CN107454027B - Frequency offset estimation method and device - Google Patents
Frequency offset estimation method and device Download PDFInfo
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- CN107454027B CN107454027B CN201610378428.9A CN201610378428A CN107454027B CN 107454027 B CN107454027 B CN 107454027B CN 201610378428 A CN201610378428 A CN 201610378428A CN 107454027 B CN107454027 B CN 107454027B
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- H—ELECTRICITY
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- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
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- H—ELECTRICITY
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- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
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- H04L27/2669—Details of algorithms characterised by the domain of operation
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- H—ELECTRICITY
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- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0024—Carrier regulation at the receiver end
- H04L2027/0026—Correction of carrier offset
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Abstract
A method and a device for estimating frequency offset are provided, the method comprises: acquiring a received baseband signal; performing frequency offset compensation on the baseband signal according to the frequency offset compensation value; wherein: the frequency offset compensation value is related to the last open-loop frequency offset estimation value and a frequency offset reference value, and the frequency offset reference value is related to the inherent frequency offset of the user equipment and the base station; performing Fourier transform and channel estimation on the signal after the frequency offset compensation; calculating the current open-loop frequency offset estimation value and the reference signal receiving quality parameter according to the signal after the channel estimation; determining to obtain a reported frequency offset reference value according to the reference signal receiving quality parameter; and calculating a corresponding frequency offset compensation value, and taking the calculated frequency offset compensation value as a next frequency offset compensation value. By adopting the scheme, the accuracy of frequency offset estimation and the calculation accuracy of the reference signal receiving quality parameter can be improved.
Description
Technical Field
The present invention relates to the field of communications, and in particular, to a method and an apparatus for frequency offset estimation.
Background
When a User Equipment (UE) is in a high-speed moving environment (such as a high-speed rail environment), a downlink channel of the UE exhibits a high doppler characteristic, and due to the superposition of the inherent frequency offset of the UE and a base station (eNodeB) and the high doppler, a downlink received Signal of the UE will have a large frequency offset, which may affect the estimation of Reference Signal Receiving Power (RSRP)/Reference Signal Receiving Quality (RSRQ) and the frequency offset/time offset tracking of neighboring cells.
Currently, the Frequency offset estimation is performed using Resource Elements (REs) of Cell specific reference symbols (CRS) in Orthogonal Frequency Division Multiplexing (OFDM) symbols.
However, if the above method is used for frequency offset estimation, the estimation range is limited, the accuracy of frequency offset estimation is low, and RSRP/RSRP calculation is inaccurate.
Disclosure of Invention
The problem to be solved by the invention is how to improve the accuracy of frequency offset estimation and the calculation accuracy of RSRP/RSRP.
In order to solve the above problem, an embodiment of the present invention provides a method for estimating a frequency offset, where the method includes: acquiring a received baseband signal; performing frequency offset compensation on the baseband signal according to the frequency offset compensation value; wherein: the frequency offset compensation value is related to the last open-loop frequency offset estimation value and a frequency offset reference value, and the frequency offset reference value is related to the inherent frequency offset of the user equipment and the base station; the inherent frequency offset is: the corresponding frequency deviation is carried out when the relative motion speed between the user equipment and the base station is not greater than a preset speed threshold; performing Fourier transform and channel estimation on the signal after the frequency offset compensation; calculating the current open-loop frequency offset estimation value and the reference signal receiving quality parameter according to the signal after the channel estimation; selecting and obtaining a reported frequency offset reference value according to the reference signal receiving quality parameter; and calculating a corresponding frequency offset compensation value according to the open-loop frequency offset estimation value and the frequency offset reference value, and taking the frequency offset compensation value obtained by calculation as a next frequency offset compensation value.
Optionally, the frequency offset reference value belongs to a preset frequency offset reference value set.
Optionally, the selecting the reported frequency offset reference value according to the reference signal reception quality parameter includes: and selecting the frequency offset reference value when the corresponding reference signal receiving quality parameter is maximum from the frequency offset reference value set as the reported frequency offset reference value.
Optionally, the calculating the current open-loop frequency offset estimation value according to the signal after channel estimation includes:
wherein:
for the estimated value of the frequency offset of the open loop at this time, delta f is the interval of subcarriers, delta L is the interval of adjacent symbols, L is the number of specific reference symbols of a cell, NvrsIs the number of resource elements containing cell-specific reference symbols, NFFTFor the number of points of the fourier transform, Rx is the number of receiving antennas, the function angle (y) is expressed as an angle taking the complex value y, and P represents the signal estimation result value on the reference symbol.
Optionally, before the calculating the corresponding frequency offset compensation value, the method further includes: filtering the open-loop frequency offset estimation value of this time to obtain a frequency offset value after the filtering of this time; and executing the operation of calculating the corresponding frequency offset compensation value according to the frequency offset value after the filtering and the frequency offset reference value.
Optionally, the following formula is used to filter the current open-loop frequency offset estimation value, so as to obtain a current filtered frequency offset value:
wherein:
for the open-loop frequency offset estimation value of this time,
filter (y) represents filtering y for the frequency offset value after the previous filtering,
the frequency offset value after the filtering is obtained.
Optionally, the reference signal received quality parameter is a reference signal received quality or a reference signal received power.
The embodiment of the invention provides a frequency offset estimation device, which comprises: an acquisition unit adapted to acquire a received baseband signal; the frequency offset compensation unit is suitable for performing frequency offset compensation on the baseband signal according to a frequency offset compensation value; wherein: the frequency offset compensation value is related to the last open-loop frequency offset estimation value and a frequency offset reference value, and the frequency offset reference value is related to the inherent frequency offset of the user equipment and the base station; the inherent frequency offset is: the corresponding frequency deviation is carried out when the relative motion speed between the user equipment and the base station is not greater than a preset speed threshold; a Fourier transform unit adapted to perform Fourier transform on the frequency offset compensated signal; the channel estimation unit is suitable for carrying out channel estimation on the signal after the frequency offset compensation; the first calculating unit is suitable for calculating the current open-loop frequency offset estimation value according to the signal after the channel estimation; the second calculation unit is suitable for calculating a reference signal receiving quality parameter according to the signal after the channel estimation; the selection unit is suitable for selecting and obtaining a reported frequency offset reference value according to the reference signal receiving quality parameter; and the third calculating unit is suitable for calculating a corresponding frequency offset compensation value according to the frequency offset reference value and the estimated value of the open-loop frequency offset at this time, and taking the frequency offset compensation value obtained by calculation as a next frequency offset compensation value.
Optionally, the frequency offset reference value belongs to a preset frequency offset reference value set.
Optionally, the selecting unit is adapted to select, from the frequency offset reference value set, a frequency offset reference value when the corresponding reference signal received quality parameter is maximum, as the reported frequency offset reference value.
Optionally, the first calculating unit is adapted to calculate the current estimated value of the open-loop frequency offset by using the following formula:
wherein:for the estimated value of the frequency offset of the open loop at this time, delta f is the interval of subcarriers, delta L is the interval of adjacent symbols, L is the number of specific reference symbols of a cell, NvrsIs the number of resource elements containing cell-specific reference symbols, NFFTIs Fourier transformRx is the number of receiving antennas, the function angle (y) is represented as an angle taking the complex value y, and P represents the signal estimation result value on the reference symbol.
Optionally, the apparatus further comprises: the filtering unit is suitable for filtering the current open-loop frequency offset estimation value before the corresponding frequency offset compensation value is calculated to obtain the current filtered frequency offset value;
and the third calculating unit is adapted to perform the operation of calculating the corresponding frequency offset compensation value according to the frequency offset value after the current filtering and the frequency offset reference value.
Optionally, the filtering unit is adapted to filter the current open-loop frequency offset estimation value by using the following formula, so as to obtain a current filtered frequency offset value:wherein:
for the open-loop frequency offset estimation value of this time,
filter (y) represents filtering y for the frequency offset value after the previous filtering,
the frequency offset value after the filtering is obtained.
Optionally, the reference signal received quality parameter is a reference signal received quality or a reference signal received power.
Compared with the prior art, the technical scheme of the invention has the following advantages:
firstly, according to the frequency offset compensation value, carrying out frequency offset compensation on the signal, then carrying out Fourier transform and channel estimation on the signal after frequency offset compensation, further calculating a reference signal receiving quality parameter according to the signal after channel estimation, then selecting and obtaining the reported frequency offset reference value according to the reference signal receiving quality parameter, and calculating a corresponding frequency offset compensation value, and then taking the calculated frequency offset compensation value as the next frequency offset compensation value, because the actual frequency offset is the sum of the inherent frequency offset and the frequency offset caused by the relative speed of operation when the user equipment is in a high-speed operation environment, and the frequency offset compensation value is related to the previous open-loop frequency offset estimation value and the frequency offset reference value related to the inherent frequency offset between the base station and the user equipment, the frequency offset compensation value and the actual frequency offset value can be the same in magnitude, the estimation range is increased, so that the frequency offset compensation value can be close to the true frequency offset value, the accuracy of frequency offset estimation can be improved, and the calculation accuracy of the reference signal receiving quality parameter can be improved.
Further, the frequency offset value after the filtering is obtained by filtering the frequency offset estimation value of the open loop this time, and then the operation of calculating the corresponding frequency offset compensation value is executed according to the frequency offset value after the filtering and the frequency offset reference value of the frequency this time, so that the frequency offset estimation value of the open loop can be smoothed, and the stability of the frequency offset estimation can be improved.
Drawings
FIG. 1 is a flow chart illustrating a method of frequency offset estimation according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a frequency offset estimation in an embodiment of the present invention;
fig. 3 is a schematic structural diagram of an apparatus for frequency offset estimation in an embodiment of the present invention.
Detailed Description
When a User Equipment (UE) is in a high-speed moving environment (such as a high-speed rail environment), a downlink channel of the UE exhibits a high doppler characteristic, and due to the superposition of the inherent frequency offset of the UE and a base station (eNodeB) and the high doppler, a downlink received Signal of the UE will have a large frequency offset, which may affect the estimation of Reference Signal Receiving Power (RSRP)/Reference Signal Receiving Quality (RSRQ) and the frequency offset/time offset tracking of neighboring cells.
Currently, the Frequency offset estimation is performed using Resource Elements (REs) of Cell specific reference symbols (CRS) in Orthogonal Frequency Division Multiplexing (OFDM) symbols.
However, if the above method is used for frequency offset estimation, the estimation range is limited, the accuracy of frequency offset estimation is low, and the RSRP/RSRP calculation is inaccurate.
To solve the above problems, embodiments of the present invention perform frequency offset compensation on the signal according to a frequency offset compensation value, then, Fourier transform and channel estimation are carried out on the signal after the frequency offset compensation, and then, the receiving quality parameter of the reference signal is calculated according to the signal after the channel estimation, because the actual frequency offset is the sum of the inherent frequency offset and the frequency offset caused by the relative speed of operation when the user equipment is in a high-speed operation environment, the frequency offset compensation value is related to the previous open-loop frequency offset estimation value and a frequency offset reference value related to the inherent frequency offset between the base station and the user equipment, so that the frequency offset compensation value is the same as the actual frequency offset value in terms of magnitude order, the estimation range is improved, the frequency offset compensation value is close to the true frequency offset value, therefore, the accuracy of frequency offset estimation can be improved, and the calculation accuracy of the reference signal receiving quality parameter can be improved.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
A method for frequency offset estimation in an embodiment of the present invention is shown below, and as shown in fig. 1, the method is described in detail in the following steps, and the method may include the following steps:
step S11: a received baseband signal is acquired.
In a specific implementation, a baseband signal on a time domain of a downlink channel may be downsampled, the baseband signal is filtered and signal-normalized to extract a complete OFDM symbol, and a sampling rate used in the downsampling is selected according to the number of resource blocks required for measurement.
Step S12: performing frequency offset compensation on the baseband signal according to the frequency offset compensation value; wherein: the frequency offset compensation value is related to the last open-loop frequency offset estimation value and a frequency offset reference value, and the frequency offset reference value is related to the inherent frequency offset of the user equipment and the base station.
In a specific implementation, the known frequency offset of the baseband signal may be cancelled, that is, the frequency offset compensation is performed on the baseband signal according to the frequency offset compensation value. Specifically, the following formula (1) may be adopted to perform frequency offset compensation on the baseband signal in the time domain:
wherein: wherein r isiIs the time domain received signal before frequency offset compensation, riFor the frequency offset compensated signal, theta is the initial phase of the symbol, related to the symbol interval, i is the index of the sample point in the symbol,
and R is a time domain sampling rate.
It should be noted that the frequency offset compensation value is related to the last estimated value of the open-loop frequency offset and the frequency offset reference value, and the frequency offset reference value is related to the inherent frequency offset of the user equipment and the base station. It is understood that the inherent frequency offset is: in other words, the inherent frequency offset is the inherent frequency offset which exists when the relative motion speed between the user equipment and the base station is not larger than the preset speed threshold value, because the RF crystal oscillator frequencies of the UE and the base station are different and the like.
In a specific implementation, the frequency offset reference value may belong to a preset frequency offset reference value set, that is, all frequency offset reference values belonging to the frequency offset reference value set may be used for calculating frequency offset compensation. And, the frequency offset reference value set may be selected according to the inherent frequency offset range of the base station and the user equipment. For example, if the inherent frequency offset between the base station and the ue is 1000Hz, 800Hz, 500Hz, -800Hz, and-500 Hz may be selected to form the frequency offset reference value set.
Step S13: and carrying out Fourier transform and channel estimation on the signal after the frequency offset compensation.
In order to transform the received signal from the time domain to the frequency domain, in an implementation, the frequency offset compensated signal may be fourier transformed.
Because the CRS frequency domain positions of adjacent processing symbols are dislocated, in a specific implementation, the channel estimation may be performed on the frequency offset compensated signal, and a frequency domain channel response corresponding to a null subcarrier is interpolated according to the CRS positions in the channel estimation.
Step S14: and calculating the current open-loop frequency offset estimation value and the reference signal receiving quality parameter according to the signal after the channel estimation.
In a specific implementation, the current open-loop frequency offset estimation value may be calculated according to the channel-estimated signal by using adjacent CRS symbols according to the following formula (2):
wherein:
for the estimated value of the frequency offset of the open loop at this time, delta f is the interval of subcarriers, delta L is the interval of adjacent symbols, L is the number of specific reference symbols of a cell, NvrsIs the number of resource elements containing cell-specific reference symbols, NFFTFor the number of points of the fourier transform, Rx is the number of receiving antennas, the function angle (y) represents the angle of the complex value of y, and P represents the signal estimation result value on the reference symbol. And different deltal for different symbol intervals. Maximum Ratio Combining (MRC) may be used for different receiving antennas, and specifically, a Signal to interference plus Noise Ratio (SINR) of each receiving antenna may be estimated, and a Combining coefficient of MRC may be determined by SINR.
In a specific implementation, the Reference Signal received Quality parameter may be in various forms, such as Reference Signal Receiving Quality (RSRQ) or Reference Signal Receiving Power (RSRP). The form of the reference signal reception quality parameter does not set any limit to the scope of the present invention, as long as the parameter can reflect the reception quality of the reference signal.
Step S15: and selecting the reported frequency offset reference value according to the reference signal receiving quality parameter.
In a specific implementation, as described above, the frequency offset reference value belongs to a preset frequency offset reference value set, that is, there are multiple frequency offset reference values, so that each frequency offset reference value in the frequency offset reference value set can be calculated according to the processes of the above steps S11 to S14 to obtain a corresponding reference signal reception quality parameter. And determining to obtain a reported frequency offset reference value according to the reference signal reception quality parameter, namely selecting the frequency offset reference value corresponding to the maximum reference signal reception quality parameter from the frequency offset reference value set as the reported frequency offset reference value. In other words, the maximum reference signal received quality parameter and the determined frequency offset reference value can be reported.
Therefore, the selected frequency offset reference value is a value which can maximize the reference signal receiving quality parameter, that is, the compensated channel quality is the best, that is, the frequency offset compensation value obtained according to the frequency offset reference value is closest to the real channel frequency offset value, so that the accuracy of frequency offset estimation can be improved, and the accuracy of the reference signal receiving quality parameter can be improved.
Step S16: and calculating a corresponding frequency offset compensation value according to the frequency offset estimation value of the open loop and the frequency offset reference value of this time, and taking the frequency offset compensation value obtained by calculation as a next frequency offset compensation value.
In order to improve the stability of frequency offset estimation, in a specific implementation, before the corresponding frequency offset compensation value is calculated, the current open-loop frequency offset estimation value may be filtered to obtain a current filtered frequency offset value, and then the operation of calculating the corresponding frequency offset compensation value is performed according to the current filtered frequency offset value and the frequency offset reference value.
In a specific implementation, the following formula is adopted to filter the current open-loop frequency offset estimation value to obtain a current filtered frequency offset value:
wherein:
for the open-loop frequency offset estimation value of this time,
for the frequency offset value after the previous filtering, filter () represents filtering the parameter in parentheses,
the frequency offset value after the filtering is obtained.
In an embodiment of the present invention, the corresponding frequency offset compensation value is a sum of the current open-loop frequency offset estimation value and the reported frequency offset reference value.
To enable those skilled in the art to better understand and implement the present invention, the following provides another principle diagram of frequency offset estimation in the embodiment of the present invention, which may involve the following components as shown in fig. 2: buffer 21, numerically controlled oscillator 22, FFT unit 23, channel estimation unit 24, channel quality calculation unit 25, and compensation value calculation unit 26, where:
it should be noted that, when the user equipment is in a high-speed operating environment such as on a high-speed rail, a frequency offset reference value set may be selected according to the inherent frequency offset ranges of the base station and the user equipment, and then a certain cell to be measured is correspondingly set to a plurality of candidate cells (the candidate cells are respectively in one-to-one correspondence with the frequency offset reference values), then the measurement and frequency offset estimation of the reference signal reception quality parameters are independently performed on the plurality of candidate cells, and then the measurement value of the candidate cell is selected as the measurement value of the cell to be measured and reported by using the selection rule in the following formula (4), that is, the maximum measurement value calculated by using the frequency offset reference value in the frequency offset reference value set is reported, and the time offset frequency offset estimation value of the candidate cell is used as the frequency offset estimation value of the cell to be measured.
In one embodiment of the present invention, equation (4) may be as follows:
wherein: fprioiAs a set of frequency offset references, fprioiIs a frequency offset reference value.
The buffer 21 is adapted to down-sample the DL time domain signal to extract a complete OFDM symbol.
In a specific implementation, the Time domain signal data after analog-to-digital conversion may be received, then the signal may be downsampled, and then the signal may be buffered in a buffer (Time BUF), and a complete OFDM symbol may be read out, where the downsampling rate is determined according to the number of RBs required for measurement.
The numerically controlled oscillator 22 is adapted to perform frequency offset compensation.
In a specific implementation, the formula (1) may be used to perform frequency offset compensation of time domain on the signal, and the frequency offset compensation value
Consists of two parts: the frequency offset reference value of the candidate cell and the smooth value of the previous open-loop frequency offset estimation value of the candidate cell, and the symbol interval is considered in the initial phase calculation of the frequency offset compensation.
The FFT unit 23 is adapted to perform a fourier transform on the signal.
In a specific implementation, the time domain symbol after frequency offset compensation can be transformed into the frequency domain through fourier transform.
The channel estimation unit 24 is adapted to perform channel estimation.
In a specific implementation, the channel estimation unit 24 may perform channel estimation and extract channel estimation values corresponding to CRS REs. Due to the fact that the CRS frequency domain positions of adjacent processing symbols are staggered, when the channel estimation is carried out, frequency domain channel responses corresponding to the blank subcarriers can be interpolated according to the CRS positions.
The channel quality calculation unit 25 is adapted to calculate channel quality parameters.
In a specific implementation, the channel quality parameter may be calculated according to the signal after channel estimation, such as calculating to obtain RSRP, or obtaining RSR.
The compensation value calculating unit 26 is adapted to calculate the next frequency offset compensation value.
In a specific implementation, adjacent CRS symbols may be used, and the open-loop frequency offset estimate may be calculated according to equation (2), with different Δ L calculations for different symbol intervals.
In order to improve the stability of the frequency offset estimation, in a specific implementation, smoothing filtering may be performed on the open-loop frequency offset estimation value.
In one embodiment of the present invention, alpha filtering may be employed. Specifically, alpha filtering may be performed on the linear average of the multiple estimated values, and the filter coefficient determines the loop convergence rate. The filtering can be implemented by using formula (3), and details are not repeated herein.
Since the current estimated value of the open-loop frequency offset and the true frequency offset in the channel satisfy the relationship shown in the following formula (5), that is, the loop converges after multiple iterations in the static channel, and the current filtered frequency offset value approaches to the difference between the true frequency offset of the channel and the frequency offset reference value, in specific implementation, the smoothed estimated value of the open-loop frequency offset may be combined with the frequency offset reference value, that is, the sum of the filtered frequency offset value and the frequency offset reference value, to be fed back to the numerically controlled oscillator 22 for the next iteration, that is, the sum of the filtered frequency offset value and the frequency offset reference value is used as the known frequency offset for the next measurement.
In a specific implementation, the formula (5) may be:
wherein f is the true frequency offset.
In summary, by performing frequency offset compensation on the signal according to the frequency offset compensation value, then performing fourier transform and channel estimation on the frequency offset compensated signal, and further calculating the reference signal reception quality parameter according to the channel estimated signal, because the actual frequency offset is the sum of the inherent frequency offset and the frequency offset caused by the relative speed of operation when the user equipment is in a high-speed operation environment, and the frequency offset compensation value is related to the previous open loop frequency offset estimation value and a frequency offset reference value related to the inherent frequency offset between the base station and the user equipment, the frequency offset compensation value is the same as the actual frequency offset value in magnitude order, the estimation range is improved, so the frequency offset compensation value is close to the real frequency offset value, therefore, the accuracy of frequency offset estimation can be improved, and the calculation accuracy of the reference signal receiving quality parameter can be improved.
To make the present invention better understood and realized by those skilled in the art, the following provides an apparatus that can implement the method of frequency offset estimation in the above-mentioned embodiment, as shown in fig. 3, the apparatus may include: an obtaining unit 31, a frequency offset compensation unit 32, a fourier transform unit 33, a channel estimation unit 34, a first calculation unit 37, a second calculation unit 35, a selecting unit 36, and a third calculation unit 38, wherein:
the acquiring unit 31 is adapted to acquire a received baseband signal;
the frequency offset compensation unit 32 is adapted to perform frequency offset compensation on the baseband signal according to a frequency offset compensation value; wherein: the frequency offset compensation value is related to the last open-loop frequency offset estimation value and a frequency offset reference value, and the frequency offset reference value is related to the inherent frequency offset of the user equipment and the base station; the inherent frequency offset is: the corresponding frequency deviation is carried out when the relative motion speed between the user equipment and the base station is not greater than a preset speed threshold;
the fourier transform unit 33 is adapted to perform fourier transform on the frequency offset compensated signal;
the channel estimation unit 34 is adapted to perform channel estimation on the frequency offset compensated signal;
the first calculating unit 37 is adapted to calculate the current open-loop frequency offset estimation value according to the signal after channel estimation;
the second calculating unit 35 is adapted to calculate a reference signal received quality parameter according to the channel estimated signal;
the selecting unit 36 is adapted to select the reported frequency offset reference value according to the reference signal reception quality parameter;
the third calculating unit 38 is adapted to calculate a corresponding frequency offset compensation value according to the frequency offset reference value and the estimated value of the open loop frequency offset this time, and use the calculated frequency offset compensation value as a next frequency offset compensation value. Channel estimation section 34 in fig. 3 is the same as channel estimation section 24 in fig. 2.
In a specific implementation, the frequency offset reference value belongs to a preset frequency offset reference value set.
In a specific implementation, the selecting unit 36 is adapted to select, from the frequency offset reference value set, a frequency offset reference value when the corresponding reference signal received quality parameter is maximum, as the reported frequency offset reference value.
In a specific implementation, the first calculating unit 37 is adapted to calculate the current open-loop frequency offset estimation value by using the following formula:
wherein:
for the estimated value of the frequency offset of the open loop at this time, delta f is the interval of subcarriers, delta L is the interval of adjacent symbols, L is the number of specific reference symbols of a cell, NvrsIs the number of resource elements containing cell-specific reference symbols, NFFTFor the number of points of the fourier transform, Rx is the number of receiving antennas, angle () represents the angle at which the complex value is taken, and P represents the signal estimation result value on the reference symbol.
In a specific implementation, the apparatus may further include: a filtering unit 39, adapted to filter the current open-loop frequency offset estimation value before the corresponding frequency offset compensation value is calculated, so as to obtain a current filtered frequency offset value;
the third calculating unit 38 is adapted to perform the operation of calculating the corresponding frequency offset compensation value according to the frequency offset value after the current filtering and the frequency offset reference value.
In a specific implementation, the filtering unit 39 is adapted to filter the current open-loop frequency offset estimation value by using the following formula, so as to obtain a current filtered frequency offset value:
wherein:
for the open-loop frequency offset estimation value of this time,
for the frequency offset value after the previous filtering, filter (x) indicates that the parameter x in parentheses is filtered.
In a specific implementation, the reference signal received quality parameter is a reference signal received quality or a reference signal received power.
Those skilled in the art will appreciate that all or part of the steps in the methods of the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer-readable storage medium, and the storage medium may include: ROM, RAM, magnetic or optical disks, and the like.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (12)
1. A method of frequency offset estimation, comprising:
acquiring a received baseband signal;
performing frequency offset compensation on the baseband signal according to the frequency offset compensation value; wherein: the frequency offset compensation value is related to a last open-loop frequency offset estimation value and a frequency offset reference value, the frequency offset reference value belongs to a preset frequency offset reference value set, and the frequency offset reference value set is selected according to the inherent frequency offset range of the base station and the user equipment; the inherent frequency offset is: the corresponding frequency deviation is carried out when the relative motion speed between the user equipment and the base station is not greater than a preset speed threshold;
performing Fourier transform and channel estimation on the signal after the frequency offset compensation;
calculating the current open-loop frequency offset estimation value and the reference signal receiving quality parameter according to the signal after the channel estimation;
selecting and obtaining a reported frequency offset reference value according to the reference signal receiving quality parameter;
and calculating a corresponding frequency offset compensation value according to the frequency offset estimation value of the open loop and the frequency offset reference value of this time, and taking the frequency offset compensation value obtained by calculation as a next frequency offset compensation value.
2. The method of frequency offset estimation according to claim 1, wherein the selecting the reported frequency offset reference value according to the reference signal reception quality parameter comprises:
and selecting the frequency offset reference value when the corresponding reference signal receiving quality parameter is maximum from the frequency offset reference value set as the reported frequency offset reference value.
3. The method of frequency offset estimation according to claim 1, wherein said calculating the current value of frequency offset of open loop according to the signal after channel estimation comprises:
wherein:for the estimated value of the frequency offset of the open loop at this time, delta f is the interval of subcarriers, delta L is the interval of adjacent symbols, L is the number of specific reference symbols of a cell, NvrsIs the number of resource elements containing cell-specific reference symbols, NFFTFor the number of points of the fourier transform, Rx is the number of receiving antennas, the function angle (y) is expressed as an angle taking the complex value y, and P represents the signal estimation result value on the reference symbol.
4. The method of frequency offset estimation according to claim 1, further comprising, before said calculating corresponding frequency offset compensation values:
filtering the open-loop frequency offset estimation value of this time to obtain a frequency offset value after the filtering of this time;
and executing the operation of calculating the corresponding frequency offset compensation value according to the frequency offset value after the filtering and the frequency offset reference value.
5. The method of frequency offset estimation according to claim 4, wherein the current value of the open-loop frequency offset is filtered by using the following formula to obtain the current filtered value of the frequency offset:
wherein:
for the open-loop frequency offset estimation value of this time,filter (y) represents filtering y for the frequency offset value after the previous filtering,
the frequency offset value after the filtering is obtained.
6. The method of frequency offset estimation according to claim 1, wherein said reference signal received quality parameter is a reference signal received quality or a reference signal received power.
7. An apparatus for frequency offset estimation, comprising:
an acquisition unit adapted to acquire a received baseband signal;
the frequency offset compensation unit is suitable for performing frequency offset compensation on the baseband signal according to a frequency offset compensation value; wherein: the frequency offset compensation value is related to a last open-loop frequency offset estimation value and a frequency offset reference value, the frequency offset reference value belongs to a preset frequency offset reference value set, and the frequency offset reference value set is selected according to the inherent frequency offset range of the base station and the user equipment; the inherent frequency offset is: the corresponding frequency deviation is carried out when the relative motion speed between the user equipment and the base station is not greater than a preset speed threshold;
a Fourier transform unit adapted to perform Fourier transform on the frequency offset compensated signal;
the channel estimation unit is suitable for carrying out channel estimation on the signal after the frequency offset compensation;
the first calculating unit is suitable for calculating the current open-loop frequency offset estimation value according to the signal after the channel estimation;
the second calculation unit is suitable for calculating a reference signal receiving quality parameter according to the signal after the channel estimation;
the selection unit is suitable for selecting and obtaining a reported frequency offset reference value according to the reference signal receiving quality parameter;
and the third calculating unit is suitable for calculating a corresponding frequency offset compensation value according to the frequency offset reference value and the estimated value of the open-loop frequency offset at this time, and taking the frequency offset compensation value obtained by calculation as a next frequency offset compensation value.
8. The apparatus for frequency offset estimation according to claim 7, wherein the selecting unit is adapted to select, from the set of frequency offset reference values, a frequency offset reference value corresponding to a time when the reference signal received quality parameter is maximum as the reported frequency offset reference value.
9. The apparatus for frequency offset estimation according to claim 7, wherein the first calculating unit is adapted to calculate the current open-loop frequency offset estimation value by using the following formula:
wherein:
for the estimated value of the frequency offset of the open loop at this time, delta f is the interval of subcarriers, delta L is the interval of adjacent symbols, L is the number of specific reference symbols of a cell, NvrsIs the number of resource elements containing cell-specific reference symbols, NFFTFor the number of points of the fourier transform, Rx is the number of receiving antennas, the function angle (y) is expressed as an angle taking the complex value y, and P represents the signal estimation result value on the reference symbol.
10. The apparatus for frequency offset estimation according to claim 7, further comprising: the filtering unit is suitable for filtering the current open-loop frequency offset estimation value before the corresponding frequency offset compensation value is calculated to obtain the current filtered frequency offset value;
and the third calculating unit is adapted to perform the operation of calculating the corresponding frequency offset compensation value according to the frequency offset value after the current filtering and the frequency offset reference value.
11. The apparatus for frequency offset estimation according to claim 10, wherein the filtering unit is adapted to filter the current open-loop frequency offset estimation value by using the following formula to obtain the current filtered frequency offset value:
wherein:
for the open-loop frequency offset estimation value of this time,
filter (y) represents filtering y for the frequency offset value after the previous filtering,
the frequency offset value after the filtering is obtained.
12. The apparatus of frequency offset estimation according to claim 7, wherein said reference signal received quality parameter is a reference signal received quality or a reference signal received power.
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| CN112217756B (en) * | 2019-07-12 | 2022-03-29 | 华为技术有限公司 | Doppler frequency offset estimation method and communication device |
| CN111224910B (en) * | 2019-12-27 | 2021-08-24 | 京信网络系统股份有限公司 | Frequency offset compensation method, device, equipment and storage medium |
| CN113271279B (en) * | 2021-05-14 | 2022-07-05 | 成都爱瑞无线科技有限公司 | High-precision detection method for random access channel of narrow-band Internet of things |
| CN114726702B (en) * | 2022-05-26 | 2022-08-26 | 为准（北京）电子科技有限公司 | Method and device for estimating and compensating channel frequency offset |
| CN118632314B (en) * | 2024-08-12 | 2024-10-25 | 成都爱瑞无线科技有限公司 | Frequency offset compensation method and device |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1774875A (en) * | 2002-09-05 | 2006-05-17 | 高通股份有限公司 | Compensating for frequency shift and timing shift in frequency and time tracking loops based on mobile unit velocity |
| WO2010148676A1 (en) * | 2009-11-20 | 2010-12-29 | 中兴通讯股份有限公司 | Method and apparatus for data-based frequency offset estimation |
| CN101990291A (en) * | 2009-07-30 | 2011-03-23 | 中兴通讯股份有限公司 | Method for pre-compensating frequency bias as well as device |
| CN102263719A (en) * | 2010-05-24 | 2011-11-30 | 中兴通讯股份有限公司 | Frequency offset compensating and balancing method and device for orthogonal frequency division multiplexing system |
| CN102263710A (en) * | 2010-05-24 | 2011-11-30 | 中兴通讯股份有限公司 | Channel estimation method and device as well as frequency offset estimation method and device |
| CN102647226A (en) * | 2012-04-11 | 2012-08-22 | 上海交通大学 | Method for carrier frequency offset compensation of receiving signals under high-speed rail environment |
| CN103384990A (en) * | 2010-10-29 | 2013-11-06 | 理立系统有限公司 | System and method of frequency offset compensation for radio system with fast doppler shift |
| US9231787B1 (en) * | 2015-01-23 | 2016-01-05 | Huawei Technologies Co., Ltd. | Method and apparatus with improved estimation accuracy and robustness for fine frequency offset estimation in coherent receivers |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101200736B1 (en) * | 2006-03-14 | 2012-11-13 | 퀄컴 인코포레이티드 | Apparatus and method for transmitting and receiving packet data in a smart antenna system |
-
2016
- 2016-05-31 CN CN201610378428.9A patent/CN107454027B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1774875A (en) * | 2002-09-05 | 2006-05-17 | 高通股份有限公司 | Compensating for frequency shift and timing shift in frequency and time tracking loops based on mobile unit velocity |
| CN101990291A (en) * | 2009-07-30 | 2011-03-23 | 中兴通讯股份有限公司 | Method for pre-compensating frequency bias as well as device |
| WO2010148676A1 (en) * | 2009-11-20 | 2010-12-29 | 中兴通讯股份有限公司 | Method and apparatus for data-based frequency offset estimation |
| CN102263719A (en) * | 2010-05-24 | 2011-11-30 | 中兴通讯股份有限公司 | Frequency offset compensating and balancing method and device for orthogonal frequency division multiplexing system |
| CN102263710A (en) * | 2010-05-24 | 2011-11-30 | 中兴通讯股份有限公司 | Channel estimation method and device as well as frequency offset estimation method and device |
| CN103384990A (en) * | 2010-10-29 | 2013-11-06 | 理立系统有限公司 | System and method of frequency offset compensation for radio system with fast doppler shift |
| CN102647226A (en) * | 2012-04-11 | 2012-08-22 | 上海交通大学 | Method for carrier frequency offset compensation of receiving signals under high-speed rail environment |
| US9231787B1 (en) * | 2015-01-23 | 2016-01-05 | Huawei Technologies Co., Ltd. | Method and apparatus with improved estimation accuracy and robustness for fine frequency offset estimation in coherent receivers |
Non-Patent Citations (1)
| Title |
|---|
| "高动态环境下的伪码同步与频偏估计算法研究";郭祥平;《中国优秀硕士学位论文全文数据库信息科技辑》;20151201;全文 * |
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