An emitter identification system arranged to: receive a detected signal including one or more emitter signals from one or more emitters respectively where each of the emitter signals includes a unique signal characteristic related to a unique physical feature of a hardware structure associated with each of the emitters; apply a modulation signal to the detected signal to generate pulse in-phase and quadrature (IQ) data associated with the one or more emitter signals; extract one or more amplitude envelopes associated with the one or more emitter signals, where each amplitude envelope is related to the unique signal characteristic associated with each of the one or more emitters; estimate the unique signal characteristic of each of the one or more emitter signals; estimate a number of clusters related to a number of emitter signals; and identify each of the emitters by applying an unsupervised learning function.

In a modulation correction method, an adjusted amplitude is determined based on an amplitude between adjacent zero crossings of a modulated signal, the adjacent zero crossings are shifted to determine shifted zero crossings, and the modulated signal is adapted based on the adjusted amplitude and the shifted zero crossings to generate a corrected modulated signal corresponding to the modulated signal.

Transceiver array synchronization by receiving a clock signal and at least one synchronization pulse signal at each transceiver IC of a plurality of transceiver integrated circuit (IC) subarrays, wherein each transceiver IC subarray contains a respective set of serially connected transceiver ICs; and synchronizing the transceiver IC with other transceiver ICs of the respective set of serially connected transceiver ICs by resetting a delta-sigma modulator (DSM) circuit to a predetermined state in accordance with the received at least one synchronization pulse signal.

A carrier-phase recovery method includes: (i) applying a first carrier-phase recovery algorithm to complex-valued symbols of a signal received by a product detector, yielding coarse phase-estimates, the signal being modulated per an M-QAM scheme; (ii) modelling the coarse phase-estimates as a weighted sum of M probability-density functions of an M-component mixture model; (iii) optimizing the M probability-density functions with an expectation-maximization algorithm to yield M optimized probability-density functions; (iv) mapping, based on the M optimized probability-density functions, the coarse phase-estimates to one of M symbols corresponding to the QAM scheme, each coarse phase-estimate mapped to a same symbol belonging to a same one of M clusters; (v) applying a second carrier-phase recovery algorithm to each of the M clusters to generate refined phase-estimates each corresponding to a respective coarse phase-estimate; and (vi) mapping, based on the M optimized probability-density functions, each refined phase-estimate to one of the M symbols.

Disclosed is a modem system for transmitting and receiving multi-rotational waveforms comprising at least one waveform modulation subsystem, and a demodulation subsystem programmed to receive a second plurality of sequentially modulated communication waveforms.

A mobile communication device may include a storage element and a baseband processing component operatively coupled to the storage element. The baseband processing component may generate representations of one or more symbols, provide the representations of the one or more symbols through an interface to a buffer element to process, and reduce communications through the interface to the buffer element during at least a portion of the processing of the representations of the one or more symbols.

A UE receives an indication for transmitting a first DMRS sequence having a first length in an uplink transmission. The first DMRS sequence is time domain based. The first DMRS sequence is associated with one or more other DMRS sequences each having a different length. The UE generates the first DMRS sequence and modulates the first DMRS sequence to obtain a set of modulation symbols. The UE maps the set of modulation symbols to a first set of resource elements. An interference, to a first modulation symbol of the set of modulation symbols and mapped to a first resource element of the first set of resource elements, that would be caused by a respective modulation symbol, obtained from a respective one of the one or more other DMRS sequences and mapped to the first resource element if generated, is in a predetermined relationship with the first modulation symbol.

Systems and methods for up-sampling a polar amplitude sample stream in a polar modulator are disclosed. In some embodiments, a process includes receiving, at a polar modulator, an in-phase sample stream and a quadrature sample stream which together characterize a data signal in an IQ plane. The process includes generating a polar amplitude sample stream and a polar phase sample stream. The process includes generating an up-sampled polar amplitude sample stream by (i) identifying an origin crossing of the data signal in the IQ plane, (ii) responsively adjusting an inversion trigger, (iii) selectively applying an inversion to the polar amplitude sample stream based on the inversion trigger, (iv) interpolating the selectively inverted polar amplitude sample stream, and (v) removing the inversion from the interpolated selectively inverted polar amplitude sample stream. The process includes modulating a carrier signal using the up-sampled polar amplitude stream and the polar phase sample stream.

A communication system transmits an input block of bits over a communication channel using a prefix tree that maps a dyadic distribution of compositions of output symbols to prefixes of variable lengths. A path to each leaf of the prefix tree is defined by a prefix formed by a unique sequence of binary values of a length equal to a depth of the leaf. Each leaf is associated with a composition that has at least a number of unique permutations equals to two in a power of a length of a suffix of the block of input bits. The system selects a composition identified in the prefix tree by a prefix, permutes the selected composition according to a suffix, and transmits the permuted composition over a communication channel. The compositions are selected to reduce one or combination of energy and kurtosis of transmission.

An envelope tracking (ET) amplifier circuit is provided. The voltage mDPD circuit is provided in an ET amplifier circuit and configured to determine a voltage deviation relative to an ET modulated target voltage signal, execute an mDPD polynomial in one or more iterations to extract an mDPD coefficient(s), and adjust a time-variant target voltage envelope of the ET modulated target voltage signal based on the mDPD coefficient(s) extracted in each of the mDPD iterations to reduce the voltage deviation to a predefined threshold. By reducing the voltage deviation in the ET modulated voltage, it is possible improve linearity (e.g., gain linearity) of the ET amplifier circuit, which can lead to reduced power consumption and improved radio frequency (RF) performance.