Techniques are presented for receiving Quadrature Amplitude Modulated (QAM) symbols from a transmitter via a transmission path. In one example, a demodulator is configured to down-convert an incoming Radio Frequency (RF) signal to a baseband signal and convert the baseband signal to digital samples, and output the digital samples. A demapper is configured to receive the digital samples output from the demodulator and output data encoded in QAM symbols. The demapper is further configured to: determine from a constellation of QAM symbols a subset of QAM symbols that a digital sample from the demodulator may represent; apply an offset to each QAM symbol in the subset of QAM symbols of the constellation to result in a subset of offset QAM symbols; determine which QAM symbol in the subset of offset QAM symbols the digital sample most likely represents; and output data representing a determined QAM symbol.

A quadrature modulator and the transmission unit output a modulated wave obtained by performing quadrature modulation on a carrier wave using a first I signal and a first Q signal and wirelessly transmit the modulated wave. A reception unit and the quadrature detector detect a received signal corresponding to a wireless signal transmitted from the wireless tag using the carrier wave and to output a second I signal and a second Q signal. A filter and the amplification unit amplify a frequency component higher than a cutoff frequency in the second I signal and the second Q signal. A detector and the decoding unit decode data based on a detection signal obtained by detecting the amplified second I signal and the amplified second Q signal. A generation unit generates the first I signal and the first Q signal such that the modulated wave is a signal obtained by shifting a frequency of the carrier wave by a frequency shift amount more than the cutoff frequency and to input the first I signal and the first Q signal to the quadrature modulator.

There are provided an orthogonal frequency division multiplexing (OFDM) demodulator, a demodulation method and a receiver. The OFDM demodulator includes a phase analog-to-digital converter and a determiner, wherein the phase analog-to-digital converter is configured to acquire an OFDM analog signal, extract and quantize phase information of a modulated signal on each subcarrier in the OFDM analog signal, and output a phase quantified value corresponding to the phase information of the each subcarrier; and the determiner is configured to perform determination according to the phase quantified value, to obtain modulation information corresponding to the each subcarrier.

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.

The present aspects provide apparatuses, methods, and computer-readable medium for wireless communication at a user equipment (UE), including receiving, from a base station, an in-phase and quadrature-phase tracking reference signal (IQTRS) configured for an estimation of an IQ impairment at the UE; estimating the IQ impairment based on the IQTRS; and compensating for the IQ impairment in a decoding process configured to decode one or more signals received from the base station.

A phase spectrum based delay estimating method of tracking channel responses, extracting phase responses from the tracked channel responses, and generating a delay estimate, wherein the delay estimate is based on a slope and intercept estimates of the extracted phase responses with high quality metric to improve delay estimation, and a system thereof.

An apparatus and method for in-phase/quadrature (I/Q) imbalance correction in a transceiver. The apparatus includes an I/Q imbalance correction circuit and a correction coefficient generation circuit. The I/Q imbalance correction circuit is configured to modify I/Q data in a frequency domain using correction coefficients to generate corrected I/Q data. The correction coefficient generation circuit is configured to generate the correction coefficients for the I/Q imbalance correction circuit based on the I/Q data and reference data.

An electronic device includes a feedback oscillator configured to output a first oscillation signal and a second oscillation signal, the second oscillation signal having a defined phase difference from the first oscillation signal, the feedback oscillator including a phase shifter configured to receive the first oscillation signal and output the second oscillation signal, an up-conversion mixer configured to output a first loopback signal obtained by mixing the first oscillation signal with a reference tone signal, and output a second loopback signal obtained by mixing the second oscillation signal with the reference tone signal, and a receiver configured to generate a first reference IQ signal from the first loopback signal, generate a second reference IQ signal from the second loopback signal, and compare an actual phase difference between the first reference IQ signal and the second reference IQ signal with the defined phase difference.

A method performed by an encoder of a base station system, for handling a data stream for transmission over a transmission connection between a remote unit and a base unit of the base station system, the remote unit being arranged to transmit wireless signals to, and receive from, mobile stations. The method comprises quantizing a plurality of IQ samples, converting the quantized plurality of IQ samples to IQ predictions, calculating per sample a difference between the quantized plurality of IQ samples and the IQ predictions in order to create IQ prediction errors. The method further comprises quantizing the IQ predictions or the IQ prediction errors, entropy encoding the IQ prediction errors and sending the entropy encoded IQ prediction errors over the transmission connection to a decoder of the base station system. The method can be performed by a decoder.

There are provided an orthogonal frequency division multiplexing (OFDM) demodulator, a demodulation method and a receiver. The OFDM demodulator includes a phase analog-to-digital converter and a determiner, wherein the phase analog-to-digital converter is configured to acquire an OFDM analog signal, extract and quantize phase information of a modulated signal on each subcarrier in the OFDM analog signal, and output a phase quantified value corresponding to the phase information of the each subcarrier; and the determiner is configured to perform determination according to the phase quantified value, to obtain modulation information corresponding to the each subcarrier.