A receiving circuit includes: a first receiving terminal for receiving a RF signal; a second receiving terminal for receiving an external oscillating signal generated by an external oscillator; a low-noise amplifier coupled with the first receiving terminal and the second receiving terminal and utilized for generating an output signal; a first switch element positioned between the second receiving terminal and the low-noise amplifier; an in-phase signal processing circuit for generating an in-phase detection signal based on the output signal; an quadrature signal processing circuit for generating an quadrature detection signal based on the output signal; and a calibration circuit for controlling the first switch element and capable of performing an I/Q mismatch calibration operation according to the in-phase detection signal and the quadrature detection signal when the first switch element is turned on.

A method is provided for detecting an access zone configuration of a downlink wireless transmission received from a wireless network by a receiver. The method includes steps of activating the receiver, synchronizing the receiver with the wireless network, detecting, by the receiver after the step of synchronizing, a received access zone of the downlink wireless transmission, determining a base symbol of the detected access zone, ascertaining a first gap and a second gap from repetitive information contained within the determined base symbol, concluding, from the ascertained first and second gaps, that the detected access zone is part of a multiple access zone configuration, and registering, after the step of concluding, the receiver with the wireless network.

Multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) communication is provided which allows high accuracy estimation of frequency offset, high accuracy estimation of a transmission path fluctuation and high accuracy synchronization/signal detection. Pilot symbol mapping is provided for forming pilot carriers by assigning orthogonal sequences to corresponding subcarriers among OFDM signals which are transmitted at the same time from respective antennas in the time domain. Even when pilot symbols are multiplexed among a plurality of channels (antennas), this allows frequency offset/phase noise to be estimated with high accuracy.

A phase locked loop circuit that is capable of stabilizing a frequency of an input signal even in the case where the frequency is unstable is provided. The phase locked loop circuit 12 that corrects a frequency error of an output signal from an oscillator to a predetermined target frequency; an ADC 121 that converts the output signal to a digital signal; reference frequency output means 123 that outputs a reference frequency signal; frequency error detection means 122a that detects the frequency error based on the digital signal and the reference frequency signal; correction signal generation means 122b that generates an error correction signal based on the frequency error; a DAC 124 that converts the error correction signal to an analog signal; and a multiplier 125 that multiplies the output signal by the analog signal to correct the frequency error of the output signal.

Embodiments of the present invention provide a carrier synchronization method, circuit, and system. The method includes performing n times frequency multiplication on a received signal; performing narrowband filtering at least twice and rectangular wave shaping at least twice on the signal obtained after the n times frequency multiplication; and performing n times frequency division on the signal obtained after the filtering and shaping, to restore a carrier signal. The variable n is a positive integer greater than or equal to 4.

Clustering-based methods, apparatuses for frequency offset determination and elimination and electronic devices are disclosed. The clustering-based method for frequency offset determination includes: determining a constellation diagram for a received signal; determining N different values within a preset frequency interval, as N frequency offset estimates for a frequency offset of the received signal; for each of the frequency offset estimates, correcting the constellation diagram based on the frequency offset estimate to obtain a corrected constellation diagram, clustering signal points on the corrected constellation diagram, and calculating an area of a signal region in the corrected constellation diagram after clustering; and determining a frequency offset estimate corresponding to a signal region with a minimum area as a value of the frequency offset. The embodiments of the present invention can improve the accuracy and stability of the calculated value of the frequency offset.

Methods, systems, and apparatus, including computer programs encoded on computer-storage media, for compensating for frequency-dependent I-Q imbalance. In some implementations, a radio receiver includes an in-phase mixer configured to generate an in-phase (I) signal and a quadrature mixer configured to generate a quadrature (Q) signal. A first analog-to-digital (A/D) converter is configured to generate first digital samples from one of the I signal and the Q signal. A second analog-to-digital (A/D) converter is configured to generate second digital samples from the other of the I signal and the Q signal. A compensation system includes a feedback loop configured to compensate for frequency-dependent I-Q imbalance based on results, for each of multiple of the first digital samples, of cross-correlation of the first digital sample with each of multiple of the second digital samples.

A system of measuring and correcting for distortions in homodyne systems and a method for operating a data processing system to provide an estimate of distortions in homodyne systems are disclosed. The method for operating a data processing system to provide an estimate of a distortion introduced by a homodyne system when the homodyne system processes a time a multi-tone time domain input signal, x(t), to obtain a time domain output signal, y(t) includes receiving a frequency spectrum, X(f), of the multi-tone time domain input signal, x(t) and measuring an output frequency spectrum, Y(f), when the homodyne system operates on x(t). A plurality of parameters of a model that represents a linear frequency response of the homodyne system when operating on X(f) to arrive at Y(f) by fitting the model to Y(f) and X(f) is determined, and the model is applied to X(f) and Y(f) to estimate the distortions.

Methods, systems, and apparatus, including computer programs encoded on computer-storage media, for compensating for frequency-dependent I-Q imbalance. In some implementations, a radio receiver includes an in-phase mixer configured to generate an in-phase (I) signal and a quadrature mixer configured to generate a quadrature (Q) signal. A first analog-to-digital (A/D) converter is configured to generate first digital samples from one of the I signal and the Q signal. A second analog-to-digital (A/D) converter is configured to generate second digital samples from the other of the I signal and the Q signal. A compensation system includes a feedback loop configured to compensate for frequency-dependent I-Q imbalance based on results, for each of multiple of the first digital samples, of cross-correlation of the first digital sample with each of multiple of the second digital samples.

Clustering-based methods, apparatuses for frequency offset determination and elimination and electronic devices are disclosed. The clustering-based method for frequency offset determination includes: determining a constellation diagram for a received signal; determining N different values within a preset frequency interval, as N frequency offset estimates for a frequency offset of the received signal; for each of the frequency offset estimates, correcting the constellation diagram based on the frequency offset estimate to obtain a corrected constellation diagram, clustering signal points on the corrected constellation diagram, and calculating an area of a signal region in the corrected constellation diagram after clustering; and determining a frequency offset estimate corresponding to a signal region with a minimum area as a value of the frequency offset. The embodiments of the present invention can improve the accuracy and stability of the calculated value of the frequency offset.