CN109450837B - Sampling frequency offset estimation and compensation method and system - Google Patents
Sampling frequency offset estimation and compensation method and system Download PDFInfo
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- CN109450837B CN109450837B CN201811452250.3A CN201811452250A CN109450837B CN 109450837 B CN109450837 B CN 109450837B CN 201811452250 A CN201811452250 A CN 201811452250A CN 109450837 B CN109450837 B CN 109450837B
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Abstract
The application provides a method and a system for estimating and compensating sampling frequency offset, wherein the method comprises the following steps: determining the windowing position of the current symbol, and acquiring the sampling point of the current symbol from the data cache according to the windowing position; after the absolute value of the sampling point of the current symbol is taken, five sampling values at equal intervals in each symbol period are calculated; utilizing five equal-interval sampling values to iteratively calculate a first decision expression and a second decision expression; and when the sampling frequency offset compensation is determined to be required according to the first decision expression, determining a windowing adjusting parameter by using a second decision expression so as to adjust the windowing position. The method can realize the sampling frequency offset estimation and compensation of the GFSK system only by a small amount of addition and subtraction and comparison operation, overcomes the problem that the symbol synchronization position gradually shifts and makes errors in a receiver due to the sampling frequency offset effect, can realize stable and reliable sampling frequency offset estimation and compensation under the condition of a signal-to-noise ratio as low as 2dB, and is particularly suitable for the high-sensitivity GFSK system.
Description
Technical Field
The present application relates to the field of communications technologies, and in particular, to a method and a system for estimating and compensating sampling frequency offset.
Background
GFSK (gaussian Frequency Shift Keying) modulation has been widely used in bluetooth, bluetooth low energy and various 2.4G proprietary protocol wireless communication systems because of its advantages of constant amplitude envelope, concentrated power spectrum, narrow Frequency spectrum, etc.
However, since the transmitter and the receiver of the wireless communication system usually have different crystal oscillators to provide the operating clocks, and the frequencies of the different crystal oscillators have a certain deviation, and the sampling frequency offset effect is gradually accumulated, the short frame transmission and reception may only result in a certain deterioration of the receiving performance, and the long frame transmission and reception may result in a complete failure of correct reception. For example: assuming that the transmitter and the receiver both use crystal oscillators with the precision of 50ppm, when the deviation directions of the transmitter and the receiver are opposite, the maximum deviation of the clock frequency of the receiver and the transmitter is 100ppm, that is, due to the existence of the deviation of the sampling frequency, every 1 ten thousand data sampling points will deviate by 1 sampling point, and every 10 ten thousand data sampling points will deviate by 10 sampling points cumulatively. In the receiver, even if perfect symbol synchronization is achieved at the beginning of a frame, due to the influence of sampling frequency offset, the original accurate symbol synchronization position will gradually shift and make errors along with the accumulation of the offset number of data sampling points.
Therefore, how to overcome the gradual deviation error of the symbol synchronization position caused by the sampling frequency offset effect in the receiver is a problem that needs to be solved by those skilled in the art.
Disclosure of Invention
In view of this, the present application provides a method and a system for estimating and compensating sampling frequency offset, which overcome the problem of gradual offset error of symbol synchronization position caused by sampling frequency offset effect in a receiver.
In order to achieve the purpose, the application provides the following technical scheme:
a sampling frequency offset estimation and compensation method comprises the following steps:
determining the windowing position of the current symbol, and acquiring the sampling point of the current symbol from the data cache according to the windowing position;
after the absolute value of the sampling point of the current symbol is taken, five sampling values at equal intervals in each symbol period are calculated;
iteratively calculating a first decision expression and a second decision expression by utilizing the five equal-interval sampling values;
and when the sampling frequency offset compensation is determined to be required according to the first decision expression, determining a windowing adjusting parameter by using the second decision expression so as to adjust the windowing position.
Preferably, the determining the windowing position of the current symbol comprises:
when the current symbol is an initial symbol, taking a preset position as a windowing position of the current symbol;
and when the current symbol is not the initial symbol, determining the windowing position of the current symbol according to the windowing position of the previous symbol and the windowing adjusting parameter.
Preferably, the first decision expression is: e (j) ═ E (j-1) + S _2(j) - (S _0(j) + S _4(j))/2, where E (-1) is 0;
the second decision expression is: f (j) -F (j-1) + S _1(j) -S _3(j), wherein F (-1) is 0;
wherein j represents a GFSK symbol counter value, the counting period of the GFSK symbol counter is N, namely the j value is 0-N-1; s _0(j), S _1(j), S _2(j), S _3(j), S _4(j) represent five equally spaced sample values of the jth GFSK symbol, S _0(j) is the sample value of the start position within the GFSK symbol period, S _1(j) is the sample value of the 1/4 position within the GFSK symbol period, S _2(j) is the sample value of the 1/2 position within the GFSK symbol period, S _3(j) is the sample value of the 3/4 position within the GFSK symbol period, S _4(j) is the sample value of the end position within the GFSK symbol period.
Preferably, the determining that the frequency offset compensation needs to be performed by the first decision expression includes:
when the value j of the GFSK symbol counter is N-1, judging whether offset caused by sampling frequency offset exists or not by using the first judgment expression;
and when the value of the first decision expression is less than or equal to a preset threshold value, determining that sampling frequency offset compensation is required.
Preferably, the determining a windowing adjustment parameter by using the second decision expression includes:
judging whether the value of the second judgment expression is greater than or equal to 0;
when the value of the second determination expression is greater than or equal to 0, the windowing adjustment parameter indicates that the symbol synchronization position is adjusted by + M sampling points; when the value of the second judgment expression is less than 0, the windowing adjustment parameter indicates that the symbol synchronization position is adjusted by-M sampling points; and M is a positive integer.
A sampling frequency offset estimation and compensation system, the system comprising:
the symbol windowing unit is used for determining the windowing position of the current symbol and acquiring the sampling point of the current symbol from the data cache according to the windowing position;
the sampling value calculation unit is used for calculating five sampling values at equal intervals in each symbol period after the absolute value of the sampling point of the current symbol is taken;
the iterative computation unit is used for iteratively computing a first decision expression and a second decision expression by utilizing the five equal-interval sampling values;
the judgment unit is used for determining whether the sampling frequency offset compensation is needed or not according to the first judgment expression;
and the adjusting parameter determining unit is used for determining a windowing adjusting parameter by using the second decision expression so as to adjust the windowing position when the sampling frequency offset compensation is determined to be required according to the first decision expression.
Preferably, the symbol windowing unit includes:
the first sub-windowing unit is used for taking a preset position as a windowing position of the current symbol when the current symbol is the initial symbol;
the second sub-windowing unit is used for determining the windowing position of the current symbol according to the windowing position and the windowing adjusting parameter of the previous symbol when the current symbol is not the initial symbol;
and the sampling point acquisition unit is used for acquiring the sampling point of the current symbol from the data cache according to the windowing position determined by the first sub-windowing unit or the second sub-windowing unit.
Preferably, the first decision expression is: e (j) ═ E (j-1) + S _2(j) - (S _0(j) + S _4(j))/2, where E (-1) is 0;
the second decision expression is: f (j) -F (j-1) + S _1(j) -S _3(j), wherein F (-1) is 0;
wherein j represents a GFSK symbol counter value, the counting period of the GFSK symbol counter is N, namely the j value is 0-N-1; s _0(j), S _1(j), S _2(j), S _3(j), S _4(j) represent five equally spaced sample values of the jth GFSK symbol, S _0(j) is the sample value of the start position within the GFSK symbol period, S _1(j) is the sample value of the 1/4 position within the GFSK symbol period, S _2(j) is the sample value of the 1/2 position within the GFSK symbol period, S _3(j) is the sample value of the 3/4 position within the GFSK symbol period, S _4(j) is the sample value of the end position within the GFSK symbol period.
Preferably, the decision unit includes:
the first judgment unit is used for judging whether offset caused by sampling frequency offset exists or not by utilizing the first judgment expression when the value j of the GFSK symbol counter is N-1;
and the first determining unit is used for determining that the sampling frequency offset compensation is required when the value of the first decision expression is less than or equal to a preset threshold value, otherwise, not performing the sampling frequency offset compensation.
Preferably, the adjustment parameter determining unit includes:
a second judgment unit operable to judge whether or not the value of the second judgment expression is greater than or equal to 0;
a second determining unit, configured to adjust + M sampling points of the windowing adjustment parameter indicating symbol synchronization position when the value of the second determination expression is greater than or equal to 0; when the value of the second judgment expression is less than 0, the windowing adjustment parameter indicates that the symbol synchronization position is adjusted by-M sampling points; and M is a positive integer.
According to the technical scheme, the sampling frequency offset estimation and compensation method mainly comprises four key steps of symbol windowing, calculation of five equal-interval sampling values, calculation of two judgment expressions and judgment and generation of symbol windowing adjustment parameters. The frequency offset estimation and compensation method provided by the application can realize the sampling frequency offset estimation and compensation of the GFSK system only by a small amount of addition and subtraction and comparison operation, overcomes the problem that the symbol synchronization position gradually deviates and makes mistakes due to the sampling frequency offset effect in a receiver, can realize stable and reliable sampling frequency offset estimation and compensation under the condition of a signal-to-noise ratio as low as 2dB, and is particularly suitable for a high-sensitivity GFSK system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a flowchart of a sampling frequency offset estimation and compensation method according to an embodiment of the present disclosure;
FIG. 2 is a block diagram illustrating steps for implementing a sampling frequency offset estimation and compensation method according to the present invention;
FIG. 3 is a schematic diagram of an equally spaced sample value calculation provided herein;
fig. 4 is a schematic structural diagram of a sampling frequency offset estimation and compensation system according to a third embodiment of the present application;
fig. 5 is a schematic structural diagram of a symbol windowing unit according to a fourth embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to overcome the problem that the symbol synchronous position gradually deviates and makes mistakes due to the sampling frequency offset effect in a receiver, the application provides a method and a system for estimating and compensating the sampling frequency offset, and the specific scheme is as follows:
example one
An embodiment of the present application provides a sampling frequency offset estimation and compensation method, which is applied to a GFSK modulation system, as shown in fig. 1, and the method includes:
s101, determining the windowing position of the current symbol, and acquiring the sampling point of the current symbol from the data cache according to the windowing position;
specifically, determining the windowing position of the current symbol includes:
when the current symbol is the initial symbol, taking the preset position as the windowing position of the current symbol;
and when the current symbol is not the initial symbol, determining the windowing position of the current symbol according to the windowing position of the previous symbol and the windowing adjusting parameter.
Referring to fig. 2, fig. 2 is a block diagram illustrating steps of a sampling frequency offset estimation and compensation method according to the present application. The data buffer stores 40 continuous sampling point data in total, and in the embodiment, a GFSK symbol after phase difference demodulation in the receiver is oversampled by 8 times, that is, one GFSK symbol contains 8 sampling points in the data buffer. And determining the current windowing position, and acquiring the data sampling point of the current GFSK symbol from the data cache according to the current windowing position. The ideal symbol windowing position is determined by other synchronization modules in the system at the beginning, and is specifically D16 to D23 as the preset position, that is, 8 sampling points of the ith windowing GFSK symbol are X _0(i) ═ D16, X _1(i) ═ D17, X _2(i) ═ D18, and so on. When the windowing position is adjusted by +2 sampling points, 8 sampling points of one windowed GFSK symbol are X _0(i) ═ D (16+2), X _1(i) ═ D (17+2), X _2(i) ═ D (18+2), and so on. When the windowing position is adjusted by-2 sampling points, 8 sampling points of one windowed GFSK symbol are X _0(i) ═ D (16-2), X _1(i) ═ D (17-2), X _2(i) ═ D (18-2), and so on. Since the data buffer module stores 40 continuous sampling point data, the embodiment can adjust the symbol windowing position forward or backward by 16 sampling points at most.
S102, calculating five sampling values at equal intervals in each symbol period after taking the absolute value of the sampling point of the current symbol;
since the value of the sampling point of the current symbol may be a negative value, it is necessary to first take the absolute value of the sampling point of the current symbol, and then calculate five sampling values at equal intervals in each symbol period.
Specifically, the abs function may be used in this application to calculate five equally spaced sample values in each symbol period.
S103, utilizing five equal-interval sampling values to iteratively calculate a first decision expression and a second decision expression;
and S104, when the sampling frequency offset compensation is determined to be needed according to the first decision expression, determining a windowing adjusting parameter by using a second decision expression so as to adjust the windowing position.
It can be known from the above technical solutions that the sampling frequency offset estimation and compensation method provided in the first embodiment of the present application can implement sampling frequency offset estimation and compensation of a GFSK system only with a small number of addition and subtraction and comparison operations, and overcome the problem of gradual offset error of symbol synchronization position caused by sampling frequency offset effect in a receiver, and the scheme can implement stable and reliable sampling frequency offset estimation and compensation under the condition of a signal-to-noise ratio as low as 2dB, and is particularly suitable for a high-sensitivity GFSK system.
Example two
On the basis of the first embodiment, the second embodiment of the present application provides a more specific sampling frequency offset estimation and compensation method, and the main steps can still be seen in fig. 1 and fig. 2, where the method includes:
s101, determining the windowing position of the current symbol, and acquiring the sampling point of the current symbol from the data cache according to the windowing position;
specifically, determining the windowing position of the current symbol includes:
when the current symbol is the initial symbol, taking the preset position as the windowing position of the current symbol;
and when the current symbol is not the initial symbol, determining the windowing position of the current symbol according to the windowing position of the previous symbol and the windowing adjusting parameter.
Referring to fig. 2, fig. 2 is a block diagram illustrating steps of a sampling frequency offset estimation and compensation method according to the present application. The data buffer stores 40 continuous sampling point data in total, and in the embodiment, a GFSK symbol after phase difference demodulation in the receiver is oversampled by 8 times, that is, one GFSK symbol contains 8 sampling points in the data buffer. And determining the current windowing position, and acquiring the data sampling point of the current GFSK symbol from the data cache according to the current windowing position. The ideal symbol windowing position is determined by other synchronization modules in the system at the beginning, and is specifically D16 to D23 as the preset position, that is, 8 sampling points of the ith windowing GFSK symbol are X _0(i) ═ D16, X _1(i) ═ D17, X _2(i) ═ D18, and so on. When the windowing position is adjusted by +2 sampling points, 8 sampling points of one windowed GFSK symbol are X _0(i) ═ D (16+2), X _1(i) ═ D (17+2), X _2(i) ═ D (18+2), and so on. When the windowing position is adjusted by-2 sampling points, 8 sampling points of one windowed GFSK symbol are X _0(i) ═ D (16-2), X _1(i) ═ D (17-2), X _2(i) ═ D (18-2), and so on. Since the data buffer module stores 40 continuous sampling point data, the embodiment can adjust the symbol windowing position forward or backward by 16 sampling points at most.
S102, calculating five sampling values at equal intervals in each symbol period after taking the absolute value of the sampling point of the current symbol;
since the value of the sampling point of the current symbol may be a negative value, it is necessary to first take the absolute value of the sampling point of the current symbol, and then calculate five sampling values at equal intervals in each symbol period.
Firstly, the absolute value of the sampling point value of the GFSK symbol obtained by windowing in the step S101 is taken, then sampling values of five equally spaced positions including the start position, the 1/4 position, the 1/2 position, the 3/4 position and the end position in each GFSK symbol period are calculated, and the sampling values of the ith GFSK symbol are represented by S _0(i), S _1(i), S _2(i), S _3(i) and S _4(i), respectively.
Specifically, the abs function may be used in this application to calculate five equally spaced sample values in each symbol period. A specific calculation schematic diagram can be seen in fig. 3, where S _0(i) ≈ abs (X _0(i)), S _1(i) ═ abs (X _1(i)) + abs (X _2(i)))/2, S _2(i) ═ abs (X _3(i)) + abs (X _4(i)))/2, S _3(i) ═ abs (X _5(i)) + abs (X _6(i)))/2, S _4(i) ≈ abs (X _7 (i)).
S103, utilizing five equal-interval sampling values to iteratively calculate a first decision expression and a second decision expression;
and calculating decision expressions E (j) and F (j), wherein j represents the value of the GFSK symbol counter, the counting period is N, namely the value of j is 0 to N-1, wherein N is a system design parameter and can be specifically determined according to different application simulations.
Iteratively calculating a first decision expression as: e (j) ═ E (j-1) + S _2(j) - (S _0(j) + S _4(j))/2, where E (-1) is 0;
further, the iterative computation second decision expression is: f (j) -F (j-1) + S _1(j) -S _3(j), where F (-1) is 0.
And S104, when the sampling frequency offset compensation is determined to be needed according to the first decision expression, determining a windowing adjusting parameter by using a second decision expression so as to adjust the windowing position.
And when the value j of the GFSK symbol counter is N-1, judging whether offset caused by sampling frequency offset exists or not, and if the value of a first judgment expression E (N-1) is larger than a preset threshold value STR _ TH, indicating that the offset of a sampling position caused by the sampling frequency offset is small, and keeping the symbol windowing position unchanged, namely keeping the windowing adjusting parameter to be 0 without carrying out sampling offset compensation processing. When the value of the first decision expression E (N-1) is less than or equal to the preset threshold value STR _ TH, the further sampling frequency offset compensation processing is required, the sampling frequency offset compensation is realized by adjusting the symbol synchronization position forwards or backwards, and the M sampling points can be obtained by one-time adjustment. When the value of the first decision expression E (N-1) is smaller than or equal to a preset threshold value STR _ TH, further comparing whether the value of the second decision expression F (N-1) is larger than or equal to 0, when F (N-1) is larger than or equal to 0, adjusting the symbol synchronization position by + M sampling points, otherwise, when F (N-1) is smaller than 0, adjusting the symbol synchronization position by-M sampling points. Wherein M is a positive integer, and is usually 1 or 2, that is, 1 or 2 sampling points are adjusted forward or backward at a time, and other values may be selected, which is not limited in this application.
For example, when the counting period N is 2048, i.e., j is 0 to 2047, the first decision expression E (j) ═ E (j-1) + S _2(j) - (S _0(j) + S _4(j))/2 is iteratively calculated, where E (-1) is 0. A second decision expression F (j) ═ F (j-1) + S _1(j) -S _3(j) is calculated further iteratively, where F (-1) is 0.
And when the value j of the GFSK symbol counter is 2047, judging whether offset caused by sampling frequency offset exists, and if the value of a first decision expression E (2047) is greater than a preset threshold value STR _ TH which is 150, indicating that the offset of a sampling position caused by the sampling frequency offset is small, and keeping the symbol windowing position unchanged, namely keeping the windowing adjusting parameter at 0 without carrying out sampling offset compensation processing. When the value of the first decision expression E (2047) is less than or equal to the preset threshold STR _ TH, it indicates that further sampling frequency offset compensation processing is required.
When the value of the first decision expression E (2047) is less than or equal to the preset threshold STR _ TH, further comparing whether the value of the second decision expression F (2047) is greater than or equal to 0, when F (2047) is greater than or equal to 0, the symbol synchronization position is adjusted by +2 sampling points, otherwise, when F (2047) is less than 0, the symbol synchronization position is adjusted by-2 sampling points.
It should be noted that the above is only an example, and the value of each specific parameter may be selected by simulation according to a specific application, and taking N2048 is only one preferred value in this embodiment.
It can be known from the above technical solutions that the sampling frequency offset estimation and compensation method provided in the second embodiment of the present application can implement sampling frequency offset estimation and compensation of a GFSK system only with a small number of addition and subtraction and comparison operations, and overcome the problem of gradual offset error of symbol synchronization position caused by sampling frequency offset effect in a receiver, and the scheme can implement stable and reliable sampling frequency offset estimation and compensation under the condition of a signal-to-noise ratio as low as 2dB, and is particularly suitable for a high-sensitivity GFSK system.
EXAMPLE III
On the basis of the first embodiment, and implementing the method described in the embodiment, a third embodiment of the present application provides a sampling frequency offset estimation and compensation system, as shown in fig. 4, fig. 4 is a schematic structural diagram of the sampling frequency offset estimation and compensation system provided in the third embodiment of the present application, and the system includes: a symbol windowing unit 101, a sample value calculation unit 102, an iterative calculation unit 103, a decision unit 104, and an adjustment parameter determination unit 105, wherein,
the symbol windowing unit 101 is used for determining the windowing position of the current symbol and acquiring the sampling point of the current symbol from the data cache according to the windowing position;
the sampling value calculation unit 102 is configured to calculate five equally spaced sampling values in each symbol period after taking an absolute value of a sampling point of a current symbol;
the iterative computation unit 103 is used for iteratively computing a first decision expression and a second decision expression by utilizing five equal-interval sampling values;
a decision unit 104, configured to determine whether sampling frequency offset compensation is required according to a first decision expression;
and an adjusting parameter determining unit 105, configured to determine a windowing adjusting parameter by using a second decision expression to adjust the windowing position when it is determined that the sampling frequency offset compensation needs to be performed according to the first decision expression.
It can be known from the above technical solutions that the sampling frequency offset estimation and compensation system provided in the first embodiment of the present application can implement sampling frequency offset estimation and compensation of a GFSK system only with a small number of addition and subtraction and comparison operations, and overcome the problem of gradual offset error of symbol synchronization position caused by sampling frequency offset effect in a receiver, and the solution can implement stable and reliable sampling frequency offset estimation and compensation under the condition of a signal-to-noise ratio as low as 2dB, and is particularly suitable for a high-sensitivity GFSK system.
Example four
On the basis of the third embodiment, the fourth embodiment of the present application provides a more specific sampling frequency offset estimation and compensation system, and the main structure of the system can still be seen in fig. 4, where the system includes: a symbol windowing unit 101, a sample value calculation unit 102, an iterative calculation unit 103, a decision unit 104, and an adjustment parameter determination unit 105, wherein,
the symbol windowing unit 101 is used for determining the windowing position of the current symbol and acquiring the sampling point of the current symbol from the data cache according to the windowing position;
specifically, as shown in fig. 5, fig. 5 is a schematic structural diagram of a symbol windowing unit provided in the fourth embodiment of the present application, where the symbol windowing unit includes:
a first sub-windowing unit 201, configured to, when the current symbol is an initial symbol, take a preset position as a windowing position of the current symbol;
a second sub-windowing unit 202, configured to determine, when the current symbol is not the initial symbol, a windowing position of the current symbol according to the windowing position of the previous symbol and the windowing adjustment parameter;
and the sampling point acquisition unit 203 is configured to acquire a sampling point of the current symbol from the data buffer according to the windowing position determined by the first sub-windowing unit or the second sub-windowing unit.
The sampling value calculation unit 102 is configured to calculate five equally spaced sampling values in each symbol period after taking an absolute value of a sampling point of a current symbol;
since the value of the sampling point of the current symbol may be a negative value, it is necessary to first take the absolute value of the sampling point of the current symbol, and then calculate five sampling values at equal intervals in each symbol period.
Firstly, the absolute value of the sampling point value of the GFSK symbol obtained by windowing is taken, then sampling values of five equally spaced positions including the starting position, the 1/4 position, the 1/2 position, the 3/4 position and the ending position in each GFSK symbol period are calculated, and the sampling values of the ith GFSK symbol are represented by S _0(i), S _1(i), S _2(i), S _3(i) and S _4(i), respectively.
Specifically, the abs function may be used in this application to calculate five equally spaced sample values in each symbol period.
The iterative computation unit 103 is used for iteratively computing a first decision expression and a second decision expression by utilizing five equal-interval sampling values;
wherein the first decision expression is: e (j) ═ E (j-1) + S _2(j) - (S _0(j) + S _4(j))/2, where E (-1) is 0;
the second decision expression is: f (j) -F (j-1) + S _1(j) -S _3(j), wherein F (-1) is 0;
wherein j represents a GFSK symbol counter value, the counting period of the GFSK symbol counter is N, namely the j value is 0-N-1; s _0(j), S _1(j), S _2(j), S _3(j), S _4(j) represent five equally spaced sample values of the jth GFSK symbol, S _0(j) is the sample value of the start position within the GFSK symbol period, S _1(j) is the sample value of the 1/4 position within the GFSK symbol period, S _2(j) is the sample value of the 1/2 position within the GFSK symbol period, S _3(j) is the sample value of the 3/4 position within the GFSK symbol period, S _4(j) is the sample value of the end position within the GFSK symbol period.
A decision unit 104, configured to determine whether sampling frequency offset compensation is required according to a first decision expression;
specifically, the decision unit includes:
the first judgment unit is used for judging whether offset caused by sampling frequency offset exists or not by utilizing a first judgment expression when the value j of the GFSK symbol counter is N-1;
and the first determining unit is used for determining that the sampling frequency offset compensation is required when the value of the first decision expression is less than or equal to a preset threshold value, otherwise, not performing the sampling frequency offset compensation.
And an adjusting parameter determining unit 105, configured to determine a windowing adjusting parameter by using a second decision expression to adjust the windowing position when it is determined that the sampling frequency offset compensation needs to be performed according to the first decision expression.
Specifically, the adjustment parameter determining unit includes:
a second judgment unit operable to judge whether or not the value of the second judgment expression is greater than or equal to 0;
a second determining unit, configured to adjust + M sampling points for the symbol synchronization position by the windowing adjustment parameter when the value of the second determination expression is greater than or equal to 0; when the value of the second judgment expression is less than 0, adjusting the symbol synchronization position by the windowing adjustment parameter indication symbols by-M sampling points; m is a positive integer.
In addition, it should be noted that the same or similar parts in the embodiments of the present application may be referred to each other, and are not described in detail in the present application.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (4)
1. A method for estimating and compensating sampling frequency offset, the method comprising:
determining the windowing position of the current symbol, and acquiring the sampling point of the current symbol from the data cache according to the windowing position;
after the absolute value of the sampling point of the current symbol is taken, five sampling values at equal intervals in each symbol period are calculated;
iteratively calculating a first decision expression and a second decision expression by utilizing the five equal-interval sampling values; the first decision expression is: e (j) ═ E (j-1) + S _2(j) - (S _0(j) + S _4(j))/2, where E (-1) is 0; the second decision expression is: f (j) -F (j-1) + S _1(j) -S _3(j), wherein F (-1) is 0; wherein j represents a GFSK symbol counter value, the counting period of the GFSK symbol counter is N, namely the j value is 0-N-1; s _0(j), S _1(j), S _2(j), S _3(j), S _4(j) represent five equally-spaced sampling values of the j-th GFSK symbol, S _0(j) is a sampling value of the start position in the GFSK symbol period, S _1(j) is a sampling value of the 1/4 position in the GFSK symbol period, S _2(j) is a sampling value of the 1/2 position in the GFSK symbol period, S _3(j) is a sampling value of the 3/4 position in the GFSK symbol period, and S _4(j) is a sampling value of the end position in the GFSK symbol period;
when the sampling frequency offset compensation is determined to be required according to the first decision expression, determining a windowing adjusting parameter by using the second decision expression so as to adjust the windowing position; wherein the determining that the frequency offset compensation needs to be performed by the first decision expression comprises: when the value j of the GFSK symbol counter is N-1, judging whether offset caused by sampling frequency offset exists or not by using the first judgment expression; when the value of the first decision expression is smaller than or equal to a preset threshold value, determining that sampling frequency offset compensation is required; the determining a windowing adjustment parameter using the second decision expression comprises: judging whether the value of the second judgment expression is greater than or equal to 0; when the value of the second determination expression is greater than or equal to 0, the windowing adjustment parameter indicates that the symbol synchronization position is adjusted by + M sampling points; when the value of the second judgment expression is less than 0, the windowing adjustment parameter indicates that the symbol synchronization position is adjusted by-M sampling points; and M is a positive integer.
2. The method of claim 1, wherein determining the windowed position for the current symbol comprises:
when the current symbol is an initial symbol, taking a preset position as a windowing position of the current symbol;
and when the current symbol is not the initial symbol, determining the windowing position of the current symbol according to the windowing position of the previous symbol and the windowing adjusting parameter.
3. A sampling frequency offset estimation and compensation system, the system comprising:
the symbol windowing unit is used for determining the windowing position of the current symbol and acquiring the sampling point of the current symbol from the data cache according to the windowing position;
the sampling value calculation unit is used for calculating five sampling values at equal intervals in each symbol period after the absolute value of the sampling point of the current symbol is taken;
the iterative computation unit is used for iteratively computing a first decision expression and a second decision expression by utilizing the five equal-interval sampling values; the first decision expression is: e (j) ═ E (j-1) + S _2(j) - (S _0(j) + S _4(j))/2, where E (-1) is 0; the second decision expression is: f (j) -F (j-1) + S _1(j) -S _3(j), wherein F (-1) is 0; wherein j represents a GFSK symbol counter value, the counting period of the GFSK symbol counter is N, namely the j value is 0-N-1; s _0(j), S _1(j), S _2(j), S _3(j), S _4(j) represent five equally-spaced sampling values of the j-th GFSK symbol, S _0(j) is a sampling value of the start position in the GFSK symbol period, S _1(j) is a sampling value of the 1/4 position in the GFSK symbol period, S _2(j) is a sampling value of the 1/2 position in the GFSK symbol period, S _3(j) is a sampling value of the 3/4 position in the GFSK symbol period, and S _4(j) is a sampling value of the end position in the GFSK symbol period;
the judgment unit is used for determining whether the sampling frequency offset compensation is needed or not according to the first judgment expression; the decision unit includes:
the first judgment unit is used for judging whether offset caused by sampling frequency offset exists or not by utilizing the first judgment expression when the value j of the GFSK symbol counter is N-1;
a first determining unit, configured to determine that sampling frequency offset compensation is required when the value of the first decision expression is less than or equal to a preset threshold, and otherwise, not perform sampling frequency offset compensation;
an adjustment parameter determining unit, configured to determine a windowing adjustment parameter by using the second decision expression to adjust a windowing position when it is determined that sampling frequency offset compensation needs to be performed according to the first decision expression; the adjustment parameter determination unit includes:
a second judgment unit operable to judge whether or not the value of the second judgment expression is greater than or equal to 0;
a second determining unit, configured to adjust + M sampling points of the windowing adjustment parameter indicating symbol synchronization position when the value of the second determination expression is greater than or equal to 0; when the value of the second judgment expression is less than 0, the windowing adjustment parameter indicates that the symbol synchronization position is adjusted by-M sampling points; and M is a positive integer.
4. The system of claim 3, wherein the symbol windowing unit comprises:
the first sub-windowing unit is used for taking a preset position as a windowing position of the current symbol when the current symbol is the initial symbol;
the second sub-windowing unit is used for determining the windowing position of the current symbol according to the windowing position and the windowing adjusting parameter of the previous symbol when the current symbol is not the initial symbol;
and the sampling point acquisition unit is used for acquiring the sampling point of the current symbol from the data cache according to the windowing position determined by the first sub-windowing unit or the second sub-windowing unit.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101022442A (en) * | 2007-01-16 | 2007-08-22 | 西安交通大学 | Joint time synchronizing and frequency-offset estimating method in OFDM system |
| CN102075485A (en) * | 2011-01-20 | 2011-05-25 | 深圳市阿派斯实业有限公司 | Sampling clock synchronization method for orthogonal frequency division multiplexing (OFDM) system |
| CN102480452A (en) * | 2010-11-26 | 2012-05-30 | 中国科学院微电子研究所 | Carrier frequency synchronization circuit and method of OFDM system |
| CN104168224A (en) * | 2013-05-20 | 2014-11-26 | 普天信息技术研究院有限公司 | Frequency offset estimation and compensation method |
| CN106534023A (en) * | 2016-09-20 | 2017-03-22 | 西安电子科技大学 | Timing and carrier united synchronization method of MQAM in non-cooperative communication |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7116727B2 (en) * | 2002-01-30 | 2006-10-03 | Mediatek Inc. | Frequency offset estimation apparatus for intersymbol interference channels |
| US20170180171A1 (en) * | 2015-12-18 | 2017-06-22 | Qualcomm Incorporated | Frequency synchronization of convolutionally coded gfsk signals |
-
2018
- 2018-11-30 CN CN201811452250.3A patent/CN109450837B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101022442A (en) * | 2007-01-16 | 2007-08-22 | 西安交通大学 | Joint time synchronizing and frequency-offset estimating method in OFDM system |
| CN102480452A (en) * | 2010-11-26 | 2012-05-30 | 中国科学院微电子研究所 | Carrier frequency synchronization circuit and method of OFDM system |
| CN102075485A (en) * | 2011-01-20 | 2011-05-25 | 深圳市阿派斯实业有限公司 | Sampling clock synchronization method for orthogonal frequency division multiplexing (OFDM) system |
| CN104168224A (en) * | 2013-05-20 | 2014-11-26 | 普天信息技术研究院有限公司 | Frequency offset estimation and compensation method |
| CN106534023A (en) * | 2016-09-20 | 2017-03-22 | 西安电子科技大学 | Timing and carrier united synchronization method of MQAM in non-cooperative communication |
Non-Patent Citations (1)
| Title |
|---|
| "带频偏校准的GMSK解调器设计与实现";郑婧怡，王志华等;《通信与网络》;20160803;全文 * |
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