Carrier frequency offset and I / Q joint compensation method and system for Bluetooth receiver

Abstract

The invention discloses a carrier frequency offset and I / Q joint compensation method and system for a Bluetooth receiver, and the method comprises the steps: obtaining an initial receiving signal of the Bluetooth receiver, and carrying out the time domain preprocessing and fast Fourier transform, thereby obtaining a frequency spectrum; calculating normalized frequency offset based on the spectral line with the maximum amplitude in the frequency spectrum; according to the normalized frequency offset, adaptively selecting a target interpolation algorithm to obtain a fine carrier frequency offset estimation value; carrying out smoothing processing, and carrying out frequency offset compensation on the initial receiving signal by using a smoothed frequency offset estimation value to obtain a baseband I / Q signal; performing low-pass filtering, down-sampling and DC removal processing on the baseband I / Q signal to obtain a zero-mean baseband signal; and estimating a gain imbalance parameter and a phase imbalance parameter based on the zero-mean baseband signal, performing blind compensation, and outputting a compensated orthogonal I / Q signal. According to the method, the carrier frequency offset is estimated with high precision through a dynamic selection interpolation algorithm, I / Q imbalance is compensated cooperatively, and the demodulation performance and robustness of the Bluetooth receiver are improved.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and more specifically to a carrier frequency offset and I / Q joint compensation method and system for Bluetooth receivers. Background Technology

[0002] In wireless communication systems (such as Bluetooth, Wi-Fi, and IoT narrowband communication), receiver performance is directly limited by carrier frequency offset (CFO) and the imbalance between the I / Q signals.

[0003] First, due to limitations in crystal oscillator accuracy and temperature drift, an inherent frequency offset exists between the transmitter and receiver. If not corrected in time, this can lead to constellation diagram rotation and severe bit errors. Existing frequency offset estimation algorithms are mostly based on spectral analysis following Fast Fourier Transform (FFT). However, traditional methods have significant drawbacks:

[0004] Limitations of fixed interpolation algorithms: Most schemes use fixed interpolation formulas (such as simple parabolic interpolation or fixed Quinn algorithms). When the signal-to-noise ratio is low or the frequency offset is large, resulting in severe spectral leakage, fixed algorithms cannot adapt to different spectral characteristics, leading to a significant decrease in estimation accuracy and even divergence.

[0005] Noise sensitivity issue in single-shot estimation: Existing technologies perform estimation within a single frame of signal, which is susceptible to channel noise, multipath fading, and sudden interference, resulting in large variance in the estimated value, making it difficult to meet the requirements of high-sensitivity reception.

[0006] Secondly, due to the non-ideal nature of analog front-end circuits, the I and Q paths of the received signal often exhibit amplitude gain errors and phase quadrature errors (i.e., I / Q imbalance). This leads to signal spectrum mirroring interference, severely degrading the signal-to-noise ratio.

[0007] Currently, the industry typically treats frequency offset correction and I / Q imbalance correction as two separate modules processed sequentially. This separate processing method has the following drawbacks: Error propagation: Inaccurate frequency offset estimation will directly affect the calculation of subsequent I / Q correction parameters, and vice versa, leading to the accumulation of cascaded errors.

[0008] Resource waste: Independent modules need to repeatedly perform spectrum analysis or related calculations, which increases the complexity of hardware logic and power consumption, and is not conducive to the application of low-power IoT devices.

[0009] Therefore, proposing a method for efficient joint compensation of carrier frequency offset and I / Q imbalance to solve the above-mentioned technical problems is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0010] In view of the above problems, the present invention is proposed to provide a carrier frequency offset and I / Q joint compensation method and system for Bluetooth receivers that overcomes or at least partially solves the above problems. By dynamically selecting interpolation algorithms and multi-frame joint processing, the carrier frequency offset is estimated with high accuracy, and I / Q imbalance is compensated in a coordinated manner, effectively suppressing noise and interference, and significantly improving the demodulation performance and robustness of the wireless receiver.

[0011] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, embodiments of the present invention provide a method for joint compensation of carrier frequency offset and I / Q for a Bluetooth receiver, comprising the following steps: S1. Obtain the initial received signal from the Bluetooth receiver, perform time-domain preprocessing and fast Fourier transform to obtain the spectrum; calculate the normalized frequency offset based on the spectral line with the largest amplitude in the spectrum; adaptively select the target interpolation algorithm according to the normalized frequency offset to obtain the fine carrier frequency offset estimate. S2. The fine carrier frequency offset estimate is smoothed, and the smoothed frequency offset estimate is used to compensate for the frequency offset of the initial received signal to obtain the baseband I / Q signal. S3. Perform low-pass filtering, downsampling, and DC removal processing on the baseband I / Q signal to obtain a zero-mean baseband signal; S4. Estimate the gain imbalance parameter and phase imbalance parameter based on the zero-mean baseband signal, and perform blind compensation on the zero-mean baseband signal based on the estimated parameters to output the compensated quadrature I / Q signal.

[0012] Furthermore, in step S1, the time-domain preprocessing specifically includes: The initial received signal is subjected to moving average filtering to suppress random noise; A Hanning window is applied to the filtered signal to suppress spectral leakage, resulting in a preprocessed signal.

[0013] Further, in step S1, based on the spectral line with the largest amplitude in the spectrum, the normalized frequency offset is calculated; according to the normalized frequency offset, an adaptive target interpolation algorithm is selected to obtain a fine carrier frequency offset estimate; specifically including: Locate the spectral line with the largest amplitude in the spectrum, and based on the amplitude distribution of the spectral line with the largest amplitude and its adjacent spectral lines, generate a rough estimate representing the frequency offset state as a normalized frequency offset; The normalized frequency offset is compared with a preset threshold. If the normalized frequency offset is less than the preset threshold, then the amplitude-phase joint interpolation algorithm is used to calculate the interpolation correction term using the real part of the spectral line with the largest amplitude and its adjacent spectral lines. If the normalized frequency offset is greater than or equal to the preset threshold, the phase-corrected Rife interpolation algorithm is used to determine the interpolation direction by using the phase ratio of the spectral line with the largest amplitude to its adjacent spectral lines, and to calculate the interpolation correction term based on the amplitude ratio of the spectral line with the largest amplitude to the second largest spectral line. The basic frequency offset of the spectrum is added to the relevant values ​​of the interpolation correction term to obtain the fine carrier frequency offset estimate.

[0014] Furthermore, step S4 specifically includes: S41. Based on the zero-mean baseband signal, calculate the I branch power, Q branch power, and the cross-correlation value between I and Q, and estimate the gain imbalance parameter and phase imbalance parameter. S42. Compare the gain imbalance parameter and phase imbalance parameter with the corresponding threshold standard. If either exceeds the standard, perform blind compensation and output the compensated quadrature I / Q signal.

[0015] Furthermore, in step S41, the calculation formulas for the gain imbalance parameter and the phase imbalance parameter are as follows:

[0016]

[0017] in, Indicates the gain imbalance parameter. Indicates the phase imbalance parameter. Indicates the power of branch I. Indicates the power of branch Q. This represents the cross-correlation value between I and Q.

[0018] Furthermore, in step S42, the blind compensation specifically includes: Keep the Q-branch signal of the zero-mean baseband signal unchanged; Using the aforementioned gain imbalance parameter and phase imbalance parameter, a gain compensation coefficient and a phase compensation coefficient are constructed. The gain compensation coefficient and phase compensation coefficient are applied together to the I-branch signal to complete the gain and phase synchronization calibration of the I-branch.

[0019] Furthermore, the formulas for calculating the gain compensation coefficient and the phase compensation coefficient are as follows:

[0020]

[0021] in, Indicates the gain compensation coefficient. This represents the phase compensation coefficient.

[0022] Secondly, embodiments of the present invention provide a carrier frequency offset and I / Q joint compensation system for a Bluetooth receiver, employing the carrier frequency offset and I / Q joint compensation method for a Bluetooth receiver as described in any of the first aspects, comprising the following modules: Acquisition and frequency offset estimation module: used to acquire the initial received signal of the Bluetooth receiver, perform time-domain preprocessing and fast Fourier transform to obtain the spectrum; calculate the normalized frequency offset based on the spectral line with the largest amplitude in the spectrum; and adaptively select the target interpolation algorithm according to the normalized frequency offset to obtain the fine carrier frequency offset estimate. Frequency offset compensation module: used to smooth the fine carrier frequency offset estimate and use the smoothed frequency offset estimate to compensate for the frequency offset of the initial received signal to obtain the baseband I / Q signal; DC removal module: used to perform low-pass filtering, downsampling and DC removal processing on the baseband I / Q signal to obtain a zero-mean baseband signal; I / Q compensation module: used to estimate the gain imbalance parameter and phase imbalance parameter based on the zero-mean baseband signal, and to perform blind compensation on the zero-mean baseband signal based on the estimated parameters, and output the compensated quadrature I / Q signal.

[0023] Thirdly, embodiments of the present invention provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the carrier frequency offset and I / Q joint compensation method for a Bluetooth receiver as described in any one of the first aspects.

[0024] Fourthly, embodiments of the present invention provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the carrier frequency offset and I / Q joint compensation method for a Bluetooth receiver as described in any one of the first aspects.

[0025] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a carrier frequency offset and I / Q joint compensation method and system for Bluetooth receivers, which has the following beneficial effects: 1. Excellent frequency offset estimation performance: The adaptive target selection interpolation algorithm greatly improves the accuracy of frequency offset estimation, and the moving average filtering further reduces random errors. Moreover, no additional training sequences are required, and no system overhead is increased.

[0026] 2. Strong I / Q compensation adaptability: The blind compensation scheme based on statistical characteristics does not require special calibration signals. The compensation coefficient can track channel changes in real time, and the accuracy of gain and phase imbalance correction is high, and constellation diagram distortion is significantly improved.

[0027] 3. The joint processing has significant advantages: the collaborative processing mechanism for frequency offset and I / Q imbalance avoids mutual interference, reduces the cumulative error of residual frequency offset and I / Q imbalance, and further reduces the receiver bit error rate in low signal-to-noise ratio scenarios.

[0028] 4. Independent Deployment on the Receiver Side, No Transmitter Coupling: Carrier frequency offset estimation and compensation, and I / Q imbalance assessment and compensation are completed within the receiver, without the need to feed back parameters to the transmitter or send a joint compensation model. This invention can be independently deployed and upgraded in standard low-power Bluetooth and low-Earth orbit satellite IoT receivers without modifying the transmitter or changing the air interface protocol, reducing system coupling and deployment costs. It is suitable for application scenarios where the transmitter is uncontrollable or compatibility with existing network equipment is required. It can be directly integrated into the existing receiver architecture without significant hardware modifications, demonstrating strong practicality and compatibility. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0030] Figure 1 This is a flowchart of a carrier frequency offset and I / Q joint compensation method for a Bluetooth receiver provided in an embodiment of the present invention; Figure 2 This is a flowchart of carrier frequency offset estimation based on adaptive target selection interpolation algorithm provided in an embodiment of the present invention; Figure 3 Frequency offset provided in the embodiments of the present invention Comparison of results between the API-Q-Rife algorithm of this invention and the traditional FFT frequency offset estimation algorithm at 70kHz; Figure 4 Frequency offset provided in the embodiments of the present invention Comparison of results between the API-Q-Rife algorithm of this invention and the traditional FFT frequency offset estimation algorithm at 90kHz; Figure 5 This is a framework diagram of a carrier frequency offset and I / Q joint compensation system for a Bluetooth receiver provided in an embodiment of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1 This invention discloses a carrier frequency offset and I / Q joint compensation method for a Bluetooth receiver, referring to... Figure 1 As shown, it includes the following steps: S1. Obtain the initial received signal from the Bluetooth receiver, perform time-domain preprocessing and fast Fourier transform to obtain the spectrum; calculate the normalized frequency offset based on the spectral line with the largest amplitude in the spectrum; adaptively select the target interpolation algorithm according to the normalized frequency offset to obtain the fine carrier frequency offset estimate. S2. Smooth the fine carrier frequency offset estimate and use the smoothed frequency offset estimate to compensate for the frequency offset of the initial received signal to obtain the baseband I / Q signal. S3. Perform low-pass filtering, downsampling, and DC removal on the baseband I / Q signal to obtain a zero-mean baseband signal; S4. Estimate the gain imbalance parameter and phase imbalance parameter based on the zero-mean baseband signal, and perform blind compensation on the zero-mean baseband signal based on the estimated parameters, and output the compensated quadrature I / Q signal.

[0033] This embodiment applies to a high-sensitivity, low-power Bluetooth (BLE) long-range receiver. When the gateway receives Bluetooth data packets from a remote sensor, it first performs signal acquisition and coarse analysis to obtain an initial spectrum. Then, it dynamically selects an interpolation algorithm based on frequency offset estimation. Following this, it performs multi-frame fine estimation and tracking, and finally achieves joint compensation for carrier frequency offset and I / Q imbalance. This perfectly combines the flexibility of "dynamic algorithm selection," the noise immunity of "multi-frame averaging," and the efficiency of "joint compensation," solving the communication challenges of Bluetooth Low Energy in extremely weak signal and complex electromagnetic environments. It is a key technological support for building a highly reliable industrial Internet of Things (IoT).

[0034] The implementation steps of this embodiment are described in detail below: First, following step S1, the initial received signal of the Bluetooth receiver is obtained. In this embodiment, this signal contains a frequency offset, and the carrier frequency offset value needs to be estimated. This embodiment performs a Fast Fourier Transform (FFT) directly after time-domain preprocessing, and then interpolates or corrects based on the amplitude and phase information of adjacent spectral lines on the basis of the maximum FFT spectral line to obtain a fine frequency offset estimate; refer to... Figure 2 As shown, this section specifically introduces carrier frequency offset estimation based on an adaptive target selection interpolation algorithm: (1) Preprocessing and noise reduction.

[0035] This embodiment applies a moving average filter to the initial received signal to suppress random noise, and then applies a Hanning window to the filtered signal to suppress spectral leakage, resulting in a preprocessed signal. This dual noise reduction method of "moving average + Hanning window" is used in low signal-to-noise ratio scenarios, reducing the interference of noise on subsequent spectral line estimation.

[0036] (2) FFT and maximum spectral line location.

[0037] This embodiment extracts N consecutive sampling points from the preprocessed signal for FFT and performs data rearrangement on the spectrum to obtain an amplitude spectrum centered at zero frequency. The position of the spectral line corresponding to the maximum amplitude in the amplitude spectrum is found and denoted as the maximum spectral line index. This "maximum spectral line position" and information such as the amplitude, real part, or phase ratio of this spectral line to its left and right adjacent spectral lines are used for subsequent interpolation.

[0038] (3) Adaptive target selection interpolation algorithm.

[0039] This embodiment generates a rough estimate of the frequency offset state as a normalized frequency offset based on the amplitude distribution of the maximum spectral line and its adjacent spectral lines; specifically including: Perform spectral peak search and location on the amplitude spectrum obtained after data rearrangement to find the index of the spectral line with the largest amplitude. Extract the amplitude values ​​of the maximum spectral line and the two spectral lines to its left and right, and construct a local amplitude set containing three key points; Using the three amplitude values ​​mentioned above, the asymmetry ratio ρ, which characterizes the direction of the main lobe offset in the spectrum, is calculated. Since the actual carrier frequency is usually located between two discrete frequency points, the main lobe of the spectrum will tilt, resulting in unequal amplitudes on the left and right sides. Based on the preset mapping relationship, the asymmetry ratio ρ is converted into a normalized coarse estimate of the frequency bias.

[0040] Subsequently, this embodiment compares the current coarse judgment result of normalized frequency offset with a preset threshold and dynamically selects the difference method. The preset threshold in this embodiment is 0.25.

[0041] When the normalized frequency offset is less than 0.25, the amplitude-phase joint interpolation algorithm (API) is used: the amplitude-phase joint interpolation correction term is calculated using the real parts of the maximum spectral line and its left and right adjacent spectral lines. delta_star .

[0042] When the normalized frequency offset is greater than or equal to 0.25, the phase-corrected Rife interpolation algorithm (Q-Rife) is used: the interpolation direction is determined by the phase ratio of the left and right adjacent spectral lines to the center spectral line, and then the Rife correction term is calculated based on the amplitude ratio of the largest spectral line to the second largest spectral line. delta_star .

[0043] (4) Frequency offset calculation and interpolation correction.

[0044] Based on the system sampling rate and the number of FFT points, calculate the smallest unit of resolution in the frequency domain, i.e., the frequency resolution:

[0045] in, The physical frequency interval corresponding to each FFT frequency point. The sampling frequency of the receiver's baseband signal. The number of data points used to perform the Fast Fourier Transform (FFT).

[0046] In the spectrum after data rearrangement, the zero-frequency center index position is:

[0047] Index position by maximum spectral line Relative zero-frequency center index position offset multiplied The fundamental frequency offset is obtained.

[0048] The refined carrier frequency offset estimate is obtained by adding the relevant values ​​of the interpolation correction term to the fundamental frequency offset. The relevant values ​​of the interpolation correction term are as follows: .

[0049] In this embodiment, the absolute value of the frequency offset estimate exceeds the Nyquist limit. When this occurs, amplitude limiting is applied to restrict the estimated value to a certain range. Within the specified range, outliers should be avoided from affecting subsequent frequency offset compensation.

[0050] This embodiment uses an adaptive target selection interpolation algorithm for carrier frequency offset estimation. By interpolating the amplitude and phase of adjacent spectral lines, the effective resolution is improved, which is better than the coarse estimation that only takes the peak frequency of FFT. The preprocessing adopts dual noise reduction of moving average and Hanning window, which is suitable for low SNR scenarios. By dynamically switching between API and Q-Rfie, i.e., API-Q-Rife algorithm, the estimation accuracy of different frequency offset intervals is taken into account.

[0051] Then, according to step S2, the fine carrier frequency offset estimates of multiple frames or consecutive frames are smoothed, and the smoothed frequency offset estimates are used to compensate for the frequency offset of the initial received signal to obtain the baseband I / Q signal.

[0052] This embodiment performs a moving average filter on the sequence of fine frequency offset estimates obtained within multiple consecutive frames (or multiple symbol periods) to generate a smoothed frequency offset estimate; it smooths the instantaneous estimation error and can track slowly changing frequency offsets, achieving a balance between response speed and smoothness.

[0053] The frequency offset estimate obtained above is then used to compensate for the frequency offset of the original received signal. After that, a second down-conversion is performed to obtain the baseband I / Q signal, which is the input of step S3.

[0054] Then, following step S3, the baseband I / Q signals are subjected to low-pass filtering, downsampling, and DC removal to obtain a zero-mean baseband signal.

[0055] For low-pass filtering, this embodiment selects a finite impulse response (FIR) low-pass filter or a cascaded integrator comb (CIC) filter. The FIR filter has linear phase characteristics, which can avoid signal waveform distortion; the CIC filter is suitable for high-rate decimation and has extremely high computational efficiency.

[0056] The cutoff frequency setting in this embodiment is as follows: Let the original sampling rate be... The target downsampling factor is M, which means the sampling rate after downsampling is... ; Filter cutoff frequency .

[0057] After filtering by the above filter, the downsampling factor, i.e. the decimation factor, is set to decimate the signal to reduce the data rate and match the processing rate of subsequent baseband processing modules (such as symbol synchronization and equalizer).

[0058] Receiver hardware (especially zero-IF or direct-conversion architectures) often introduces a fixed DC bias into the baseband signal due to local oscillator leakage or ADC non-ideals. This DC component severely affects the accuracy of the I / Q imbalance estimation algorithm (leading to systematic deviations in amplitude / phase estimation), and therefore must be removed to obtain a zero-mean baseband signal.

[0059] Finally, in this embodiment, according to step S4, the gain imbalance parameter and phase imbalance parameter are estimated, and blind compensation is performed on the zero-mean baseband signal based on the estimated parameters to output the compensated quadrature I / Q signal.

[0060] This embodiment calculates the I-branch power, Q-branch power, and cross-correlation value of I and Q based on the zero-mean baseband signal, and estimates the gain imbalance parameter and phase imbalance parameter.

[0061] The power of the I branch represents the average energy (or variance) of the signal on the in-phase branch; the calculation method of the power of the Q branch is completely symmetrical with that of the I branch, except that the input signal is replaced with data from the quadrature branch; the cross-correlation value C_IQ of I and Q is used to measure the linear correlation (or covariance) between the I and Q branch signals, reflecting whether there is coupling or non-orthogonality between them.

[0062] The formulas for calculating the power of branch I, the power of branch Q, and the cross-correlation value between I and Q are as follows:

[0063]

[0064]

[0065] in, Indicates the power of branch I. Indicates the power of branch Q. This represents the cross-correlation value between I and Q; , These represent the sampled values ​​of the nth I and Q branches, respectively; N represents the sequence length; n and k are the sampling point indices, with values ​​ranging from 0, 1, ..., N-1.

[0066] The formulas for calculating the gain imbalance parameter and the phase imbalance parameter are as follows:

[0067]

[0068] in, Indicates the gain imbalance parameter. This represents the phase imbalance parameter.

[0069] Next, the gain imbalance parameter and phase imbalance parameter are compared with the corresponding threshold standard. When either exceeds the standard, blind compensation is performed, and the compensated quadrature I / Q signal is output.

[0070] This embodiment first sets thresholds for gain imbalance and phase imbalance, and then checks whether a single parameter exceeds the limit. If a single parameter does not exceed the limit, it further determines the critical conditions of multiple parameters. Finally, it checks whether I / Q imbalance compensation is needed. If so, blind I / Q compensation is performed.

[0071] Regarding blind I / Q compensation, the specific details include: (1) Preprocessing: Eliminate DC component.

[0072] Mean subtraction is performed on the I and Q branch signals of the zero-mean baseband signal to eliminate DC offset introduced by circuit zero drift and environmental noise, avoid interference of DC component on subsequent power and cross-correlation statistical calculations, and provide a clean AC signal basis for imbalance parameter estimation.

[0073] (2) Extraction of imbalance features.

[0074] Based on the I and Q signals after DC removal, the average power of the I-channel, the average power of the Q-channel, and the cross-correlation value of the I / Q branches are calculated to quantify the degree of imbalance in the I / Q branches.

[0075] (3) Estimation of gain and phase imbalance parameters.

[0076] This embodiment uses the Q branch as a reference, keeping the Q branch signal unchanged to avoid introducing additional errors through bidirectional compensation. The gain compensation coefficient and phase compensation coefficient of the I branch are calculated separately. The square root of the I / Q branch power ratio is used to match the amplitudes of the I and Q branches, eliminating gain imbalance. The phase shift of the I branch is corrected using cross-correlation values, eliminating the quadrature error between the I and Q branches. This can be expressed by the following formula:

[0077]

[0078] in, Indicates the gain compensation coefficient. This represents the phase compensation coefficient.

[0079] Then, the gain compensation coefficient and the phase compensation coefficient are combined and applied to the I branch to complete the gain and phase synchronization calibration of the I branch. The Q branch keeps the original signal unchanged, and finally the compensated quadrature I / Q signal pair is obtained.

[0080] The final result of this embodiment is a high-quality baseband digital signal that has eliminated carrier frequency offset, DC component, and I / Q gain / phase imbalance, which can be directly used for subsequent Bluetooth protocol demodulation. Subsequent demodulation algorithms (such as frequency discriminators, matched filters, and decision circuits) will directly utilize this high-quality signal for bit recovery, thereby significantly reducing the bit error rate (BER) and improving the sensitivity and anti-interference capability of the Bluetooth receiver.

[0081] This embodiment also included simulation experiments. Based on a GFSK modulated signal (carrier frequency 2MHz, 48 times oversamp), a multipath fading channel and Doppler frequency offset scenario (frequency offset range ±90kHz) were constructed. Frequency offset was estimated using the API-Q-Rife hybrid frequency offset estimation algorithm of this invention, with reference to... Figure 3 As shown, frequency offset is illustrated. A comparison of the performance of the API-Q-Rife algorithm of this invention with that of the traditional FFT frequency offset estimation algorithm at 70kHz is shown in the figure. (Refer to...) Figure 4 As shown, frequency offset is illustrated. The graph compares the performance of the API-Q-Rife algorithm of this invention with that of the traditional FFT frequency offset estimation algorithm at 90kHz. The horizontal axis represents SNR, and the vertical axis represents BER, indicating the bit error rate. Figure 3 and Figure 4 The results show a comparison of the bit error rate performance of the two algorithms under different frequency offsets and signal-to-noise ratios.

[0082] Example 2 This invention discloses a carrier frequency offset and I / Q joint compensation system for a Bluetooth receiver, referring to... Figure 5 As shown, it includes the following modules: Acquisition and frequency offset estimation module: used to acquire the initial received signal of the Bluetooth receiver, perform time-domain preprocessing and fast Fourier transform to obtain the spectrum; calculate the normalized frequency offset based on the spectral line with the largest amplitude in the spectrum; and adaptively select the target interpolation algorithm according to the normalized frequency offset to obtain the fine carrier frequency offset estimate. Frequency offset compensation module: used to smooth the fine carrier frequency offset estimate and use the smoothed frequency offset estimate to compensate for the frequency offset of the initial received signal to obtain the baseband I / Q signal; DC removal module: used to perform low-pass filtering, downsampling and DC removal processing on the baseband I / Q signal to obtain a zero-mean baseband signal; I / Q compensation module: used to estimate the gain imbalance parameter and phase imbalance parameter based on the zero-mean baseband signal, and to perform blind compensation on the zero-mean baseband signal based on the estimated parameters, and output the compensated quadrature I / Q signal.

[0083] In this embodiment, the received signal is preprocessed in the time domain and then directly subjected to FFT. After determining the position of the maximum spectral line in the amplitude spectrum, API or Q-Rife interpolation is dynamically selected based on the normalized coarse frequency offset judgment result. The interpolation correction amount is obtained using the amplitude and phase information of adjacent spectral lines. The basic frequency offset and the interpolation correction amount are combined to obtain a fine frequency offset estimate. This embodiment achieves high-precision frequency offset estimation in low signal-to-noise ratio scenarios, improves frequency resolution, and requires no additional training sequences, balancing accuracy and low overhead.

[0084] The following steps are executed sequentially within the receiver: frequency offset estimation based on API-Q_Rife, moving average of the frequency offset estimation result, frequency offset compensation and second down-conversion, I / Q low-pass filtering, downsampling and DC removal, I / Q imbalance assessment, and gain / phase-based compensation decision. Frequency offset estimation and I / Q assessment are performed on the received signal, and compensation is completed within the receiver without feedback or pre-distortion to the transmitter, forming a dedicated joint compensation process for BLE / Low Earth Orbit satellite IoT receivers.

[0085] The frequency offset estimation results of multiple frames or consecutive frames are averaged to smooth the instantaneous error and track the slowly varying frequency offset; the frequency offset relative to the local reference is obtained and then used for local oscillator correction or equivalent frequency offset compensation, so as to ensure accuracy while taking into account the implementation complexity and real-time performance.

[0086] Example 3 The present invention further provides a computer device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; When the processor executes the program, it implements the carrier frequency offset and I / Q joint compensation method for the Bluetooth receiver in Example 1. For the sake of simplicity, it will not be described in detail here.

[0087] It should be understood that in this embodiment, the processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0088] Memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of memory may also include non-volatile random access memory. For example, memory may also store information about the device type.

[0089] In the implementation process, each step of the above method can be completed by the integrated logic circuits in the processor hardware or by software instructions.

[0090] Example 4 The present invention also provides a computer-readable storage medium storing computer program instructions, which, when executed by a processor, cause the processor to perform a carrier frequency offset and I / Q joint compensation method for a Bluetooth receiver as described in any of the embodiments in Example 1.

[0091] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0092] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for joint compensation of carrier frequency offset and I / Q for Bluetooth receivers, characterized in that, Includes the following steps: S1. Obtain the initial received signal from the Bluetooth receiver, perform time-domain preprocessing and fast Fourier transform to obtain the spectrum; calculate the normalized frequency offset based on the spectral line with the largest amplitude in the spectrum; adaptively select the target interpolation algorithm according to the normalized frequency offset to obtain the fine carrier frequency offset estimate. S2. The fine carrier frequency offset estimate is smoothed, and the smoothed frequency offset estimate is used to compensate for the frequency offset of the initial received signal to obtain the baseband I / Q signal. S3. Perform low-pass filtering, downsampling, and DC removal processing on the baseband I / Q signal to obtain a zero-mean baseband signal; S4. Estimate the gain imbalance parameter and phase imbalance parameter based on the zero-mean baseband signal, and perform blind compensation on the zero-mean baseband signal based on the estimated parameters to output the compensated quadrature I / Q signal.

2. The method as described in claim 1, characterized in that, In step S1, the time-domain preprocessing specifically includes: The initial received signal is subjected to moving average filtering to suppress random noise; A Hanning window is applied to the filtered signal to suppress spectral leakage, resulting in a preprocessed signal.

3. The method as described in claim 1, characterized in that, In step S1, based on the spectral line with the largest amplitude in the spectrum, the normalized frequency offset is calculated; according to the normalized frequency offset, an adaptive target interpolation algorithm is selected to obtain a fine carrier frequency offset estimate; specifically including: Locate the spectral line with the largest amplitude in the spectrum, and based on the amplitude distribution of the spectral line with the largest amplitude and its adjacent spectral lines, generate a rough estimate representing the frequency offset state as a normalized frequency offset; The normalized frequency offset is compared with a preset threshold. If the normalized frequency offset is less than the preset threshold, then the amplitude-phase joint interpolation algorithm is used to calculate the interpolation correction term using the real part of the spectral line with the largest amplitude and its adjacent spectral lines. If the normalized frequency offset is greater than or equal to the preset threshold, the phase-corrected Rife interpolation algorithm is used to determine the interpolation direction by using the phase ratio of the spectral line with the largest amplitude to its adjacent spectral lines, and to calculate the interpolation correction term based on the amplitude ratio of the spectral line with the largest amplitude to the second largest spectral line. The basic frequency offset of the spectrum is added to the relevant values ​​of the interpolation correction term to obtain the fine carrier frequency offset estimate.

4. The method as described in claim 1, characterized in that, Step S4 specifically includes: S41. Based on the zero-mean baseband signal, calculate the I branch power, Q branch power, and the cross-correlation value between I and Q, and estimate the gain imbalance parameter and phase imbalance parameter. S42. Compare the gain imbalance parameter and phase imbalance parameter with the corresponding threshold standard. If either exceeds the standard, perform blind compensation and output the compensated quadrature I / Q signal.

5. The method as described in claim 4, characterized in that, In step S41, the calculation formulas for the gain imbalance parameter and the phase imbalance parameter are as follows: in, Indicates the gain imbalance parameter. Indicates the phase imbalance parameter. Indicates the power of branch I. Indicates the power of branch Q. This represents the cross-correlation value between I and Q.

6. The method as described in claim 4, characterized in that, In step S42, the blind compensation specifically includes: Keep the Q-branch signal of the zero-mean baseband signal unchanged; Using the aforementioned gain imbalance parameter and phase imbalance parameter, a gain compensation coefficient and a phase compensation coefficient are constructed. The gain compensation coefficient and phase compensation coefficient are applied together to the I-branch signal to complete the gain and phase synchronization calibration of the I-branch.

7. The method as described in claims 5 and 6, characterized in that, The formulas for calculating the gain compensation coefficient and the phase compensation coefficient are as follows: in, Indicates the gain compensation coefficient. This represents the phase compensation coefficient.

8. A carrier frequency offset and I / Q joint compensation system for a Bluetooth receiver, comprising the carrier frequency offset and I / Q joint compensation method for a Bluetooth receiver as described in any one of claims 1-7, characterized in that, Includes the following modules: Acquisition and frequency offset estimation module: used to acquire the initial received signal of the Bluetooth receiver, perform time-domain preprocessing and fast Fourier transform to obtain the spectrum; calculate the normalized frequency offset based on the spectral line with the largest amplitude in the spectrum; and adaptively select the target interpolation algorithm according to the normalized frequency offset to obtain the fine carrier frequency offset estimate. Frequency offset compensation module: used to smooth the fine carrier frequency offset estimate and use the smoothed frequency offset estimate to compensate for the frequency offset of the initial received signal to obtain the baseband I / Q signal; DC removal module: used to perform low-pass filtering, downsampling and DC removal processing on the baseband I / Q signal to obtain a zero-mean baseband signal; I / Q compensation module: used to estimate the gain imbalance parameter and phase imbalance parameter based on the zero-mean baseband signal, and to perform blind compensation on the zero-mean baseband signal based on the estimated parameters, and output the compensated quadrature I / Q signal.

9. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the carrier frequency offset and I / Q joint compensation method for a Bluetooth receiver as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the carrier frequency offset and I / Q joint compensation method for a Bluetooth receiver as described in any one of claims 1 to 7.

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