CN-122027414-A - Carrier frequency offset and I/Q joint compensation method and system for Bluetooth receiver

CN122027414ACN 122027414 ACN122027414 ACN 122027414ACN-122027414-A

Abstract

The invention discloses a carrier frequency offset and I/Q joint compensation method and system for a Bluetooth receiver, wherein the method comprises the steps of obtaining an initial receiving signal of the Bluetooth receiver, performing time domain preprocessing and fast Fourier transformation to obtain a frequency spectrum; calculating normalized frequency offset based on spectral line with maximum amplitude in frequency spectrum, adaptively selecting target interpolation algorithm according to normalized frequency offset to obtain fine carrier frequency offset estimation value, smoothing, performing frequency offset compensation on initial received signal by using smoothed frequency offset estimation value to obtain baseband I/Q signal, performing low-pass filtering, downsampling and DC removal on baseband I/Q signal to obtain zero-mean baseband signal, estimating gain imbalance parameter and phase imbalance parameter based on zero-mean baseband signal, performing blind compensation, and outputting compensated quadrature I/Q signal. According to the invention, the carrier frequency offset is estimated with high precision by dynamically selecting the interpolation algorithm, and the I/Q imbalance is compensated in a cooperative manner, so that the demodulation performance and the robustness of the Bluetooth receiver are improved.

Inventors

Jing Xiaoyue
WANG KEPING
WANG LEI
CAI LINGFENG

Assignees

北京蓝凌星通科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260326

Claims (10)

1. The carrier frequency offset and I/Q joint compensation method for the Bluetooth receiver is characterized by comprising the following steps of: S1, acquiring an initial receiving signal of a Bluetooth receiver, performing time domain preprocessing and fast Fourier transformation to obtain a frequency spectrum, calculating a normalized frequency offset based on a spectral line with the largest amplitude in the frequency spectrum, and adaptively selecting a target interpolation algorithm according to the normalized frequency offset to obtain a fine carrier frequency offset estimation value; S2, carrying out smoothing treatment on the fine carrier frequency offset estimation value, and carrying out frequency offset compensation on the initial received signal by utilizing the smoothed frequency offset estimation value to obtain a baseband I/Q signal; s3, carrying out low-pass filtering, downsampling and DC removal on the baseband I/Q signals to obtain zero-mean baseband signals; S4, estimating gain imbalance parameters and phase imbalance parameters based on the zero-mean baseband signals, performing blind compensation on the zero-mean baseband signals based on the estimated parameters, and outputting compensated quadrature I/Q signals.
2. The method according to claim 1, wherein in step S1, the time domain preprocessing specifically includes: performing moving average filtering on the initial received signal to suppress random noise; and adding a hanning window to the filtered signal to inhibit spectrum leakage, so as to obtain a preprocessed signal.
3. The method of claim 1, wherein in step S1, based on the spectral line with the largest amplitude in the frequency spectrum, calculating normalized frequency offset, adaptively selecting a target interpolation algorithm according to the normalized frequency offset, and obtaining a fine carrier frequency offset estimation value, specifically comprising: Positioning a spectral line with the largest amplitude in the frequency spectrum, and generating rough estimation representing a frequency offset state as a normalized frequency offset based on the amplitude distribution of the spectral line with the largest amplitude and the adjacent spectral line; comparing the normalized frequency offset with a preset threshold value; if the normalized frequency deviation is smaller than the preset threshold, an amplitude-phase joint interpolation algorithm is adopted, and an interpolation correction term is calculated by utilizing the spectral line with the largest amplitude and the real part of the adjacent spectral line; If the normalized frequency deviation is greater than or equal to the preset threshold, a Rife interpolation algorithm of phase correction is adopted, the interpolation direction is determined by utilizing the phase ratio of the spectral line with the largest amplitude to the adjacent spectral line, and an interpolation correction term is calculated according to the amplitude ratio of the spectral line with the largest amplitude to the next largest spectral line; and adding the basic frequency offset of the frequency spectrum with the correlation value of the interpolation correction term to obtain a fine carrier frequency offset estimation value.
4. The method according to claim 1, wherein step S4 specifically comprises: s41, calculating the I branch power, the Q branch power and the cross-correlation values of I and Q based on the zero-mean baseband signal, and estimating a gain imbalance parameter and a phase imbalance parameter; S42, comparing the gain imbalance parameter and the phase imbalance parameter with corresponding threshold standards, performing blind compensation when any one of the gain imbalance parameter and the phase imbalance parameter exceeds the standard, and outputting a compensated quadrature I/Q signal.
5. The method of claim 4, wherein in step S41, the gain imbalance parameter and the phase imbalance parameter are calculated according to the following formula: Wherein, the Representing the gain imbalance parameter(s), Representing the phase imbalance parameter(s), The power of the I branch is indicated, Representing the Q-branch power and, Representing the cross-correlation values of I and Q.
6. The method of claim 4, wherein in step S42, the blind compensation specifically includes: Keeping the Q branch signal of the zero-mean baseband signal unchanged; constructing a gain compensation coefficient and a phase compensation coefficient by using the gain imbalance parameter and the phase imbalance parameter; and the gain compensation coefficient and the phase compensation coefficient are combined to act on the I branch signal to finish the gain and phase synchronous calibration of the I branch.
7. The method of claims 5 and 6, wherein the gain compensation coefficient and phase compensation coefficient are calculated as: Wherein, the Representing the gain compensation coefficient(s), Representing the phase compensation coefficient.
8. A carrier frequency offset and I/Q joint compensation system for a bluetooth receiver, employing a carrier frequency offset and I/Q joint compensation method for a bluetooth receiver according to any one of claims 1-7, comprising the following modules: The acquisition and frequency offset estimation module is used for acquiring an initial receiving signal of the Bluetooth receiver, performing time domain pretreatment and fast Fourier transform to obtain a frequency spectrum, calculating normalized frequency offset based on a spectral line with the largest amplitude in the frequency spectrum, and adaptively selecting a target interpolation algorithm according to the normalized frequency offset to obtain a fine carrier frequency offset estimation value; The frequency offset compensation module is used for carrying out smoothing processing on the fine carrier frequency offset estimation value, and carrying out frequency offset compensation on the initial received signal by utilizing the smoothed frequency offset estimation value to obtain a baseband I/Q signal; The DC removing module is used for carrying out low-pass filtering, downsampling and DC removing processing on the baseband I/Q signals to obtain zero-mean baseband signals; and the I/Q compensation module is used for estimating a gain imbalance parameter and a phase imbalance parameter based on the zero-mean baseband signal, performing blind compensation on the zero-mean baseband signal based on the estimated parameters and outputting a compensated quadrature I/Q signal.
9. Computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the carrier frequency offset and I/Q joint compensation method for a bluetooth receiver according to any of the claims 1-7 when executing the program.
10. Computer readable storage medium, having stored thereon a computer program, which when executed by a processor implements a carrier frequency offset and I/Q joint compensation method for a bluetooth receiver according to any of claims 1-7.

Description

Carrier frequency offset and I/Q joint compensation method and system for Bluetooth receiver Technical Field The invention relates to the technical field of wireless communication, in particular to a carrier frequency offset and I/Q joint compensation method and system for a Bluetooth receiver. Background In wireless communication systems (e.g., bluetooth, wi-Fi, internet of things narrowband communication), receiver performance is directly limited by the imbalance of the Carrier Frequency Offset (CFO) and I/Q signals. First, the accuracy and temperature drift of the crystal oscillator are limited, and there is a natural frequency deviation between the transmitting end and the receiving end. If not corrected in time, the constellation diagram rotates, and serious error code is caused. The existing frequency offset estimation algorithm is mostly based on spectral line analysis after Fast Fourier Transform (FFT). However, the conventional method has obvious drawbacks: The limitations of the fixed interpolation algorithm are that most schemes employ a fixed interpolation formula (e.g., simple parabolic interpolation or fixed Quinn algorithm). When the spectral line leakage is serious due to a low signal-to-noise ratio or a large frequency offset, the fixed algorithm cannot adapt to different spectral characteristics, so that the estimation accuracy is greatly reduced, and even divergence occurs. The noise sensitivity problem of single estimation is that the prior art estimates in a single frame signal, is easily influenced by channel noise, multipath fading and burst interference, has large estimation value variance, and is difficult to meet the requirement of high-sensitivity reception. Second, the I and Q paths of the received signal often have amplitude gain errors and phase quadrature errors (i.e., I/Q imbalance) due to the non-idealities of the analog front-end circuitry. This can lead to signal spectrum image interference, severely degrading the signal-to-noise ratio. Currently, the industry typically processes frequency offset correction and I/Q imbalance correction serially as two separate modules. The separation treatment mode has the following defects: error transfer-offset misalignment can directly affect the calculation of subsequent I/Q correction parameters and vice versa, resulting in cascading error accumulation. The resource waste is that the independent module needs to repeatedly perform spectrum analysis or related operation, so that the complexity and the power consumption of hardware logic are increased, and the application of low-power consumption Internet of things equipment is not facilitated. Therefore, a method for implementing efficient joint compensation of carrier frequency offset and I/Q imbalance is proposed to solve the above technical problems, which is a problem to be solved by those skilled in the art. Disclosure of Invention In view of the above problems, the present invention is provided to provide a method and a system for carrier frequency offset and I/Q joint compensation for a bluetooth receiver, which overcome or at least partially solve the above problems, and estimate carrier frequency offset with high accuracy by dynamically selecting an interpolation algorithm and performing joint processing with multiple frames, and cooperatively compensate I/Q imbalance, thereby effectively suppressing noise and interference, and significantly improving demodulation performance and robustness of the wireless receiver. In order to achieve the above purpose, the present invention adopts the following technical scheme: In a first aspect, an embodiment of the present invention provides a carrier frequency offset and I/Q joint compensation method for a bluetooth receiver, including the steps of: S1, acquiring an initial receiving signal of a Bluetooth receiver, performing time domain preprocessing and fast Fourier transformation to obtain a frequency spectrum, calculating a normalized frequency offset based on a spectral line with the largest amplitude in the frequency spectrum, and adaptively selecting a target interpolation algorithm according to the normalized frequency offset to obtain a fine carrier frequency offset estimation value; S2, carrying out smoothing treatment on the fine carrier frequency offset estimation value, and carrying out frequency offset compensation on the initial received signal by utilizing the smoothed frequency offset estimation value to obtain a baseband I/Q signal; s3, carrying out low-pass filtering, downsampling and DC removal on the baseband I/Q signals to obtain zero-mean baseband signals; S4, estimating gain imbalance parameters and phase imbalance parameters based on the zero-mean baseband signals, performing blind compensation on the zero-mean baseband signals based on the estimated parameters, and outputting compensated quadrature I/Q signals. Further, in step S1, the time domain preprocessing specifically includes: performing moving average fil