CN117880021B - DC estimation method and device for OFDM signal - Google Patents
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Abstract
The application provides a direct current estimation method and device of an OFDM signal. The method comprises the following steps: carrying out orthogonal frequency division multiplexing demodulation on the received data of the preset set symbols; channel estimation is carried out on the channel frequency response according to the ideal frequency domain data and the second frequency domain data to obtain a first channel response coefficient, and smoothing or low-pass filtering is carried out on the first channel response coefficient to obtain a second channel response coefficient; processing the ideal frequency domain data by adopting a second channel response coefficient to obtain third frequency domain data; if the set bandwidth contains a zero frequency point, filling the third frequency domain data into the set bandwidth of the first frequency domain data to obtain fourth frequency domain data in the full bandwidth; and acquiring a direct current component according to the average value of the reference time sequence data and the received data, wherein the reference time sequence data is obtained by performing orthogonal frequency division multiplexing modulation on the fourth frequency domain data. The technical scheme of the embodiment of the application can improve the measurement accuracy of direct current estimation.
Description
Technical Field
The present application relates to the field of computer technologies, and in particular, to a method and an apparatus for estimating direct current of an OFDM signal.
Background
OFDM (Orthogonal Frequency Division Multiplexing ) is a signal modulation technique.
In the OFDM modulation scheme, the dc offset affects the accuracy of the carrier frequency offset estimation algorithm. In the related art, the dc offset may be determined by summing a plurality of received samples or complex magnitudes of the received samples to obtain a sum value, and dividing the sum value by the number of received samples. The measurement accuracy of the direct current offset estimation by adopting the scheme is low, and the requirements of equipment such as a radio frequency consistency test instrument cannot be met.
Disclosure of Invention
In view of this, the embodiment of the application provides a method and a device for estimating direct current of an OFDM signal, so as to solve the technical problem in the prior art that the measurement accuracy of direct current estimation of the OFDM signal is low.
In a first aspect of an embodiment of the present application, a direct current estimation method of an OFDM signal is provided, where the method includes: carrying out orthogonal frequency division multiplexing demodulation on the received data of the preset set symbols to obtain first frequency domain data, wherein the received data is OFDM data; channel estimation is carried out on channel frequency response according to ideal frequency domain data and second frequency domain data, a first channel response coefficient is obtained, smoothing processing or low-pass filtering processing is carried out on the first channel response coefficient, and a second channel response coefficient is obtained, wherein the second frequency domain data is a part of the first frequency domain data in a preset set bandwidth; processing the ideal frequency domain data by adopting a second channel response coefficient to obtain third frequency domain data; if the set bandwidth contains a zero frequency point, filling the third frequency domain data into the set bandwidth of the first frequency domain data to obtain fourth frequency domain data in the full bandwidth; and acquiring a direct current component according to the average value of the reference time sequence data and the received data, wherein the reference time sequence data is obtained by performing orthogonal frequency division multiplexing modulation on the fourth frequency domain data.
In a second aspect of an embodiment of the present application, there is provided a direct current estimation apparatus for an OFDM signal, the apparatus including: the demodulation module is used for carrying out orthogonal frequency division multiplexing demodulation on the received data of the preset set symbols to obtain first frequency domain data, wherein the received data is OFDM data; the estimation module is used for carrying out channel estimation on the channel frequency response according to ideal frequency domain data and second frequency domain data to obtain a first channel response coefficient, and carrying out smoothing processing or low-pass filtering processing on the first channel response coefficient to obtain a second channel response coefficient, wherein the second frequency domain data is a part of the first frequency domain data in a preset set bandwidth; the processing module is used for processing the ideal frequency domain data by adopting the second channel response coefficient to obtain third frequency domain data; the correction module is used for filling the third frequency domain data into the set bandwidth of the first frequency domain data when the set bandwidth contains a zero frequency point, so as to obtain fourth frequency domain data in the full bandwidth; the acquisition module is used for acquiring a direct current component according to the average value of the reference time sequence data and the received data, wherein the reference time sequence data is obtained by performing orthogonal frequency division multiplexing modulation on the fourth frequency domain data.
In a third aspect of the embodiments of the present application, there is provided an electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, the processor implementing the steps of the above method when executing the computer program.
In a fourth aspect of the embodiments of the present application, there is provided a computer readable storage medium storing a computer program which, when executed by a processor, implements the steps of the above method.
Compared with the prior art, the embodiment of the application has the beneficial effects that: according to the technical scheme, the channel frequency response is subjected to channel estimation to obtain the frequency domain channel response, smoothing or low-pass filtering is carried out on the frequency domain channel response, then the processed frequency domain channel response is used for processing ideal frequency domain data to obtain target frequency domain data, and then the direct current component is obtained according to the target frequency domain data and the received data, so that estimation of the direct current component is realized, and the accuracy of direct current estimation is improved.
Specifically, by performing smoothing processing or low-pass filtering processing on the first channel response coefficient, correction processing on the frequency domain channel response can be realized, and the corrected frequency domain channel response is adopted to process the frequency domain data, so that the accuracy of direct current estimation can be improved, and the technical scheme of the embodiment of the application can eliminate the influence caused by possible synchronous estimation errors and effectively improve the accuracy of direct current estimation.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic flow chart of a direct current estimation method of an OFDM signal according to an embodiment of the present application;
fig. 2 is a schematic flow chart of another dc estimation method of an OFDM signal according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of a dc estimation device for OFDM signals according to an embodiment of the present application;
Fig. 4 is a schematic structural diagram of an electronic device according to an embodiment of the present application.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
In the related art, an estimation of DC (Direct Current) offset may be determined by summing a plurality of received samples or complex magnitudes of the received samples and dividing the sum by the number of received samples. The sum may also be removed by summing a predetermined number of received samples and using the predetermined number. The DC offset may then be stored for future use, or updated periodically to account for changes in aging and changing temperatures.
In the technical scheme in the prior art, the measurement accuracy of DC offset estimation is low, and the requirements of equipment such as a radio frequency consistency test instrument cannot be met.
In order to solve the above technical problems, the technical solution of the embodiments of the present application provides a dc estimation solution for an OFDM signal.
A dc estimation method according to an embodiment of the present application will be described in detail with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of a direct current estimation method of an OFDM signal according to an embodiment of the present application. The method provided by the embodiment of the application can be executed by any electronic device with computer processing capability, such as a terminal or a server. As shown in fig. 1, the direct current estimation method of the OFDM signal includes:
Step S101, orthogonal frequency division multiplexing demodulation is carried out on the received data of the preset set symbols to obtain first frequency domain data, wherein the received data is OFDM data.
Specifically, the set symbol may be a preset known reference symbol, generally a reference symbol of a communication system, or may be a symbol of a known sequence, where the known sequence is a known sequence of received data, and when determining the symbol of the known sequence, an accurate timing position of the symbol may be determined.
Step S102, channel estimation is carried out on channel frequency response according to ideal frequency domain data and second frequency domain data, a first channel response coefficient is obtained, smoothing processing or low-pass filtering processing is carried out on the first channel response coefficient, and a second channel response coefficient is obtained, wherein the second frequency domain data is a part of the first frequency domain data in a preset set bandwidth.
In particular, the ideal frequency domain data is an ideal frequency domain sequence of a signal of the received data, which is a reference sequence of the communication system. Before step S102, a partial sequence of the first frequency domain data allocated within the set bandwidth needs to be extracted to obtain second frequency domain data.
And step S103, processing the ideal frequency domain data by adopting the second channel response coefficient to obtain third frequency domain data.
Specifically, the third frequency domain sequence is a frequency domain sequence obtained by performing channel estimation on the ideal frequency domain sequence according to the second channel response coefficient.
Step S104, if the set bandwidth contains zero frequency point, the third frequency domain data is filled into the set bandwidth of the first frequency domain data, and fourth frequency domain data in the whole bandwidth is obtained.
Specifically, the fourth frequency domain data is frequency domain data after the third frequency domain data is subjected to the correction within the full bandwidth. The set bandwidth may or may not include a zero frequency point. If the set bandwidth does not contain the zero frequency point, after step S101 is performed, the component of the first frequency domain data near the zero frequency point is set to zero, step S102 and step S103 are performed, and the third frequency domain data is filled into the set bandwidth of the first frequency domain data, so as to obtain fourth frequency domain data in the full bandwidth.
Step S105, a direct current component is obtained according to the average value of the reference time sequence data and the received data, wherein the reference time sequence data is obtained by performing orthogonal frequency division multiplexing modulation on the fourth frequency domain data.
The first channel response coefficient is subjected to smoothing processing or low-pass filtering processing, so that correction processing of the frequency domain channel response can be realized, the corrected frequency domain channel response is adopted to process the frequency domain data, and the accuracy of direct current estimation can be improved, so that the technical scheme of the embodiment of the application can eliminate the influence caused by possible synchronous estimation errors, and the accuracy of direct current estimation is effectively improved.
If the set bandwidth does not contain the zero frequency point, setting a first quantity of components of the first frequency domain data nearest to the periphery of the zero frequency point as 0; and filling the third frequency domain data into the set bandwidth of the first frequency domain data to obtain fourth frequency domain data in the full bandwidth.
When the received data of the preset set symbol is subjected to orthogonal frequency division multiplexing demodulation, the received data can be demodulated by adopting fast Fourier transform.
In particular, fourier transforms represent transforms that represent some function that satisfies a certain condition as a trigonometric function or a linear combination of their integrals, which can transform time domain data into corresponding frequency domain data. The discrete fourier transform in embodiments of the present application may be performed using an FFT (Fast Fourier Transform ) algorithm. The number of outputs and inputs of the fast fourier transform is identical. When fast Fourier transform is performed, the size of the Fourier transform can be set according to requirements.
Before the direct current component is obtained according to the average value of the reference time sequence data and the received data, the method further comprises the following steps: and carrying out orthogonal frequency division multiplexing modulation on the fourth frequency domain data by adopting inverse fast Fourier transform to obtain reference time sequence data.
The inverse fourier transform is an operation of solving for its corresponding primitive function F (t) for a given fourier transform F (j ω) and can transform frequency domain data into corresponding time domain data. In the embodiment of the present application, an IFFT (INVERSE FAST Fourier Transform inverse fast fourier transform) algorithm may be used to perform the discrete fourier transform in the embodiment of the present application.
Before the orthogonal frequency division multiplexing demodulation is carried out on the received data of the preset set symbols, if the set symbols are the symbols with known sequences, the orthogonal frequency division multiplexing OFDM signals to be processed can be detected, and ideal frequency domain data and the set symbols with accurate timing positions can be obtained.
In step S102, when channel estimation is performed on the channel frequency response according to the ideal frequency domain data and the second frequency domain data, channel estimation may be performed according to the following formula (1):
（1）
Wherein Y is second frequency domain data, R is ideal frequency domain data, and H is first channel response coefficient.
In step S103, when the ideal frequency domain data is processed using the second channel response coefficient, the ideal frequency domain data may be processed according to the following formula (2):
（2）
Wherein Y1 is third frequency domain data, R is ideal frequency domain data, and H1 is a second channel response coefficient.
Frequency domain channel estimation is a technique for acquiring the characteristics of a communication channel that involves converting an original time domain signal into a frequency domain representation by fourier transformation. In this frequency domain, an appropriate filter can be designed by estimating the frequency response of the channel to improve the accuracy of the channel estimation. Specifically, the received time domain signal X (t) may be first converted into frequency domain data X (f) by fourier transform. Then, the channel frequency response is estimated from the channel model, and a channel filter H (f) is obtained. The resulting channel filter is applied to the frequency domain data X (f) to form a processed signal Y (f). The processed signal Y (f) is transformed back into the time domain signal Y (t) by an inverse fourier transform, resulting in an estimated transmitted signal s (t).
Orthogonal frequency division multiplexing data techniques divide a channel into smaller time-frequency resource units. Through the division of the orthogonal frequency division multiplexing data, a plurality of users can transmit in parallel, and the channel utilization rate is improved. The data and pilot in each time-frequency resource unit are contiguous and consecutive within the orthogonal frequency division multiplexing data subchannel. The orthogonal frequency division multiplexing data technique is implemented by fast fourier transform and inverse fast fourier transform. In the ofdm data, a channel is divided into a plurality of subcarriers, each of which is orthogonal and does not interfere with each other, so that there is no guard interval between the subcarriers. In the ofdm data, a subcarrier is also allocated as a null subcarrier, which does not carry any data, and is used to prevent Inter-carrier interference (Inter-CARRIER INTERFERENCE, ICI for short).
For ease of computation, the size of the fourier transform is typically a power of 2, i.e., 2 n, where n is a natural number. The size of the fourier transform may be referred to as the length of the fourier transform.
The above fourier transform size values are only exemplary descriptions and common values, and in practical applications, the fourier transform size values are not limited thereto, and only needs to ensure that the in-band signal is not damaged.
OFDMA (Orthogonal Frequency Division Multiple Access ) is a multi-user OFDM (Orthogonal Frequency Division Multiplexing, orthogonal frequency division multiplexing) technology, and the main idea of OFDMA is to divide radio resources of a system into Resource Blocks (RBs) from two dimensions of the time domain and the frequency domain, where each user occupies one or more of the Resource blocks. From a frequency domain perspective, a radio resource block includes a plurality of subcarriers; in the time domain, a radio resource block includes a plurality of OFDM symbol periods.
As shown in fig. 2, in the embodiment of the present application, orthogonal frequency division multiplexing demodulation is performed on the received data s 1 (t) of the preset set symbol, so as to obtain first frequency domain data X 1 (f); selecting a part of the first frequency domain data X 1 (f) within a preset set bandwidth to obtain second frequency domain data X 2 (f); channel estimation is carried out on the channel frequency response according to the ideal frequency domain data X 0 (f) and the second frequency domain data X 2 (f), and a first channel response coefficient H 1 (f) is obtained; performing correction processing such as smoothing processing or low-pass filtering processing on the first channel response coefficient H 1 (f) to obtain a second channel response coefficient H 2 (f); and processing the ideal frequency domain data by adopting the second channel response coefficient H 2 (f) to obtain third frequency domain data X 3 (f). If the set bandwidth contains a zero frequency point, filling the third frequency domain data X 3 (f) into the set bandwidth of the first frequency domain data to obtain fourth frequency domain data X 4 (f) in the full bandwidth; performing orthogonal frequency division multiplexing modulation on the fourth frequency domain data X 4 (f) to obtain reference time sequence data s 2 (t); obtaining a DC component from the mean value of the reference time series data s 2 (t) and the received data s 1 (t)。
Specifically, in acquiring the direct current component from the average value of the reference time series data and the received data, the direct current component may be calculated according to the following formula (3)：
（3）
Wherein the function isFor averaging the sequences, the reference timing data s 2 (t) and the received data s 1 (t) are both sequences.
When the technical scheme of the embodiment of the application is applied to an LTE (Long Term Evolution ) system, 1/2 subcarrier offset processing is needed before orthogonal frequency division multiplexing demodulation is carried out on received data according to an OFDM protocol. When the technical scheme of the embodiment of the application is applied to an NR (New Radio)/WIFI (WIRELESS FIDELITY ) system, 1/2 subcarrier offset processing is not needed before orthogonal frequency division multiplexing demodulation is carried out on received data. In addition, when the technical scheme of the embodiment of the application is applied to the WIFI system, the WIFI system does not have special reference symbols, so that the short training sequence and the long training sequence can be used for carrying out the same estimation processing. In addition, the reference signal in the middle of each reference symbol can also be used for direct current estimation, but interpolation is needed after OFDM demodulation, and then frequency domain low-pass filtering or smoothing and other processing is needed.
In the direct current estimation method of the embodiment of the application, the channel frequency response is subjected to channel estimation to obtain the frequency domain channel response, smoothing or low-pass filtering is carried out, then the processed frequency domain channel response is used for processing ideal frequency domain data to obtain target frequency domain data, and then the direct current component is obtained according to the target frequency domain data and the received data, so that the estimation of the direct current component is realized, and the accuracy of direct current estimation is improved.
The following are examples of the apparatus of the present application that may be used to perform the method embodiments of the present application. The dc estimation device described below and the dc estimation method described above may be referred to correspondingly to each other. For details not disclosed in the embodiments of the apparatus of the present application, please refer to the embodiments of the method of the present application.
Fig. 3 is a schematic diagram of a dc estimation device for an OFDM signal according to an embodiment of the present application. As shown in fig. 3, the direct current estimation device of the OFDM signal includes:
The demodulation module 301 is configured to perform OFDM demodulation on received data of a preset set symbol to obtain first frequency domain data, where the received data is OFDM data.
Specifically, the set symbol may be a preset known reference symbol, generally a reference symbol of a communication system, or may be a symbol of a known sequence, where the known sequence is a known sequence of received data, and when determining the symbol of the known sequence, an accurate timing position of the symbol may be determined.
The estimation module 302 is configured to perform channel estimation on the channel frequency response according to the ideal frequency domain data and the second frequency domain data, obtain a first channel response coefficient, and perform smoothing processing or low-pass filtering processing on the first channel response coefficient, so as to obtain a second channel response coefficient, where the second frequency domain data is a portion of the first frequency domain data within a preset set bandwidth.
In particular, the ideal frequency domain data is an ideal frequency domain sequence of a signal of the received data, which is a reference sequence of the communication system. Before step S102, a partial sequence of the first frequency domain data allocated within the set bandwidth needs to be extracted to obtain second frequency domain data.
And the processing module 303 is configured to process the ideal frequency domain data by using the second channel response coefficient to obtain third frequency domain data.
Specifically, the third frequency domain sequence is a frequency domain sequence obtained by performing channel estimation on the ideal frequency domain sequence according to the second channel response coefficient.
And the correction module 304 is configured to fill the third frequency domain data into the set bandwidth of the first frequency domain data when the set bandwidth includes the zero frequency point, and obtain fourth frequency domain data in the full bandwidth.
Specifically, the fourth frequency domain data is frequency domain data after the third frequency domain data is subjected to the correction within the full bandwidth. If the set bandwidth does not contain the zero frequency point, the component of the first frequency domain data near the zero frequency point is set to zero after the first frequency domain data is obtained, then channel estimation is carried out, ideal frequency domain data are processed, and third frequency domain data are filled into the set bandwidth of the first frequency domain data, so that fourth frequency domain data in the whole bandwidth are obtained.
The obtaining module 305 is configured to obtain a direct current component according to an average value of reference time sequence data and received data, where the reference time sequence data is obtained by performing orthogonal frequency division multiplexing modulation on fourth frequency domain data.
The first channel response coefficient is subjected to smoothing processing or low-pass filtering processing, so that correction processing of the frequency domain channel response can be realized, the corrected frequency domain channel response is adopted to process the frequency domain data, and the accuracy of direct current estimation can be improved, so that the technical scheme of the embodiment of the application can eliminate the influence caused by possible synchronous estimation errors, and the accuracy of direct current estimation is effectively improved.
In the embodiment of the present application, the direct current estimation device of the OFDM signal may further include a zero setting module, configured to set, when the set bandwidth does not include a zero frequency point, a first number of components of the first frequency domain data closest to the periphery of the zero frequency point to be 0; the correction module 304 fills the third frequency domain data into the set bandwidth of the first frequency domain data to obtain fourth frequency domain data within the full bandwidth.
The demodulation module 301 may demodulate the received data with a fast fourier transform when performing ofdm demodulation on the received data with the preset symbol. The number of outputs and inputs of the fast fourier transform is identical. When fast Fourier transform is performed, the size of the Fourier transform can be set according to requirements.
In the embodiment of the present application, the direct current estimation device of the OFDM signal may further include a modulation module, where the modulation module is configured to perform orthogonal frequency division multiplexing modulation on the fourth frequency domain data by using inverse fast fourier transform before acquiring the direct current component according to the average value of the reference time sequence data and the received data, so as to obtain the reference time sequence data.
Before the orthogonal frequency division multiplexing demodulation is carried out on the received data of the preset set symbols, if the set symbols are the symbols with known sequences, the orthogonal frequency division multiplexing OFDM signals to be processed can be detected, and ideal frequency domain data and the set symbols with accurate timing positions can be obtained.
The estimation module 302 may perform channel estimation according to the following formula (1) when performing channel estimation on the channel frequency response according to the ideal frequency domain data and the second frequency domain data:
（1）
Wherein Y is second frequency domain data, R is ideal frequency domain data, and H is first channel response coefficient.
The processing module 303 may process the ideal frequency domain data according to the following formula (2) when processing the ideal frequency domain data using the second channel response coefficient:
（2）
Wherein Y1 is third frequency domain data, R is ideal frequency domain data, and H1 is a second channel response coefficient.
Since each functional module of the dc estimation device according to the exemplary embodiment of the present application corresponds to a step of the foregoing exemplary embodiment of the dc estimation method, for details not disclosed in the embodiment of the device according to the present application, please refer to the foregoing embodiment of the dc estimation method according to the present application.
According to the direct current estimation device provided by the embodiment of the application, the channel frequency response is subjected to channel estimation to obtain the frequency domain channel response, smoothing or low-pass filtering is performed, then the processed frequency domain channel response is used for processing ideal frequency domain data to obtain target frequency domain data, and then the direct current component is obtained according to the target frequency domain data and the received data, so that the estimation of the direct current component is realized, and the accuracy of direct current estimation is improved.
Fig. 4 is a schematic diagram of an electronic device 4 according to an embodiment of the present application. As shown in fig. 4, the electronic apparatus 4 of this embodiment includes: a processor 401, a memory 402 and a computer program 403 stored in the memory 402 and executable on the processor 401. The steps of the various method embodiments described above are implemented by processor 401 when executing computer program 403. Or the processor 401, when executing the computer program 403, performs the functions of the modules in the above-described device embodiments.
The electronic device 4 may be a desktop computer, a notebook computer, a palm computer, a cloud server, or the like. The electronic device 4 may include, but is not limited to, a processor 401 and a memory 402. It will be appreciated by those skilled in the art that fig. 4 is merely an example of the electronic device 4 and is not limiting of the electronic device 4 and may include more or fewer components than shown, or different components.
The Processor 401 may be a central processing unit (Central Processing Unit, CPU) or may be other general purpose Processor, digital signal Processor (DIGITAL SIGNAL Processor, DSP), application SPECIFIC INTEGRATED Circuit (ASIC), field-Programmable gate array (Field-Programmable GATE ARRAY, FPGA) or other Programmable logic device, discrete gate or transistor logic device, discrete hardware components, or the like.
The memory 402 may be an internal storage unit of the electronic device 4, for example, a hard disk or a memory of the electronic device 4. The memory 402 may also be an external storage device of the electronic device 4, such as a plug-in hard disk, a smart memory card (SMART MEDIA CARD, SMC), a Secure Digital (SD) card, a flash memory card (FLASH CARD) or the like, which are provided on the electronic device 4. Memory 402 may also include both internal storage units and external storage devices of electronic device 4. The memory 402 is used to store computer programs and other programs and data required by the electronic device.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functional distribution may be performed by different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-described functions. The functional units and modules in the embodiment may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit, where the integrated units may be implemented in a form of hardware or a form of a software functional unit.
The integrated modules, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the present application may implement all or part of the flow of the method of the above embodiment, or may be implemented by a computer program to instruct related hardware, and the computer program may be stored in a computer readable storage medium, where the computer program, when executed by a processor, may implement the steps of each of the method embodiments described above. The computer program may comprise computer program code, which may be in source code form, object code form, executable file or in some intermediate form, etc. The computer readable medium may include: any entity or device capable of carrying computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), an electrical carrier signal, a telecommunications signal, a software distribution medium, and so forth. It should be noted that the content of the computer readable medium can be appropriately increased or decreased according to the requirements of the jurisdiction's jurisdiction and the patent practice, for example, in some jurisdictions, the computer readable medium does not include electrical carrier signals and telecommunication signals according to the jurisdiction and the patent practice.
The above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.
Claims (6)
1. A direct current estimation method of an orthogonal frequency division multiplexing OFDM signal, the direct current estimation method comprising:
Performing orthogonal frequency division multiplexing demodulation on received data of preset set symbols by adopting fast Fourier transform to obtain first frequency domain data, wherein the received data is OFDM data;
Channel estimation is carried out on channel frequency response according to ideal frequency domain data and second frequency domain data, a first channel response coefficient is obtained, smoothing processing or low-pass filtering processing is carried out on the first channel response coefficient, and a second channel response coefficient is obtained, wherein the second frequency domain data is a part of the first frequency domain data in a preset set bandwidth;
Processing the ideal frequency domain data by adopting the second channel response coefficient to obtain third frequency domain data;
if the set bandwidth contains a zero frequency point, filling the third frequency domain data into the set bandwidth of the first frequency domain data to obtain fourth frequency domain data in the full bandwidth;
obtaining a direct current component according to the average value of reference time sequence data and the received data, wherein the reference time sequence data is obtained by performing orthogonal frequency division multiplexing modulation on the fourth frequency domain data by adopting inverse fast Fourier transform;
Wherein performing channel estimation on the channel frequency response according to the ideal frequency domain data and the second frequency domain data comprises: channel estimation is performed according to the following formula:
wherein Y is second frequency domain data, R is ideal frequency domain data, and H is a first channel response coefficient;
processing the ideal frequency domain data using the second channel response coefficient, including: the ideal frequency domain data is processed according to the following formula:
Wherein Y1 is third frequency domain data, R is ideal frequency domain data, and H1 is a second channel response coefficient.
2. The direct current estimation method according to claim 1, wherein if the set bandwidth does not include the zero frequency point, a first number of components of the first frequency domain data closest to the periphery of the zero frequency point are set to 0; and filling the third frequency domain data into the set bandwidth of the first frequency domain data to obtain fourth frequency domain data in the full bandwidth.
3. The direct current estimation method according to claim 1, wherein before performing orthogonal frequency division multiplexing demodulation on the received data of the preset set symbol, the method further comprises:
And detecting the Orthogonal Frequency Division Multiplexing (OFDM) signal to be processed to obtain the ideal frequency domain data and a set symbol with an accurate timing position.
4. A direct current estimation device for an OFDM signal, the device comprising:
the demodulation module is used for carrying out orthogonal frequency division multiplexing demodulation on the received data of the preset set symbols by adopting fast Fourier transform to obtain first frequency domain data, wherein the received data is OFDM data;
The estimation module is used for carrying out channel estimation on channel frequency response according to ideal frequency domain data and second frequency domain data to obtain a first channel response coefficient, and carrying out smoothing processing or low-pass filtering processing on the first channel response coefficient to obtain a second channel response coefficient, wherein the second frequency domain data is a part of the first frequency domain data in a preset set bandwidth;
The processing module is used for processing the ideal frequency domain data by adopting the second channel response coefficient to obtain third frequency domain data;
The correction module is used for filling the third frequency domain data into the set bandwidth of the first frequency domain data when the set bandwidth contains a zero frequency point, so as to obtain fourth frequency domain data in the full bandwidth;
the acquisition module is used for acquiring a direct current component according to the average value of reference time sequence data and the received data, wherein the reference time sequence data is obtained by performing orthogonal frequency division multiplexing modulation on the fourth frequency domain data by adopting inverse fast Fourier transform;
The estimation module is further configured to perform channel estimation on the channel frequency response according to the ideal frequency domain data and the second frequency domain data, and includes: channel estimation is performed according to the following formula:
wherein Y is second frequency domain data, R is ideal frequency domain data, and H is a first channel response coefficient;
The processing module is further configured to process the ideal frequency domain data using the second channel response coefficient, including: the ideal frequency domain data is processed according to the following formula:
Wherein Y1 is third frequency domain data, R is ideal frequency domain data, and H1 is a second channel response coefficient.
5. An electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any of claims 1 to 3 when the computer program is executed.
6. A computer readable storage medium storing a computer program, characterized in that the computer program when executed by a processor implements the steps of the method according to any one of claims 1 to 3.
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