CN106453184B - A method and device for frequency offset estimation - Google Patents

Abstract

The embodiment of the invention provides a kind of methods of offset estimation, are related to wireless communication field, can obtain offset estimation in the distribution situation that these subcarriers are investigated in receiving end by adjusting the transmission power of OFDM symbol sub-carriers to be sent.This method includes that the transmission power of the T subcarrier respective to two adjacent OFDM symbols carries out power adjustment, and T is the integer not less than 1 and no more than N, and N is total number of sub-carriers；According to each subcarrier of power emission adjusted；Acquire the reception power of described two all subcarriers of adjacent OFDM symbol；According to the reception power of described two all subcarriers of adjacent OFDM symbol, offset estimation value is calculated.Technical solution provided in an embodiment of the present invention can be suitable for including during carrying out blind estimate to integer frequency bias the systems such as single-input single-output (SISO)-OFDM and multiple-input and multiple-output MIMO-OFDM.

Description

A method and device for frequency offset estimation

【Technical field】

The present invention relates to the field of wireless communication, and in particular, to a method and device for frequency offset estimation.

【Background technique】

As a high-speed wireless transmission technology, Orthogonal Frequency Division Multiplexing (OFDM) technology has the advantages of resisting frequency selective fading and narrowband interference, and supporting high-speed information transmission. field has been widely used. Due to the mismatch of receiver and transmitter oscillators and the time-varying characteristics of the environment in OFDM technology, it is sensitive to carrier frequency offset. The integer frequency offset will cause the demodulation signal to have a cyclic shift, so that the system bit error rate is 50%, so the receiver needs to correct the integer frequency offset. The prior art generally performs blind estimation and compensation for integer frequency offset by transmitting null carriers.

In the process of realizing the present invention, the inventor found that there are at least the following problems in the prior art:

According to the existing frequency offset estimation method, in the process of performing blind estimation and compensation for the integer frequency offset, it is necessary to transmit an empty carrier, which occupies a certain bandwidth and affects normal service transmission.

[Content of the invention]

In view of this, embodiments of the present invention provide a method and apparatus for frequency offset estimation, by adjusting the transmit power of the subcarriers in the OFDM symbol to be sent, and examining the distribution of the subcarriers at the receiving end to obtain the frequency offset estimation value.

In a first aspect, an embodiment of the present invention provides a method for frequency offset estimation, and the method includes:

Perform power adjustment on the transmit power of the T-th sub-carriers of two adjacent OFDM symbols, where T is an integer not less than 1 and not greater than N, and N is the total number of sub-carriers;

Transmit each subcarrier according to the adjusted power;

collecting the received power of all subcarriers of the two adjacent OFDM symbols;

According to the received power of all sub-carriers of the two adjacent OFDM symbols, the estimated frequency offset is calculated and obtained.

In a second aspect, an embodiment of the present invention provides a method for frequency offset estimation, the method comprising:

Perform power adjustment on the transmit power of at least two subcarriers of two adjacent OFDM symbols, the at least two subcarriers include b1 to bJth subcarriers, where b1 to bJ are integers not less than 1 and not greater than N, J is an integer not less than 1 and not greater than N, and N is the total number of subcarriers;

Transmit each subcarrier according to the adjusted power;

collecting the received power of all subcarriers of the two adjacent OFDM symbols;

According to the received power of all sub-carriers of the two adjacent OFDM symbols, the estimated frequency offset is calculated and obtained.

In a third aspect, an embodiment of the present invention provides a method for frequency offset estimation, the method comprising:

performing power adjustment on the transmit power of at least two subcarriers of each of consecutive even OFDM symbols, the consecutive even OFDM symbols including m1th to mzth OFDM symbols, the at least two subcarriers including b1th to bJth subcarriers, b1 to bJ is an integer not less than 1 and not greater than N, J is an integer not less than 1 and not greater than N, N is the total number of subcarriers, and z is not greater than the total number of OFDM symbols;

Transmit each subcarrier according to the adjusted power;

collecting the received power of all subcarriers of the consecutive even-numbered OFDM symbols;

According to the received power of all the subcarriers of the consecutive even-numbered OFDM symbols, the estimated frequency offset is obtained by calculation.

In a fourth aspect, an embodiment of the present invention provides an apparatus for frequency offset estimation, where the apparatus includes:

an adjustment unit, configured to perform power adjustment on the transmit power of the T-th subcarriers of two adjacent OFDM symbols, where T is an integer not less than 1 and not greater than N, and N is the total number of subcarriers;

a transmitting unit, configured to transmit each subcarrier according to the adjusted power;

a collection unit, configured to collect the received power of all subcarriers of the two adjacent OFDM symbols;

A calculation unit, configured to calculate and obtain the estimated frequency offset according to the received powers of all subcarriers of the two adjacent OFDM symbols.

In a fifth aspect, an embodiment of the present invention provides an apparatus for frequency offset estimation, where the apparatus includes:

an adjustment unit, configured to perform power adjustment on the transmit power of at least two subcarriers of two adjacent OFDM symbols, the at least two subcarriers include b1 to bJth subcarriers, and b1 to bJ are not less than 1 and not greater than An integer of N, J is an integer not less than 1 and not greater than N, and N is the total number of subcarriers;

a transmitting unit, configured to transmit each subcarrier according to the adjusted power;

a collection unit, configured to collect the received power of all subcarriers of the two adjacent OFDM symbols;

A calculation unit, configured to calculate and obtain the estimated frequency offset according to the received powers of all subcarriers of the two adjacent OFDM symbols.

In a sixth aspect, an embodiment of the present invention provides an apparatus for frequency offset estimation, where the apparatus includes:

an adjustment unit, configured to perform power adjustment on the transmit power of at least two subcarriers of consecutive even-numbered OFDM symbols, where the consecutive even-numbered OFDM symbols include m1th to mzth OFDM symbols, and the at least two subcarriers include b1th to bJth OFDM symbols subcarriers, b1 to bJ are integers not less than 1 and not greater than N, J is an integer not less than 1 and not greater than N, N is the total number of subcarriers, and z is an integer not greater than the total number of OFDM symbols;

a transmitting unit, configured to transmit each subcarrier according to the adjusted power;

a collection unit, configured to collect the received power of all subcarriers of the consecutive even-numbered OFDM symbols;

A calculation unit, configured to calculate and obtain the estimated frequency offset value according to the received power of all the subcarriers of the consecutive even OFDM symbols.

In a method and device for frequency offset estimation provided by the embodiments of the present invention, the frequency offset estimation can be obtained by adjusting the transmit power of the subcarriers in the OFDM symbol to be sent, and examining the distribution of these subcarriers after discrete Fourier transform at the receiving end. . This frequency offset estimation method does not need to transmit empty carriers or pilots, which saves the effective bandwidth of the system. By selecting multiple subcarriers to obtain channel diversity and using multiple OFDM symbols to participate in frequency offset estimation, the performance of the method under multipath channels is improved, and the accuracy of frequency offset estimation is higher.

【Description of drawings】

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

1 is a flowchart of a method for frequency offset estimation provided by an embodiment of the present invention;

2 is a flowchart of another method for frequency offset estimation provided by an embodiment of the present invention;

3 is a flowchart of another method for frequency offset estimation provided by an embodiment of the present invention;

4 is a flowchart of another method for frequency offset estimation provided by an embodiment of the present invention;

5 is a flowchart of another method for frequency offset estimation provided by an embodiment of the present invention;

6 is a flowchart of another method for frequency offset estimation provided by an embodiment of the present invention;

7 is a flowchart of another method for frequency offset estimation provided by an embodiment of the present invention;

8 is a flowchart of another method for frequency offset estimation provided by an embodiment of the present invention;

9 is a flowchart of another method for frequency offset estimation provided by an embodiment of the present invention;

10 is a flowchart of another method for frequency offset estimation provided by an embodiment of the present invention;

11 is a flowchart of another method for frequency offset estimation provided by an embodiment of the present invention;

12 is a flowchart of another method for frequency offset estimation provided by an embodiment of the present invention;

13 is a flowchart of another method for frequency offset estimation provided by an embodiment of the present invention;

14 is a block diagram of a composition of an apparatus for frequency offset estimation provided by an embodiment of the present invention;

15 is a block diagram of another frequency offset estimation apparatus provided by an embodiment of the present invention;

16 is a block diagram of another frequency offset estimation apparatus provided by an embodiment of the present invention;

17 is a block diagram of another frequency offset estimation apparatus provided by an embodiment of the present invention;

FIG. 18 is a block diagram of another frequency offset estimation apparatus provided by an embodiment of the present invention;

FIG. 19 is a block diagram of another frequency offset estimation apparatus provided by an embodiment of the present invention;

FIG. 20 is a block diagram of another frequency offset estimation apparatus provided by an embodiment of the present invention;

FIG. 21 is a block diagram of another frequency offset estimation apparatus provided by an embodiment of the present invention;

FIG. 22 is a block diagram of another frequency offset estimation apparatus provided by an embodiment of the present invention;

FIG. 23 is a block diagram of another frequency offset estimation apparatus provided by an embodiment of the present invention;

FIG. 24 is a block diagram of another frequency offset estimation apparatus provided by an embodiment of the present invention;

FIG. 25 is a block diagram of another frequency offset estimation apparatus provided by an embodiment of the present invention;

FIG. 26 is a block diagram of another frequency offset estimation apparatus provided by an embodiment of the present invention.

【Detailed ways】

In order to better understand the technical solutions of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

It should be understood that the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. As used in the embodiments of the present invention and the appended claims, the singular forms "a," "the," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise.

It should be understood that the term "and/or" used in this document is only an association relationship to describe the associated objects, indicating that there may be three kinds of relationships, for example, A and/or B, which may indicate that A exists alone, and A and B exist at the same time. B, there are three cases of B alone. In addition, the character "/" in this document generally indicates that the related objects are an "or" relationship.

Depending on the context, the word "if" as used herein can be interpreted as "at" or "when" or "in response to determining" or "in response to detecting." Similarly, the phrases "if determined" or "if detected (the stated condition or event)" can be interpreted as "when determined" or "in response to determining" or "when detected (the stated condition or event)," depending on the context )" or "in response to detection (a stated condition or event)".

The embodiment of the present invention provides a method for frequency offset estimation, which can be applied to the process of blindly estimating integer frequency offset in systems including single-input single-output (SISO)-OFDM and multiple-input multiple-output MIMO-OFDM. As shown in Figure 1, the method includes:

101. Perform power adjustment on the transmit power of the T-th subcarrier of two adjacent OFDM symbols.

Among them, T is an integer not less than 1 and not greater than N, T can take any value within the range, and N is the total number of sub-carriers. The occurrence of T and N in the following description is explained.

Wherein, the OFDM symbol is composed of discrete samples after fast Fourier transform of sub-carriers, and each sample in the symbol contains all sub-carrier information.

102. Transmit each subcarrier according to the adjusted power.

Among them, it is assumed that in the process of transmitting subcarriers, the channel remains unchanged for the duration of two adjacent OFDM symbols.

103. Collect the received powers of all subcarriers of the two adjacent OFDM symbols.

104. Calculate, according to the received powers of all subcarriers of the two adjacent OFDM symbols, an estimated frequency offset value.

In a method for frequency offset estimation provided by an embodiment of the present invention, the frequency offset estimation can be obtained by adjusting the transmit power of the subcarriers in the OFDM symbol to be sent, and examining the distribution of these subcarriers after discrete Fourier transform at the receiving end. This frequency offset estimation method does not need to transmit empty carriers or pilots, which saves the effective bandwidth of the system.

Further, in combination with the foregoing method flow, another possible implementation manner of the embodiment of the present invention provides specific steps for how to perform power adjustment on the transmit power of the T-th subcarrier of each of two adjacent OFDM symbols. The implementation of step 101 provides the following specific process, as shown in FIG. 2 , including:

1011. Adjust the transmit power of the T-th subcarrier of the first OFDM symbol to be greater than the transmit power of all other subcarriers of the first OFDM symbol to obtain the first transmit power.

Wherein, the transmit power of the T-th subcarrier of the first OFDM symbol is denoted as d _m,T , and the first transmit power is βd _m,T .

Among them, m refers to the serial number of the OFDM symbol, and β refers to the power amplification factor, and both m and β appear in the following explanation.

1012. Adjust the transmit power of the T-th subcarrier of the second OFDM symbol to be smaller than the transmit power of all other subcarriers of the second OFDM symbol to obtain the second transmit power.

Wherein, the transmit power of the T-th subcarrier of the second OFDM symbol is d _m+1,T , and the second transmit power is d _m+1,T /β.

Wherein, the two adjacent OFDM symbols include a first OFDM symbol and a second OFDM symbol.

It should be noted that the values of the power amplification factor β and 1/β are relative, and the value of β is not limited, so β can also be used as a power reduction factor.

Further, on the basis of the foregoing method flow, in order to ensure that the total power of each OFDM symbol does not change, in another possible implementation manner of the embodiment of the present invention, how to The power adjustment method for other subcarriers except the Tth subcarrier, as shown in FIG. 3 , includes:

1013. Evenly distribute the power difference between the rated transmit power of a single OFDM and the first transmit power to other sub-carriers except the T-th sub-carrier in the sub-carriers of the first OFDM symbol.

Wherein, the transmit power of other sub-carriers except the T-th sub-carrier in the sub-carriers of the first OFDM symbol is d _m,k , and after power adjustment, the transmit power of other sub-carriers is transformed into

Wherein, k refers to the sequence number of the subcarriers in the OFDM symbol, which is an integer not less than 1 and not greater than N, and the occurrence of k is explained below.

Wherein, d _m,T and d _m,k described above all refer to the transmission power of data on each subcarrier of the first OFDM symbol, and are generally set to be the same.

1014. Evenly distribute the power difference between the rated transmit power of a single OFDM and the second transmit power to other sub-carriers except the T-th sub-carrier in the sub-carriers of the second OFDM symbol.

Wherein, the transmit power of other sub-carriers except the T-th sub-carrier in the sub-carriers of the second OFDM symbol is d _m+1,k . After power adjustment, the transmit power of other sub-carriers is transformed into

Wherein, both d _m+1,T and d _m+1,k described above refer to the transmission power of data on each subcarrier of the second OFDM symbol, and are generally set to be the same.

Further, in combination with the foregoing method flow, another possible implementation manner of the embodiment of the present invention provides a specific method of how to calculate and obtain the estimated frequency offset value according to the received power of all sub-carriers of the two adjacent OFDM symbols step, the following specific flow is provided for the realization of step 104, as shown in Figure 4, including:

1041. Obtain the estimated frequency offset value and the cost function.

Wherein, the estimated frequency offset value refers to a conventional integer frequency offset estimated value.

Wherein, the cost function is related to the adjusted subcarrier power ratio of adjacent OFDM symbols.

1042. Calculate and obtain the estimated frequency offset according to the received power of all subcarriers of the two adjacent OFDM symbols, the estimated frequency offset, and the cost function.

Further, in conjunction with the foregoing method flow, another possible implementation manner of the embodiment of the present invention provides specific steps of how to obtain the cost function, and provides the following specific flow for the implementation of step 1041, including:

Step 1. The symbols d _m and d _m+1 after power allocation are transmitted through the channel, and the conventional integer frequency offset compensation of the traditional method is performed. The received signal after compensation is:

Wherein, the OFDM system adopts constant envelope modulation.

where υ represents the actual value of the integer frequency offset, represents the integer frequency offset estimate (ie, the conventional integer frequency offset estimate), L is the length of the cyclic prefix, W represents the inverse discrete Fourier transform (IDFT) matrix, and all symbols appear in the following for this explanation.

Among them, Φ and H represent the frequency offset matrix and the channel frequency response matrix, respectively:

Φ(υ)=diag{1,e ^j2πυ/N ,…,e j2π ^(N-1)υ/N }

H=diag{Hm _,0 ,Hm _,1 ,...,Hm _,N-1 }.

where w _m represents white Gaussian noise.

Step 2: Calculate the power ratio of the received signal after the compensation, in the case that the integer frequency offset is correctly compensated (ie ), the data modulated on the kth subcarrier is still demodulated to the kth subcarrier, and the received signal after compensation has the following relation:

Wherein, the influence of w _m is ignored when calculating the power ratio of the received signal after compensation.

Wherein, the relational expression of the received signal after compensation does not hold when the integer frequency offset cannot be correctly compensated.

Step 3. According to the above specific process, deduce the cost function of the method:

Wherein, σ refers to the integer frequency offset estimation value obtained according to the technical solution.

Further, in combination with the foregoing method flow, another possible implementation manner of the embodiment of the present invention provides how to use the received power of all subcarriers of the two adjacent OFDM symbols, the estimated frequency offset, and Cost function, the specific steps for calculating the frequency offset estimate value, the following specific procedures are provided for the implementation of step 1042, including:

Step 1. Maximize the cost function to obtain the estimated frequency offset.

Among them, when the frequency offset estimated value When it is equal to the actual value of the frequency offset υ, the cost function achieves the maximum value, so the maximization of the cost function can estimate the estimated frequency offset value, which can be expressed as:

Further, in combination with the foregoing method flow, another possible implementation manner of the embodiment of the present invention provides a specific method of how to calculate and obtain the estimated frequency offset value according to the received power of all sub-carriers of the two adjacent OFDM symbols step, which is also a further simplification of step 1041 and step 1042, the calculation process of the frequency offset estimated value σ does not involve the frequency offset estimated value The following specific flow is provided for the realization of step 104, as shown in FIG. 5, including:

1043. Calculate the ratio of the received power of the kth subcarrier in the first OFDM symbol to the kth subcarrier in the second OFDM symbol.

Wherein, the calculation method of the received power ratio is similar to step 1 and step 2 in step 1041 .

Wherein, the received powers of the kth subcarrier in the first OFDM symbol and the kth subcarrier in the second OFDM symbol do not undergo conventional integer frequency offset compensation, that is,

1044. Determine the Pth subcarrier according to all received power ratios.

Wherein, the received power ratio between the Pth subcarrier in the first OFDM symbol and the Pth subcarrier in the second OFDM symbol is the maximum value among all received power ratios.

Wherein, P refers to the sequence number of the subcarriers in the OFDM symbol, which is an integer not less than 1 and not greater than N.

Among them, when When the maximum value is obtained, k=P.

1045. Determine the estimated frequency offset value according to the absolute value of the difference between P and T.

Among them, the estimated frequency offset values of N sub-carriers are all recorded as P-T, that is, the difference after normalizing the frequencies of sub-carriers P and T, which can be expressed as:

where k∈[0,N-1].

In a method for frequency offset estimation provided by an embodiment of the present invention, the frequency offset estimation can be obtained by adjusting the transmit power of the subcarriers in the OFDM symbol to be sent, and examining the distribution of these subcarriers after discrete Fourier transform at the receiving end. This frequency offset estimation method does not need to transmit empty carriers or pilots, which saves the effective bandwidth of the system.

The embodiment of the present invention provides a method for frequency offset estimation, which can be applied to the process of blindly estimating integer frequency offset in systems including single-input single-output (SISO)-OFDM and multiple-input multiple-output MIMO-OFDM. As shown in Figure 6, the method includes:

201. Perform power adjustment on the transmit power of at least two subcarriers of two adjacent OFDM symbols.

Wherein, the at least two sub-carriers include b1 to bJth sub-carriers, b1 to bJ are integers not less than 1 and not greater than N, J is an integer not less than 1 and not greater than N, and relevant expressions appearing below shall be interpreted accordingly .

202. Transmit each subcarrier according to the adjusted power.

Among them, it is assumed that in the process of transmitting subcarriers, the channel remains unchanged for the duration of two adjacent OFDM symbols.

203. Collect the received powers of all subcarriers of the two adjacent OFDM symbols.

204. Calculate, according to the received powers of all subcarriers of the two adjacent OFDM symbols, an estimated frequency offset value.

In a method for frequency offset estimation provided by the embodiment of the present invention, the frequency offset estimation is obtained by adjusting the transmit power of at least two subcarriers in the OFDM symbol to be sent, and examining the distribution of these subcarriers after discrete Fourier transform at the receiving end. Adjusting the transmit power of at least two subcarriers exploits the diversity of the channel frequency response to combat multipath effects in wireless communication systems. When the b1 to bJth subcarriers are in deep fading, the influence of white Gaussian noise on the estimation of the integer frequency offset is prevented, and the estimation accuracy of the method is improved.

Further, in conjunction with the foregoing method flow, another possible implementation manner of the embodiment of the present invention provides specific steps for how to perform power adjustment on the transmit power of at least two subcarriers of two adjacent OFDM symbols. The implementation of step 201 provides the following specific process, as shown in FIG. 7 , including:

2011 . Adjust the transmit powers of the b1 th to bJth subcarriers of the first OFDM symbol to the first transmit power.

Wherein, the first transmit power is greater than the transmit power of all other subcarriers of the first OFDM symbol.

Wherein, the transmit power of the b1th to bJth subcarriers of the first OFDM symbol is d _m,b , and the first transmit power is βd _m,b .

Among them, the selection of the b1 to bJ subcarriers will affect the performance of the algorithm, and the following three criteria need to be followed:

1) Try to select on the entire frequency band to obtain the maximum channel diversity characteristics.

2) In order to prevent the error caused by the cyclic displacement caused by the frequency offset of the sub-carriers, the distances between the adjacent selected sub-carriers must be different from each other, namely:

c ₁ =b ₂ -b ₁

c ₂ =b ₃ -b ₂ …

c _J =b ₁ -b _J

c _j-1 ≠c _j , 1≤j≤J.

Among them, c refers to the difference between the center frequencies of the two subcarriers.

3) The sum of any two consecutive distances must also be different, namely:

c ₁ +c ₂ ≠c ₃ +c ₄

c ₃ +c ₄ ≠c ₅ +c ₆ …

c _J-1 +c _J ≠c ₁ +c ₂

That is, c _j-1 +c _j ≠c _j+1 +c _j+2 .

2012 . Adjust the transmit powers of the b1 th to bJth subcarriers of the second OFDM symbol to the second transmit power.

Wherein, the second transmit power is smaller than the transmit power of all other subcarriers of the second OFDM symbol.

Wherein, the transmit power of the b1 to bJth subcarriers of the second OFDM symbol is d _m+1,b , and the second transmit power is d _m+1,b /β.

Wherein, the two adjacent OFDM symbols include a first OFDM symbol and a second OFDM symbol.

Further, on the basis of the foregoing method flow, in order to ensure that the total power of each OFDM symbol does not change, in another possible implementation manner of the embodiment of the present invention, how to The power adjustment methods for other subcarriers except the b1th to bJth subcarriers, as shown in FIG. 8 , include:

2013. Evenly distribute the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1 to bJth subcarriers of the first OFDM symbol to the subcarriers of the first OFDM symbol except for the b1th to bJth subcarriers other subcarriers.

Wherein, the transmit power of other sub-carriers except the b1 to bJ sub-carriers in the sub-carriers of the first OFDM symbol is d _m,k . After power adjustment, the transmit power of other sub-carriers is transformed into

Wherein, d _m,b and d _m,k mentioned in the foregoing description both refer to the transmission power of data on each sub-carrier of the first OFDM symbol, and are generally set to be the same.

2014. Evenly distribute the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1 to bJ subcarriers of the second OFDM symbol to dividing the b1 to bJ subcarriers in the subcarriers of the second OFDM symbol other sub-carriers than the carrier.

Wherein, the transmission power of other subcarriers except the b1 to bJ subcarriers in the subcarriers of the second OFDM symbol is d _m+1,k . After power adjustment, the transmission power of other subcarriers is transformed into

Wherein, d _m+1,b and d _m+1,k described above both refer to the transmission power of data on each subcarrier of the second OFDM symbol, and are generally set to be the same.

Further, in combination with the foregoing method flow, another possible implementation manner of the embodiment of the present invention provides a specific method of how to calculate and obtain the estimated frequency offset value according to the received power of all sub-carriers of the two adjacent OFDM symbols step, the following specific flow is provided for the realization of step 204, as shown in Figure 9, including:

2041 . Obtain the estimated frequency offset and the cost functions corresponding to the b1 th to bJ th subcarriers.

Wherein, for the specific steps of how to obtain the cost functions corresponding to the b1 th to bJth subcarriers, please refer to step 1 to step 3 in step 1041 .

Wherein, the frequency offset estimation value refers to an integer frequency offset estimation value in a conventional OFDM system.

2042. Calculate and obtain an estimated frequency offset value according to the received power of all subcarriers of the two adjacent OFDM symbols, the estimated frequency offset value, and the respective cost functions corresponding to the b1 to bJth subcarriers.

Wherein, according to the received power of all subcarriers of the two adjacent OFDM symbols, the estimated frequency offset value, and the corresponding cost functions of the b1 to bJth subcarriers, the obtained frequency offset estimated value can be expressed by the formula as: :

Wherein, σ∈[0,N-1], Γ _J ={b ₁ ,b ₂ ,...,b _J ,b ₁ <b ₂ ...<b _J <N}.

In a method for frequency offset estimation provided by the embodiment of the present invention, the frequency offset estimation is obtained by adjusting the transmit power of at least two subcarriers in an OFDM symbol to be sent, and examining the distribution of these subcarriers after discrete Fourier transform at the receiving end. Adjusting the transmit power of at least two subcarriers exploits the diversity of the channel frequency response to combat multipath effects. When the b1 to bJth subcarriers are in deep fading, the influence of Gaussian white noise on the integer frequency offset estimation is prevented, and the estimation accuracy of the method is improved.

The embodiment of the present invention provides a method for frequency offset estimation, which can be applied to the process of blindly estimating integer frequency offset in systems including single-input single-output (SISO)-OFDM and multiple-input multiple-output MIMO-OFDM. As shown in Figure 10, the method includes:

301. Perform power adjustment on the transmit power of at least two subcarriers in each of consecutive even-numbered OFDM symbols.

Wherein, the consecutive even-numbered OFDM symbols include m1th to mzth OFDM symbols, and the at least two subcarriers include b1th to bJth subcarriers.

Wherein, z is an integer not greater than the total number of OFDM symbols, which is explained below.

302. Transmit each subcarrier according to the adjusted power.

Among them, it is assumed that in the process of transmitting subcarriers, the channel remains unchanged for the duration of consecutive OFDM symbols.

303. Collect the received powers of all the subcarriers of the consecutive even-numbered OFDM symbols.

304. Calculate and obtain an estimated frequency offset value according to the received powers of all subcarriers of the consecutive even OFDM symbols.

A method for frequency offset estimation provided by an embodiment of the present invention is obtained by adjusting the transmit power of at least two sub-carriers of consecutive even-numbered OFDM symbols to be sent, and examining the distribution of these sub-carriers after discrete Fourier transform at the receiving end. Frequency offset estimation. Adjusting the transmit power of consecutive even-numbered OFDM symbol subcarriers prevents the influence of noise on integer frequency offset estimation when other subcarriers except the b1 to bJth subcarriers are in deep fading, and improves the estimation accuracy of the method.

Further, in combination with the foregoing method flow, another possible implementation manner of the embodiment of the present invention provides specific steps of how to perform power adjustment on the transmit power of at least two subcarriers of each of the consecutive even OFDM symbols, The following specific flow is provided for the implementation of step 301, as shown in Figure 11, including:

3011. Adjust the transmit powers of the b1th to bJth subcarriers of the m1th OFDM symbol to the first transmit power.

Wherein, the first transmit power is greater than the transmit power of all other subcarriers of the m1th OFDM symbol.

Wherein, the transmit power of the b1th to bJth subcarriers of the m1th OFDM symbol is d _m1,b , and the first transmit power is βd _m1,b .

where b∈[b1,b2…bJ].

3012. Adjust the transmit powers of the b1th to bJth subcarriers of the m2th OFDM symbol to the second transmit power.

Wherein, the second transmit power is smaller than the transmit power of all other subcarriers of the m2th OFDM symbol.

Wherein, the transmit power of the b1th to bJth subcarriers of the m2th OFDM symbol is d _m2,b , and the second transmit power is d _m2,b /β.

3013 , and so on, until the transmit powers of the b1th to bJth subcarriers of the mz-1th OFDM symbol are all adjusted to the z-1th transmit power.

Wherein, the z-1th transmit power is greater than the transmit power of all other subcarriers of the mz-1th OFDM symbol.

Wherein, the transmit power of the b1th to bJth subcarriers of the mz-1th OFDM symbol is d _mz-1,b , and the z-1th transmit power is βdmz _-1,b .

3014. Adjust the transmit powers of the b1th to bJth subcarriers of the mzth OFDM symbol to the Mth transmit power.

Wherein, the zth transmit power is smaller than the transmit power of all other subcarriers of the mzth OFDM symbol.

Wherein, the transmit power of the b1th to bJth subcarriers of the mzth OFDM symbol is d _mz,b , and the zth transmit power is _dmz,b /β.

Further, on the basis of the foregoing method flow, in order to ensure that the total power of each OFDM symbol does not change, in another possible implementation manner of the embodiment of the present invention, in the mzth OFDM symbol b1 to bJ After the transmit power of each subcarrier is adjusted to the zth transmit power, as shown in Figure 12, it also includes:

3015. Evenly distribute the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1 to bJth subcarriers of the m1th OFDM symbol to other subcarriers in the m1th OFDM symbol except the b1th to bJth subcarriers subcarrier.

Wherein, the transmission power of other subcarriers except the b1th to bJth subcarriers in the subcarriers of the m1th OFDM symbol is d _m1,k . After power adjustment, the transmission power of the other subcarriers is transformed into

Among them, k refers to the sequence number of the subcarriers in the OFDM symbol, and k≠b.

Wherein, both d _m1,b and d _m1,k described above refer to the transmission power of data on each subcarrier of the m1th OFDM symbol, and are generally set to be the same.

3016. Evenly distribute the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1th to bJth subcarriers of the m2th OFDM symbol to the subcarriers of the m2th OFDM symbol except for the b1th to bJth subcarriers other subcarriers.

Wherein, the transmission power of other subcarriers except the b1 to bJ subcarriers in the subcarriers of the m2th OFDM symbol is d _m2,k . After power adjustment, the transmission power of the other subcarriers is transformed into

Wherein, both d _m2,b and d _m2,k described above refer to the transmission power of data on each subcarrier of the m2th OFDM symbol, and are generally set to be the same.

3017. By analogy, until the power difference between the rated transmit power of a single OFDM and the sum of the transmit powers of the b1 to bJth subcarriers of the mz OFDM symbol is evenly allocated to dividing the b1th to bJth subcarriers in the mzth OFDM symbol Subcarriers other than bJ subcarriers.

Wherein, the transmission power of other subcarriers except the b1th to bJth subcarriers in the subcarriers of the mzth OFDM symbol is d _mz,k . After power adjustment, the transmission power of other subcarriers is transformed into

Wherein, both d _mz,b and d _mz,k described above refer to the transmission power of data on each subcarrier of the mzth OFDM symbol, and are generally set to be the same.

Further, in combination with the foregoing method flow, another possible implementation manner of the embodiment of the present invention provides specific steps of how to calculate and obtain the estimated frequency offset value according to the received power of all subcarriers of the consecutive even OFDM symbols , the following specific flow is provided for the realization of step 304, as shown in Figure 13, including:

3041 . Obtain the estimated frequency offset and the cost functions corresponding to the b1 th to bJ th subcarriers corresponding to the OFDM symbol pair.

The OFDM symbol pair is one of two adjacent OFDM component symbol pairs in the m1th to mzth OFDM.

Wherein, the frequency offset estimation value refers to an integer frequency offset estimation value in a conventional OFDM system.

Wherein, for the specific steps of obtaining the cost functions corresponding to the b1 to bJ th subcarriers corresponding to the OFDM symbol pair, please refer to steps 1 to 3 in step 1041 .

Wherein, the logarithm of the OFDM symbols is z/2, and correspondingly, the cost function that can be obtained for each possible frequency offset estimation value is also z/2.

3042. Calculate and obtain the estimated frequency offset value according to the received power of all subcarriers corresponding to the OFDM symbol pair, the estimated frequency offset value, and the respective cost functions corresponding to the b1 to bJth subcarriers corresponding to the OFDM symbol pair.

Wherein, the cost functions corresponding to the b1th to bJth subcarriers corresponding to the OFDM symbol pair are the optimal values among the z/2 cost functions.

Wherein, the optimal value of the cost function is the minimum value.

The process of judging that the optimal value of the cost function is the minimum value is as follows:

Combining steps 1 to 3 in step 1041, the cost functions corresponding to the b1th to bJth subcarriers corresponding to the mth OFDM symbol and the m+1th OFDM symbol pair are in When the value is:

If it is not the T-th subcarrier, but other subcarriers are in deep fading, even a small noise can make the denominator tend to zero and cause misjudgment, so when the cost function is the optimal value, the corresponding function The value should be the smallest, that is, the optimal value of the cost function is the smallest value.

Wherein, according to the received power of all subcarriers corresponding to the OFDM symbol pair, the estimated frequency offset value, and the cost functions corresponding to the b1 to bJth subcarriers corresponding to the OFDM symbol pair, the frequency offset estimated value is obtained, and the formula can be used Expressed as:

Wherein, σ∈[0,N-1], Γ _J ={b ₁ ,b ₂ ,...,b _J ,b ₁ <b ₂ ...<b _J <N}.

where m∈[0,2,…z-4,z-2].

Among them, it should be noted that m, m+1, m1, m2...mz-1, mz all represent the serial number of the OFDM symbol. For the convenience of expression, we use different expressions.

A method for frequency offset estimation provided by an embodiment of the present invention is obtained by adjusting the transmit power of at least two sub-carriers of consecutive even-numbered OFDM symbols to be sent, and examining the distribution of these sub-carriers after discrete Fourier transform at the receiving end. Frequency offset estimation. Adjusting the transmit power of consecutive even-numbered OFDM symbol subcarriers prevents the influence of noise on integer frequency offset estimation when other subcarriers except the b1 to bJth subcarriers are in deep fading, and improves the estimation accuracy of the method.

An embodiment of the present invention provides an apparatus for frequency offset estimation, which can be used to implement the flow of the foregoing methods, and its composition is shown in FIG. 14 , including:

The adjustment unit 41 is configured to perform power adjustment on the transmit power of the T-th sub-carrier of two adjacent OFDM symbols, where T is an integer not less than 1 and not greater than N, and N is the total number of sub-carriers.

The transmitting unit 42 is configured to transmit each subcarrier according to the adjusted power.

The collecting unit 43 is configured to collect the received powers of all subcarriers of the two adjacent OFDM symbols.

The calculating unit 44 is configured to calculate and obtain the estimated frequency offset value according to the received power of all subcarriers of the two adjacent OFDM symbols.

Optionally, as shown in FIG. 15 , the adjustment unit 41 includes:

The first adjustment module 411 is configured to adjust the transmission power of the T-th subcarrier of the first OFDM symbol to be greater than the transmission power of all other subcarriers of the first OFDM symbol to obtain the first transmission power.

The second adjustment module 412 is configured to adjust the transmission power of the T-th subcarrier of the second OFDM symbol to be smaller than the transmission power of all other subcarriers of the second OFDM symbol to obtain the second transmission power.

Wherein, the two adjacent OFDM symbols include a first OFDM symbol and a second OFDM symbol.

Optionally, as shown in FIG. 16 , the adjustment unit 41 further includes:

The first allocating module 413 is configured to evenly allocate the power difference between the rated transmit power of a single OFDM and the first transmit power to other subcarriers except the Tth subcarrier in the subcarriers of the first OFDM symbol .

The second allocating module 414 is configured to evenly allocate the power difference between the rated transmit power of a single OFDM and the second transmit power to other subcarriers except the Tth subcarrier in the subcarriers of the second OFDM symbol .

Optionally, as shown in FIG. 17 , the computing unit 44 includes:

The obtaining module 441 is used to obtain the estimated frequency offset value and the cost function.

The first calculation module 442 is configured to calculate and obtain the estimated frequency offset according to the received power of all subcarriers of the two adjacent OFDM symbols, the estimated frequency offset and the cost function.

Optionally, as shown in FIG. 18 , the computing unit 44 further includes:

The second calculation module 443 is configured to calculate the received power ratio between the kth subcarrier in the first OFDM symbol and the kth subcarrier in the second OFDM symbol.

The first determination module 444 is configured to determine the pth subcarrier according to all received power ratios; wherein, the received power ratio of the pth subcarrier in the first OFDM symbol to the pth subcarrier in the second OFDM symbol is all received power ratios the maximum value in .

The second determination module 445 determines the estimated frequency offset value according to the absolute value of the difference between P and T.

An apparatus for frequency offset estimation provided by an embodiment of the present invention can obtain frequency offset estimation by adjusting the transmit power of subcarriers in the to-be-sent OFDM symbol, and examining the distribution of these subcarriers after discrete Fourier transform at the receiving end. This device for frequency offset estimation does not need to transmit null carriers or pilots, which saves the effective bandwidth of the system.

An embodiment of the present invention provides an apparatus for frequency offset estimation, which can be used to implement the flow of the foregoing methods, and its composition is shown in FIG. 19 , including:

An adjustment unit 51, configured to perform power adjustment on the transmit power of at least two subcarriers of two adjacent OFDM symbols, where the at least two subcarriers include b1 to bJth subcarriers, and b1 to bJ are not less than 1 and not less than 1 An integer greater than N, J is an integer not less than 1 and not greater than N, and N is the total number of subcarriers.

The transmitting unit 52 is configured to transmit each subcarrier according to the adjusted power.

The collecting unit 53 is configured to collect the received power of all subcarriers of the two adjacent OFDM symbols.

The calculating unit 54 is configured to calculate and obtain the estimated frequency offset value according to the received power of all subcarriers of the two adjacent OFDM symbols.

Optionally, as shown in FIG. 20 , the adjustment unit 51 includes:

The first adjustment module 511 is configured to adjust the transmit power of the b1th to bJth subcarriers of the first OFDM symbol to a first transmit power, where the first transmit power is greater than that of all other subcarriers of the first OFDM symbol transmit power.

The second adjustment module 512 is configured to adjust the transmit power of the b1th to bJth subcarriers of the second OFDM symbol to a second transmit power, where the second transmit power is smaller than that of all other subcarriers of the second OFDM symbol transmit power.

Wherein, the two adjacent OFDM symbols include a first OFDM symbol and a second OFDM symbol.

Optionally, as shown in FIG. 21 , the adjustment unit 51 further includes:

The first allocating module 513 is configured to equally distribute the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1 to bJth subcarriers of the first OFDM symbol to the subcarriers of the first OFDM symbol divided by the th Subcarriers other than b1 to bJ subcarriers.

The second allocating module 514 is configured to equally allocate the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1 to bJth subcarriers of the second OFDM symbol to the subcarriers of the second OFDM symbol divided by Other subcarriers except the b1th to bJth subcarriers.

Optionally, as shown in Figure 22, the computing unit 54 includes:

The obtaining module 541 is configured to obtain the estimated frequency offset value and the corresponding cost functions of the b1 th to bJth subcarriers.

A calculation module 542, configured to calculate and obtain a frequency offset estimate according to the received power of all subcarriers of the two adjacent OFDM symbols, the estimated frequency offset value, and the respective cost functions corresponding to the b1 to bJth subcarriers value.

An apparatus for frequency offset estimation provided by an embodiment of the present invention obtains a frequency offset estimation by adjusting the transmit power of at least two subcarriers in an OFDM symbol to be sent, and examining the distribution of these subcarriers after discrete Fourier transform at the receiving end. Adjusting the transmit power of at least two subcarriers exploits the diversity of the channel frequency response to combat multipath effects. The influence of white Gaussian noise on the estimation of the integer frequency offset is prevented when the subcarriers b1 to bJ are in deep fading, and the estimation accuracy is improved.

An embodiment of the present invention provides an apparatus for frequency offset estimation, which can be used to implement the flow of the foregoing methods. The composition is shown in FIG. 23 , including:

An adjustment unit 61, configured to perform power adjustment on the transmit power of at least two subcarriers of consecutive even-numbered OFDM symbols, where the consecutive even-numbered OFDM symbols include m1th to mzth OFDM symbols, and the at least two subcarriers include b1th to mzth OFDM symbols bJ subcarriers, b1 to bJ are integers not less than 1 and not greater than N, J is an integer not less than 1 and not greater than N, N is the total number of subcarriers, and z is an integer not greater than the total number of OFDM symbols.

The transmitting unit 62 is configured to transmit each subcarrier according to the adjusted power.

The collecting unit 63 is configured to collect the received powers of all the subcarriers of the consecutive even-numbered OFDM symbols.

The calculating unit 64 is configured to calculate and obtain the estimated frequency offset value according to the received power of all the subcarriers of the consecutive even OFDM symbols.

Optionally, as shown in Figure 24, the adjustment unit 61 includes:

The first adjustment module 611 is configured to adjust the transmit power of the b1 to bJ th subcarriers of the m1th OFDM symbol to a first transmit power, where the first transmit power is greater than the transmit power of all other subcarriers of the m1th OFDM symbol .

The second adjustment module 612 is configured to adjust the transmit power of the b1 th to bJ th subcarriers of the m2th OFDM symbol to a second transmit power, where the second transmit power is smaller than the transmit power of all other subcarriers of the m2th symbol .

The third adjustment module 613, and so on, is configured to adjust the transmit power of the b1th to bJth subcarriers of the mz-1th OFDM symbol to the z-1th transmit power, where the z-1th transmit power is greater than the z-1th transmit power. The transmit power of all other subcarriers of the mz-1 OFDM symbol.

The fourth adjustment module 614 is configured to adjust the transmit power of the b1th to bJth subcarriers of the mzth OFDM symbol to the zth transmit power, where the zth transmit power is smaller than the transmit power of all other subcarriers of the mzth symbol .

Optionally, as shown in FIG. 25 , the adjustment unit 61 further includes:

The first allocating module 615 is configured to equally distribute the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1 to bJth subcarriers of the m1th OFDM symbol to the subcarriers of the m1th OFDM symbol divided by the b1th to bJth subcarriers. Subcarriers other than bJ subcarriers.

The second allocating module 616 is configured to equally distribute the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1 to bJth subcarriers of the m2th OFDM symbol to the subcarriers of the m2th OFDM symbol by dividing the Subcarriers other than b1 to bJ subcarriers.

The third allocating module 617, and so on, is configured to evenly allocate the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1 to bJ th subcarriers of the mz OFDM symbol to the subcarriers in the mz OFDM symbol Subcarriers other than the b1 to bJth subcarriers.

Optionally, as shown in Figure 26, the computing unit 64 includes:

The obtaining module 641 is configured to obtain the estimated frequency offset and the cost functions corresponding to the b1th to bJth subcarriers corresponding to the OFDM symbol pair, where the OFDM symbol pair is composed of two adjacent OFDM symbols in the m1th to mzth OFDM one of the pair.

The calculation module 642 is configured to calculate the frequency offset according to the received power of all subcarriers corresponding to the OFDM symbol pair, the estimated frequency offset value, and the cost functions corresponding to the b1th to bJth subcarriers corresponding to the OFDM symbol pair. estimated value.

An apparatus for frequency offset estimation provided by an embodiment of the present invention is obtained by adjusting the transmit power of at least two sub-carriers of consecutive even-numbered OFDM symbols to be sent, and examining the distribution of these sub-carriers after discrete Fourier transform at the receiving end. Frequency offset estimation. Adjusting the transmit power of consecutive even-numbered OFDM symbol subcarriers prevents the influence of noise on integer frequency offset estimation when other subcarriers except the b1 to bJth subcarriers are in deep fading, and improves estimation accuracy.

Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system, device and unit described above may refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

In the several embodiments provided by the present invention, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined. Either it can be integrated into another system, or some features can be omitted, or not implemented. On the other hand, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware, or may be implemented in the form of hardware plus software functional units.

The above-mentioned integrated units implemented in the form of software functional units can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, and includes several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor (Processor) to execute the methods described in the various embodiments of the present invention. some steps. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program codes .

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the present invention. within the scope of protection.

Claims (18)

1. a method for frequency offset estimation, is characterized in that, comprises: Perform power adjustment on the transmit power of the T-th sub-carriers of two adjacent OFDM symbols, where T is an integer not less than 1 and not greater than N, and N is the total number of sub-carriers; Transmit each subcarrier according to the adjusted power; collecting the received power of all subcarriers of the two adjacent OFDM symbols; According to the received power of all sub-carriers of the two adjacent OFDM symbols, the estimated frequency offset is obtained by calculating; According to the received powers of all sub-carriers of the two adjacent OFDM symbols, the calculated frequency offset estimate includes: Obtain the estimated frequency offset and cost function; According to the received power of all subcarriers of the two adjacent OFDM symbols, the estimated frequency offset and the cost function, the estimated frequency offset is obtained by calculating; According to the received powers of all sub-carriers of the two adjacent OFDM symbols, the calculated frequency offset estimate includes: Calculate the received power ratio of the kth subcarrier in the first OFDM symbol to the kth subcarrier in the second OFDM symbol; Determine the Pth subcarrier according to all received power ratios; wherein, the received power ratio between the Pth subcarrier in the first OFDM symbol and the Pth subcarrier in the second OFDM symbol is the maximum value among all received power ratios; The estimated frequency offset value is determined according to the absolute value of the difference between P and T. 2 . The method according to claim 1 , wherein the power adjustment of the transmit power of the T-th subcarrier of each of two adjacent OFDM symbols comprises: 2 . adjusting the transmit power of the T-th subcarrier of the first OFDM symbol to be greater than the transmit power of all other subcarriers of the first OFDM symbol to obtain the first transmit power; adjusting the transmit power of the T-th subcarrier of the second OFDM symbol to be smaller than the transmit power of all other subcarriers of the second OFDM symbol to obtain the second transmit power; Wherein, the two adjacent OFDM symbols include a first OFDM symbol and a second OFDM symbol. 3 . The method according to claim 2 , wherein, after adjusting the transmit power of the T-th sub-carrier of the second OFDM symbol to be smaller than the transmit power of all other sub-carriers of the second OFDM symbol, the second OFDM symbol is obtained. 4 . After the transmit power, it also includes: evenly allocating the power difference between the rated transmit power of a single OFDM and the first transmit power to other sub-carriers except the T-th sub-carrier in the sub-carriers of the first OFDM symbol; The power difference between the rated transmit power of a single OFDM and the second transmit power is equally distributed to other subcarriers except the Tth subcarrier in the subcarriers of the second OFDM symbol. 4. A method for frequency offset estimation, comprising: Perform power adjustment on the transmit power of at least two subcarriers of two adjacent OFDM symbols, the at least two subcarriers include b1 to bJth subcarriers, where b1 to bJ are integers not less than 1 and not greater than N, J is an integer not less than 1 and not greater than N, where N is the total number of subcarriers; Transmit each subcarrier according to the adjusted power; collecting the received power of all subcarriers of the two adjacent OFDM symbols; According to the received power of all sub-carriers of the two adjacent OFDM symbols, the estimated frequency offset is obtained by calculating; The calculating and obtaining the estimated frequency offset value according to the received power of all subcarriers of the two adjacent OFDM symbols includes: obtaining the estimated frequency offset and the respective cost functions corresponding to the b1th to bJth subcarriers; According to the received power of all subcarriers of the two adjacent OFDM symbols, the estimated frequency offset value, and the respective cost functions corresponding to the b1 to bJth subcarriers, the estimated frequency offset value is calculated and obtained. 5 . The method according to claim 4 , wherein the power adjustment of the transmit power of at least two subcarriers in two adjacent OFDM symbols comprises: 5 . adjusting the transmit power of the b1 to bJth subcarriers of the first OFDM symbol to a first transmit power, where the first transmit power is greater than the transmit power of all other subcarriers of the first OFDM symbol; adjusting the transmit power of the b1 to bJth subcarriers of the second OFDM symbol to a second transmit power, where the second transmit power is smaller than the transmit power of all other subcarriers of the second OFDM symbol; Wherein, the two adjacent OFDM symbols include a first OFDM symbol and a second OFDM symbol. 6. The method according to claim 5, wherein after adjusting the transmit power of the b1 to bJth subcarriers of the second OFDM symbol to the second transmit power, the method further comprises: The power difference between the rated transmit power of a single OFDM and the sum of the transmit powers of the b1 to bJth subcarriers of the first OFDM symbol is evenly distributed to other subcarriers except the b1th to bJth subcarriers in the first OFDM symbol subcarrier; The power difference between the rated transmit power of a single OFDM and the sum of the transmit powers of the b1 to bJth subcarriers of the second OFDM symbol is evenly distributed to the subcarriers of the second OFDM symbol except for the b1th to bJth subcarriers other subcarriers. 7. A method for frequency offset estimation, comprising: performing power adjustment on the transmit power of at least two subcarriers of each of consecutive even OFDM symbols, the consecutive even OFDM symbols including m1th to mzth OFDM symbols, the at least two subcarriers including b1th to bJth subcarriers, b1 to bJ is an integer not less than 1 and not greater than N, J is an integer not less than 1 and not greater than N, N is the total number of subcarriers, and z is an integer not greater than the total number of OFDM symbols; Transmit each subcarrier according to the adjusted power; collecting the received power of all subcarriers of the consecutive even-numbered OFDM symbols; According to the received power of all the subcarriers of the consecutive even OFDM symbols, the frequency offset estimate is obtained by calculating; According to the received power of all the subcarriers of the consecutive even OFDM symbols, the calculated frequency offset estimated value includes: Obtain the estimated frequency offset and cost functions corresponding to the b1th to bJth subcarriers corresponding to the OFDM symbol pair, where the OFDM symbol pair is one of two adjacent OFDM component symbol pairs in the m1th to mzth OFDM; According to the received power of all subcarriers corresponding to the OFDM symbol pair, the estimated frequency offset value, and the respective cost functions corresponding to the b1 to bJth subcarriers corresponding to the OFDM symbol pair, the estimated frequency offset value is calculated and obtained. 8 . The method according to claim 7 , wherein the power adjustment of the transmit power of at least two subcarriers of each of consecutive even-numbered OFDM symbols comprises: 8 . adjusting the transmit power of the b1 to bJth subcarriers of the m1th OFDM symbol to a first transmit power, where the first transmit power is greater than the transmit power of all other subcarriers of the m1th OFDM symbol; adjusting the transmit power of the b1 to bJ th subcarriers of the m2th OFDM symbol to a second transmit power, where the second transmit power is smaller than the transmit power of all other subcarriers of the m2th symbol; And so on, until the transmit power of the b1th to bJth subcarriers of the mz-1th OFDM symbol is adjusted to the z-1th transmit power, and the z-1th transmit power is greater than all other subcarriers of the mz-1th OFDM symbol. The transmit power of the carrier; The transmit powers of the b1th to bJth subcarriers of the mzth OFDM symbol are all adjusted to the zth transmit power, where the zth transmit power is smaller than the transmit power of all other subcarriers of the mzth symbol. 9 . The method according to claim 8 , wherein after adjusting the transmission power of the b1th to bJth subcarriers of the mzth OFDM symbol to the zth transmission power, the method further comprises: 10 . The power difference between the rated transmit power of a single OFDM and the sum of the transmit powers of the b1 to bJth subcarriers of the m1th OFDM symbol is evenly distributed to other subcarriers except the b1th to bJth subcarriers in the subcarriers of the m1th OFDM symbol ; The power difference between the rated transmit power of a single OFDM and the sum of the transmit powers of the b1 to bJth subcarriers of the m2 OFDM symbol is evenly distributed to other subcarriers in the m2th OFDM symbol except the b1th to bJth subcarriers subcarrier; And so on, until the power difference between the rated transmit power of a single OFDM and the sum of the transmit powers of the b1 to bJth subcarriers of the mzOFDM symbol is evenly allocated to dividing the b1th to bJth subcarriers in the subcarriers of the mzOFDM symbol other sub-carriers than the carrier. 10. A device for frequency offset estimation, comprising: an adjustment unit, configured to perform power adjustment on the transmit power of the T-th subcarriers of two adjacent OFDM symbols, where T is an integer not less than 1 and not greater than N, and N is the total number of subcarriers; a transmitting unit, configured to transmit each subcarrier according to the adjusted power; a collection unit, configured to collect the received power of all subcarriers of the two adjacent OFDM symbols; a calculation unit, configured to calculate and obtain the estimated frequency offset according to the received power of all subcarriers of the two adjacent OFDM symbols; The calculation unit includes: an acquisition module for acquiring a frequency offset estimated value and a cost function; a first calculation module, configured to calculate and obtain the estimated frequency offset according to the received power of all subcarriers of the two adjacent OFDM symbols, the estimated frequency offset and the cost function; The computing unit also includes: a second calculation module, configured to calculate the received power ratio between the kth subcarrier in the first OFDM symbol and the kth subcarrier in the second OFDM symbol; The first determination module is configured to determine the Pth subcarrier according to all received power ratios; wherein, the received power ratio of the Pth subcarrier in the first OFDM symbol and the Pth subcarrier in the second OFDM symbol is among all the received power ratios. the maximum value of ; The second determining module determines the estimated frequency offset value according to the absolute value of the difference between P and T. 11. The device according to claim 10, wherein the adjustment unit comprises: a first adjustment module, configured to adjust the transmit power of the T-th sub-carrier of the first OFDM symbol to be greater than the transmit power of all other sub-carriers of the first OFDM symbol to obtain the first transmit power; a second adjustment module, configured to adjust the transmission power of the T-th subcarrier of the second OFDM symbol to be smaller than the transmission power of all other subcarriers of the second OFDM symbol to obtain the second transmission power; Wherein, the two adjacent OFDM symbols include a first OFDM symbol and a second OFDM symbol. 12. The device according to claim 11, wherein the adjustment unit further comprises: a first allocating module, configured to equally distribute the power difference between the rated transmit power of a single OFDM and the first transmit power to other subcarriers except the Tth subcarrier in the subcarriers of the first OFDM symbol; The second allocating module is configured to evenly allocate the power difference between the rated transmit power of a single OFDM and the second transmit power to other sub-carriers in the sub-carriers of the second OFDM symbol except the T-th sub-carrier. 13. A device for frequency offset estimation, comprising: an adjustment unit, configured to perform power adjustment on the transmit power of at least two subcarriers of two adjacent OFDM symbols, the at least two subcarriers include b1 to bJth subcarriers, and b1 to bJ are not less than 1 and not greater than An integer of N, J is an integer not less than 1 and not greater than N, and N is the total number of subcarriers; a transmitting unit, configured to transmit each subcarrier according to the adjusted power; a collection unit, configured to collect the received power of all subcarriers of the two adjacent OFDM symbols; a calculation unit, configured to calculate and obtain the estimated frequency offset according to the received power of all subcarriers of the two adjacent OFDM symbols; The computing unit includes: an acquisition module, configured to acquire the estimated frequency offset value and the respective cost functions corresponding to the b1 to bJ subcarriers; a calculation module, configured to calculate and obtain the estimated frequency offset according to the received power of all subcarriers of the two adjacent OFDM symbols, the estimated frequency offset, and the corresponding cost functions of the b1 to bJth subcarriers . 14. The device according to claim 13, wherein the adjustment unit comprises: a first adjustment module, configured to adjust the transmit power of the b1 to bJth subcarriers of the first OFDM symbol to a first transmit power, where the first transmit power is greater than the transmit power of all other subcarriers of the first OFDM symbol power; a second adjustment module, configured to adjust the transmit power of the b1 to bJth subcarriers of the second OFDM symbol to a second transmit power, where the second transmit power is smaller than the transmit power of all other subcarriers of the second OFDM symbol power; Wherein, the two adjacent OFDM symbols include a first OFDM symbol and a second OFDM symbol. 15. The device according to claim 14, wherein the adjustment unit further comprises: The first allocating module is configured to equally distribute the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1 to bJth subcarriers of the first OFDM symbol to the subcarriers of the first OFDM symbol divided by the b1th to subcarriers other than bJ subcarriers; The second allocating module is configured to equally distribute the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1 to bJth subcarriers of the second OFDM symbol to dividing the subcarriers of the second OFDM symbol by the power difference Subcarriers other than the b1 to bJth subcarriers. 16. A device for frequency offset estimation, comprising: an adjustment unit, configured to perform power adjustment on the transmit power of at least two subcarriers of consecutive even-numbered OFDM symbols, where the consecutive even-numbered OFDM symbols include m1th to mzth OFDM symbols, and the at least two subcarriers include b1th to bJth OFDM symbols subcarriers, b1 to bJ are integers not less than 1 and not greater than N, J is an integer not less than 1 and not greater than N, N is the total number of subcarriers, and z is an integer not greater than the total number of OFDM symbols; a transmitting unit, configured to transmit each subcarrier according to the adjusted power; a collection unit, configured to collect the received power of all subcarriers of the consecutive even-numbered OFDM symbols; a calculation unit, configured to calculate and obtain the estimated frequency offset value according to the received power of all the subcarriers of the consecutive even OFDM symbols; The computing unit also includes: an acquisition module, configured to acquire the estimated frequency offset and the cost functions corresponding to the b1th to bJth subcarriers corresponding to the OFDM symbol pair, where the OFDM symbol pair is a pair of two adjacent OFDM symbols in the m1th to mzth OFDM one of the; A calculation module, configured to calculate the frequency offset estimate according to the received power of all subcarriers corresponding to the OFDM symbol pair, the estimated frequency offset value, and the cost functions corresponding to the b1 to bJth subcarriers corresponding to the OFDM symbol pair. value. 17. The device according to claim 16, wherein the adjustment unit comprises: a first adjustment module, configured to adjust the transmit power of the b1 to bJth subcarriers of the m1th OFDM symbol to a first transmit power, where the first transmit power is greater than the transmit power of all other subcarriers of the m1th OFDM symbol; a second adjustment module, configured to adjust the transmit power of the b1 to bJ th subcarriers of the m2th OFDM symbol to a second transmit power, where the second transmit power is smaller than the transmit power of all other subcarriers of the m2th symbol; The third adjustment module, and so on, is used to adjust the transmit power of the b1th to bJth subcarriers of the mz-1th OFDM symbol to the z-1th transmit power, where the z-1th transmit power is greater than the mzth transmit power The transmit power of all other subcarriers of -1 OFDM symbol; The fourth adjustment module is configured to adjust the transmit power of the b1th to bJth subcarriers of the mzth OFDM symbol to the zth transmit power, where the zth transmit power is smaller than the transmit power of all other subcarriers of the mzth symbol. 18. The device according to claim 17, wherein the adjustment unit further comprises: The first allocating module is configured to equally distribute the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1 to bJth subcarriers of the m1th OFDM symbol to dividing the b1th to bJth subcarriers in the subcarriers of the m1th OFDM symbol Subcarriers other than subcarriers; The second allocating module is configured to equally distribute the power difference between the rated transmit power of a single OFDM and the sum of transmit powers of the b1 to bJth subcarriers of the m2th OFDM symbol to the subcarriers of the m2th OFDM symbol by dividing the b1th OFDM symbol to subcarriers other than bJ subcarriers; The third allocation module, and so on, is used to evenly allocate the power difference between the rated transmit power of a single OFDM and the sum of the transmit powers of the b1 to bJth subcarriers of the mzOFDM symbol to the subcarriers in the mzOFDM symbol divided by other subcarriers other than the b1th to bJth subcarriers.