WO2021184198A1 - Frequency offset estimation method, and receiving device and storage medium - Google Patents

Abstract

Disclosed are a frequency offset estimation method, and a receiving device and a storage medium. The method comprises: acquiring a first frequency domain received signal and a second frequency domain received signal, which correspond to two transmitting signals, time domains of which are adjacent; obtaining a first frequency domain channel value according to the first frequency domain received signal and a reference signal, and obtaining a second frequency domain channel value according to the second frequency domain received signal and the reference signal; performing time domain conversion on the first frequency domain channel value to obtain a first time domain channel impulse response, and performing time domain conversion on the second frequency domain channel value to obtain a second time domain channel impulse response; according to energy values of the first time domain channel impulse response and the second time domain channel impulse response, determining first target response data for the first time domain channel impulse response and second target response data for the second time domain channel impulse response; and performing carrier frequency offset estimation according to the first target response data and the second target response data. By using the embodiments of the present invention, error of a frequency offset estimation result may be reduced.

Description

Frequency offset estimation method, receiving equipment and storage medium Technical field

This application relates to the field of communication technology, and in particular to a frequency offset estimation method, receiving device and storage medium.

Background technique

In a wireless communication system, the clock frequencies of the transmitting device and the receiving device cannot be exactly the same, and the clock frequency will shift over time. For an orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) system, the frequency offset will eventually cause the demodulation performance of the receiving device to degrade. Therefore, the receiving device needs to estimate the frequency offset from the transmitting device to the receiving device, that is, perform frequency offset estimation, and then adjust its own clock frequency according to the estimated frequency offset.

At present, the receiving device calculates the frequency domain channel value according to the received signal to estimate the frequency offset. In the case of low signal-to-noise ratio and strong interference signal, the error of the frequency offset estimation result is relatively large.

Summary of the invention

The embodiment of the present invention provides a frequency offset estimation method, receiving device and storage medium, which can reduce the error of frequency offset estimation when the signal-to-noise ratio is low and the interference signal is strong.

In the first aspect, an embodiment of the present invention provides a frequency offset estimation method. The method is used to estimate the carrier frequency offset between a transmitting device and a receiving device in a wireless communication system. The method includes: acquiring two adjacent ones in the time domain. The first frequency domain reception signal and the second frequency domain reception signal corresponding to each transmission signal, the transmission signal contains a preset reference signal; the first frequency domain channel value is obtained according to the first frequency domain reception signal and the reference signal, and the first frequency domain channel value is obtained according to the first frequency domain reception signal and the reference signal. The second frequency domain received signal and the reference signal are used to obtain the second frequency domain channel value; the first frequency domain channel value is subjected to time domain transformation to obtain the first time domain channel impulse response, and the second frequency domain channel value is subjected to time domain transformation to obtain the first frequency domain channel value. Second time domain channel impulse response; according to the energy value of the first time domain channel impulse response and the second time domain channel impulse response, determine the first target response data of the first time domain channel impulse response, and the second time The second target response data of the domain channel impulse response; the carrier frequency offset estimation is performed according to the first target response data and the second target response data.

In the second aspect, an embodiment of the present invention provides a receiving device, including: a memory and a processor;

The memory stores program codes;

The processor calls the program code, and when the program code is executed, is used to perform the following operations:

Acquiring a first frequency domain received signal and a second frequency domain received signal corresponding to two adjacent transmitted signals in the time domain, where the transmitted signal includes a preset reference signal;

Obtain a first frequency domain channel value according to the first frequency domain received signal and a reference signal, and obtain a second frequency domain channel value according to the second frequency domain received signal and the reference signal;

Time-domain transforming the first frequency-domain channel value to obtain a first time-domain channel impulse response, and time-domain transforming the second frequency-domain channel value to obtain a second time-domain channel impulse response;

According to the energy values of the first time domain channel impulse response and the second time domain channel impulse response, the first target response data of the first time domain channel impulse response and the second time domain channel impulse response are determined. Target response data;

Carrier frequency offset estimation is performed according to the first target response data and the second target response data.

In a third aspect, an embodiment of the present application provides a computer-readable storage medium for storing computer software instructions used by the foregoing receiving device, including instructions for executing the frequency offset estimation method described in any one of the foregoing first aspects. program of.

In the embodiment of the present invention, the receiving device determines the first target response data of the first time domain channel impulse response, and the second target response data of the first time domain channel impulse response according to the energy values of the first time domain channel impulse response and the second time domain channel impulse response. The second target response data of the time-domain channel impulse response; finally, the carrier frequency offset is estimated based on the first target response data and the second target response data, which can reduce the signal-to-noise ratio and the strong interference signal. The error of the frequency offset estimation.

Description of the drawings

In order to explain the embodiments of the present application or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the embodiments. Obviously, the drawings in the following description are only some of the present application. Embodiments, for those of ordinary skill in the art, without creative work, other drawings can be obtained based on these drawings.

FIG. 1 is a schematic diagram of the architecture of a transmission system provided by an embodiment of the present invention;

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

FIG. 3 is a time-frequency diagram of a subframe provided by an embodiment of the present invention;

4 is a schematic diagram of the relationship between the signal-to-noise ratio and the L value provided by an embodiment of the present invention;

FIG. 5 is a schematic diagram of a time-domain impulse response provided by an embodiment of the present invention;

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

7 is a schematic flowchart of a method for estimating carrier frequency offset based on correlation values according to an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of a receiving device according to an embodiment of the present invention.

Detailed ways

The embodiments of the present invention will be described below in conjunction with the drawings in the embodiments of the present invention.

At present, the receiving device estimates the frequency offset according to the frequency domain channel value. In the case of low signal-to-noise ratio and strong interference signal, the result of the frequency offset estimation error is relatively large. An embodiment of the present application proposes a frequency offset estimation method. A receiving device obtains a first frequency domain received signal and a second frequency domain received signal corresponding to two adjacent transmitted signals in the time domain, and the transmitted signal contains a preset reference Signal; obtain the first frequency domain channel value according to the first frequency domain received signal and reference signal, obtain the second frequency domain channel value according to the second frequency domain received signal and reference signal; perform time domain transformation on the first frequency domain channel value The first time domain channel impulse response, the second frequency domain channel value is time domain transformed to obtain the second time domain channel impulse response; according to the energy of the first time domain channel impulse response and the second time domain channel impulse response Value, determine the first target response data of the first time domain channel impulse response, and the second target response data of the second time domain channel impulse response; perform carrier frequency deviation based on the first target response data and the second target response data Shift estimate. The manner in which the receiving device obtains the frequency offset by estimating the carrier frequency offset through the first target response data and the second target response data can reduce the error of the frequency offset estimation.

In order to better understand the frequency offset estimation method, receiving device, and storage medium disclosed in the embodiments of the present application, the following first describes the architecture of the transmission system to which the embodiments of the present application are applicable.

Please refer to FIG. 1. FIG. 1 is a schematic structural diagram of a transmission system provided by an embodiment of the present application. As shown in FIG. 1, the transmission system 10 is composed of a transmitting device 101 and a receiving device 102. Among them, the receiving device 102 includes a digital front end 1021 and a frequency offset estimation 1022. The transmitting device 101 transmits data to the receiving device 102. There is a clock difference between the transmitting device 101 and the receiving device 102. The receiving device 102 needs to estimate the frequency offset difference from the transmitting device 101 to the receiving device 102. The frequency offset adjusts its own clock frequency to improve the performance of the receiving device 102. The receiving device 102 may obtain the first frequency domain received signal and the second frequency domain received signal corresponding to two adjacent transmit signals in the time domain, and so on. In this application, the frequency offset estimation 1022 in the receiving device 102 executes the frequency offset estimation method in the embodiment of this application. The architecture of the transmission system shown in FIG. 1 is only used as an example, and does not constitute a limitation to the embodiment of the present application.

When the transmitting device sends data to the receiving device, the receiving device obtains the first frequency domain received signal and the second frequency domain received signal corresponding to the two adjacent transmitted signals in the time domain from the transmitting device side; then, the receiving device according to the first frequency The first frequency domain channel value is obtained from the received signal in the frequency domain and the reference signal, and the second frequency domain channel value is obtained from the second frequency domain received signal and the reference signal; further, the receiving device performs time domain transformation on the first frequency domain channel value to obtain the first Time domain channel impulse response, the second frequency domain channel value is time domain transformed to obtain the second time domain channel impulse response; then, the receiving device according to the first time domain channel impulse response and the second time domain channel impulse response Determine the first target response data of the first time-domain channel impulse response and the second target response data of the second time-domain channel impulse response; finally, the receiving device is based on the first target response data and the second target response data Carrier frequency offset estimation is performed in response to the data.

Based on the foregoing description, an embodiment of the present invention proposes a frequency offset estimation method as shown in FIG. 2. The frequency offset estimation method may include S201-S205:

S201: The receiving apparatus obtains a first frequency domain received signal and a second frequency domain received signal corresponding to two adjacent transmit signals in the time domain.

Optionally, the transmission signal is an OFDM symbol, the transmission signal contains a preset reference signal, and the reference signal is a pilot symbol. The transmitting device sends each OFDM symbol to the receiving device, so that the receiving device obtains each OFDM symbol. Two adjacent transmitted signals in the time domain refer to two OFDM symbols containing pilots transmitted by the transmitting device at a preset time interval. The preset time interval can be S*T, where S is two OFDM symbols containing pilots. The number of OFDM symbols that do not contain pilots in the interval, and T is the time length occupied by each OFDM symbol. The preset time interval in the embodiment of the present application is illustrated by taking S*T as an example. The two adjacent transmitted signals in the time domain are the first OFDM symbol and the second OFDM symbol respectively. The first OFDM symbol or the second OFDM symbol may contain There are pilot symbols and data, or there may be only pilot symbols.

Exemplarily, FIG. 3 is a time-frequency diagram of a subframe proposed in an embodiment of the present application. In FIG. 3, the abscissa is time and the ordinate is frequency. In the time-frequency diagram shown in FIG. 3, the time-domain phase Two adjacent transmit signals, the first OFDM symbol and the second OFDM symbol, and there are s OFDM symbols spaced between the first OFDM symbol and the second OFDM symbol. The first OFDM symbol and the second OFDM symbol are respectively placed on the reference signal, namely the pilot symbol, the first OFDM symbol and the second OFDM symbol in the interval between the OFDM symbols are not placed on the pilot symbol, that is to say, the first OFDM symbol contains There are pilots and data, the second OFDM symbol contains pilots and data, and the OFDM symbols spaced between the first OFDM symbol and the second OFDM symbol only contain data.

The transmitting device sends the transmitted signal to the receiving device, and the receiving device can obtain the first frequency domain received signal and the second frequency domain received signal corresponding to the two adjacent transmitted signals in the time domain. The first frequency domain received signal is {y _1i , i∈I}, the second frequency domain received signal is {y _2i , i∈I}, I is a set, and the value of I is pre-configured in the communication system. Different communication systems have different I values, and i means Place the reference signal, that is, the pilot symbol, where the index of the subcarrier belongs to I, and the pilot symbol is represented by Z _i .

z _1i is the pilot symbol placed on the first OFDM symbol by the _{transmitting device, z 2i} is the pilot symbol placed on the second OFDM symbol by the transmitting device, and i is the pilot symbol placed on the first OFDM symbol or the second OFDM symbol On the location. For example, as shown in FIG. 3, z ₁₀ indicates that the pilot symbol is placed at position 0 on the first OFDM symbol, and z ₂₃ indicates that the pilot signal is placed at position 3 on the second OFDM symbol.

The reference signal corresponding to the received signal in the first frequency domain is the same or different from the reference signal corresponding to the received signal in the second frequency domain. different.

The transmitting device in the communication system transmits the two adjacent OFDM signals (the first OFDM symbol and the second OFDM symbol) on which the pilot signal is placed to the receiving device through the channel, so that the receiving device obtains the first frequency domain received signal {y _1i , I ∈ I} and the second frequency domain received signal {y _2i , i ∈ I}, {y _1i , i ∈ I} is the first frequency domain received signal corresponding to the first ODFM symbol, {y _2i , i ∈ I } Is the second frequency domain received signal corresponding to the second ODFM symbol. For example, as shown in Figure 3, y ₁₀ and y ₁₃ are the first frequency-domain received signals at positions 0 and 3 on the first ODFM symbol, and y ₂₀ and y ₂₃ are the received signals at positions 0 and 3 on the second ODFM symbol, respectively. The second frequency domain receives the signal.

S202: The receiving device obtains the first frequency domain channel value according to the first frequency domain received signal and the reference signal, and obtains the second frequency domain channel value according to the second frequency domain received signal and the reference signal.

Optionally, the receiving device uses the first frequency domain received signal and the reference signal as a least squares estimation of the frequency domain channel value to obtain the first frequency domain channel value, and uses the second frequency domain received signal and the reference signal as the frequency domain channel value The least square estimation obtains the second frequency domain channel value. The calculation method of the least square estimation is to make the ratio of the frequency domain received signal and the reference signal to obtain the frequency domain channel value, that is, h _1i =y _1i /z _1i , h _2i =y _2i /z _2i , i∈I, h _1i Is the first frequency domain channel value, and h _2i is the second frequency domain channel value.

S203: The receiving device performs time domain transformation on the first frequency domain channel value to obtain a first time domain channel impulse response, and performs time domain transformation on the second frequency domain channel value to obtain a second time domain channel impulse response.

Specifically, the receiving device first composes the first frequency domain channel value into a first frequency domain vector according to a preset reference signal, composes the second frequency domain channel value into a second frequency domain vector according to the preset reference signal, and then composes the first frequency domain The vector is subjected to inverse Fourier transform to obtain the first time domain channel impulse response, and the second frequency domain vector is subjected to inverse Fourier transform to obtain the second time domain channel impulse response.

The first frequency domain vector composed of the first frequency domain channel values by the receiving device according to the preset reference signal is h ₁ =[h ₁₀ 0 h ₁₂ ... h _1i ...] ^T , i∈I, according to the preset reference The second frequency domain vector composed of the second frequency domain channel value of the signal is h ₂ =[h ₂₀ 0 h ₂₂ ... h _2i ...] ^T , i∈I, where [] ^T represents the transposition of the matrix Operation, where the data of the position where i does not belong to I is filled with 0. For example, the first OFDM symbol corresponding to the first frequency domain signal obtained by the receiving device contains ten positions where data or pilot symbols can be placed. I=[0, 1, 4, 5, 8, 9], which means that Pilot symbols are placed at positions 0, 1, 4, 5, 8, and 9 of the ten positions, but no pilots are placed at positions 2, 3, 6, and 7, so according to the pilot symbols on the first OFDM symbol Symbol, the first frequency domain vector composed of the first frequency domain channel values is h ₁ =[h ₁₀ h ₁₁ 0 0 h ₁₄ h ₁₅ 0 0 h ₁₈ h ₁₉ ] ^T.

The receiving device performs inverse Fourier transform on the first frequency domain vector to obtain the first time domain channel impulse response h ^t ₁ =[h ^t ₁₀ h ^t ₁₁ ... h ^t _1(N-1) ] ^T = W _N *h ₁ , perform the inverse Fourier transform of the second frequency domain vector to obtain the second time domain channel impulse response h ^t ₂ =[h ^t ₂₀ h ^t ₂₁ ... h ^t _2(N-1) ] ^T = W _N *h ₂ , W _N is the inverse Fourier transform matrix of order N×N, and the element in the i-th row and j-th column of _{W N is}

S204: The receiving device determines the first target response data of the first time domain channel impulse response and the second time domain channel impulse according to the energy values of the first time domain channel impulse response and the second time domain channel impulse response The second target response data of the response.

The first target response data includes 2L+1 response data, the second target response data includes 2L+1 response data, and L is a natural number. L is determined according to the signal-to-noise ratio. When the transmission system has different signal-to-noise ratios, the value of L is different. For example, different L values corresponding to different signal-to-noise ratios are shown in Figure 4.

The L+1th response data in the first target response data is the corresponding first time domain channel when the sum of the energy of the first time domain channel impulse response and the energy of the corresponding second time domain channel impulse response is maximum Impulse response data, the L+1th response data in the second target response data corresponds to when the sum of the energy of the first time-domain channel impulse response and the corresponding second time-domain channel impulse response is maximum The second time domain channel impulse response data.

Specifically, the receiving device first determines the position of the maximum energy path corresponding to the L+1th response data according to the sum of the energy value of the first time domain channel impulse response and the corresponding energy value of the second time domain channel impulse response, which is

p is the position where the sum of the energy of the first time domain channel impulse response and the energy of the corresponding second time domain channel impulse response is maximum, and p corresponds to the maximum energy path. Therefore, the response data corresponding to p in the first time domain channel impulse response is the L+1th response data in the first target response data, and the response data corresponding to p in the second time domain channel impulse response is the first response data. 2. The L+1th response data in the target response data. Then the receiving device determines the first target response data according to the L value determined by the look-up table and the L+1th response data in the first target response data. According to the L value determined by the look-up table, the L+th response data in the second target response data is One response data determines the second target response data, that is, the first target response data includes the L+1 response data and the first L response data and the last L response data of the L+1 response data of the first target response data The response data, the second target response data includes the L+1th response data and the first L response data and the last L response data of the L+1th response data in the second target response data.

As shown in FIG. 5, the first time domain channel is determined according to the position p corresponding to the maximum sum of the energy of the first time domain channel impulse response determined by the receiving device and the corresponding second time domain channel impulse response energy. The maximum energy path of the impulse response. The first target response data includes the maximum energy path in the first time domain channel impulse response and the first time domain channel impulse corresponding to the first L channels and the last L channels starting from the maximum energy path. The shock response data corresponds to the "effective channel" in Figure 5. For the air-to-ground communication system of the UAV, there is generally a direct fire path between the UAV and the ground control station, and the maximum energy path often corresponds to the direct fire path. At the same time, the multipath wave path difference from the UAV to the ground remote is small, that is, the corresponding effective channels are concentrated in a small area (the "effective channel" in Figure 5). The other parts are invalid paths caused by noise and interference signals. According to the energy values of the first time domain channel impulse response and the second time domain channel impulse response, the first target response data of the first time domain channel impulse response and the second time domain channel impulse response are determined. Target response data. The influence of these noises and interference signals can be effectively avoided, and the error of the frequency offset estimation result can be reduced.

S205: The receiving device performs carrier frequency offset estimation according to the first target response data and the second target response data.

After the receiving device obtains the first target response data and the second target response data, it estimates the carrier frequency offset according to the first target response data and the second target response data, and obtains that the received signal in the first frequency domain and the received signal in the second frequency domain belong to The frequency offset of the subframe.

The first target response data only includes the 2L+1 first time domain channel impulse response data in the first time domain channel impulse response, and the second target response data also only includes the 2L first time domain channel impulse response data in the second time domain channel impulse response. +1 second time-domain channel impulse response data, so when the signal-to-noise ratio is low and the interference signal is strong, the receiving device performs carrier frequency offset estimation based on the first target response data and the second target response data The frequency offset error is small, and it can resist extremely low signal-to-noise ratio and anti-interference signals.

Using the embodiment of the present application, the receiving device transforms the first frequency domain channel value into the first time domain channel impulse response, transforms the second frequency domain channel value into the second time domain channel impulse response, and then according to the first time domain channel impulse response Channel impulse response and the energy value of the second time domain channel impulse response, determine the first target response data of the first time domain channel impulse response, and the second target response data of the second time domain channel impulse response, and finally Carrier frequency offset estimation is performed according to the first target response data and the second target response data to obtain the frequency offset of the subframe to which the first frequency domain received signal and the second frequency domain received signal belong. The first target response data and the second target response data only include part of the time-domain channel impulse response data. Therefore, when the signal-to-noise ratio is low and the interference signal is strong, the frequency offset estimation can be reduced by this method. The error of the resulting frequency offset.

Please refer to FIG. 6. FIG. 6 is another frequency offset estimation method provided by an embodiment of the present application. The frequency offset estimation method may include S601-S609.

S601: The receiving apparatus acquires a first frequency domain received signal and a second frequency domain received signal corresponding to two adjacent transmit signals in the time domain.

S602: The receiving device obtains the first frequency domain channel value according to the first frequency domain received signal and the reference signal, and obtains the second frequency domain channel value according to the second frequency domain received signal and the reference signal.

S603: The receiving device performs time domain transformation on the first frequency domain channel value to obtain a first time domain channel impulse response, and performs time domain transformation on the second frequency domain channel value to obtain a second time domain channel impulse response.

S604: The receiving device determines the first target response data of the first time domain channel impulse response and the second time domain channel impulse according to the energy values of the first time domain channel impulse response and the second time domain channel impulse response The second target response data of the response.

For details of steps S601-S604 in the embodiment of this application, please refer to the execution process of steps S201-S204 in the above-mentioned embodiment, which will not be repeated in the embodiment of this application.

S605: The receiving device obtains the correlation value of the first target response data and the second target response data.

Specifically, the receiving device obtains the correlation values of the 2L+1 response data in the first target response data and the 2L+1 response data in the second target response data, that is,

Where p is the channel position value corresponding to the L+1th response data in the first target response data and the second target response data,

Means to take the plural

The conjugation.

In one implementation,

The k in may appear negative or exceed the value of N-1, so it is necessary to use rewinding processing for this type of value, that is, when k<0,

The value is

When 0≤k≤N-10,

The value is

When k≥N,

The value is

When k<0,

The value is

When 0≤k≤N-10,

The value is

When k≥N,

The value is

For example, the characteristic channel position p corresponding to the L+1th response data in the first target response data and the second target response data determined by the receiving device is 2, and the value of L is 3 and the value of N is 8 by looking up the table. Then -1≤k≤5, because when k=-1, the time-domain channel impulse response data at the corresponding position is empty, so take the time-domain channel impulse response data at position 7 corresponding to the first time-domain impulse response as The first time-domain channel impulse response data with k=-1, the response data at position 7 corresponding to the second time-domain impulse response is taken as the second time-domain channel impulse response data with k=-1, then the first The target response data includes seven first time domain channel impulse response data at positions 0, 1, 2, 3, 4, 5, and 7 in the first time domain channel impulse response data. The second target response data includes the second time domain channel impulse response data. Seven second time-domain channel impulse response data at positions 0, 1, 2, 3, 4, 5, and 7 in the time-domain channel impulse response data. That is, the receiving device takes the seven first time domain channel impulse response data and the second time domain channel impulse response data at positions 0, 1, 2, 3, 4, 5, and 7 in the first time domain channel impulse response data. The correlation values of the seven second time domain channel impulse response data at positions 0, 1, 2, 3, 4, 5, and 7 in the data.

For another example, the characteristic channel position p corresponding to the L+1th response data in the first target response data and the second target response data determined by the receiving device is 7, and the value of L is 4 and the value of N is 10. , Then 3≤k≤11, because k=10 is equal to the value of N, and k=11 exceeds the value of N, so the first time-domain impulse response corresponding to the position of 0 and 1 is taken as the time-domain channel impulse The response data is used as the first time-domain channel impulse response data with k=10 and k=11, and the time-domain channel impulse response data with positions 0 and 1 corresponding to the second time-domain impulse response are taken as k=10, respectively. And k=11 the second time domain channel impulse response data, the first target response data includes the first time domain channel impulse response data at positions 0, 1, 3, 4, 5, 6, 7, 8 and 9 first time domain channel impulse response data, the second target response data includes the second time domain channel impulse response data at positions 0, 1, 3, 4, 5, 6, 7, 8, and 9 Nine second time domain channel impulse response data. That is, the receiving device takes the nine first time domain channel impulse response data and the second time domain channel impulse response data and the second time domain at positions 0, 1, 3, 4, 5, 6, 7, 8 and 9 in the first time domain channel impulse response data. The correlation values of the nine second time domain channel impulse response data at positions 0, 1, 3, 4, 5, 6, 7, 8 and 9 in the channel impulse response data.

S606: The receiving device performs carrier frequency offset estimation according to the correlation value.

After the receiving device obtains the correlation value between the first target response data and the second target response data, it performs carrier frequency offset estimation according to the correlation value. The specific method for the receiving device to estimate the carrier frequency offset according to the correlation value includes S701-S703 :

S701: The receiving device obtains the phase of the correlation value to obtain the phase value.

The receiving device performs a phase operation on the correlation value obtained in S605 to obtain a phase value, namely Phase(R).

S702: The receiving apparatus determines a time interval corresponding to the first frequency domain received signal and the second frequency domain received signal.

Specifically, the receiving device determines the number of OFDM symbols without pilot placement and the number of OFDM symbols for each OFDM symbol according to the interval between the first OFDM symbol and the second OFDM symbol corresponding to the first frequency domain received signal and the second frequency domain received signal, respectively. The time length determines the time interval corresponding to the received signal in the first frequency domain and the received signal in the second frequency domain. For example, in Figure 3, the first OFDM signal and the second OFDM signal corresponding to the first frequency domain received signal and the second frequency domain received signal are separated by S OFDM signals without pilot signals. The time length of the signal is T, and the time interval corresponding to the received signal in the first frequency domain and the received signal in the second frequency domain is S*T.

S703: The receiving device estimates the carrier frequency offset according to the phase value and the time interval, and obtains the carrier frequency offset corresponding to the subframe to which the first frequency domain received signal and the second frequency domain received signal belong.

Specifically, the calculation formula for the receiving device to estimate the carrier frequency offset according to the phase value and the time interval is:

f is the frequency offset of the corresponding carrier of the subframe to which the first frequency domain received signal and the second frequency domain received signal belong.

S607: The receiving device performs filtering processing on the frequency offset according to the frequency offset filtered in the previous cycle to obtain the filtered frequency offset.

Specifically, the receiving device uses the frequency offset and frequency offset filtered in the previous cycle as the input of the alpha filter to obtain the filtered frequency offset, namely

Is the frequency offset after filtering in the previous period, f is the frequency offset after filtering in the current subframe, α is the filter factor of the alpha filter, and 0≤α≤1.

In the embodiment of the present application, the receiving device performs frequency offset estimation according to the first target response data and the second target response data to obtain the carrier frequency offset corresponding to the subframe to which the first frequency domain received signal and the second frequency domain received signal belong , And perform filtering processing on the frequency offset according to the frequency offset filtered in the previous cycle to obtain the filtered frequency offset. In this way, in the case of the same signal-to-noise ratio, the jitter of the frequency offset estimation estimated in the embodiment of the present application is smaller, so that the communication system is more stable.

Please refer to Figure 8. Figure 8 is a schematic structural diagram of a receiving device according to an embodiment of the present invention. The receiving device 800 described in the embodiment of the present invention includes a processor 801 and a memory 802. The processor 801 and the memory 802 pass through One or more communication bus connections.

The above-mentioned processor 801 may be a central processing unit (Central Processing Unit, CPU), and the processor may also be other general-purpose processors, digital signal processors (Digital Signal Processors, DSP), application specific integrated circuits (ASICs). ), off-the-shelf programmable gate array (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The processor 801 is configured to support the receiving device to perform the corresponding functions of the receiving device in the method described in FIG. 2 or FIG. 6.

The aforementioned memory 802 may include a read-only memory and a random access memory, and provides computer programs and data to the processor 801. A part of the memory 802 may also include a non-volatile random access memory. Wherein, when the processor 801 calls the computer program, it is used to execute:

Acquiring a first frequency domain received signal and a second frequency domain received signal corresponding to two adjacent transmitted signals in the time domain, where the transmitted signal includes a preset reference signal;

Obtain a first frequency domain channel value according to the first frequency domain received signal and a reference signal, and obtain a second frequency domain channel value according to the second frequency domain received signal and the reference signal;

Time-domain transforming the first frequency-domain channel value to obtain a first time-domain channel impulse response, and time-domain transforming the second frequency-domain channel value to obtain a second time-domain channel impulse response;

According to the energy values of the first time domain channel impulse response and the second time domain channel impulse response, the first target response data of the first time domain channel impulse response and the second time domain channel impulse response are determined. Target response data;

Carrier frequency offset estimation is performed according to the first target response data and the second target response data.

In one implementation, the transmitted signal is an OFDM symbol.

In one implementation, the reference signal is a pilot symbol.

In an implementation manner, the reference signal corresponding to the first frequency domain received signal and the reference signal corresponding to the second frequency domain received signal are the same or different.

In an implementation manner, the first target response data includes 2L+1 response data, the second target response data includes 2L+1 response data, and L is a natural number.

In one implementation, L is determined according to the signal-to-noise ratio.

In an implementation manner, the L+1th response data in the first target response data is when the sum of the energy of the first time domain channel impulse response and the energy of the corresponding second time domain channel impulse response is the maximum Corresponding first time domain channel impulse response data, the L+1th response data in the second target response data is the energy of the first time domain channel impulse response and the corresponding energy of the second time domain channel impulse response The second time domain channel impulse response data corresponding to the maximum sum.

In an implementation manner, the processor 801 is further configured to obtain a correlation value between the first target response data and the second target response data; the processor 801 is further configured to perform carrier frequency offset estimation according to the correlation value.

In an implementation manner, the processor 801 is further configured to obtain the phase of the correlation value to obtain the phase value; the processor 801 is further configured to determine the time interval corresponding to the first frequency domain received signal and the second frequency domain received signal; The processor 801 is further configured to estimate the carrier frequency offset according to the phase value and the time interval to obtain the carrier frequency offset corresponding to the subframe to which the first frequency domain received signal and the second frequency domain received signal belong.

In an implementation manner, the processor 801 is further configured to perform filtering processing on the frequency offset according to the frequency offset filtered in the previous cycle to obtain the filtered frequency offset.

In an implementation manner, the processor 801 is further configured to use the frequency offset and the frequency offset filtered in the previous period as the input of the alpha filter to obtain the filtered frequency offset.

The embodiment of the present application also provides a readable storage medium, and the readable storage medium stores a computer program. When the computer program is executed by a processor, it can be used to implement the implementation corresponding to FIG. 2 or FIG. 6 of the embodiment of the present application. The frequency offset estimation method described in the example will not be repeated here.

The computer-readable storage medium may be the internal storage unit of the receiving device described in any of the foregoing embodiments, such as the hard disk or memory of the device. The computer-readable storage medium may also be an external storage device of the receiving device, such as a plug-in hard disk equipped on the device, a smart memory card (Smart Media Card, SMC), and a Secure Digital (SD) Card, Flash Card, etc. Further, the computer-readable storage medium may also include both an internal storage unit of the ICBC and an external storage device. The computer-readable storage medium is used to store the computer program and other programs and data required by the receiving device. The computer-readable storage medium can also be used to temporarily store data that has been output or will be output.

A person of ordinary skill in the art can understand that all or part of the processes in the method of the above-mentioned embodiments can be implemented by instructing relevant hardware through a computer program. The program can be stored in a readable storage medium. During execution, it may include the procedures of the above-mentioned method embodiments. Wherein, the storage medium can be a magnetic disk, an optical disc, a read-only memory (Read-Only Memory, ROM), or a random access memory (Random Access Memory, RAM), etc.

The above are only specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention. It should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (23)

1. A frequency offset estimation method, which is used to estimate the carrier frequency offset of a transmitting device and a receiving device in a wireless communication system, and is characterized in that it comprises:

   Acquiring a first frequency domain reception signal and a second frequency domain reception signal corresponding to two adjacent transmission signals in the time domain, where the transmission signal includes a preset reference signal;

   Obtaining a first frequency domain channel value according to the first frequency domain received signal and the reference signal, and obtaining a second frequency domain channel value according to the second frequency domain received signal and the reference signal;

   Time-domain transforming the first frequency-domain channel value to obtain a first time-domain channel impulse response, and time-domain transforming the second frequency-domain channel value to obtain a second time-domain channel impulse response;

   According to the energy values of the first time-domain channel impulse response and the second time-domain channel impulse response, the first target response data of the first time-domain channel impulse response and the second time-domain channel impulse response are determined Second target response data of the domain channel impulse response;

   Carrier frequency offset estimation is performed according to the first target response data and the second target response data.
2. The method according to claim 1, wherein the transmitted signal is an OFDM symbol.
3. The method according to claim 1, wherein the reference signal is a pilot symbol.
4. The method according to claim 1, wherein the reference signal corresponding to the first frequency domain received signal and the reference signal corresponding to the second frequency domain received signal are the same or different.
5. The method according to claim 1, wherein the first target response data includes 2L+1 response data, the second target response data includes 2L+1 response data, and the L is a natural number.
6. The method according to claim 5, wherein the L is determined according to the signal-to-noise ratio.
7. The method according to claim 5, wherein the L+1th response data in the first target response data is the energy of the first time-domain channel impulse response and the corresponding second time The first time-domain channel impulse response data corresponding to the maximum sum of energy of the channel impulse response in the domain, the L+1th response data in the second target response data is the first time-domain channel impulse The corresponding second time domain channel impulse response data when the sum of the energy of the response and the energy of the corresponding second time domain channel impulse response is the maximum.
8. The method according to claim 1, wherein said performing carrier frequency offset estimation according to said first target response data and said second target response data comprises:

   Acquiring the correlation value of the first target response data and the second target response data;

   Carrier frequency offset estimation is performed according to the correlation value.
9. The method according to claim 8, wherein said performing carrier frequency offset estimation according to said correlation value comprises:

   Acquiring the phase of the correlation value to obtain the phase value;

   Determining a time interval corresponding to the first frequency domain received signal and the second frequency domain received signal;

   Carrier frequency offset estimation is performed according to the phase value and the time interval to obtain the carrier frequency offset corresponding to the subframe to which the first frequency domain received signal and the second frequency domain received signal belong.
10. The method according to claim 9, wherein the frequency offset is obtained by periodic estimation, and the carrier frequency offset estimation is performed according to the correlation value and the time interval to obtain the first frequency offset. After the frequency offset of the received signal in the second frequency domain and the subframe to which the received signal in the second frequency domain belongs, the method further includes:

    Perform filtering processing on the frequency offset according to the frequency offset filtered in the previous cycle to obtain the filtered frequency offset.
11. The method according to claim 10, wherein the filtering the frequency offset according to the frequency offset filtered in the previous period to obtain the filtered frequency offset comprises:

    The filtered frequency offset and the frequency offset of the previous period are used as inputs of the alpha filter to obtain the filtered frequency offset.
12. A receiving device, characterized in that it comprises a memory and a processor;

    The memory is used to store program code;

    The processor calls the program code, and when the program code is executed, is used to perform the following operations:

    Acquiring a first frequency domain reception signal and a second frequency domain reception signal corresponding to two adjacent transmission signals in the time domain, where the transmission signal includes a preset reference signal;

    Obtaining a first frequency domain channel value according to the first frequency domain received signal and the reference signal, and obtaining a second frequency domain channel value according to the second frequency domain received signal and the reference signal;

    Time-domain transforming the first frequency-domain channel value to obtain a first time-domain channel impulse response, and time-domain transforming the second frequency-domain channel value to obtain a second time-domain channel impulse response;

    According to the energy values of the first time-domain channel impulse response and the second time-domain channel impulse response, the first target response data of the first time-domain channel impulse response and the second time-domain channel impulse response are determined Second target response data of the domain channel impulse response;

    Carrier frequency offset estimation is performed according to the first target response data and the second target response data.
13. The receiving device according to claim 12, wherein the transmission signal is an OFDM symbol.
14. The receiving device according to claim 12, wherein the reference signal is a pilot symbol.
15. The receiving device according to claim 12, wherein the reference signal corresponding to the first frequency domain received signal and the reference signal corresponding to the second frequency domain received signal are the same or different.
16. The receiving device according to claim 12, wherein the first target response data includes 2L+1 response data, the second target response data includes 2L+1 response data, and the L is Natural number.
17. The receiving device according to claim 16, wherein the L is determined according to a signal-to-noise ratio.
18. The receiving device according to claim 16, wherein the L+1th response data in the first target response data is the energy of the first time-domain channel impulse response and the corresponding second When the sum of the energy of the time-domain channel impulse response is the maximum, the corresponding first time-domain channel impulse response data, the L+1th response data in the second target response data is the first time-domain channel impulse response data The corresponding second time domain channel impulse response data when the sum of the energy of the excitation response and the energy of the corresponding second time domain channel impulse response is the maximum.
19. The receiving device according to claim 12, wherein the processor performs carrier frequency offset estimation according to the first target response data and the second target response data, and is specifically configured to perform the following operations:

    Acquiring the correlation value of the first target response data and the second target response data;

    Carrier frequency offset estimation is performed according to the correlation value.
20. The receiving device according to claim 19, wherein the processor performs carrier frequency offset estimation according to the correlation value, which is specifically configured to perform the following operations:

    Acquiring the phase of the correlation value to obtain the phase value;

    Determining a time interval corresponding to the first frequency domain received signal and the second frequency domain received signal;

    Carrier frequency offset estimation is performed according to the phase value and the time interval to obtain the carrier frequency offset corresponding to the subframe to which the first frequency domain received signal and the second frequency domain received signal belong.
21. The receiving device according to claim 20, wherein the frequency offset is obtained by periodic estimation, and the processor performs carrier frequency offset estimation according to the correlation value and the time interval to obtain the After the frequency offset of the subframe to which the first frequency domain received signal and the second frequency domain received signal belong, the processor is further configured to perform the following operations:

    Perform filtering processing on the frequency offset according to the frequency offset filtered in the previous cycle to obtain the filtered frequency offset.
22. The receiving device according to claim 21, wherein the processor performs filtering processing on the frequency offset according to the frequency offset filtered in the previous cycle to obtain the filtered frequency offset, which is specifically used to perform The following operations:

    The filtered frequency offset and the frequency offset of the previous period are used as inputs of the alpha filter to obtain the filtered frequency offset.
23. A computer-readable storage medium, wherein a computer program is stored on the computer-readable storage medium, and the computer program, when executed, realizes the frequency offset according to any one of claims 1 to 11 Estimate method.

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