To mitigate phase noise and amplitude noise in a 5G or 6G message, the transmitter can include an extremely compact demodulation reference with a predetermined format including a first branch and an orthogonal second branch. The first branch can exhibit the maximum positive amplitude level of the modulation scheme, and the second branch can exhibit either the minimum positive level or the maximum negative level, depending on implementation. The receiver can determine, from the received branch amplitudes, a phase correction and an amplitude correction. Upon receiving a message including noise, the receiver can calculate a sum-signal amplitude and sum-signal phase according to the branch amplitudes of each message element, subtract the amplitude correction and phase correction, derive corrected branch amplitudes, and compare them to the predetermined amplitude levels of the modulation scheme. The receiver can thereby demodulate the message element with the phase noise and amplitude noise largely negated.

Short-form pulse-amplitude demodulation references disclosed herein may enable low-cost receivers to demodulate wireless messages while avoiding complex 5G and 6G protocols, thereby enabling a multitude of cost-constrained applications. Despite their small footprint, the short-form pulse-amplitude demodulation references enable the receiver to determine all of the amplitude levels of the modulation scheme, including the effects of noise and interference. Mitigation of noise and interference can therefore be provided by embedding short-form pulse-amplitude demodulation references within longer messages, thereby providing an immediate refresh of the modulation calibrations, enhancing communication reliability, and avoiding costly message faults despite high background interference. Short-form pulse-amplitude demodulation references disclosed herein can be used as a default standard demodulation reference in 5G and 6G wireless messages.

A device and method for correcting in-phase and quadrature phase (IQ) baseband components to drive a speaker is provided. The device: controls a local oscillator of an RF downmixing device to a plurality of baseband frequency offsets over a range that includes a given baseband frequency offset; determines, at the plurality of baseband frequency offsets, for a received RF signal, amplitude ratio error and phase error for respective IQ baseband components of the received RF signal; generates, using the amplitude ratio error and the phase error for the respective IQ baseband components, for the given offset, filter coefficients for a given baseband frequency range which compensates for respective amplitude ratio error and respective phase error for the given baseband frequency range; and filters, with the filter coefficients, IQ baseband components of the received RF signal, with the local oscillator operating at the given offset, to generate corrected IQ baseband components.

To mitigate phase noise and amplitude noise in a 5G or 6G message, the transmitter can include an extremely compact demodulation reference with a predetermined format including a first branch and an orthogonal second branch. The first branch can exhibit the maximum positive amplitude level of the modulation scheme, and the second branch can exhibit either the minimum positive level or the maximum negative level, depending on implementation. The receiver can determine, from the received branch amplitudes, a phase correction and an amplitude correction. Upon receiving a message including noise, the receiver can calculate a sum-signal amplitude and sum-signal phase according to the branch amplitudes of each message element, subtract the amplitude correction and phase correction, derive corrected branch amplitudes, and compare them to the predetermined amplitude levels of the modulation scheme. The receiver can thereby demodulate the message element with the phase noise and amplitude noise largely negated.

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive pilot signaling associated with inphase and quadrature (IQ) mismatch estimation for a set of antennas of a base station. The UE may measure pilot signals for each of the set of antennas based on a pilot signal pattern of the pilot signaling, and calculate an estimation of an IQ mismatch for each antenna of the set of antennas of the base station based on measuring the pilot signals. The base station may receive, from the UE, a report including an indication of the estimation of the IQ mismatch for each antenna of the set of antennas of the base station based on the pilot signals.

A method of pre-compensating for transmitter in-phase (I) and quadrature (Q) mismatch (IQMM) may include sending a signal through an up-converter of a transmit path to provide an up-converted signal, determining the up-converted signal, determining one or more IQMM parameters for the transmit path based on the determined up-converted signal, and determining one or more pre-compensation parameters for the transmit path based on the one or more IQMM parameters for the transmit path. In some embodiments, the up-converted signal may be determined through a receive feedback path. In some embodiments, the up-converted signal may be determined through an envelope detector.

Example operations may include determining a first noise estimate of noise that propagates along a receive path of a device. The operations may further include determining a second noise estimate of the noise and determining a cross-relationship estimate with respect to the noise. In addition, the operations may include adjusting one or more correction filters configured to correct for imbalances between a first branch and a second branch of the receive path. The adjusting may be based on the first noise estimate, the second noise estimate, and the cross-relationship estimate.

A communication unit comprises a modem configured to generate a first and second test digital quadrature signal. The modem is configured to: estimate a first sampling error performance associated with a first quadrature path from the first received test digital quadrature signal; estimate a second sampling error performance associated with a second quadrature path from the second received test digital quadrature signal; and generate at least one sampling error compensation signal based on the first estimated sampling error performance and second estimated sampling error performance to be applied to at least one of the receiver and transmitter.

A sampling phase difference compensation apparatus includes a signal generator, a signal analyzer and a compensator. The signal generator generates a first signal and a second signal, and outputs the first and second signals to a first path in a first time interval and a second path in a second time interval, respectively. The signal analyzer receives a transmitted first signal from the first path and a transmitted second signal from the second path, and performs a predetermined calculation on the transmitted first and second signals to determine a phase difference relationship, which is associated with a frequency-dependent phase difference and a sampling phase difference, between the transmitted first and second signals. The transmitted first signal is associated with the first signal, and the transmitted second signal is associated with the second signal. The compensator performs a phase difference compensation according to the phase difference relationship.

A communication system including a transmitter and a receiver is disclosed. The transmitter transmits frames, at least two consecutive frames containing different training sequences. The receiver receives data communicated from the transmitter over a channel. The receiver combines and jointly processes the at least two consecutive frames transmitted by the transmitter to estimate a channel state of the channel.