WIFI7 symbol clock error compensation method

Abstract

The invention discloses a WIFI7 symbol clock error compensation method, which belongs to the technical field of measurement, and comprises the following steps: generating an ideal EHT-LTF signal, and carrying out least square (LS) channel estimation on the ideal EHT-LTF signal and an actually received EHT-LTF signal to obtain an initial channel estimation value; generating an ideal pilot signal on each symbol of the data segment, and performing LS channel estimation on the ideal pilot signal and an actually received pilot signal; performing conjugate multiplication on the EHT-LTF channel estimation value and the pilot frequency channel estimation value to obtain a pilot frequency error; respectively calculating the phase and the amplitude of the pilot frequency error, and estimating a phase calibration value by using the least square; and finally, compensating the calibration value into the original data segment signal. According to the method, the EHT-LTF channel estimation value is used as the reference, the influence caused by the clock error is quantized through the deviation between the subsequent symbol and the reference symbol, the calculation complexity is low, and the vector amplitude error (EVM) index of the system can be effectively reduced.

Description

Technical Field

[0001] The invention belongs to the field of measurement technology, and in particular relates to a symbol clock error compensation method for WIFI7. Background Art

[0002] As WIFI technology matures, the demand for communication network test instruments continues to expand, which also means that the demand for WIFI signal processing technology continues to expand. Channel estimation is an important part of WIFI signal processing.

[0003] In WIFI 7 technology, since it adopts OFDM (Orthogonal Frequency Division Multiplexing) technology, ideally, the sampling rates of the transmitter and the receiver are consistent, and the receiver can correctly restore the original transmitted signal after synchronous demodulation. However, due to the error of the sampling clock crystal oscillator, there must be a certain deviation between the sampling clocks of the transmitter and the receiver. This deviation will cause serious phase distortion of the OFDM signal on each subcarrier, which seriously affects the reliability of system data transmission. For WIFI 7, due to the longer symbol length of its data part, its sampling clock deviation will accumulate more, and this effect will be more obvious. Therefore, in order to improve the demodulation performance of the receiver, it is a vital task to compensate for the sampling clock deviation of the WIFI signal during the demodulation process.

[0004] Currently, the symbol clock error can be estimated through the CP (Cyclic Prefix) sliding window. CP is a copy of a part of the data in the OFDM symbol, which means that the CP and the corresponding data part are the same, and this similarity can be used to estimate the symbol clock error. The symbol clock error can also be estimated through training symbols. In the estimation process, the autocorrelation characteristics of the same OFDM training symbols can be used to obtain similarity and thus estimate the symbol clock error.

[0005] These measurement methods have low calculation accuracy and are easily affected by the channel environment. Summary of the invention

[0006] In view of the above-mentioned technical problems existing in the prior art, the present invention proposes a symbol clock error compensation method for WIFI7, which has a reasonable design, overcomes the shortcomings of the prior art, and has good effects.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for compensating a symbol clock error of WIFI7 comprises the following steps:

[0009] Step 1: Generate an ideal EHT-LTF signal, perform LS channel estimation on the ideal EHT-LTF signal and the actual received EHT-LTF signal to obtain an initial channel estimation value;

[0010] Step 2: Generate a pilot signal on each symbol of the ideal data segment, perform LS channel estimation on the ideal pilot signal and the actual received pilot signal to obtain a pilot channel estimation value;

[0011] Step 3: Conjugate multiply the EHT-LTF channel estimation value and the pilot channel estimation value to obtain the pilot error;

[0012] Step 4: Calculate the phase and amplitude of the pilot error respectively, and estimate the phase calibration value using least squares;

[0013] Step 5: Compensate the calibration value to the original data segment signal.

[0014] Preferably, step 1 specifically includes the following steps:

[0015] Step S11: acquiring an ideal EHT-LTF sequence according to the provisions of the protocol 802.11be;

[0016] Step S12: According to the WIFI7 frame structure, the actual EHT-LTF symbol position is obtained, and time-frequency conversion is performed to obtain the actual EHT-LTF sequence;

[0017] Step S13: Divide the actual EHT-LTF sequence by the ideal EHT-LTF sequence to obtain an EHT-LTF channel estimation value, as shown in formula (1):

[0018]

[0019] Among them C EHTLTF represents the ideal EHT-LTF sequence, C′ EHTLTF represents the actual EHT-LTF sequence, H EHT-LTF Indicates the EHT-LTF channel estimation value.

[0020] Preferably, step 2 specifically includes the following steps:

[0021] Step S21: acquiring an ideal pilot sequence according to the provisions of protocol 802.11be;

[0022] Step S22: According to the WIFI7 frame structure, the time domain position of the data segment is obtained, time-frequency conversion is performed, and the actual pilot sequence is obtained through the frequency domain position;

[0023] Step S23: The actual pilot sequence is divided by the ideal pilot sequence to obtain a pilot channel estimation value, as shown in formula (2):

[0024]

[0025] Among them C pilot represents the ideal pilot sequence, C′ pilot represents the actual EHT-LTF sequence, H pilot Represents the pilot channel estimation value.

[0026] Preferably, in step 3, the EHT-LTF channel estimation value and the pilot channel estimation value are conjugate multiplied to obtain the pilot error, as shown in formula (3):

[0027] ΔH=H EHT-LTF ×conj(H pilot ) (3)

[0028] Where ΔH represents the pilot error.

[0029] Preferably, step 4 specifically includes the following steps:

[0030] Step S41: Calculate the amplitude and phase of the pilot error, as shown in formula (4):

[0031]

[0032] Where Pha represents the phase of the pilot error, and Mag represents the phase of the pilot error;

[0033] Step S42: Substitute the amplitude and phase of the pilot error into the least squares estimation formula, as shown in formula (5):

[0034] X=lscov(A,Mag,Pha) (5)

[0035] Wherein, A represents the actual position of the pilot in the frequency domain, and X represents the generalized least squares solution that minimizes r′×inv(Pha)×r, where r=Mag-A×X.

[0036] Beneficial technical effects brought by the present invention:

[0037] The method of the present invention estimates the symbol clock error by calculating the channel estimation error between different symbols and reference symbols on the basis of channel estimation, has low calculation complexity, and improves the EVM index of demodulation without affecting the demodulation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0040] like Figure 1 As shown, a WIFI7 symbol clock error compensation method includes the following steps:

[0041] Step 1: Generate an ideal EHT-LTF signal, perform LS channel estimation on the ideal EHT-LTF signal and the actual received EHT-LTF signal, and obtain an initial channel estimation value; specifically, the steps include:

[0042] Step S11: acquiring an ideal EHT-LTF sequence according to the provisions of the protocol 802.11be;

[0043] Step S12: According to the WIFI7 frame structure, the actual EHT-LTF symbol position is obtained, and time-frequency conversion is performed to obtain the actual EHT-LTF sequence;

[0044] Step S13: Divide the actual EHT-LTF sequence by the ideal EHT-LTF sequence to obtain an EHT-LTF channel estimation value, as shown in formula (1):

[0045]

[0046] Among them C EHTLTF represents the ideal EHT-LTF sequence, C′ EHTLTF represents the actual EHT-LTF sequence, H EHT-LTF Indicates the EHT-LTF channel estimation value.

[0047] Step 2: Generate a pilot signal on each symbol of the ideal data segment, perform LS channel estimation on the ideal pilot signal and the actual received pilot signal, and obtain a pilot channel estimation value; specifically, the following steps are included:

[0048] Step S21: acquiring an ideal pilot sequence according to the provisions of protocol 802.11be;

[0049] Step S22: According to the WIFI7 frame structure, the time domain position of the data segment is obtained, time-frequency conversion is performed, and the actual pilot sequence is obtained through the frequency domain position;

[0050] Step S23: The actual pilot sequence is divided by the ideal pilot sequence to obtain a pilot channel estimation value, as shown in formula (2):

[0051]

[0052] Among them C pilot represents the ideal pilot sequence, C′ pilot represents the actual EHT-LTF sequence, H pilot Represents the pilot channel estimation value.

[0053] Step 3: conjugate multiply the EHT-LTF channel estimation value and the pilot channel estimation value to obtain the pilot error; specifically, the steps include:

[0054] Step S31: conjugate multiply the EHT-LTF channel estimation value and the pilot channel estimation value to obtain the pilot error, as shown in formula (3):

[0055] ΔH=H EHT-LTF ×conj(H pilot ) (3)

[0056] Where ΔH represents the pilot error.

[0057] Step 4: Calculate the phase and amplitude of the pilot error respectively, and estimate the phase calibration value using least squares; specifically, the following steps are included:

[0058] Step S41: Calculate the amplitude and phase of the pilot error, as shown in formula (4):

[0059]

[0060] Where Pha represents the phase of the pilot error, and Mag represents the phase of the pilot error;

[0061] Step S42: Substitute the amplitude and phase of the pilot error into the least squares estimation formula, as shown in formula (5):

[0062] X=lscov(A,Mag,Pha) (5)

[0063] Wherein, A represents the actual position of the pilot in the frequency domain, and X represents the generalized least squares solution that minimizes r′×inv(Pha)×r, where r=Mag-A×X.

[0064] Step 5: Compensate the calibration value to the original data segment signal.

[0065] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A symbol clock error compensation method for WIFI7, characterized in that: The steps include: Step 1: Generate an ideal EHT-LTF signal, perform LS channel estimation on the ideal EHT-LTF signal and the actual received EHT-LTF signal to obtain an initial channel estimation value; Step 2: Generate a pilot signal on each symbol of the ideal data segment, perform LS channel estimation on the ideal pilot signal and the actual received pilot signal to obtain a pilot channel estimation value; Step 3: Conjugate multiply the EHT-LTF channel estimation value and the pilot channel estimation value to obtain the pilot error; Step 4: Calculate the phase and amplitude of the pilot error respectively, and estimate the phase calibration value using least squares; Step 5: Compensate the calibration value to the original data segment signal.

2. The symbol clock error compensation method of WIFI7 according to claim 1, characterized in that: Step 1 specifically includes the following steps: Step S11: acquiring an ideal EHT-LTF sequence according to the provisions of the protocol 802.11be; Step S12: According to the WIFI7 frame structure, the actual EHT-LTF symbol position is obtained, and time-frequency conversion is performed to obtain the actual EHT-LTF sequence; Step S13: Divide the actual EHT-LTF sequence by the ideal EHT-LTF sequence to obtain an EHT-LTF channel estimation value, as shown in formula (1): Among them C EHTLTF represents the ideal EHT-LTF sequence, C′ EHTLTF represents the actual EHT-LTF sequence, H EHT-LTF Indicates the EHT-LTF channel estimation value.

3. The symbol clock error compensation method of WIFI7 according to claim 1, characterized in that: Step 2 specifically includes the following steps: Step S21: acquiring an ideal pilot sequence according to the provisions of protocol 802.11be; Step S22: According to the WIFI7 frame structure, the time domain position of the data segment is obtained, time-frequency conversion is performed, and the actual pilot sequence is obtained through the frequency domain position; Step S23: The actual pilot sequence is divided by the ideal pilot sequence to obtain a pilot channel estimation value, as shown in formula (2): Among them C pilot represents the ideal pilot sequence, C′ pilot represents the actual EHT-LTF sequence, H pilot Represents the pilot channel estimation value.

4. The symbol clock error compensation method of WIFI7 according to claim 1, characterized in that: In step 3, the EHT-LTF channel estimation value is conjugate-multiplied with the pilot channel estimation value to obtain the pilot error, as shown in formula (3): ΔH=H EHT-LTF ×conj(H pilot ) (3) Where ΔH represents the pilot error.

5. The symbol clock error compensation method of WIFI7 according to claim 1, characterized in that: Step 4 specifically includes the following steps: Step S41: Calculate the amplitude and phase of the pilot error, as shown in formula (4): Where Pha represents the phase of the pilot error, and Mag represents the phase of the pilot error; Step S42: Substitute the amplitude and phase of the pilot error into the least squares estimation formula, as shown in formula (5): X=lscov(A,Mag,Pha) (5) Wherein, A represents the actual position of the pilot in the frequency domain, and X represents the generalized least squares solution that minimizes r′×inv(Pha)×r, where r=Mag-A×X.

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