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.

An apparatus includes a radio frequency (RF) receiver. The RF receiver includes a timing correlator and frequency offset estimator. The timing correlator and frequency offset estimator: (a) extracts timing from a set of samples derived from an RF signal, and (b) determines a frequency offset estimate from the set of samples.

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 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.

A digital signal processor (DSP) for a receiver and a method for processing signals in a receiver are provided. The DSP comprises a processor configured to: receive a digital signal at a symbol rate in a frequency domain; and compensate an impairment of the digital signal in the frequency domain.

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.

DLOS and reflected signal components of an RF carrier signal are received. The reflected component is reflected from a point on the surface of the earth. The DLOS and reflected components are converted to digital DLOS IF and reflected IF signals, respectively. Modeled parameters are generated using the digital DLOS IF signal and locations of one or more antennas, the transmitter, and the point. A reference signal is generated based on the modeled parameters. The reference signal is correlated with the digital reflected IF signal to produce in-phase and quadrature-phase correlation results. A C/N0 and an estimated phase (EP) are calculated for the digital reflected IF signal from the correlation results. A KF is applied to the EP to produce an estimated filter phase (EFP). The KF is adapted to filter the EP using the estimated C/N0 to reduce cycle slips and noise in the EFP.

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.