An in-phase and quadrature mismatch compensator for a quadrature transmitter includes a delay element, a complex-valued filter and an adder. The delay element receives an input transmit signal and outputs a delayed transmit signal. The complex-valued filter receives the input transmit signal and outputs a selected part of a filtered output transmit signal. The adder adds the delayed transmit signal and the selected part of the filtered output transmit signal and outputs a pre-compensated transmit signal. In one embodiment, the selected part of the filtered output transmit signal includes the real part of the complex-valued output transmit signal. In another embodiment, the selected part of the filtered output transmit signal includes the imaginary part of the complex-valued output transmit signal. Two transmit real-valued compensators are also disclosed that combine the in-phase and quadrature signals before being filtered.

IQ impairments compensation in sub-terahertz (sub-THz) communication is disclosed. According to some aspects, a user equipment (UE) determines an estimated in-phase (I) and quadrature phase (Q) impairment of the UE, the IQ impairment of the UE comprising a mismatch of phase and/or amplitude, between an I path and a Q path within an analog receiver circuitry of the UE, and reports the estimated IQ impairment of the UE to a base station (BS). The BS determines a pre-compensation to compensate for the estimated IQ impairment of the UE and uses the determined pre-compensation when transmitting to the UE.

An in-phase and quadrature mismatch compensator for a quadrature transmitter includes a delay element, a complex-valued filter and an adder. The delay element receives an input transmit signal and outputs a delayed transmit signal. The complex-valued filter receives the input transmit signal and outputs a selected part of a filtered output transmit signal. The adder adds the delayed transmit signal and the selected part of the filtered output transmit signal and outputs a pre-compensated transmit signal. In one embodiment, the selected part of the filtered output transmit signal includes the real part of the complex-valued output transmit signal. In another embodiment, the selected part of the filtered output transmit signal includes the imaginary part of the complex-valued output transmit signal. Two transmit real-valued compensators are also disclosed that combine the in-phase and quadrature signals before being filtered.

A method for providing IQ mismatch (IQMM) compensation includes: estimating an overall frequency response of a compensation filter by stepping through a frequency range starting at an initial frequency and performing (1) through (3) at each step, a selected frequency at each step being a multiple of a subcarrier frequency of the initial frequency: (1) sending a single tone signal at the selected frequency, (2) determining a first response of a mismatched signal at the selected frequency and a second response of the mismatched signal at an image frequency of the selected frequency, and (3) estimating a frequency response of the compensation filter at the selected frequency based on the first response and the second response; generating time-domain filter taps based on the estimated overall frequency response of the compensation filter; determining a time delay based on the time-domain filter taps; and generating a compensated signal based on the time delay.

According to one aspect of the present disclosure, there is provided a device that includes: a first quadrature modulator configured to receive an in-phase portion of a baseband signal and a quadrature portion of the baseband signal, and to produce a first portion of an output signal according to the in-phase and quadrature portions of the baseband signal; a second quadrature modulator configured to receive a first modified signal and a second modified signal, and to produce a second portion of the output signal according to the first and second modified signals; an output circuit configured to sum the first and second portions of the output signal, and to transmit the output signal to an antenna; and a mode selection circuit configured to turn on the first quadrature modulator, to receive a control signal, and to determine whether to turn on the second quadrature modulator according to the control signal.

This document describes methods, devices, systems, and means for user-equipment-coordination-set (404) control aggregation that facilitates more efficient control-plane signaling in comparison to conventional wireless communication systems. Overhead for control-plane signaling is reduced by communicating reports and control commands for the multiple user equipments (110) in the user-equipment-coordination-set (404) in a single message instead of communicating a single control message for each user equipment (110). Additionally, the user-equipment-coordination-set (404) uses joint-reception and joint-transmission, to increase the reliability of communicating reports and control commands, especially in the case of challenging radio communication conditions between a base station (121) and an individual UE (110) located near the edge of a cell provided by the vase station.

A method of compensating for IQ mismatch (IQMM) in a transceiver may include sending first and second signals from a transmit path through a loopback path, using a phase shifter to introduce a phase shift in at least one of the first and second signals, to obtain first and second signals received by a receive path, using the first and second signals received by the receive path to obtain joint estimates of transmit and receive IQMM, at least in part, by estimating the phase shift, and compensating for IQMM using the estimates of IQMM. Using the first and second signals received by the receive path to obtain estimates of the IQMM may include processing the first and second signals received by the receive path as a function of one or more frequency-dependent IQMM parameters.

A method for calibrating a radio transceiver begins by injecting a low-frequency tone at a transmit power amplifier input of the radio transceiver, where the low frequency tone is at least an order of magnitude lower than the operating frequency of a local oscillator coupled to the transmitter input. The method continues by upconverting the low-frequency tone to produce a plurality of tones at a transmit power amplifier output and then determining which tone of the plurality of tones is a local oscillator feedthrough tone associated with a transmit power amplifier output and which tone of the plurality of tones is representative of an in-phase and quadrature (I/Q) imbalance associated with the transmit power amplifier output. The method continues by determining a DC offset, based on the local oscillator feedthrough tone, where the DC offset is representative of local oscillator feedthrough in the transmit power amplifier output and finally determining, based on the tone representative of an I/Q imbalance, an I/Q offset associated with the transmit power amplifier output.

Message reliability is a key requirement of 5G/6G communications. In many challenging network environments, two successive retransmissions of a message can both be corrupted, greatly reducing reliability. Therefore, methods are disclosed for identifying faulted message elements according to a metric that includes the waveform or SNR of the message element, its modulation quality, and a consistency check between the received versions. The receiver can then assemble a merged message version by selecting the higher quality version of each message element from the two (or more) corrupted versions, and thereby avoid requesting yet another retransmission. In addition, the receiver can monitor the background level and, if it is above a predetermined limit, can request that the receiver store the message for a predetermined time, or until the background level subsides below the limit.

Message faults are inevitable in the high-throughput environment of 5G and planned 6G. Retransmissions are costly in time and resources, while generating extra backgrounds and interference. Therefore, methods are disclosed for recovering a faulted message by identifying and correcting each mis-demodulated message element. The faulted message elements generally have substantially lower modulation quality than the correctly demodulated elements, and can be identified by determining the modulation quality of each received message element. If the number of faulted message elements is small, the receiver may correct them using a grid search tested by an associated error-detection code. If the number of faults exceeds a predetermined threshold, the receiver can request a retransmission, and then assemble a merged copy of the message by selecting the message element with the best modulation quality from each version. Substantial time and resources may be saved, and reliable communication may be restored despite poor reception.