CN115987740B - Frequency offset estimation method, device, computer equipment and storage medium - Google Patents
Frequency offset estimation method, device, computer equipment and storage medium Download PDFInfo
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Abstract
The application relates to a frequency offset estimation method, a device, computer equipment and a storage medium. The method includes acquiring a signal and channel related information based on a pilot; the signal and channel related information comprises a plurality of time domain paths and time domain path corresponding characteristics, pilot frequency domain distribution intervals, pilot frequency domain offset, subcarrier intervals and time delay intervals between two adjacent time domain symbols with pilot symbols inserted; screening the time domain paths by using a preset threshold value to obtain a plurality of effective paths; acquiring effective path time delay according to the pilot frequency domain distribution interval and the effective path; acquiring a phase change value between two adjacent time domain symbols inserted with pilot symbols according to the effective path time delay, the pilot frequency domain offset, the subcarrier spacing and the effective path; and obtaining a frequency offset estimated value according to the phase change value and the time delay interval. The method can be suitable for frequency offset estimation of the pilot frequency domain distribution asymmetric scene, and has excellent performance on anti-noise interference.
Description
Technical Field
The present disclosure relates to the field of communications technologies, and in particular, to a method, an apparatus, a computer device, and a storage medium for frequency offset estimation.
Background
Mismatch of the oscillators between the transmitter and the receiver or the presence of doppler shift can result in sampling clock frequency deviations, which are simply referred to as frequency offsets. In the field of mobile communications, some technologies, such as OFDM (Orthogonal Frequency Division Multiplexing ), require that the sub-carriers satisfy mutually orthogonal characteristics, and are therefore relatively sensitive to frequency offset. In order to solve the frequency offset problem, the frequency offset is estimated first, and then a compensation scheme is provided for the frequency offset.
In the technology of frequency offset estimation, there is a scheme with excellent anti-noise interference performance, namely, frequency offset measurement is performed by estimating the phase change of time domain paths among different symbols. Specifically, the phase difference of the two pilots is obtained by conjugate multiplication of the time domain tap values of the two time domain symbols, and then the frequency offset of the two pilots is obtained according to the phase difference.
However, the above-mentioned technical solution is only applicable to the case where the pilot frequency domain distribution is symmetrical, but is not applicable to the case where the pilot frequency domain distribution is asymmetrical, and the problem needs to be solved.
Disclosure of Invention
Based on the foregoing, it is necessary to provide a frequency offset estimation method, apparatus, computer device and storage medium suitable for the situation of asymmetric pilot frequency domain distribution.
In a first aspect, the present application provides a method for estimating a frequency offset. The method comprises the following steps:
acquiring signals and channel related information based on the pilot frequency; the signal and channel related information comprises a plurality of time domain paths and time domain path corresponding characteristics, pilot frequency domain distribution intervals, pilot frequency domain offset, subcarrier intervals and time delay intervals between two adjacent time domain symbols with pilot symbols inserted;
screening the time domain paths by using a preset threshold value to obtain a plurality of effective paths;
acquiring effective path time delay according to the pilot frequency domain distribution interval and the effective path;
acquiring a phase change value between two adjacent time domain symbols inserted with pilot symbols according to the effective path time delay, the pilot frequency domain offset, the subcarrier spacing and the effective path;
and obtaining a frequency offset estimated value according to the phase change value and the time delay interval.
In one embodiment, acquiring signals and channel related information based on pilots includes:
channel estimation is carried out based on pilot frequency, and a frequency domain channel estimation value is obtained;
and carrying out inverse Fourier transform on the frequency domain channel estimation value to obtain a time domain tap value for representing the corresponding characteristic of the time domain path.
In one embodiment, the filtering the time domain paths by using a preset threshold value, and obtaining the plurality of effective paths includes:
acquiring a decision reference value corresponding to each time domain path; the decision reference value is the square of the modulus of the time domain tap value corresponding to the time domain path;
multiplying the largest decision reference value in all the decision reference values with a preset threshold value to obtain a first product;
comparing each judgment reference value with the first product, and selecting an effective path from the time domain paths according to the comparison result; the decision reference value corresponding to the effective path is greater than the first product.
In one embodiment, according to the pilot frequency domain distribution interval and the effective path, obtaining the effective path delay includes:
acquiring the relative position of the effective path in the time domain path sequence, and acquiring the effective path time delay by combining the pilot frequency domain distribution interval;
the time domain path sequence is obtained by arranging time domain paths according to time sequence.
In one embodiment, obtaining the phase change value between two adjacent time domain symbols inserted with pilot symbols according to the effective path delay, the pilot frequency domain offset, the subcarrier spacing and the effective path includes: according to the effective path time delay, pilot frequency domain offset and subcarrier spacing, obtaining a phase difference introduced by carrier offset;
for the same effective path, performing conjugate multiplication on two adjacent time domain symbols inserted with pilot symbols corresponding to the time domain tap values of the effective path, and multiplying the time domain tap values with the phase difference to obtain a second product;
summing the second products corresponding to the effective paths to obtain a total number;
and extracting the phase angle of the total number to obtain a phase change value.
In one embodiment, obtaining the frequency offset estimate according to the phase change value and the delay interval includes:
and obtaining a frequency offset estimation value according to the ratio of the phase change value to the time delay interval.
In a second aspect, the present application further provides a frequency offset estimation device. The device comprises:
a parameter acquisition module for acquiring signals and channel related information based on pilot frequency; the signal and channel related information comprises a plurality of time domain paths and time domain path corresponding characteristics, pilot frequency domain distribution intervals, pilot frequency domain offset, subcarrier intervals and time delay intervals between two adjacent time domain symbols with pilot symbols inserted;
the screening module is used for screening the time domain paths by using a preset threshold value to obtain a plurality of effective paths;
the first acquisition module is used for acquiring effective path time delay according to the pilot frequency domain distribution interval and the effective path;
the second acquisition module is used for acquiring a phase change value between two adjacent time domain symbols inserted with pilot symbols according to the effective path time delay, the pilot frequency domain offset, the subcarrier spacing and the effective path;
the estimation module is used for obtaining a frequency offset estimation value according to the phase change value and the time delay interval.
In one embodiment, the parameter obtaining module is further configured to perform channel estimation based on the pilot frequency to obtain a plurality of frequency domain channel estimation values; and carrying out inverse Fourier transform on the frequency domain channel estimation value to obtain a time domain tap value for representing the corresponding characteristic of the time domain path.
In a third aspect, the present application also provides a computer device. The computer device comprises a memory and a processor, the memory stores a computer program, and the processor executes the computer program to realize the following steps:
acquiring signals and channel related information based on the pilot frequency; the signal and channel related information comprises a plurality of time domain paths and time domain path corresponding characteristics, pilot frequency domain distribution intervals, pilot frequency domain offset, subcarrier intervals and time delay intervals between two adjacent time domain symbols with pilot symbols inserted;
screening the time domain paths by using a preset threshold value to obtain a plurality of effective paths;
acquiring effective path time delay according to the pilot frequency domain distribution interval and the effective path;
acquiring a phase change value between two adjacent time domain symbols inserted with pilot symbols according to the effective path time delay, the pilot frequency domain offset, the subcarrier spacing and the effective path;
and obtaining a frequency offset estimated value according to the phase change value and the time delay interval.
In a fourth aspect, the present application also provides a computer-readable storage medium. The computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of:
acquiring signals and channel related information based on the pilot frequency; the signal and channel related information comprises a plurality of time domain paths and time domain path corresponding characteristics, pilot frequency domain distribution intervals, pilot frequency domain offset, subcarrier intervals and time delay intervals between two adjacent time domain symbols with pilot symbols inserted;
screening the time domain paths by using a preset threshold value to obtain a plurality of effective paths;
acquiring effective path time delay according to the pilot frequency domain distribution interval and the effective path;
acquiring a phase change value between two adjacent time domain symbols inserted with pilot symbols according to the effective path time delay, the pilot frequency domain offset, the subcarrier spacing and the effective path; and obtaining a frequency offset estimated value according to the phase change value and the time delay interval.
The frequency offset estimation method, the device, the computer equipment and the storage medium acquire the signal and the channel related information based on the pilot frequency, calculate the phase change value according to the effective path time delay, the pilot frequency domain offset, the subcarrier interval and the effective path in the signal and the channel related information, and can be suitable for frequency offset estimation of the asymmetric scene of the pilot frequency domain distribution; meanwhile, the frequency offset estimation is performed based on inter-symbol time domain tap cross correlation, so that the excellent performance of anti-noise interference is guaranteed.
Drawings
FIG. 1 is a diagram of an application environment of a frequency offset estimation method according to an embodiment;
FIG. 2 is a schematic diagram showing the comparison of the symmetric and asymmetric pilot frequency domain distribution;
FIG. 3 is a flow chart of a method for estimating frequency offset according to an embodiment;
FIG. 4 is a statistical diagram of frequency offset estimation results in one embodiment;
FIG. 5 is a flowchart of a method for estimating frequency offset according to an embodiment;
FIG. 6 is a block diagram of an embodiment of a frequency offset estimation device;
fig. 7 is an internal structural diagram of a computer device in one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
The frequency offset estimation method provided by the embodiment of the application can be applied to an application environment shown in fig. 1. Wherein the terminal 102 communicates with the server 104 via a communication network. The data storage system may store data that the server 104 needs to process. The data storage system may be integrated on the server 104 or may be located on a cloud or other network server. The terminal 102 may be, but is not limited to, various personal computers, notebook computers, smart phones, and tablet computers. The server 104 may be implemented as a stand-alone server or as a server cluster of multiple servers.
In channel estimation, an effective method is to insert a certain number of pilots in an RB (Resource Block), and then perform channel estimation using the inserted pilot sequences at the receiving end. As shown in fig. 2, taking OFDM as an example, an RB occupies 7 OFDM symbols in the time domain and occupies 12 consecutive subcarriers in the frequency domain. One grid in fig. 2 represents one RE (Resource Element), occupies 1 symbol in the time domain, and occupies 1 subcarrier in the frequency domain. The RS (Reference Signal) in fig. 2 is the pilot symbol inserted. The pilot is a known signal that is continuously transmitted at a fixed frequency. The position numbers of the 12 sub-carriers in FIG. 2 are marked from top to bottom by natural numbers from 0 to 11, l 1 And l 2 Respectively representing two different time domain symbols. When l 1 And l 2 The RE resource relations among the pilot symbols are symmetrical when the pilot symbols are all in the number 1, the number 4, the number 7 and the number 10. While when l 1 Upper pilot symbolOccurs in bit 1, bit 4, bit 7 and bit 10, and l 2 When the upper pilot symbol appears in bits 2, 5, 8 and 11, the RE resource relationship between pilot symbols is asymmetric.
In the traditional frequency offset estimation method, the phase difference of two pilot frequencies is obtained by carrying out conjugate multiplication on the time domain tap values of two time domain symbols, and then the frequency offset of the two pilot frequencies is obtained according to the phase difference.
However, the above conventional technical solution is only suitable for a scenario where the frequency domain distribution of the pilot frequency between symbols is symmetric, and when the frequency domain distribution of the pilot frequency between symbols is asymmetric, the phase rotation amount caused by the frequency offset is introduced in the process of calculating the phase difference, so that the frequency offset estimation value cannot be directly calculated.
In one embodiment, as shown in fig. 3, a frequency offset estimation method is provided, which is illustrated by using the method applied to the terminal 102 in fig. 1 as an example, and includes the following steps:
step 302, acquiring signals and channel related information based on pilot frequency; the signal and channel related information includes a plurality of time domain paths and time domain path corresponding characteristics, pilot frequency domain distribution intervals, pilot frequency domain offsets, subcarrier intervals and time delay intervals between two adjacent time domain symbols with pilot symbols inserted.
The transmission data is received at the receiving end by inserting known data (pilot symbols) of a fixed frequency in the transmission data stream. And the receiving end compares the known data with the original pilot frequency symbol according to the change of the known data after the channel attenuation, and obtains the estimated value of the channel attenuation on the time and the subcarrier of the pilot frequency signal, namely, the channel estimation, and obtains the channel related information. And according to the signal received by the receiving end, the related information of the signal can be analyzed and acquired at the same time. Thus, the signal and channel are analyzed to obtain signal and channel related information.
And screening the time domain paths by using a preset threshold value, and setting the time domain paths meeting certain conditions as effective paths. That is, the set of effective paths is a subset of the set of time domain paths. The screening conditions may include power, etc.
The time delay of the time domain path can be obtained through the pilot frequency domain distribution interval, and then the time delay of the effective path can be obtained according to the relation between the effective path and the time domain path.
According to the effective path time delay, pilot frequency domain offset and subcarrier spacing, the phase difference introduced by carrier offset is obtained, and then the phase change value between two time domain symbols is obtained by combining the characteristics of the effective paths of the two time domain symbols. The phase change value is for two adjacent time domain symbols in which pilot symbols are inserted.
And calculating the phase change value and the time delay interval, and finally obtaining the frequency offset estimation value.
In the frequency offset estimation method, the signal and the channel related information are acquired based on the pilot frequency, and the phase change value is calculated according to the effective path time delay, the pilot frequency domain offset, the subcarrier interval and the effective path in the signal and the channel related information, so that the frequency offset estimation method can be suitable for frequency offset estimation of an asymmetric scene of pilot frequency domain distribution; meanwhile, the frequency offset estimation is performed based on the inter-symbol time domain path characteristics, so that the excellent performance of anti-noise interference is guaranteed.
In one embodiment, step 302 includes: channel estimation is carried out based on pilot frequency, and a plurality of frequency domain channel estimation values are obtained; and carrying out inverse Fourier transform on the frequency domain channel estimation value to obtain a time domain tap value for representing the corresponding characteristic of the time domain path.
A method for performing channel estimation based on pilot frequency, such as LS (least square method ), MMSE (MinimumMean Squared Error, minimum mean square error method), and the like, obtains a plurality of frequency domain channel estimation values. And then carrying out inverse Fourier transform on the frequency domain channel estimation value to obtain a time domain tap value. The transformation formula is as follows:
wherein,,
for the frequency domain channel estimate, k represents an index of the frequency domain channel estimate,
n is the number of points of the inverse Fourier transform; />
Representing an inverse fourier transform function; />
Representing the time domain tap values obtained by inverse fourier transform of N-point, < >>
N represents the index of the time domain path.
In one embodiment, the data stream sent by the sending end is a scrambled data stream, and the receiving end needs to perform channel estimation after descrambling, that is, the frequency domain channel estimation value is a frequency domain channel estimation value after descrambling.
In one embodiment, step 304 includes: acquiring a decision reference value corresponding to each time domain path; the decision reference value is the square of the modulus of the time domain tap value corresponding to the time domain path; multiplying the largest decision reference value in all the decision reference values with a preset threshold value to obtain a first product; comparing each judgment reference value with the first product, and selecting an effective path from the time domain paths according to the comparison result; the decision reference value corresponding to the effective path is greater than the first product.
In particular, the method comprises the steps of,
and->
For the time domain symbols obtained according to step 302, respectively>
And time domain symbol->
Time domain tap values, < >>
And->
Is two adjacent time domain symbols with pilot symbols inserted. Where n is the index of the time domain path. The effective diameter is screened from the time domain diameter, which is actually screened according to the time domain tap value corresponding to the time domain diameter, so that the screening is from +.>
And->
Screening->
And->
. The screening method of the effective diameter comprises the following steps: when n satisfies->
When n satisfying the condition is added +.>
A set of components. Wherein (1)>
The square of the modulus of the time domain tap value, in this embodiment the decision reference value;
is the maximum decision reference value; />
I.e. the first product; />
For the preset threshold value, it can be determined according to simulation. Thereby determining->
Correspond to->
A set of components. />
Correspond to->
The set consists of->
Correspond to->
The set of components is determined.
In one embodiment, step 306 includes: acquiring the relative position of the effective path in the time domain path sequence, and acquiring the effective path time delay by combining the pilot frequency domain distribution interval; the time domain path sequence is obtained by arranging time domain paths according to time sequence.
In this embodiment, the relative position of the effective diameter in the time domain diameter sequence is determined by the index of the effective diameter. The indexes N of the time domain path sequences are 0, 1, 2, … and N-1 in sequence, and the indexes of the effective paths are selected from the N time domain paths
For a partial integer between 0 and N-1, the relative position of the effective diameter in the time domain diameter sequence can be expressed as +.>
Ratio to N. The effective path time delay calculation formula is as follows:
wherein,,
is corresponding to->
Is>
The pilot frequency domain distribution interval is expressed in Hz. />
In one embodiment, step 308 comprises: according to the effective path time delay, pilot frequency domain offset and subcarrier spacing, obtaining a phase difference introduced by carrier offset; for the same effective path, performing conjugate multiplication on two adjacent time domain symbols inserted with pilot symbols corresponding to the time domain tap values of the effective path, and multiplying the time domain tap values with the phase difference to obtain a second product; summing the second products corresponding to the effective paths to obtain a total number; and extracting the phase angle of the total number to obtain a phase change value.
The calculation formula of the phase change value is as follows:
wherein,,
，/>
is pilot frequency domain offset, +.>
Is a subcarrier spacing;
is a phase difference; />
For two adjacent time domain symbols with pilot symbols inserted +.>
And->
The result of conjugate multiplication of the time domain tap value corresponding to the effective path.
I.e. the second product. And summing the second products corresponding to the effective paths to obtain the total number. Finally use->
The function extracts the phase angle of the total number to obtain the +.>
And->
Phase change value +.>
。
In one embodiment, step 310 includes: and obtaining a frequency offset estimation value according to the ratio of the phase change value to the time delay interval.
Frequency offset estimation value
The calculation formula of (2) is as follows:
wherein,,
for two adjacent time domain symbols with pilot symbols inserted +.>
And->
Time delay interval between->
Is the phase change value.
In the case of asymmetric pilot frequency symbol frequency domain distribution, the method based on inter-symbol time domain tap cross-correlation can also be used for frequency offset estimation, and the anti-noise interference characteristic based on the time domain tap cross-correlation frequency offset measurement scheme is inherited. The following was demonstrated:
wherein,,
，/>
k represents an index of a frequency domain channel estimation value, N represents an index of a time domain path, and N is the number of points of inverse Fourier transform; for the asymmetric distribution of pilot frequency symbol frequency domain, pilot frequency domain offset +.>
And->
Different; />
Is Gaussian noise; />
For ideal channel estimation value, +.>
Is the pilot frequency domain distribution interval. />
And->
The physical frequency domain carriers actually represented are different, and for better expressing the relation between the two, a single-path channel is assumed, and the ratio is +.>
If 0, then there are:
wherein,,
representing the phase difference introduced due to carrier offset;
；/>
the frequency domain subcarrier spacing is in Hz; />
And the time delay of the time domain path is transmitted for the corresponding channel, and the unit is s. If->
Non-0 and->
And->
Different (frequency domain asymmetric), the term value is not 1./>
Is the amount of phase rotation caused by the frequency offset, wherein +.>
Representing frequency offset, < >>
Is symbol->
And->
Inter-delay intervals. />
And->
The conjugate multiplication result of (2) is derived as follows:
thereby, it is possible to obtain
And->
The result of the conjugate multiplication of (2) is
. Substituting it into the phase change value +.>
The calculation formula of (1) is as follows:
finally, the phase change value can be passed
And obtaining a final frequency offset estimation value.
When the frequency domain distribution of the pilot frequency symbols is asymmetric and symmetric, the time delay between the asymmetric symbols is smaller, and the frequency offset measurement range is larger. The specific deduction is as follows:
it can be seen that the smaller the delay interval, the larger the frequency offset measurement range. For example, in the LET (long Term Evolution ) technology, a CRS (Cell Reference Signal, cell reference signal) pilot symbol is asymmetric on the 0 th and 4 th time domain symbols, symmetric on the 0 th and 7 th time domain symbols, the 0 and 4 time delay intervals are about half of 0 and 7, the frequency offset measurement range is enlarged by nearly one time, and the method is suitable for frequency offset estimation in a high-speed scene. If pilot symbols 0 and 7 are used in LTE, only the frequency offset of plus or minus 1kHz can be estimated, the frequency domain estimation is carried out on the 0 and 4 frequency domain asymmetric symbols by adopting the method, and the frequency offset estimation result of 1.5kHz is shown in figure 4. The abscissa of fig. 4 is the frequency offset estimation, and the ordinate is the CDF (Cumulative Distribution Function, which refers to the cumulative distribution function) for describing the probability distribution of random variables. The performance was evaluated to be good from the frequency offset estimates of AWGN (Additive White Gaussian Noise ) and ETU (Extended TypicalUrban model, extended typical urban model). Compared with the situation that the frequency domain distribution of the pilot frequency symbols is symmetrical, the situation that the frequency domain distribution of the pilot frequency symbols is asymmetrical has larger measurement range of frequency offset, so that the application of the pilot frequency symbols with the asymmetrical frequency domain distribution has a certain practical significance. Accordingly, the method and the device provide for frequency offset estimation under the condition that the frequency domain distribution of the pilot frequency symbols is asymmetric, and are also beneficial to accurately evaluating frequency offset and compensating subsequent frequency offset, so that the demodulation performance of the system is improved.
In one embodiment, as shown in fig. 5, in the LTE network, the eNB is collectively referred to as an Evolved Node B, which is a radio base station in the LTE network. The UE is collectively referred to as User Equipment. After receiving the downlink reference signal from the eNB, the UE obtains a time domain tap value through channel estimation, and then carries out frequency offset estimation according to the time domain tap value. And when the pilot frequency domain distribution is asymmetric, acquiring a frequency offset estimation value according to the frequency offset estimation method based on the time domain tap value.
In one embodiment, the frequency offset estimation method comprises the steps of:
acquiring signals and channel related information based on the pilot frequency; the signal and channel related information comprises a plurality of time domain paths and time domain path corresponding characteristics, pilot frequency domain distribution intervals, pilot frequency domain offset, subcarrier intervals and time delay intervals between two adjacent time domain symbols with pilot symbols inserted; the method for acquiring the characteristics of the time domain path comprises the following steps: obtaining a frequency domain channel estimation value by carrying out channel estimation based on pilot frequency; and carrying out inverse Fourier transform on the frequency domain channel estimation value to obtain a time domain tap value for representing the corresponding characteristic of the time domain path.
Acquiring a decision reference value corresponding to each time domain path; the decision reference value is the square of the modulus of the time domain tap value corresponding to the time domain path; multiplying the largest decision reference value in all the decision reference values with a preset threshold value to obtain a first product; comparing each judgment reference value with the first product, and selecting an effective path from the time domain paths according to the comparison result; the decision reference value corresponding to the effective path is greater than the first product.
Acquiring the relative position of the effective path in the time domain path sequence, and acquiring the effective path time delay by combining the pilot frequency domain distribution interval; the time domain path sequence is obtained by arranging time domain paths according to time sequence.
According to the effective path time delay, pilot frequency domain offset and subcarrier spacing, obtaining a phase difference introduced by carrier offset; for the same effective path, performing conjugate multiplication on two adjacent time domain symbols inserted with pilot symbols corresponding to the time domain tap values of the effective path, and multiplying the time domain tap values with the phase difference to obtain a second product; summing the second products corresponding to the effective paths to obtain a total number; and extracting the phase angle of the total number to obtain a phase change value.
And obtaining a frequency offset estimation value according to the ratio of the phase change value to the time delay interval.
It should be understood that, although the steps in the flowcharts related to the embodiments described above are sequentially shown as indicated by arrows, these steps are not necessarily sequentially performed in the order indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in the flowcharts described in the above embodiments may include a plurality of steps or a plurality of stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of the steps or stages is not necessarily performed sequentially, but may be performed alternately or alternately with at least some of the other steps or stages.
Based on the same inventive concept, the embodiment of the application also provides a frequency offset estimation device for realizing the above related frequency offset estimation method. The implementation scheme of the solution to the problem provided by the apparatus is similar to the implementation scheme described in the above method, so the specific limitation in the embodiments of the one or more frequency offset estimation apparatuses provided below may be referred to the limitation of the frequency offset estimation method hereinabove, and will not be repeated here.
In one embodiment, as shown in fig. 6, there is provided a frequency offset estimation apparatus, including: a parameter acquisition module 602, a screening module 604, a first acquisition module 606, a second acquisition module 608, and an estimation module 610, wherein:
a parameter acquisition module 602, configured to acquire a signal and channel related information based on a pilot; the signal and channel related information comprises a plurality of time domain paths and time domain path corresponding characteristics, pilot frequency domain distribution intervals, pilot frequency domain offset, subcarrier intervals and time delay intervals between two adjacent time domain symbols with pilot symbols inserted;
a screening module 604, configured to screen the time domain paths by using a preset threshold value, so as to obtain a plurality of effective paths;
a first obtaining module 606, configured to obtain an effective path delay according to the pilot frequency domain distribution interval and the effective path;
a second obtaining module 608, configured to obtain a phase change value between two adjacent time domain symbols inserted with pilot symbols according to the effective path delay, the pilot frequency domain offset, the subcarrier spacing, and the effective path;
the estimation module 610 is configured to obtain a frequency offset estimation value according to the phase change value and the delay interval.
The parameter obtaining module 602 is further configured to perform channel estimation based on the pilot frequency, and obtain a frequency domain channel estimation value; and carrying out inverse Fourier transform on the frequency domain channel estimation value to obtain a time domain tap value for representing the corresponding characteristic of the time domain path.
The filtering module 604 is further configured to obtain a decision reference value corresponding to each time domain path; the decision reference value is the square of the modulus of the time domain tap value corresponding to the time domain path; multiplying the largest decision reference value in all the decision reference values with a preset threshold value to obtain a first product; comparing each judgment reference value with the first product, and selecting an effective path from the time domain paths according to the comparison result; the decision reference value corresponding to the effective path is greater than the first product.
The first obtaining module 606 is further configured to obtain a relative position of the effective path in the time domain path sequence, and obtain an effective path delay in combination with the pilot frequency domain distribution interval; the time domain path sequence is obtained by arranging time domain paths according to time sequence.
The second obtaining module 608 is further configured to obtain a phase difference introduced by carrier offset according to the effective path delay, the pilot frequency domain offset, and the subcarrier spacing; for the same effective path, performing conjugate multiplication on two adjacent time domain symbols inserted with pilot symbols corresponding to the time domain tap values of the effective path, and multiplying the time domain tap values with the phase difference to obtain a second product; summing the second products corresponding to the effective paths to obtain a total number; and extracting the phase angle of the total number to obtain a phase change value.
The estimation module 610 is further configured to obtain a frequency offset estimation value according to a ratio of the phase change value to the delay interval.
The above-mentioned various modules in the frequency offset estimation device may be implemented in whole or in part by software, hardware, and combinations thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.
In one embodiment, a computer device is provided, which may be a server, the internal structure of which may be as shown in fig. 7. The computer device includes a processor, a memory, an Input/Output interface (I/O) and a communication interface. The processor, the memory and the input/output interface are connected through a system bus, and the communication interface is connected to the system bus through the input/output interface. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The database of the computer device is used to store the signal data. The input/output interface of the computer device is used to exchange information between the processor and the external device. The communication interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to implement a method of frequency offset estimation.
It will be appreciated by those skilled in the art that the structure shown in fig. 7 is merely a block diagram of some of the structures associated with the present application and is not limiting of the computer device to which the present application may be applied, and that a particular computer device may include more or fewer components than shown, or may combine certain components, or have a different arrangement of components.
In an embodiment, a computer device is provided comprising a memory and a processor, the memory having stored therein a computer program, the processor implementing all the steps of the above-described method embodiments when the computer program is executed.
In one embodiment, a computer readable storage medium is provided, on which a computer program is stored which, when executed by a processor, implements all the steps of the method embodiments described above.
In an embodiment, a computer program product is provided comprising a computer program which, when executed by a processor, implements all the steps of the above-described method embodiments.
It should be noted that, the user information (including, but not limited to, user equipment information, user personal information, etc.) and the data (including, but not limited to, data for analysis, stored data, presented data, etc.) referred to in the present application are information and data authorized by the user or sufficiently authorized by each party, and the collection, use and processing of the related data are required to comply with the related laws and regulations and standards of the related countries and regions.
Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, database, or other medium used in the various embodiments provided herein may include at least one of non-volatile and volatile memory. The nonvolatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical Memory, high density embedded nonvolatile Memory, resistive random access Memory (ReRAM), magnetic random access Memory (Magnetoresistive Random Access Memory, MRAM), ferroelectric Memory (FerroelectricRandom Access Memory, FRAM), phase change Memory (Phase Change Memory, PCM), graphene Memory, and the like. Volatile memory can include random access memory (Random Access Memory, RAM) or external cache memory, and the like. By way of illustration, and not limitation, RAM can be in the form of a variety of forms, such as static random access memory (Static Random Access Memory, SRAM) or dynamic random access memory (Dynamic Random Access Memory, DRAM), and the like. The databases referred to in the various embodiments provided herein may include at least one of relational databases and non-relational databases. The non-relational database may include, but is not limited to, a blockchain-based distributed database, and the like. The processors referred to in the embodiments provided herein may be general purpose processors, central processing units, graphics processors, digital signal processors, programmable logic units, quantum computing-based data processing logic units, etc., without being limited thereto.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the present application. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application shall be subject to the appended claims.
Claims (6)
1. A method for frequency offset estimation, the method comprising:
acquiring signals and channel related information based on the pilot frequency; the signal and channel related information comprises a plurality of time domain paths, corresponding characteristics of the time domain paths, pilot frequency domain distribution intervals, pilot frequency domain offset, subcarrier intervals and time delay intervals between two adjacent time domain symbols with pilot symbols inserted;
screening the time domain paths by using a preset threshold value to obtain a plurality of effective paths;
acquiring effective path time delay according to the pilot frequency domain distribution interval and the effective path;
acquiring a phase change value between two adjacent time domain symbols inserted with pilot symbols according to the effective path time delay, the pilot frequency domain offset, the subcarrier interval and the effective path;
acquiring a frequency offset estimation value according to the ratio of the phase change value to the time delay interval;
the acquiring the signal and the channel related information based on the pilot frequency comprises:
channel estimation is carried out based on pilot frequency, and a plurality of frequency domain channel estimation values are obtained;
performing inverse Fourier transform on the frequency domain channel estimation value to obtain a time domain tap value for representing the corresponding characteristic of the time domain path;
the step of screening the time domain paths by using a preset threshold value, and the step of obtaining a plurality of effective paths comprises the following steps:
acquiring a decision reference value corresponding to each time domain path; the decision reference value is the square of the modulus of the time domain tap value corresponding to the time domain path;
multiplying the largest judgment reference value in all the judgment reference values with the preset threshold value to obtain a first product;
comparing each judgment reference value with the first product, and selecting the effective path from the time domain paths according to comparison results; the decision reference value corresponding to the effective path is greater than the first product.
2. The method of claim 1, wherein the obtaining an effective path delay from the pilot frequency domain distribution interval and the effective path comprises:
acquiring the relative position of the effective diameter in a time domain diameter sequence, and acquiring the effective diameter time delay by combining the pilot frequency domain distribution interval; the time domain path sequence is obtained by arranging the time domain paths in time sequence.
3. The method of claim 1, wherein the obtaining the phase change value between two adjacent time domain symbols with pilot symbols inserted according to the effective path delay, the pilot frequency domain offset, the subcarrier spacing, and the effective path comprises:
acquiring a phase difference introduced by carrier offset according to the effective path delay, the pilot frequency domain offset and the subcarrier interval;
for the same effective path, performing conjugate multiplication on the two adjacent time domain symbols inserted with pilot symbols corresponding to the time domain tap values of the effective path, and multiplying the time domain tap values with the phase difference to obtain a second product;
summing the second products corresponding to the effective paths to obtain a total number;
and extracting the phase angle of the total number to obtain the phase change value.
4. A frequency offset estimation apparatus, the apparatus comprising:
a parameter acquisition module for acquiring signals and channel related information based on pilot frequency; the signal and channel related information comprises a plurality of time domain paths and time domain path corresponding characteristics, pilot frequency domain distribution intervals, pilot frequency domain offset, subcarrier intervals and time delay intervals between two adjacent time domain symbols with pilot symbols inserted;
the screening module is used for screening the time domain paths by using a preset threshold value to obtain a plurality of effective paths;
the first acquisition module is used for acquiring effective path time delay according to the pilot frequency domain distribution interval and the effective path;
the second acquisition module is used for acquiring a phase change value between two adjacent time domain symbols inserted with pilot symbols according to the effective path time delay, the pilot frequency domain offset, the subcarrier interval and the effective path;
the estimation module is used for obtaining a frequency offset estimation value according to the ratio of the phase change value to the time delay interval;
the parameter acquisition module is also used for carrying out channel estimation based on pilot frequency to acquire a plurality of frequency domain channel estimation values; performing inverse Fourier transform on the frequency domain channel estimation value to obtain a time domain tap value for representing the corresponding characteristic of the time domain path;
the screening module is also used for acquiring a judgment reference value corresponding to each time domain path; the decision reference value is the square of the modulus of the time domain tap value corresponding to the time domain path; multiplying the largest judgment reference value in all the judgment reference values with the preset threshold value to obtain a first product; comparing each judgment reference value with the first product, and selecting the effective path from the time domain paths according to comparison results; the decision reference value corresponding to the effective path is greater than the first product.
5. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor implements the steps of the method of any one of claims 1 to 3 when the computer program is executed.
6. A computer readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the method of any of claims 1 to 3.
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