CN107317779B - Frequency offset estimation method and device - Google Patents
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Abstract
The invention discloses a frequency offset estimation method. The method comprises the following steps: 102, carrying out frequency offset pre-compensation processing on received data by using a set pre-compensation value to obtain compensation data; 104, determining a frequency offset estimation value according to pilot frequency data in the compensation data; step 106, according to the pilot frequency data in the compensation data, performing frequency offset re-compensation processing on the compensation data, and determining the communication quality parameters of the compensation data after the frequency offset re-compensation processing; step 108, judging whether the current communication quality meets the preset communication quality requirement or not according to the communication quality parameter, if so, executing step 102; if not, the pre-compensation value is reset and step 102 is performed using the reset pre-compensation value. In the embodiment, the frequency offset pre-compensation is performed on the received signal at the signal receiving end by setting the pre-compensation value, so that the frequency offset estimation range is effectively expanded, and the method can be applied to the scene of ultra-high speed movement.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a frequency offset estimation method and apparatus.
Background
In an LTE (Long Term Evolution) system, OFDM (Orthogonal Frequency Division Multiple Access) is a core technology thereof. The OFDM technology can well eliminate the interference between symbols, and the channel equalization is relatively easy. However, OFDM is sensitive to frequency offset, because the frequency offset introduces phase rotation in the time domain, which destroys orthogonality among subcarriers of the OFDM system, and when the frequency offset reaches a certain degree, demodulation performance deteriorates sharply. For a super-high speed mobile scenario, such as a high-speed railway scenario, if demodulation is performed directly under the condition of a large frequency offset, the demodulation performance will be poor. It is therefore necessary to estimate the frequency offset and then compensate for the frequency offset.
In the existing frequency offset estimation technology, there is a method of performing frequency offset estimation by using CP (Cyclic Prefix), and there is also a method of performing frequency offset estimation by using pilot symbols.
Because the CP is a partial repetition of the data FFT symbol, and the CP portion and the data repetition portion have a small time interval, the use of the CP for frequency offset estimation can cover a large frequency offset range, but there is a problem of interference between users, and the accuracy of the frequency offset estimation is poor.
In the OFDM system, the information contained in the pilot symbols is the same, and if there is a frequency offset, there is a fixed phase difference between the time domain pilot symbols, and this phase difference can be estimated easily, and then a frequency offset value can be estimated according to this phase difference. However, in the ultra-high speed mobile scenario, the time interval of the pilot frequency is large, the range of the frequency offset estimation is limited, and the accuracy of the frequency offset estimation is still poor.
Disclosure of Invention
The invention provides a frequency offset estimation method and a frequency offset estimation device, which are used for solving the problem that the frequency offset estimation range is limited in an ultra-high-speed mobile scene.
In view of the above technical problems, the present invention is achieved by the following technical solutions.
The invention provides a frequency offset estimation method, which comprises the following steps: 102, carrying out frequency offset pre-compensation processing on received data by using a set pre-compensation value to obtain compensation data; 104, determining a frequency offset estimation value according to pilot frequency data in the compensation data; step 106, according to the pilot frequency data in the compensation data, performing frequency offset re-compensation processing on the compensation data, and determining the communication quality parameters of the compensation data after the frequency offset re-compensation processing; step 108, judging whether the current communication quality meets the preset communication quality requirement or not according to the communication quality parameter, if so, executing step 102; if not, the pre-compensation value is reset and step 102 is performed using the reset pre-compensation value.
Wherein, the theoretical frequency deviation estimation range is [ -ffreqoffset_ES,ffreqoffset_ES](ii) a The expected frequency offset estimation range is [ -ffreqoffset,ffreqoffset](ii) a The following condition is satisfied between the reset pre-compensation value f2 and the original pre-compensation value f 1: f1 > f 2; l ffreqoffset-f1|<ffreqoffset_ES；|f1-f2|<ffreqoffset_ES；|f2-(-ffreqoffset)|<ffreqoffset_ES。
Wherein, determining the frequency offset estimation value according to the pilot frequency data in the compensation data comprises: calculating a frequency offset value according to pilot frequency data in the compensation data; and the frequency offset estimation value is the sum of the frequency offset value and a currently set pre-compensation value.
Wherein, according to the pilot frequency data in the compensation data, performing frequency offset re-compensation processing on the compensation data, including: and calculating a frequency offset value according to pilot frequency data in the compensation data, and performing frequency offset re-compensation processing on the compensation data by using the frequency offset value.
And the communication quality parameter is a signal-to-interference-and-noise ratio or a cyclic redundancy check result.
When the communication quality parameter is the signal-to-interference-and-noise ratio, judging whether the current communication quality meets a preset communication quality requirement according to the communication quality parameter, including: and if the SINR is less than the preset SINR threshold for the first time, judging that the current communication quality does not meet the preset communication quality requirement, and otherwise, judging that the current communication quality meets the preset communication quality requirement.
When the communication quality parameter is a cyclic redundancy check result, judging whether the current communication quality meets a preset communication quality requirement according to the communication quality parameter, including: and if the cyclic redundancy check results of the second preset times are all errors, judging that the current communication quality does not meet the preset communication quality requirement, and otherwise, judging that the current communication quality meets the preset communication quality requirement.
The invention also provides a frequency offset estimation device, which comprises: the pre-compensation module is used for carrying out frequency offset pre-compensation processing on the received data by using the set pre-compensation value to obtain compensation data; a determining module, configured to determine a frequency offset estimation value according to pilot data in the compensation data; the re-compensation module is used for carrying out frequency offset re-compensation processing on the compensation data according to the pilot frequency data in the compensation data and determining the communication quality parameters of the compensation data after the frequency offset re-compensation processing; the judging module is used for judging whether the current communication quality meets the preset communication quality requirement or not according to the communication quality parameter, and calling the precompensation module under the condition of judging yes; and under the condition that the judgment result is no, resetting a pre-compensation value, and calling the pre-compensation module to enable the pre-compensation module to execute frequency offset pre-compensation processing by using the reset pre-compensation value.
Wherein, the theoretical frequency deviation estimation range is [ -ffreqoffset_ES,ffreqoffset_ES](ii) a The expected frequency offset estimation range is [ -ffreqoffset,ffreqoffset](ii) a The judging module is used for setting a pre-compensation value; wherein the following condition is satisfied between the reset pre-compensation value f2 and the original pre-compensation value f 1: f1 > f 2; l ffreqoffset-f1|<ffreqoffset_ES；|f1-f2|<ffreqoffset_ES；|f2-(-ffreqoffset)|<ffreqoffset_ES。
Wherein the determining module is configured to: calculating a frequency offset value according to pilot frequency data in the compensation data; and the frequency offset estimation value is the sum of the frequency offset value and a currently set pre-compensation value.
Wherein the re-compensation module is configured to: and calculating a frequency offset value according to pilot frequency data in the compensation data, and performing frequency offset re-compensation processing on the compensation data by using the frequency offset value.
And the communication quality parameter is a signal-to-interference-and-noise ratio or a cyclic redundancy check result.
Wherein, when the communication quality parameter is the signal to interference plus noise ratio, the judging module is configured to: and if the SINR is less than the preset SINR threshold for the first time, judging that the current communication quality does not meet the preset communication quality requirement, and otherwise, judging that the current communication quality meets the preset communication quality requirement.
Wherein, when the communication quality parameter is a cyclic redundancy check result, the determining module is configured to: and if the cyclic redundancy check results of the second preset times are all errors, judging that the current communication quality does not meet the preset communication quality requirement, and otherwise, judging that the current communication quality meets the preset communication quality requirement.
The invention has the following beneficial effects:
in the embodiment, the frequency offset pre-compensation is performed on the received signal at the signal receiving end by setting the pre-compensation value, so that the frequency offset estimation range is effectively expanded, and the method can be applied to the scene of ultra-high speed movement. Furthermore, the invention judges whether the current precompensation value is proper or not according to the communication quality parameters, and adjusts the precompensation value under the improper condition, so that the operation complexity is low and the precision of the frequency offset estimation value is high.
Drawings
FIG. 1 is a flow chart of a method of frequency offset estimation according to an embodiment of the present invention;
FIG. 2 is a detailed flow chart of a method of frequency offset estimation according to an embodiment of the present invention;
FIG. 3 is a flow chart diagram of a method of frequency offset estimation according to an embodiment of the invention;
FIG. 4 is a diagram illustrating the setting of pre-compensation values according to an embodiment of the present invention;
fig. 5 is a block diagram of a frequency offset estimation apparatus according to an embodiment of the present invention.
Detailed Description
The method comprises the steps of pre-compensating a received signal by using a currently set pre-compensation value to enlarge a frequency offset estimation range, then performing frequency offset estimation and frequency offset compensation on the pre-compensated signal by using a pilot frequency to determine a communication quality parameter, determining whether the currently set pre-compensation value is proper or not according to the communication quality parameter, if so, continuing to use, and if not, setting a new pre-compensation value.
The invention effectively enlarges the frequency offset estimation range by setting the pre-compensation value at the signal receiving end, and can be suitable for the scene of ultra-high speed movement. Furthermore, the invention judges whether the current precompensation value is proper or not according to the communication quality parameters, and adjusts the precompensation value under the improper condition, so that the operation complexity is low and the precision of the frequency offset estimation value is high.
The present invention will be described in further detail below with reference to the drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
The embodiment of the invention provides a frequency offset estimation method. Fig. 1 is a flow chart of a frequency offset estimation method according to an embodiment of the present invention.
Step S101, using the set pre-compensation value to perform frequency offset pre-compensation processing on the received data to obtain compensation data.
And a signal receiving end of the OFDM system carries out time domain sampling on the received data to obtain time domain data. And carrying out frequency offset pre-compensation processing on the time domain data by using the set pre-compensation value to obtain compensation data.
The pre-compensation value is used for frequency offset compensation. Two pre-compensation values f1 and f2 can be obtained in advance according to the theoretical frequency offset estimation range and the expected frequency offset estimation range, one pre-compensation value f1 is set as the currently used pre-compensation value, and in the subsequent execution process, when the currently used pre-compensation value f1 is determined to be inappropriate, the other pre-compensation value f2 is set as the currently used pre-compensation value.
Specifically, the theoretical frequency offset estimation range is calculated according to two adjacent pilot frequencies in the OFDM system, and the theoretical frequency offset estimation range is [ -f [ ]freqoffset_ES,ffreqoffset_ES](ii) a The expected frequency offset estimation range is set according to the application scene, and the expected frequency offset estimation range is [ -f [ ]freqoffset,ffreqoffset]。
The pre-compensation values f1 and f2 satisfy the following condition:
f1＞f2；
|ffreqoffset-f1|<ffreqoffset_ES；
|f1-f2|<ffreqoffset_ES；
|f2-(-ffreqoffset)|<ffreqoffset_ES。
step S102, determining a frequency offset estimation value according to the pilot frequency data in the compensation data.
Calculating a frequency offset value according to pilot frequency data in the compensation data; and the frequency offset estimation value is the sum of the frequency offset value and a currently set pre-compensation value.
Step S103, according to the pilot frequency data in the compensation data, carrying out frequency offset re-compensation processing on the compensation data, and determining the communication quality parameters of the compensation data after the frequency offset re-compensation processing.
And calculating a frequency offset value according to pilot frequency data in the compensation data, performing frequency offset re-compensation processing on the compensation data by using the frequency offset value, and determining communication quality parameters of the compensation data after the frequency offset re-compensation processing.
The communication quality parameter is SINR (Signal to Interference plus Noise Ratio) or CRC (Cyclic Redundancy Code).
Step S104, judging whether the current communication quality meets the preset communication quality requirement or not according to the communication quality parameter; if yes, executing step S101; if not, step S105 is performed.
The preset communication quality requirements include:
when the communication quality parameter is the signal-to-interference-and-noise ratio, if the signal-to-interference-and-noise ratios of the first continuous times (ErrNum1) are all smaller than a preset signal-to-interference-and-noise ratio threshold, judging that the current communication quality does not meet the preset communication quality requirement, otherwise, judging that the current communication quality meets the preset communication quality requirement.
And when the communication quality parameter is a cyclic redundancy check result, if the cyclic redundancy check results of the second preset times (ErrNum2) are all errors, judging that the current communication quality does not meet the preset communication quality requirement, otherwise, judging that the current communication quality meets the preset communication quality requirement.
ErrNum1 and ErrNum2 are positive integers, which may be 123.
In step S105, the pre-compensation value is reset, and step S110 is performed using the reset pre-compensation value.
After judging that the current communication quality does not meet the communication quality requirement, the currently set pre-compensation value f1 is indicated to be not suitable, in order to meet the communication quality requirement, the currently set pre-compensation value f1 needs to be replaced by a pre-compensation value f2, frequency offset pre-compensation processing is carried out on received data by using the pre-compensation value f2, a frequency offset estimation value is continuously obtained, and whether the communication quality after using the pre-compensation value f2 can meet the requirement or not is judged.
The embodiment adopts a low-complexity operation mode, and effectively enlarges the frequency offset estimation range by setting a pre-compensation value at a signal receiving end. The present embodiment is preferably applied to ultra-high speed moving scenes, such as: and the relative moving speed is 300 km/h. The frequency offset estimation precision can be improved by enlarging the frequency offset estimation range. Based on the embodiment, the frequency offset estimation can be carried out in real time, the frequency offset estimation value is obtained, and the problem of large-range jitter of the positive and negative frequency offsets of the receiving end can be solved.
The frequency offset estimation method of the present invention is further described below.
Fig. 2 is a detailed flowchart of a frequency offset estimation method according to an embodiment of the present invention. Fig. 3 is a flow chart of a frequency offset estimation method according to an embodiment of the invention.
In step S201, the pre-compensation values f1 and f2 are calculated, and err1 is equal to 0 and err2 is equal to 0.
The pre-compensation value f1 is set as the pre-compensation value currently used. err1 and err2 were used for counting.
Calculating theoretical frequency deviation estimation range [ -f ] by using two adjacent pilot frequenciesfreqoffset_ES,ffreqoffset_ES]。
Setting an expected frequency offset estimation range [ -f ] according to an application scenefreqoffset,ffreqoffset]。
When 2 ffreqoffset_ES>2*ffreqoffsetIn the meantime, that is, when the theoretical frequency offset estimation range is larger than the expected frequency offset estimation range, the precision of the frequency offset estimation value is higher, the pilot frequency in the OFDM system can be directly used for frequency offset estimation, and the method of using the pilot frequency for frequency offset estimation is the prior art and is not described herein.
Because the theoretical frequency offset estimation range is limited under the condition of ultra-high speed movement, the theoretical frequency offset estimation range is smaller than the expected frequency offset estimation range, namely 2 & ltf & gtfreqoffset_ES<2*ffreqoffsetIn order to enable the frequency offset estimation range to cover the whole expected frequency offset estimation range and improve the precision of the frequency offset estimation value, a pre-compensation value can be set to expand the frequency offset estimation range. This embodiment is preferably carried out at2 × ffreqoffset_ES<2*ffreqoffsetAnd 3 ffreqoffset_ES>2*ffreqoffsetThen, the pre-compensation value is set.
The pre-compensation values f1 and f2 are set to satisfy the following conditions:
f1＞f2；
|ffreqoffset-f1|<ffreqoffset_ES；
|f1-f2|<ffreqoffset_ES；
|f2-(-ffreqoffset)|<ffreqoffset_ES。
from the above conditions, it can be known that the precompensation values f1 and f2 are [ -f [ ]freqoffset,ffreqoffset]Divided into 3 parts of [ -f ] respectivelyfreqoffset,f1](f1, f2) and [ f2, ffreqoffset]. As shown in fig. 4, the theoretical frequency offset estimation range is a frequency offset estimation range 0, after pre-compensation values f1 and f2 are selected, the theoretical frequency offset estimation range will change after the frequency offset pre-compensation, and after the frequency offset pre-processing based on f1, a frequency offset estimation range 1, i.e., [ f2, f 3526 ] can be obtainedfreqoffset](ii) a After the frequency offset preprocessing based on f2, a frequency offset estimation range 2, i.e., [ -f ], can be obtainedfreqoffset,f1](ii) a Thus [ f2, ffreqoffset]And [ -f ]freqoffset,f1]Cover the whole [ -f ]freqoffset,ffreqoffset]。
For example: limited by PUCCH pilot interval in LTE (Long Term Evolution), OFDM system calculates theoretical frequency offset estimation range is [ -1750,1750] by directly using two pilots of PUCCH Format2 series; the desired frequency offset estimation range is [ -2000,2000], and therefore the conditions 2 × 1750<2 × 2000, and 3 × 1750>2 × 2000 are satisfied. Setting f 1-600, f 2-600; f1 and f2 satisfy the condition: 600 > -600, 2000-600<1750, 600- (-600) <1750, -600- (-2000) < 1750.
Step S202, a pre-compensation value f1 is set, and frequency offset pre-compensation processing is performed on the time domain data by using the pre-compensation value f 1.
A signal receiving end of the OFDM system is responsible for receiving data, and M sampling points can be sampled every millisecond, wherein M is larger than 1; the interval of every two sampling points is recorded as Ts. These sample points form the time domain data.
In the time domain data, include: pilot time domain data h (n) and non-pilot time domain data d (n), where n represents the time domain sample number in the OFDM system. Further, after removing cyclic shift (hereinafter abbreviated CP) from the time domain data, pilot time domain data h (n) and non-pilot time domain data d (n) can be obtained. The pilot time domain data is time domain data of a pilot, and the non-pilot time domain data is time domain data of service data, for example.
For example: 30720 point data are sampled every millisecond at the receiving end of the OFDM system, and the interval of every two sampling points is recorded as Ts. After removing the cyclic shift (CP), pilot time domain data h (n) and non-pilot time domain data d (n) can be obtained.
And performing frequency offset pre-compensation processing on the pilot frequency time domain data h (n) and the non-pilot frequency time domain data d (n) by using the pre-compensation value f 1. Specific examples include the following calculation methods:
and carrying out frequency offset pre-compensation processing on the pilot frequency time domain data h (n) by using a pre-compensation value f 1:
And carrying out frequency offset pre-compensation processing on the non-frequency-guide time domain data d (n) by using a pre-compensation value f 1:
wherein, FFTNum: number of points of the fourier transform. For example: FFTNum 2048.
It can be simply understood that: h is1(n)+d1And (n) is compensation data obtained after frequency offset pre-compensation is carried out by using the pre-compensation value f 1.
Step S203, pre-compensating the frequency offset to obtain pilot frequency time domain data h1(n) converting into pilot frequency domain data
And according to
The frequency offset value Δ f1 is calculated.
Pilot frequency time domain data h obtained after pre-compensating frequency offset1(n) Fourier transform, h1(n) pilot frequency domain data obtained by Fourier transform is
Wherein,
represents the time domain symbol number in the OFDM system, and k represents the frequency domain symbol number (also called frequency domain subcarrier number) in the OFDM system.
Further, N-point fourier transform is performed on the compensation data obtained by the frequency offset pre-compensation processing to obtain N-point frequency domain data corresponding to the compensation data, where the N-point frequency domain data includes pilot frequency domain data of a certain number of symbols and non-pilot frequency domain data of a certain number of symbols.
By using
The frequency offset value Δ f1 can be calculated, for example, in the following manner:
Δf1＝phase1/T
wherein, the function angel () is used for solving the radian value of the complex phase angle; the function conj () is used to find the conjugate value; 
And
respectively numbering the time domain symbols of two adjacent pilot frequencies for calculating the theoretical frequency offset estimation range;
the time domain symbol number for the previous pilot,
numbering the time domain symbols of the latter pilot frequency; t is
And
the time domain symbol number of (1).
Step S204, utilizing the first frequency deviation value delta f1 to compensate the data h1(n)+d1And (n) carrying out frequency offset re-compensation processing.
The compensation data is frequency offset compensated by the first frequency offset value Δ f1, that is, frequency offset re-compensation processing is performed, for example, as follows:
using the pairs of Δ f1
And frequency offset compensation is carried out:
using the pairs of Δ f1
And frequency offset compensation is carried out:
step S205, calculating the signal to interference plus noise ratio SINR1 of the compensation data after the frequency offset re-compensation processing.
And respectively carrying out N-point Fourier transform on the pilot frequency time domain data and the non-pilot frequency time domain data after the frequency offset re-compensation processing to obtain N-point frequency domain data. Wherein the pilot frequency time domain data
The pilot frequency domain data obtained by Fourier transform is
Non-pilot time domain data
Obtaining non-pilot frequency domain data through Fourier transformation
The SINR1 is calculated, for example, as follows:
computing
The SINR of (a) of (b) 1,
note that NI1 is interference noise of time domain data after frequency offset precompensation using f 1.
Of course, step S205 may be replaced by calculating the time domain data after the secondary frequency offset compensation respectively 
The cyclic redundancy check result CRC 1.
Step S206, determining a frequency offset estimation value, and judging whether the current communication quality meets the communication quality requirement; if yes, go to step S202; if not, step S207 is performed.
If the SINR1 is greater than or equal to the SINR threshold, determining that the frequency offset estimation value is (f1+ Δ f1), and considering that the frequency offset estimation value (f1+ Δ f1) is authentic, where the current communication quality meets the communication quality requirement, at this time, setting err1 to 0, and in the next calculation period, continuing to step S202.
If the SINR1 is less than the SINR threshold, determining that the frequency offset estimation value is (f1+ Δ f1), but considering that the frequency offset estimation value (f1+ Δ f1) is not trusted, and the current communication quality does not meet the communication quality requirement, at this time, setting err1 to err1+1, and determining whether the current err1 is less than ErrNum 1; if yes, executing step S202 in the next calculation period; if not, that is, the current err1 is greater than or equal to ErrNum1, in the next calculation cycle, go to step S207, and set err2 to 0.
If the step S205 obtains yes
The CRC1, step S206 may determine according to CRC 1. Specifically, the method comprises the following steps:
if the CRC1 is correct, it is determined that the frequency offset estimation value is (f1+ Δ f1), and the frequency offset estimation value (f1+ Δ f1) is considered to be authentic, the current communication quality meets the communication quality requirement, at this time, err1 is set to 0, and in the next calculation period, the process continues to step S220.
If CRC1 is wrong, determining that the frequency offset estimation value is (f1+ delta f1), but considering that the frequency offset estimation value is not credible, and the current communication quality does not meet the communication quality requirement, at this time, setting err1 to err1+1, and judging whether the current err1 is smaller than errNum 1; if yes, executing step S202 in the next calculation period; if not, that is, the current err1 is greater than or equal to ErrNum1, in the next calculation cycle, go to step S207, and set err2 to 0.
Step S207, setting a pre-compensation value f2, and performing frequency offset pre-compensation processing on the time domain data by using the pre-compensation value f 2.
And respectively carrying out frequency offset pre-compensation processing on the pilot frequency time domain data h (n) and the non-pilot frequency time domain data d (n) by using the pre-compensation value f 2. Frequency offset pre-compensation processing, such as the following calculation:
and carrying out frequency offset pre-compensation processing on the pilot frequency time domain data h (n) by using a pre-compensation value f 2:
and carrying out frequency offset pre-compensation processing on the non-frequency-guide time domain data d (n) by using a pre-compensation value f 2:
it can be simply understood that: h is2(n)+d2And (n) is compensation data obtained after frequency offset pre-compensation is carried out by using the pre-compensation value f 2.
Step S208, pilot frequency time domain data h obtained after frequency offset pre-compensation2(n) converting into pilot frequency domain data
And according to 
The second frequency offset value Δ f2 is calculated.
By using
The second frequency offset value Δ f2 is calculated, for example, in the following manner:
Δf2＝phase1/T
step S209, utilizing the second frequency offset value delta f2 to compensate the data h2(n)+d2And (n) carrying out frequency offset re-compensation processing.
And performing frequency offset compensation on the compensation data by using the second frequency offset value Δ f2, for example, as follows:
using the pairs of Δ f2
And frequency offset compensation is carried out:
using the pairs of Δ f2
And frequency offset compensation is carried out:
step S210, calculating the signal to interference plus noise ratio SINR2 of the compensation data after the frequency offset re-compensation processing.
And respectively carrying out N-point Fourier transform on the pilot frequency time domain data and the non-pilot frequency time domain data after the secondary frequency offset compensation processing to obtain N-point frequency domain data. Wherein the pilot frequency time domain data
The pilot frequency domain data can be obtained by Fourier transformation
Non-pilot time domain data
The non-pilot frequency domain data can be obtained as a sum through Fourier transform
The SINR2 is calculated, for example, as follows:
computing
The SINR of (a) of (b) 2,
wherein, NI2 is interference noise of time domain data after frequency offset pre-compensation by using f 2; function () H represents the conjugate transpose.
Of course, step S210 may alternatively calculate the time domains after the secondary frequency offset compensation respectivelyData of
The cyclic redundancy check result CRC 1.
Step S211, determining a frequency offset estimation value, and judging whether the current communication quality meets the communication quality requirement; if yes, go to step S207; if not, step S202 is performed.
If the SINR2 is greater than or equal to the SINR threshold, determining that the frequency offset estimation value is (f2+ Δ f2), and considering that the frequency offset estimation value (f2+ Δ f2) is authentic, where the current communication quality meets the communication quality requirement, at this time, setting err2 to 0, and in the next calculation period, continuing to step S207.
If the SINR2 is less than the SINR threshold, determining that the frequency offset estimation value is (f2+ Δ f2), but considering that the frequency offset estimation value (f2+ Δ f2) is not trusted, and the current communication quality does not meet the communication quality requirement, at this time, setting err2 to err2+1, and determining whether the current err2 is less than ErrNum 2; if yes, in the next calculation cycle, continuing to execute step 207; if not, that is, the current err2 is greater than or equal to ErrNum, in the next calculation cycle, go to step S202, and set err1 equal to 0.
If the step S210 obtains
The CRC2, step S211 can be determined according to CRC 2. Specifically, the method comprises the following steps:
if the CRC2 is correct, it is determined that the frequency offset estimation value is (f2+ Δ f2), and the frequency offset estimation value (f2+ Δ f2) is considered to be authentic, the current communication quality meets the communication quality requirement, at this time, err2 is set to 0, and in the next calculation period, the process continues to step S207.
If the CRC2 is wrong, determining that the frequency offset estimation value is (f2+ Δ f2), but the frequency offset estimation value (f2+ Δ f2) is deemed to be untrusted, and the current communication quality does not meet the communication quality requirement, at this time, setting err2 to err2+1, and determining whether the current err2 is smaller than ErrNum 2; if yes, in the next calculation cycle, continuing to execute step 207; if not, that is, the current err2 is greater than or equal to ErrNum, in the next calculation cycle, go to step S202, and set err1 equal to 0.
In a specific application scenario, between steps S202 and S203, and between step S207 and step S208, there may be a step of performing data processing on the time domain data after the frequency offset pre-compensation.
For example: in an LTE (Long Term Evolution) system, h after pre-compensation of frequency offset1(n)，h2(n)，d1(n)，d2(n) completes data processing of a PUCCH (Physical Uplink Control CHannel) Format 2.
Specifically, for h1(n) and d1(n)，h2(n) and d2(n) each perform 2048-point fourier transform, and extract frequency domain data of an RB (Resource Block) in which the PUCCH is located. Resource Element (RE) data is recorded as
Wherein constant is
The symbol number in the time domain is denoted by k 0, and the symbol numbers in the frequency domain are denoted by 1,2 … 11. Performing a base sequence (base sequence) operation on the time domain data and eliminating the cyclic shift operation of each symbol:
wherein,
which is representative of the received signal or signals,
representing a basic sequence，
For cell level cyclic shift, n' (n)s) For cyclic shift at user level, nsRepresents a slot number;
function ()*Indicating the conjugate is found and mod the modulo operation.
The PUCCH Format2 pilot data after the basic sequence and the cyclic shift are removed is obtained after the processing
Time domain symbol numbers representing pilots.
The present invention further provides a frequency offset estimation apparatus, as shown in fig. 5, which is a structural diagram of the frequency offset estimation apparatus according to an embodiment of the present invention.
The device includes:
and a pre-compensation module 510, configured to perform frequency offset pre-compensation processing on the received data by using the set pre-compensation value, so as to obtain compensation data.
A determining module 520, configured to determine a frequency offset estimation value according to pilot data in the compensation data.
A re-compensation module 530, configured to perform frequency offset re-compensation processing on the compensation data according to the pilot data in the compensation data, and determine a communication quality parameter of the compensation data after the frequency offset re-compensation processing. And the communication quality parameter is a signal-to-interference-and-noise ratio or a cyclic redundancy check result.
A judging module 540, configured to judge whether the current communication quality meets a preset communication quality requirement according to the communication quality parameter, and if yes, invoke the pre-compensation module; and under the condition that the judgment result is no, resetting a pre-compensation value, and calling the pre-compensation module to enable the pre-compensation module to execute frequency offset pre-compensation processing by using the reset pre-compensation value.
The theoretical frequency offset estimation range is [ -ffreqoffset_ES,ffreqoffset_ES](ii) a The expected frequency offset estimation range is [ -ffreqoffset,ffreqoffset](ii) a The judging module 540 is configured to set a pre-compensation value; wherein the reset pre-compensation value f2 and the original pre-compensation value f1 meet the following conditions:
f1＞f2；
|ffreqoffset-f1|<ffreqoffset_ES；
|f1-f2|<ffreqoffset_ES；
|f2-(-ffreqoffset)|<ffreqoffset_ES。
in one embodiment, the determining module 520 is configured to calculate a frequency offset value according to pilot data in the compensation data; and the frequency offset estimation value is the sum of the frequency offset value and the currently set pre-compensation value.
In another embodiment, the re-compensation module 510 is configured to calculate a frequency offset value according to pilot data in the compensation data, and perform frequency offset re-compensation processing on the compensation data by using the frequency offset value.
In another embodiment, when the communication quality parameter is a signal to interference plus noise ratio, the determining module 540 is configured to: and if the SINR is less than the preset SINR threshold for the first time, judging that the current communication quality does not meet the preset communication quality requirement, and otherwise, judging that the current communication quality meets the preset communication quality requirement. When the communication quality parameter is a cyclic redundancy check result, the determining module 540 is configured to: and if the cyclic redundancy check results of the second preset times are all errors, judging that the current communication quality does not meet the preset communication quality requirement, and otherwise, judging that the current communication quality meets the preset communication quality requirement.
The functions of the apparatus of this embodiment have already been described in the method embodiments shown in fig. 1 to fig. 4, so that reference may be made to the related descriptions in the foregoing embodiments for details in the description of this embodiment, which are not repeated herein.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, and the scope of the invention should not be limited to the embodiments described above.
Claims (12)
1. A method of frequency offset estimation, comprising:
102, carrying out frequency offset pre-compensation processing on received data by using a set pre-compensation value to obtain compensation data;
104, determining a frequency offset estimation value according to pilot frequency data in the compensation data;
step 106, according to the pilot frequency data in the compensation data, performing frequency offset re-compensation processing on the compensation data, and determining the communication quality parameters of the compensation data after the frequency offset re-compensation processing;
step 108, judging whether the current communication quality meets the preset communication quality requirement or not according to the communication quality parameter, if so, executing step 102; if not, resetting the pre-compensation value, and executing the step 102 by using the reset pre-compensation value;
The theoretical frequency offset estimation range is [ -ffreqoffset_ES,ffreqoffset_ES]；
The expected frequency offset estimation range is [ -ffreqoffset,ffreqoffset]；
The following condition is satisfied between the reset pre-compensation value f2 and the original pre-compensation value f 1:
f1＞f2；
|ffreqoffset-f1|<ffreqoffset_ES；
|f1-f2|<ffreqoffset_ES；
|f2-(-ffreqoffset)|<ffreqoffset_ES。
2. the method of claim 1, wherein determining a frequency offset estimate based on pilot data in the compensation data comprises:
calculating a frequency offset value according to pilot frequency data in the compensation data;
and the frequency offset estimation value is the sum of the frequency offset value and a currently set pre-compensation value.
3. The method of claim 1, wherein performing frequency offset re-compensation processing on the compensation data according to pilot data in the compensation data comprises:
and calculating a frequency offset value according to pilot frequency data in the compensation data, and performing frequency offset re-compensation processing on the compensation data by using the frequency offset value.
4. The method of claim 3, wherein the communication quality parameter is a signal to interference plus noise ratio or a cyclic redundancy check result.
5. The method of claim 4, wherein when the communication quality parameter is the signal-to-interference-and-noise ratio, determining whether the current communication quality meets a preset communication quality requirement according to the communication quality parameter comprises:
And if the SINR is less than the preset SINR threshold for the first time, judging that the current communication quality does not meet the preset communication quality requirement, and otherwise, judging that the current communication quality meets the preset communication quality requirement.
6. The method as claimed in claim 4, wherein when the communication quality parameter is a cyclic redundancy check result, determining whether the current communication quality meets a preset communication quality requirement according to the communication quality parameter comprises:
and if the cyclic redundancy check results of the second preset times are all errors, judging that the current communication quality does not meet the preset communication quality requirement, and otherwise, judging that the current communication quality meets the preset communication quality requirement.
7. A frequency offset estimation apparatus, comprising:
the pre-compensation module is used for carrying out frequency offset pre-compensation processing on the received data by using the set pre-compensation value to obtain compensation data;
a determining module, configured to determine a frequency offset estimation value according to pilot data in the compensation data;
the re-compensation module is used for carrying out frequency offset re-compensation processing on the compensation data according to the pilot frequency data in the compensation data and determining the communication quality parameters of the compensation data after the frequency offset re-compensation processing;
The judging module is used for judging whether the current communication quality meets the preset communication quality requirement or not according to the communication quality parameter, and calling the precompensation module under the condition of judging yes; if the judgment result is negative, resetting a pre-compensation value, and calling the pre-compensation module to enable the pre-compensation module to execute frequency offset pre-compensation processing by using the reset pre-compensation value;
the theoretical frequency offset estimation range is [ -ffreqoffset_ES,ffreqoffset_ES]；
The expected frequency offset estimation range is [ -ffreqoffset,ffreqoffset]；
The judging module is used for setting a pre-compensation value; wherein the following condition is satisfied between the reset pre-compensation value f2 and the original pre-compensation value f 1:
f1＞f2；
|ffreqoffset-f1|<ffreqoffset_ES；
|f1-f2|<ffreqoffset_ES；
|f2-(-ffreqoffset)|<ffreqoffset_ES。
8. the apparatus of claim 7, wherein the determination module is to:
calculating a frequency offset value according to pilot frequency data in the compensation data;
and the frequency offset estimation value is the sum of the frequency offset value and a currently set pre-compensation value.
9. The apparatus of claim 7, wherein the re-compensation module is to:
and calculating a frequency offset value according to pilot frequency data in the compensation data, and performing frequency offset re-compensation processing on the compensation data by using the frequency offset value.
10. The apparatus of claim 9, wherein the communication quality parameter is a signal-to-interference-and-noise ratio or a cyclic redundancy check result.
11. The apparatus as claimed in claim 10, wherein when the communication quality parameter is a signal to interference plus noise ratio, the determining module is configured to:
and if the SINR is less than the preset SINR threshold for the first time, judging that the current communication quality does not meet the preset communication quality requirement, and otherwise, judging that the current communication quality meets the preset communication quality requirement.
12. The apparatus as claimed in claim 10, wherein when the communication quality parameter is a cyclic redundancy check result, the determining module is configured to:
and if the cyclic redundancy check results of the second preset times are all errors, judging that the current communication quality does not meet the preset communication quality requirement, and otherwise, judging that the current communication quality meets the preset communication quality requirement.
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| WO2020211054A1 (en) * | 2019-04-18 | 2020-10-22 | 北京小米移动软件有限公司 | Frequency offset determination method and apparatus and resource block transmission method and apparatus |
| CN114337769A (en) * | 2020-09-28 | 2022-04-12 | 华为技术有限公司 | Frequency compensation method and frequency compensation device |
| CN112714089A (en) * | 2020-12-28 | 2021-04-27 | 四川天邑康和通信股份有限公司 | High-frequency 5G base station signal processing method and base station |
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