terminal. The input terminal receives an input signal, and each filter circuit branch includes a downconverter that downconverts the input signal to generate a downconverted signal, a filter network that generates a filtered signal by filtering the downconverted signal, and an upconverter that upconverts the filtered signal to generate a branch output signal. The filter network includes at least one low pass filter and at least one notch filter to provide a passband with in-band notches. The branch output signals from the filter circuit branches are combined to generate an output signal at the output terminal.