CN116319206B

CN116319206B - Signal compensation method, processor, system and storage medium

Info

Publication number: CN116319206B
Application number: CN202211098071.0A
Authority: CN
Inventors: 洪海敏; 占兆武; 杨祁; 李龙; 刘鑫
Original assignee: China Gridcom Co Ltd; Shenzhen Zhixin Microelectronics Technology Co Ltd
Current assignee: China Gridcom Co Ltd; Shenzhen Zhixin Microelectronics Technology Co Ltd
Priority date: 2022-09-08
Filing date: 2022-09-08
Publication date: 2023-11-21
Anticipated expiration: 2042-09-08
Also published as: CN116319206A

Abstract

The embodiment of the application provides a signal compensation method, a processor, a system and a storage medium. The method comprises the following steps: receiving a plurality of signals to be detected through a channel in real time, and taking the signals to be detected including leading symbols as sampling signals; time synchronization is carried out on the sampling signals so as to obtain target sampling signals corresponding to the sampling signals; equalizing all first preamble symbols included in the target sampling signal to determine first preamble domain data corresponding to each first preamble symbol; taking a first preamble symbol separated from each first preamble symbol by a preset distance as a second preamble symbol, and determining second preamble pilot field data corresponding to the second preamble symbol; determining an estimated value of sampling frequency offset of the sampling signal according to the first front pilot frequency domain data and the second front pilot frequency domain data; and compensating the target sampling signal according to the estimated value to obtain an accurate estimated value of sampling frequency offset under the condition of low signal-to-noise ratio, thereby improving the signal compensation effect.

Description

Signal compensation method, processor, system and storage medium

Technical Field

The present application relates to the field of communications, and in particular, to a signal compensation method, a processor, a system, and a storage medium.

Background

With the increasing demand of people for various information and the development of broadband communication technology, the power line carrier communication is also developed in the direction of high-speed broadband. In power carrier communication, OFDM technology is generally used to increase the communication rate. Frequency offsets in OFDM systems include Carrier Frequency Offset (CFO) and Sampling Frequency Offset (SFO). Wherein the sampling frequency deviation is caused by the sampling frequency difference between the transmitting-side DAC (digital-to-analog conversion) and the receiving-side ADC (analog-to-digital conversion).

In power line carrier communication, power lines are generally used for transmission based on baseband signals, carrier movement by up-down conversion is not required, and carrier frequency deviation is also avoided. Therefore, the frequency offset generated during transmission is only the sampling frequency offset. The physical layer frame structure specified by the power line carrier communication protocol is composed of preamble symbols, frame control symbols, data payload symbols, and the like. If the frame duration is longer and the error of the crystal oscillator device is larger, the phase deviation caused by the sampling frequency deviation is larger for the more backward symbol. And, the time positions of the preamble symbol and the data payload symbol in the power line system are very far apart. If the phase offset on the data payload symbol is not corrected, the result of channel estimation cannot accurately demodulate the data, and demodulation errors can occur in the data, so that the system performance is seriously reduced.

Currently, the method for estimating the sampling frequency offset comprises the modes of blind estimation, data auxiliary weighting estimation and the like. The blind estimation is adopted, a small-range sampling frequency offset estimation result can be obtained under the condition of high signal-to-noise ratio, and the general calculation complexity is high. The complexity of the frequency offset estimation is reduced in a data auxiliary estimation mode, but the frequency offset estimation can be applied only under the condition of high signal to noise ratio, and the accurate estimation value of the sampling frequency offset is difficult to determine under the condition of relatively low signal to noise ratio, so that the effect of long signal compensation cannot be ensured. The data auxiliary weighting estimation method suppresses noise through the weighting value, has higher precision than the data auxiliary estimation method, and has lower required signal-to-noise ratio, but has higher signal-to-noise ratio required by demodulation under larger frequency offset.

Disclosure of Invention

The embodiment of the application aims to provide a signal compensation method, a processor, a system and a storage medium.

In order to achieve the above object, a first aspect of the present application provides a signal compensation method, applied to a receiving end of an OFDM system, including:

receiving a plurality of signals to be detected through a channel in real time, taking the signals to be detected including leading symbols as sampling signals, wherein the signals to be detected correspond to the transmitting signals of the transmitting end of the OFDM system, and the transmitting signals are transmitted to the receiving end through the channel;

Time synchronization is carried out on the sampling signals so as to obtain target sampling signals corresponding to the sampling signals;

equalizing all first preamble symbols included in the target sampling signal to determine first preamble domain data corresponding to each first preamble symbol;

taking a first preamble symbol separated from each first preamble symbol by a preset distance as a second preamble symbol, and determining second preamble pilot field data corresponding to the second preamble symbol;

determining an estimated value of sampling frequency offset of the sampling signal according to the first front pilot frequency domain data and the second front pilot frequency domain data;

and compensating the target sampling signal according to the estimated value to correct the sampling frequency deviation of the sampling signal.

In an embodiment of the present application, receiving a plurality of signals to be detected through a channel in real time, and taking the signals to be detected including preamble symbols as sampling signals includes: for any one received signal to be detected, selecting N signal data arranged in front in the signal to be detected, wherein N is a natural number; performing fast Fourier transform on the N signal data to determine frequency domain data corresponding to the N signal data; acquiring frequency domain data of a preset preamble sequence; conjugate multiplying the frequency domain data corresponding to the N signal data with the frequency domain data of the preset preamble sequence and performing inverse Fourier transform to determine a power delay spectrum; determining a maximum value of the expected power in the power delay profile corresponding to each sampled signal; for any signal to be detected, under the condition that the maximum value of the expected power is larger than a preset threshold value, determining that a leading symbol exists in the signal to be detected, and taking the signal to be detected comprising the leading symbol as a sampling signal; and determining that the preamble symbol does not exist in any signal to be detected under the condition that the maximum value of the expected power is smaller than or equal to a preset threshold value.

In an embodiment of the present application, time synchronizing the sampling signal to obtain a target sampling signal corresponding to the sampling signal includes: for any one sampling signal, determining the signal position of signal data corresponding to the maximum value of expected power as a time delay point of the sampling signal; and carrying out time synchronization on the sampling signals according to the time delay value of the time delay point so as to obtain target sampling signals corresponding to the sampling signals.

In an embodiment of the present application, the sampling signal includes a preamble symbol, a frame control symbol, and a data payload symbol, and compensating the target sampling signal according to the estimated value to correct a sampling frequency offset of the sampling signal includes: determining a first initial value, a second initial value and a third initial value of each preamble symbol, each frame control symbol and each data load symbol respectively according to the time delay value; determining a first frequency domain compensation phase and a second frequency domain compensation phase of each preamble symbol and each frame control symbol under each subcarrier number according to the first initial value, the second initial value and the estimated value respectively; after each leading symbol and each frame control symbol are respectively compensated according to the first frequency domain compensation phase and the second frequency domain compensation phase, an estimated average value of sampling frequency offset is determined according to the compensated leading symbol and the compensated frame control symbol; determining a third frequency domain compensation phase of each data load symbol under each subcarrier number according to the third initial value and the estimated average value; and after compensating each data load symbol according to the third frequency domain compensation phase, obtaining a compensated target sampling signal so as to correct the sampling frequency offset of the sampling signal.

In an embodiment of the present application, determining the first start value, the second start value, and the third start value of the start sampling point of each preamble symbol, each frame control symbol, and each data payload symbol, respectively, according to the delay value includes:

the first starting value is determined by formula (1):

symstart(l)＝TA+l·N (1)

wherein symstart (l) refers to a first initial value, TA refers to a delay value of a delay point, l refers to a position index of a preamble symbol, and N refers to the number of points of fast Fourier transform;

the second starting value is determined by formula (2):

symstart(m)＝TA+(L _preamble +0.5)*N+m*(N+N _CP ) (2)

wherein symstart (m) refers to a second initial value, TA refers to a delay value of a delay point, L _preamble Refers to the number of preamble symbols in the target sample signal, m is the position index of the frame control symbol, N is the number of points of the fast Fourier transform, N _CP Is the cyclic prefix length of the frame control symbol;

the third starting value is determined by formula (3):

wherein symstart (p) refers to a third initial value, TA refers to a delay value of a delay point, L _preamble Refers to the number of preamble symbols in the target sampled signal, N refers to the number of points of the fast Fourier transform, N _CP Is the cyclic prefix length of the frame control symbol,is the cyclic prefix length of the data payload symbol, p is the position index of the data payload symbol, L _FC Refers to the number of frame control symbols in the target sample signal.

In an embodiment of the present application, determining an estimated average value of sampling frequency offset according to the frequency domain data of the compensated preamble symbol and the frequency domain data of the compensated frame control symbol includes: performing channel estimation on the frequency domain data of the compensated preamble symbol to determine a second equalization coefficient; equalizing and demodulating the frequency domain data of the compensated frame control symbol according to the second equalizing coefficient to determine control information in the frame control symbol, wherein the control information comprises a terminal ID of a transmitting end; determining historical estimation times of historical sampling frequency offset in a memory corresponding to the terminal ID and a historical estimation value corresponding to each historical estimation time; under the condition that the historical estimation times exceeds a preset value, determining the sum of all the historical estimation values corresponding to the historical estimation times; the sum of all historical estimates and the estimated average of the estimates are determined.

In an embodiment of the present application, performing equalization processing on all first pilot symbols included in a target sampling signal to determine first pilot domain data corresponding to the first pilot symbols includes: determining a total number of first preamble symbols included in the target sample signal; selecting first preamble symbols which are arranged in front and have the number of first preset numbers from the total number, and performing fast Fourier transform to determine initial frequency domain data of each selected first preamble symbol; selecting first preamble symbols which are arranged in front and have a second preset number from the total number, and determining a first equalization coefficient according to the initial frequency domain data of each selected first preamble symbol, wherein the first preset number and the second preset number are natural numbers, and the first preset number is larger than the second preset number; and carrying out equalization processing on all first preamble symbols included in the target sampling signal according to the first equalization coefficient so as to determine first pilot frequency domain data corresponding to each first preamble symbol.

In the embodiment of the application, the number of the first preamble symbols is multiple, the subcarrier number of the first preamble symbols is the same as the subcarrier number of the second preamble symbols, and the subcarrier number is determined according to the position of each subcarrier in the effective bandwidth; determining an estimate of a sampling frequency offset of the sampled signal based on the first pre-pilot domain data and the second pre-pilot domain data comprises: taking each first preamble symbol and a second preamble symbol corresponding to each first preamble symbol as a symbol group; performing conjugate multiplication on the first pilot frequency domain data of the first pilot symbol and the second pilot frequency domain data of the second pilot symbol included in each symbol group to determine target frequency domain data of each symbol group corresponding to each subcarrier number; determining target frequency domain total data corresponding to all subcarrier numbers according to the target frequency domain data corresponding to each subcarrier number; determining the phase angle of the total data of the target frequency domain, and determining the sampling frequency offset estimation value of each symbol group according to the phase angle; and determining the average value of the sampling frequency offset estimation values of all the symbol groups as the estimation value of the sampling frequency offset of the sampling signal.

In the embodiment of the application, the preset distance is any value in the range of 4-8 symbol interval distances.

A second aspect of the present application provides a processor configured to perform the above-described signal compensation method.

A third aspect of the present application provides a signal compensation system, the system comprising: a channel; the transmitting end is used for transmitting an originating signal through a channel; the receiving end is used for acquiring a signal to be detected, wherein the signal to be detected corresponds to a transmitting end signal of a transmitting end of the OFDM system, and the transmitting end signal is transmitted to the receiving end through a channel; a processor as described above.

A fourth aspect of the application provides a machine-readable storage medium having stored thereon instructions that, when executed by a processor, cause the processor to be configured to perform the signal compensation method described above.

Through the technical scheme, the symbol data of the sampling signal can be acquired more accurately, a good basis is provided for the follow-up accurate compensation signal, and the influence of the channel and noise on the estimated value of the determined sampling frequency offset can be reduced, so that the estimated value of the more accurate sampling frequency offset can be obtained under the condition of low signal-to-noise ratio, the signal compensation effect is greatly improved, and the frequency offset compensation performance of the system is improved.

Additional features and advantages of embodiments of the application will be set forth in the detailed description which follows.

Drawings

The accompanying drawings are included to provide a further understanding of embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain, without limitation, the embodiments of the application. In the drawings:

FIG. 1 schematically illustrates a block diagram of a signal compensation system according to an embodiment of the application;

fig. 2 schematically illustrates an example diagram of the effect of sampling frequency offset in the time domain according to an embodiment of the application;

FIG. 3 schematically shows a flow diagram of a signal compensation method according to an embodiment of the application;

fig. 4 schematically shows a flow diagram of a timing synchronization signal according to an embodiment of the application;

fig. 5 schematically illustrates a flowchart for determining an estimated value of a sampling frequency offset according to an embodiment of the present application;

fig. 6 schematically illustrates an example diagram of a sampled signal of a high-speed power line carrier communication system in accordance with an embodiment of the present application;

fig. 7 schematically shows a flow chart of a signal compensation method according to a further embodiment of the application;

FIG. 8 schematically illustrates a graph of the result of compensating and demodulating a sampling signal having an AWGN channel and a frequency offset of 40ppm, in accordance with an embodiment of the present application;

Fig. 9 schematically shows a diagram of the result of compensating and demodulating a sampling signal of AWGN channel with a frequency difference of 50ppm according to an embodiment of the present application;

fig. 10 schematically shows a diagram of the result of compensating and demodulating a sampling signal of a MultiPath channel and having a frequency offset of 40ppm according to an embodiment of the present application;

FIG. 11 schematically illustrates a diagram of the result of compensating and demodulating a sampling signal having a multi-path channel and a frequency offset of 50ppm according to an embodiment of the present application;

fig. 12 schematically shows an internal structural view of a computer device according to an embodiment of the present application.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it should be understood that the detailed description described herein is merely for illustrating and explaining the embodiments of the present application, and is not intended to limit the embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

In one embodiment, as shown in fig. 1, there is provided a signal compensation system 100, including a transmitting end 101, a channel 102, a receiving end 103, and a processor 104, wherein:

a transmitting end 101 for transmitting an originating signal through a channel.

And a receiving end 103, configured to obtain a signal to be detected, where the signal to be detected corresponds to an originating signal of a transmitting end of the OFDM system, and the originating signal is transmitted to the receiving end through a channel.

Where channel 102 may be referred to as a signal path. The transmitting end 101 may be configured to generate a signal and transmit the originating signal over a channel. The transmitting end 101 includes a D/a module, which may be used for signal reconstruction. The receiving end 103 may be used to obtain a sampled signal. The receiving end 103 includes an a/D module, which can be used for signal sampling. Further, the transmitting end 101 of the OFDM system may transmit the transmitting end signal to the receiving end 103 through the channel 102. And the originating signal of the transmitting end 101 may be interfered when transmitted through a channel. For example, the originating signal may be affected by channel and noise. In this case, the signal to be detected received by the receiving end 103 is an originating signal from which interference has been received. After the receiving end 103 receives the signal to be detected, the receiving end 103 may sample and detect the signal to be detected through the a/D module, so as to obtain a sampled signal.

In the process of receiving and transmitting actual signals, the frequency of the signal transmitted by the transmitting end and the frequency of the signal received by the receiving end of the OFDM system may deviate from the sampling clocks of the transmitting end and the receiving end of the OFDM system due to the difference of crystal oscillator physical devices. If the signal sent by the sending end is long enough, the deviation is accumulated continuously, so that the deviation occurs when the receiving end receives the sampling signal, namely the receiving signal generates sampling frequency deviation relative to the sending signal. For example, as shown in fig. 2, an exemplary plot of the effect of sampling frequency offset on the time domain is provided. If the sampling frequency and sampling period of the transmitting end are f respectively _s And T _s The sampling frequency and the sampling period of the receiving end are f 'respectively' _s And T' _s The crystal oscillator frequency difference is epsilon=f' _s -f _s /f _s Receiving endIs T' _s ＝T _s 1+ε. When epsilon is more than 0, the sampling frequency of the receiving end is higher than that of the sending end, and when epsilon is less than 0, the sampling frequency of the receiving end is lower than that of the sending end.

Fig. 3 schematically shows a flow diagram of a signal compensation method according to an embodiment of the application. As shown in fig. 3, in an embodiment of the present application, a signal compensation method is provided, and this embodiment is mainly exemplified by the method applied to the receiving end 103 in fig. 1, and includes the following steps:

Step 301, receiving a plurality of signals to be detected through a channel in real time, and taking the signals to be detected including the preamble symbol as sampling signals, wherein the signals to be detected correspond to a transmitting signal of a transmitting end of the OFDM system, and the transmitting signal is transmitted to a receiving end through the channel.

Step 302, time synchronizing the sampling signals to obtain a target sampling signal corresponding to the sampling signal.

Step 303, performing equalization processing on all first preamble symbols included in the target sampling signal to determine first preamble domain data corresponding to each first preamble symbol.

Step 304, taking the first preamble symbol separated from each first preamble symbol by a preset distance as a second preamble symbol, and determining second preamble domain data corresponding to the second preamble symbol.

Step 305, determining an estimated value of sampling frequency offset of the sampling signal according to the first pre-pilot frequency domain data and the second pre-pilot frequency domain data.

And 306, compensating the target sampling signal according to the estimated value to correct the sampling frequency deviation of the sampling signal.

The transmitting end of the OFDM system may transmit an originating signal to the processor through a channel. The processor can receive a plurality of signals to be detected through the channel in real time, wherein the signals to be detected correspond to the source signals. In particular, the originating signal may be subject to interference as it is transmitted over the channel. For example, the originating signal may be affected by channel and noise. That is, the signal to be detected may refer to the originating signal that has received the interference. Further, the signal to be detected may include a signal to be detected with a preamble symbol and a signal to be detected without a preamble symbol. The signal to be detected with the preamble symbol may refer to a useful signal to be compensated. The sample signal without the preamble symbol may be an unnecessary signal such as noise, and may be, for example, gaussian white noise. In the case of receiving a plurality of signals to be detected, the processor may detect the signals to be detected, and may use the signals to be detected including the preamble symbol as sampling signals.

In the case of determining the sampled signal, the processor may time synchronize the sampled signal to obtain a target sampled signal corresponding to the sampled signal. Wherein the target sample signal may comprise a plurality of first preamble symbols. In the case of determining the target sampling signal, the processor may perform equalization processing on the first preamble symbols included in the target sampling signal to determine first preamble domain data corresponding to each first preamble symbol. The processor may further take a first preamble symbol spaced apart from each of the first preamble symbols by a predetermined distance as a second preamble symbol, and may determine second preamble pilot field data corresponding to the second preamble symbol. In the case of determining the first and second previous pilot field data, the processor may determine an estimated value of a sampling frequency offset of the sampling signal from the first and second previous pilot field data. Further, the processor may compensate the target sampling signal according to the estimated value of the sampling frequency offset to correct the sampling frequency offset of the sampling signal.

According to the technical scheme, the sampling signals are time-synchronized to obtain the target sampling signals, the symbol data of the sampling signals can be more accurately obtained, the accuracy of subsequent compensation signals is improved, the influence of channels on determining sampling frequency offset estimated values can be reduced for all preamble symbols in the target sampling signals, the first preamble symbol of each first preamble symbol, which is separated by a preset distance, is used as a second preamble symbol, second front pilot frequency domain data corresponding to the second preamble symbol is determined, the estimated value of the sampling frequency offset is determined according to the first front pilot frequency domain data and the second front pilot frequency domain data, the influence of noise on determining the estimated value of the sampling frequency offset is greatly reduced, the estimated value of the sampling frequency offset can be more accurately obtained, and therefore the signal compensation effect is improved.

In one embodiment, receiving a plurality of signals to be detected through a channel in real time and taking a sampling signal including a preamble symbol as the sampling signal includes: for any one received signal to be detected, selecting N signal data arranged in front in the signal to be detected, wherein N is a natural number; performing fast Fourier transform on the N signal data to determine frequency domain data corresponding to the N signal data; acquiring frequency domain data of a preset preamble sequence; performing conjugate multiplication on frequency domain data corresponding to the N signal data and frequency domain data of a preset preamble sequence, and performing inverse Fourier transform to determine a power delay spectrum; determining a maximum value of expected power in a power delay spectrum corresponding to each signal to be detected; for any signal to be detected, under the condition that the maximum value of the expected power is larger than a preset threshold value, determining that a leading symbol exists in the signal to be detected, and taking the signal to be detected comprising the leading symbol as a sampling signal; and determining that the preamble symbol does not exist in any signal to be detected under the condition that the maximum value of the expected power is smaller than or equal to a preset threshold value.

For any one received signal to be detected, the processor may select N signal data arranged in front in the signal to be detected. Wherein N is a natural number. The processor may then perform a fast fourier transform on the N signal data to determine frequency domain data corresponding to the N signal data. In this case, the processor may further acquire frequency domain data of a preset preamble sequence. The frequency domain data of the preset preamble sequence can be determined according to a formula of a known signal defined in a communication protocol. The processor may perform conjugate multiplication and inverse fourier transform according to frequency domain data corresponding to the N signal data and frequency domain data of a preset preamble sequence, so as to determine a power delay spectrum.

In the case of determining the power delay profile, the processor may determine a maximum value of the desired power in the power delay profile corresponding to each signal to be detected. The processor may further obtain a preset threshold to determine whether the preamble symbol exists in the signal to be detected according to the preset threshold and a maximum value of the expected power. The preset threshold value may refer to a power maximum value obtained by simulating white noise as an input. Specifically, for any signal to be detected, if the maximum value of the expected power is greater than the preset threshold value, the processor may determine that a preamble symbol exists in the signal to be detected, and may use the signal to be detected including the preamble symbol as the sampling signal. For any signal to be detected, the processor may determine that no preamble symbol exists in the signal to be detected when the maximum value of the power delay spectrum is less than or equal to a preset threshold value. At this time, the processor may not need to process the signal to be detected.

In one embodiment, time synchronizing the sampling signals to obtain target sampling signals corresponding to the sampling signals includes: for any one sampling signal, determining the signal position of signal data corresponding to the maximum value of expected power as a time delay point of the sampling signal; and carrying out time synchronization on the sampling signals according to the time delay value of the time delay point so as to obtain target sampling signals corresponding to the sampling signals.

For any one sampling signal, the processor may determine a signal position where signal data corresponding to a maximum value of the desired power is located as a delay point of the sampling signal. The processor may time synchronize the sampling signals according to the delay value of the delay point to determine a target sampling signal corresponding to the sampling signal. By time synchronization of the sampling signals, symbol data of the sampling signals can be acquired more accurately, and accuracy of subsequent compensation signals is improved.

For example, as shown in fig. 4, a schematic flow chart of a timing synchronization signal is provided. The processor may select the first 1024 signal data of the received signal r (n) and may take the 1024 signal data as r1 (n). The processor may then perform a Fast Fourier Transform (FFT) on the 1024 signal data to obtain frequency domain data Y1 (k). The processor may further obtain a locally known preamble sequence S (k). Wherein the locally known preamble sequence S (k) may refer to frequency domain data of the preamble sequence of the transmission signal. The processor may conjugate multiply the frequency domain data Y1 (k) with the locally known preamble sequence S (k) and inverse fourier transform the result of the conjugate multiplication to obtain the correlation peak sequence r_pdfp (n). The processor may further power the correlation peak sequence r_pdfp (n) to obtain a power delay profile p_pdfp (n).

In the case of determining the power delay profile p_pdfp (n), the processor may determine a maximum desired power max (p_pdfp (n)) in the power delay profile p_pdfp (n) and a signal position index_max where signal data corresponding to the maximum desired power is located. The processor may obtain a preset threshold value thrd_ pdp. The threshold value thrd_ pdp may refer to the maximum power value obtained by emulating white noise as input. In the case where the maximum expected power max (p_pdfp (n)) is less than or equal to the threshold value thrd_ pdp, the processor may determine that the preamble is not detected, i.e., the preamble symbol is not included in the received signal r (n). The received signal r (n) at this time may not be a signal corresponding to the transmitted signal, and the processor may not process the received signal r (n).

In the case where the maximum expected power max (p_pdfp (n)) is greater than the threshold value thrd_ pdp, the processor may determine that a preamble symbol is present in the received signal r (n) and take the received signal r (n) as a sampling signal. Further, in the case of determining the sampling signal, the processor may determine the signal position index_max as a delay point of the sampling signal with respect to the preset preamble sequence, and may synchronize the sampling signal by using a delay value TA of the delay point, so as to obtain a target sampling signal corresponding to the sampling signal.

In one embodiment, performing equalization processing on all first preamble symbols included in the target sampling signal to determine first preamble domain data corresponding to the first preamble symbols includes: determining a total number of first preamble symbols included in the target sample signal; selecting first preamble symbols which are arranged in front and have the number of first preset numbers from the total number, and performing fast Fourier transform to determine initial frequency domain data of each selected first preamble symbol; selecting first preamble symbols which are arranged in front and have a second preset number from the total number, and determining a first equalization coefficient according to the initial frequency domain data of each selected first preamble symbol, wherein the first preset number and the second preset number are natural numbers, and the first preset number is larger than the second preset number; and carrying out equalization processing on all first preamble symbols included in the target sampling signal according to the first equalization coefficient so as to determine first pilot frequency domain data corresponding to each first preamble symbol.

In the case of determining the target sampled signal, the processor may determine a total number of first preamble symbols included in the target sampled signal. In particular, the processor may determine the number of times the first preamble symbol is detected as the total number of first preamble symbols. In case of determining the total number of first preamble symbols, the processor may select first preamble symbols arranged in front and in a first preset number from the total number to perform a fast fourier transform to determine initial frequency domain data of each of the selected first preamble symbols. Wherein, the initial frequency domain data may refer to frequency domain data that is not subjected to the first preamble symbol equalization process. In one embodiment, the difference between the total number of first preamble symbols and the first preset number may be greater than a preset value, which may be 2.

In case of determining the initial frequency domain data of each selected first preamble symbol, the processor may further select the first preamble symbols arranged in front and in a second preset number from the total number and determine the first equalization coefficient according to the selected initial frequency domain data of the second preset number of first preamble symbols. The first preset number and the second preset number are natural numbers, and the first preset number is larger than the second preset number. For example, the second preset number may be 4. Specifically, the processor may perform channel estimation on the initial frequency domain data of the selected second preset number of first preamble symbols by a least square method to determine the first equalization coefficient. In the case of determining the first equalization coefficient, the processor may perform equalization processing on all first preamble symbols included in the target sampling signal according to the first equalization coefficient to determine first preamble domain data corresponding to each first preamble symbol. The first pilot frequency domain data may refer to frequency domain data after the first pilot symbol equalization process.

For example, if the processor determines that the total number of first preamble symbols is L _preamble The processor may select L first preamble symbols r _preamble,1 ，r _preamble,2 ，…，r _preamble,L And determining the initial frequency domain data Y of each first preamble symbol selected _preamble (l, k). The processor can select the first 4 first preamble symbols from the L first preamble symbols, and can perform channel estimation on the selected 4 first preamble symbols by a least square method to obtain a first equalization coefficient W _equ1 (k) A. The invention relates to a method for producing a fibre-reinforced plastic composite Where k may refer to a subcarrier number corresponding to each first preamble symbol. The processor can be based on the first equalization coefficient W _equ1 (k) Equalizing the L first preamble symbols to determine first preamble field data Y corresponding to each first preamble symbol _preamble,equ (l,k)。

In one embodiment, the predetermined distance is any value from 4 to 8 of symbol spacing distance. In the case of determining the first pilot field data of each first preamble symbol included in the target sampling signal, the processing may take the first preamble symbol spaced apart from each first preamble symbol by a preset distance as the second preamble symbol, and may determine the second pilot field data corresponding to the second preamble symbol. The preset distance may be any value of 4-8 symbol interval distances.

In one embodiment, the number of the first preamble symbols is plural, the subcarrier number of the first preamble symbol is the same as the subcarrier number of the second preamble symbol, and the subcarrier number is determined according to the position of each subcarrier in the effective bandwidth; determining an estimate of a sampling frequency offset of the sampled signal based on the first pre-pilot domain data and the second pre-pilot domain data comprises: taking each first preamble symbol and a second preamble symbol corresponding to each first preamble symbol as a symbol group; performing conjugate multiplication on the first pilot frequency domain data of the first pilot symbol and the second pilot frequency domain data of the second pilot symbol included in each symbol group to determine target frequency domain data of each symbol group corresponding to each subcarrier number; determining target frequency domain total data corresponding to all subcarrier numbers according to the target frequency domain data corresponding to each subcarrier number; determining the phase angle of the total data of the target frequency domain, and determining the sampling frequency offset estimation value of each symbol group according to the phase angle; and determining the average value of the sampling frequency offset estimation values of all the symbol groups as the estimation value of the sampling frequency offset of the sampling signal.

The target sample signal may include a plurality of first preamble symbols. The subcarrier number of the first preamble symbol may be the same as the subcarrier number of the second preamble symbol. The subcarrier number may be determined based on the location of each subcarrier within the effective bandwidth. The processor may first use each first preamble symbol group and a second preamble symbol corresponding to each first preamble symbol as one symbol group when determining an estimated value of a sampling frequency offset of the sampling signal based on second preamble domain data of the first preamble domain data. Wherein each subcarrier number may correspond to at least one symbol group. The processor may conjugate multiply the first preamble field data of the first preamble symbol and the second preamble field data of the second preamble symbol included in each symbol group to determine target frequency domain data of each symbol group corresponding to each subcarrier number.

The processor may determine target frequency domain total data of each symbol group corresponding to all subcarrier numbers according to target frequency domain data of each symbol group corresponding to each subcarrier number. In this case, the processor may further determine a phase angle of the target frequency domain total data, and may determine a sampling frequency offset estimate value for each symbol group according to the phase angle. Under the condition that the sampling frequency offset estimation value of each symbol group is determined, the processor can determine the average value of the sampling frequency offset estimation values of all symbol groups according to the sampling frequency offset estimation value of each symbol group, and can determine the average value as the estimation value of the sampling frequency offset of the sampling signal.

For example, first preamble field data Y for first preamble symbol l _preamble,equ Second pre-pilot field data Y of (l, k) and second preamble symbol l+M _preamble,equ (l+M, k), each subcarrier number k corresponding to the target frequency domain data R of the symbol group _preamble (l, k) can pass through R _preamble (l,k)＝Y _preamble,equ (l,k)*conj(Y _preamble,equ (l+M, k)). Target frequency domain total data R of the symbol group corresponding to all subcarrier numbers _sum (l) Can pass throughAnd (5) determining. Phase angle of the target frequency domain total data ∈>Can be according to->And (5) determining. By passing throughA sampling frequency offset estimate for the set of symbols may be determined. Wherein k is _low May refer to the lowest subcarrier index, k, of subcarriers within the effective bandwidth _high May refer to the highest subcarrier index of subcarriers within the effective bandwidth, M may refer to the number of symbol intervals, sfo _est (groupIndex = l) may refer to the sampled frequency offset estimate for the symbol group. The processor can further determine the sampling frequency offset estimation value sfo of the L-M group _new And determining the average value of the sampling frequency offset estimation values of the L-M groups as the sampling frequency offset estimation value between the signals. In particular, it is possible to rely on +.>An estimate of the sampling frequency offset between the signals is determined.

In one embodiment, as shown in fig. 5, a flow chart is provided for determining an estimate of a sampling frequency offset.

The processor may select the first 4 preamble symbols from the signal after timing synchronization to perform channel estimation, so as to perform equalization processing on each preamble symbol according to a first equalization coefficient obtained by the channel estimation, thereby determining frequency domain data of each preamble symbol after the equalization processing. The processor may then select a preamble symbol spaced 4 symbols apart from the first preamble symbol included in the target timing synchronized signal for calculation of the sampling frequency offset estimate. Specifically, for each preamble symbol, the processor may determine the preamble symbol spaced by 4 symbols and the preamble symbol as one symbol group, and may determine the estimated value sfo (l) of the symbol group. That is, one estimated value sfo (l) is determined every two preamble symbols. The processor may then evaluate the plurality of estimates sfo (l) to obtain an estimate sfo_new of the sampling frequency offset of the received signal.

For example, taking the example that the number of preamble symbols included in the signal after timing synchronization is 6, the processor may determine the 1 st preamble symbol and the 5 th preamble symbol as a symbol group a, and the processor may determine the sampling frequency offset estimation value sfo1 of the symbol group a. The processor may determine the 2 nd preamble symbol and the 6 th preamble symbol as a symbol group B, and the processor may determine the sampling frequency offset estimation value sfo2 of the symbol group B. Further, the processor may determine the average of the sampled frequency offset estimates for symbol groups A and B, i.e., sfo1+sfo2/2, and may determine sfo1+sfo2/2 as the estimate of the sampled frequency offset between the signals. The processor can compensate the signal after timing synchronization through the estimated value of the sampling frequency offset.

In one embodiment, the sampling signal includes a preamble symbol, a frame control symbol, and a data payload symbol, and compensating the target sampling signal according to the estimated value to correct a sampling frequency offset of the sampling signal includes: determining a first initial value, a second initial value and a third initial value of each preamble symbol, each frame control symbol and each data load symbol respectively according to the time delay value; determining a first frequency domain compensation phase and a second frequency domain compensation phase of each preamble symbol and each frame control symbol under each subcarrier number according to the first initial value, the second initial value and the estimated value respectively; after each leading symbol and each frame control symbol are respectively compensated according to the first frequency domain compensation phase and the second frequency domain compensation phase, an estimated average value of sampling frequency offset is determined according to the compensated leading symbol and the compensated frame control symbol; determining a third frequency domain compensation phase of each data load symbol under each subcarrier number according to the third initial value and the estimated average value; and after compensating each data load symbol according to the third frequency domain compensation phase, obtaining a compensated target sampling signal so as to correct the sampling frequency offset of the sampling signal.

As shown in fig. 6, an example plot of a sampled signal for a high-speed power line carrier communication system is provided. Wherein there is a frame interval between every two sampled signals. One sampling signal may include a preamble symbol, a frame control symbol, and a data payload symbol. The number of preamble symbols may include a plurality. The figure schematically shows 13 preamble symbols, each of which has a symbol length of 1024, i.e., one preamble symbol may include 1024 signal data. A roll-off interval may be included before the first preamble symbol or between the last preamble symbols, which may correspond to a symbol length of 124. The number of frame control symbols may include a plurality, and each frame control symbol may include a guard interval having a symbol length of 458. The number of data payload symbols may also include a plurality, and each data payload symbol may also include a guard interval of symbol length 458. The preamble symbols may be consecutive known signals and may be used for synchronization signals, frequency offset estimation, channel estimation, etc. The frame control symbols may carry control information including source user, destination user information, and demodulation information for the data payload. The data payload symbols may include the data signal to be transmitted.

The processor may determine a first starting value, a second starting value, and a third starting value for each preamble symbol, each frame control symbol, and each data payload symbol, respectively, based on the delay value. The processor may determine a first frequency domain compensation phase and a second frequency domain compensation phase for each preamble symbol and each frame control symbol under each subcarrier number based on the first starting value, the second starting value, and the estimated value, respectively. After compensating each preamble symbol and each frame control symbol according to the first frequency domain compensation phase and the second frequency domain compensation phase, respectively, the processor may determine an estimated average value of the sampling frequency offset according to the compensated preamble symbol and the compensated frame control symbol.

In the case of compensating for all of the preamble symbols and the frame control symbols and determining an estimated average of the sampling frequency offsets, the processor may determine a third frequency domain compensation phase for each data payload symbol at each subcarrier number based on the third starting value and the estimated average. The processor may compensate each data payload symbol included in the target sample signal according to the third frequency domain compensation phase. After compensating each data payload symbol according to the third frequency domain compensation phase, the processor may obtain a compensated target sampling signal to correct a sampling frequency offset of the sampling signal.

In one embodiment, determining the estimated average value of the sampling frequency offset from the frequency domain data of the compensated preamble symbol and the frequency domain data of the compensated frame control symbol comprises: performing channel estimation on the frequency domain data of the compensated preamble symbol to determine a second equalization coefficient; equalizing and demodulating the frequency domain data of the compensated frame control symbol according to the second equalizing coefficient to determine control information in the frame control symbol, wherein the control information comprises a terminal ID of a transmitting end; determining historical estimation times of historical sampling frequency offset in a storage memory corresponding to the terminal ID, and a historical estimation value corresponding to each historical estimation time; under the condition that the historical estimation times exceeds a preset value, determining the sum of all the historical estimation values corresponding to the historical estimation times; the sum of all historical estimates and the estimated average of the estimates are determined.

The processor may perform channel estimation on the frequency domain data of the compensated preamble symbol to determine a second equalization coefficient. The processor may equalize and demodulate the frequency domain data of the compensated frame control symbol according to the second equalization coefficient to determine control information in the frame control symbol, where the control information includes a terminal ID of the transmitting end. The processor may determine a historical estimate of the frequency offset of the historical samples in the memory corresponding to the terminal ID and a historical estimate corresponding to each of the historical estimates. The processor may compare the historical estimate with a preset number. In the case that the number of history estimations exceeds a preset value, the processor may determine that all or part of the number of history estimations corresponds to The sum of all historical estimates and an estimated average of the sum of all historical estimates and the estimate may be determined. Specifically, the estimated average value may be determined by sfo _compensate ＝sfo _old ·Cnt _old +sfo _new /Cnt _old +1 determination. Wherein, sfo _compensate May refer to the estimated mean, sfo _old Can refer to a historical estimate, cnt _old May refer to the historical estimated times, sfo _new May refer to an estimated value. The processor may compensate for the data load symbols based on the estimated average. By averaging the estimated value of the sampling frequency offset and the historical estimated value of the sampling frequency offset, more accurate frequency offset estimation can be determined under the condition of low signal to noise ratio, the frequency offset compensation effect on the ultra-long symbol is better, and the frequency offset resistance of the OFDM system is improved.

In one embodiment, determining the first, second and third starting values of the starting sampling point for each preamble symbol, each frame control symbol and each data payload symbol, respectively, based on the delay value comprises:

the first starting value is determined by formula (1):

symstart(l)＝TA+l·N (1)

wherein symstart (l) refers to a first initial value, TA refers to a delay value of a delay point, l refers to a position index of a preamble symbol, N refers to the number of points of fast fourier transform, and N may be 1024;

The second starting value is determined by formula (2):

symstart(m)＝TA+(L _preamble +0.5)*N+m*(N+N _CP ) (2)

wherein symstart (m) refers to a second initial value, TA refers to a delay value of a delay point, L _preamble Refers to the number of preamble symbols in the target sample signal, m is the position index of the frame control symbol, can start from 0, N refers to the number of points of the fast Fourier transform, N can be 1024, N _CP Is the cyclic prefix length of the frame control symbol;

the third starting value is determined by formula (3):

wherein symstart (p) refers to a third initial value, TA refers to a delay value of a delay point, L _preamble Refers to the number of preamble symbols in the target sampled signal, N refers to the number of points of the fast Fourier transform, N can be 1024, N _CP Is the cyclic prefix length of the frame control symbol,is the cyclic prefix length of the data payload symbol, p is the position index of the data payload symbol, L can start from 0 _FC Refers to the number of frame control symbols in the target sample signal.

In one embodiment, the first frequency domain compensation phase is determined by equation (4):

wherein,refers to the first frequency domain compensation phase, sfo, of each preamble symbol, i, at each subcarrier number k _new May refer to an estimated value of a sampling frequency offset of the sampled signal, symstart (l) refers to a first starting value, N refers to the number of points of the fast fourier transform, and N may be 1024.

In one embodiment, the second frequency domain compensation phase is determined by equation (5):

wherein,refers to the second frequency domain compensation phase, sfo, of each frame control symbol m at each subcarrier number k _new May refer to an estimated value of a sampling frequency offset of the sampled signal, symstart (m) refers to a second starting value, N refers to the number of points of the fast fourier transform, and N may be 1024.

In one embodiment, the third frequency domain compensation phase is determined by equation (6):

wherein,refers to the third frequency domain compensation phase, sfo, of each data payload symbol p at each subcarrier number k _compensate The estimated average value that may be referred to, symstart (p) refers to the third starting value, N refers to the number of points of the fast fourier transform, and N may be 1024.

In one embodiment, as shown in fig. 7, a flow diagram of another signal compensation method is provided.

The processor may perform timing synchronization on the received signal to determine a timing synchronized signal r_ta (n). The processor may equalize the first preamble symbols included in the timing synchronized signal r_ta (n) to determine first preamble domain data corresponding to each first preamble symbol. The processor may take a first preamble symbol spaced apart from each of the first preamble symbols by a predetermined distance as a second preamble symbol, and may determine second preamble pilot field data corresponding to the second preamble symbol. Further, the processor may determine the estimated value sfo_new of the sampling frequency offset from the first pilot field data of the first preamble symbol and the second pilot field data of the second preamble symbol. That is, the processor may perform sampling frequency offset estimation through a preamble symbol included in the timing synchronized signal r_ta (n) to determine the estimated value sfo_new of the sampling frequency offset.

In determining the estimated value of the sampling frequency offset, the processor may compensate for each symbol included in the timing synchronized signal r_ta (n) to correct the sampling frequency offset. Specifically, the processor may compensate the preamble symbol according to the estimated value sfo_new of the sampling frequency offset, and may perform channel estimation on the frequency domain data of the compensated preamble symbol to determine the control information in the frame control symbol. The processor may compensate the frame control symbol according to the estimated value sfo_new of the sampling frequency offset, and may demodulate the compensated frame control symbol according to control information in the frame control symbol, so as to determine a terminal ID (UID) of the transmitting end. The processor may perform a further processing of the estimate sfo new. Specifically, the processor may determine the estimated average value sfo_uid of the sampling frequency offset according to the historical estimated times cnt_old of the historical sampling frequency offsets in the storage memory corresponding to the terminal ID and the historical estimated value sfo_old corresponding to each historical estimated time, and may update the estimated value sfo_new of the sampling frequency offset to the estimated average value sfo_uid of the sampling frequency offset. Under the condition that the estimated average value sfo_uid of the sampling frequency offset is determined, the processor can compensate the data load symbol according to the estimated average value sfo_uid of the sampling frequency offset, and then can demodulate the data load data, so that signal compensation for the received signal after timing synchronization is completed.

Through the technical scheme, the sampling signal and the second sampling signal are synchronized to obtain the target sampling signal, so that the symbol data of the sampling signal can be acquired more accurately, and a good basis is provided for the follow-up accurate compensation signal. By performing equalization processing on the first preamble symbol included in the target sampling signal, the influence of the channel on determining the estimated value of the sampling frequency offset can be reduced. The first leading symbol which is separated from each first leading symbol by a preset distance is used as a second leading symbol, second front pilot frequency domain data corresponding to the second leading symbol is determined, and the estimated value of the sampling frequency offset is determined according to the first front pilot frequency domain data and the second front pilot frequency domain data, so that the influence of noise on the estimated value of the determined sampling frequency offset is greatly reduced, and more accurate estimated value of the sampling frequency offset can be obtained under the condition of low signal-to-noise ratio, thereby greatly improving the signal compensation effect and the frequency offset compensation performance of a system.

As shown in fig. 8, a schematic diagram of the result of compensating and demodulating a sampling signal of AWGN channel with a frequency difference of 40ppm is provided. As shown in fig. 9, a schematic diagram of the result of compensating and demodulating the sampling signal of AWGN channel with a frequency difference of 50ppm is provided. Where BLER refers to block error rate and EsN0 refers to the ratio of energy per symbol to spectral density of noise energy. The present scheme is adopted in fig. 8 and 9 without adding a preamble equalization scheme, an existing weighting scheme, and the present scheme performs signal compensation and demodulation on the sampled signal. It can be seen that, under the condition of larger frequency difference, the demodulation performance of the signal after the signal is compensated by adopting the scheme is more similar to the demodulation performance of the unbiased AWGN channel PB.

As shown in fig. 10, a schematic diagram of the result of compensating and demodulating a sampling signal of a MultiPath channel with a frequency offset of 40ppm is provided. As shown in fig. 11, a schematic diagram of the result of compensating and demodulating a sampling signal of a MultiPath channel with a frequency offset of 50ppm is provided. The present scheme is adopted in fig. 10 and 11 without adding a preamble equalization scheme, an existing weighting scheme, and the present scheme performs signal compensation and demodulation on the sampled signal. It can be seen that, in the case of larger frequency difference, the demodulation performance of the signal after the signal is compensated by adopting the scheme is closer to the demodulation performance of the unbiased MultiPath channel PB.

According to the technical scheme, the influence of the channel and noise on the estimated value of the sampling frequency offset is fully considered, and the influence of the channel on the frequency offset estimation is greatly reduced by adopting a mode of firstly balancing and then estimating. And the noise is averaged on time, subcarriers and historical multiframes, so that the influence of the noise on the frequency offset estimation is greatly reduced, and a more accurate sampling frequency offset estimation value is obtained under the condition of low signal-to-noise ratio, thereby greatly improving the signal compensation effect and the frequency offset compensation performance of the system.

Fig. 3 and 7 are flow diagrams of a signal compensation method in one embodiment. It should be understood that, although the steps in the flowcharts of fig. 3 and 7 are shown in order as indicated by the arrows, these steps are not necessarily performed in order as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in fig. 3 and 7 may include multiple sub-steps or stages that are not necessarily performed at the same time, but may be performed at different times, nor does the order in which the sub-steps or stages are performed necessarily occur in sequence, but may be performed alternately or alternately with at least a portion of the sub-steps or stages of other steps or other steps.

In one embodiment, a processor is provided for running a program, wherein the program performs the signal compensation method described above when running.

In one embodiment, a storage medium is provided having a program stored thereon that when executed by a processor implements the signal compensation method described above.

In one embodiment, a computer device is provided, which may be a server, and the internal structure of which may be as shown in fig. 12. The computer device includes a processor a01, a network interface a02, a memory (not shown) and a database (not shown) connected by a system bus. Wherein the processor a01 of the computer device is adapted to provide computing and control capabilities. The memory of the computer device includes internal memory a03 and nonvolatile storage medium a04. The nonvolatile storage medium a04 stores an operating system B01, a computer program B02, and a database (not shown in the figure). The internal memory a03 provides an environment for the operation of the operating system B01 and the computer program B02 in the nonvolatile storage medium a04. The database of the computer equipment is used for storing data such as estimated values of sampling frequency offset and the like. The network interface a02 of the computer device is used for communication with an external terminal through a network connection. The computer program B02 is executed by the processor a01 to implement a signal compensation method.

It will be appreciated by those skilled in the art that the structure shown in FIG. 12 is merely a block diagram of some of the structures associated with the present inventive arrangements and is not limiting of the computer device to which the present inventive arrangements may be applied, and that a particular computer device may include more or fewer components than shown, or may combine some of the components, or have a different arrangement of components.

The embodiment of the application provides equipment, which comprises a processor, a memory and a program stored in the memory and capable of running on the processor, wherein the processor executes the program to realize the steps of a signal compensation method.

The application also provides a computer program product adapted to perform a program initialized with the steps of the signal compensation method when executed on a data processing device.

It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

In one typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.

The memory may include volatile memory in a computer-readable medium, random Access Memory (RAM) and/or nonvolatile memory, etc., such as Read Only Memory (ROM) or flash RAM. Memory is an example of a computer-readable medium.

Computer readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of storage media for a computer include, but are not limited to, phase change memory (PRAM), static Random Access Memory (SRAM), dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), read Only Memory (ROM), electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium, which can be used to store information that can be accessed by a computing device. Computer-readable media, as defined herein, does not include transitory computer-readable media (transmission media), such as modulated data signals and carrier waves.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises an element.

The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and variations of the present application will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the application are to be included in the scope of the claims of the present application.

Claims

1. A signal compensation method, applied to a receiving end of an OFDM system, the method comprising:

receiving a plurality of signals to be detected through a channel in real time, and taking the signals to be detected comprising leading symbols as sampling signals, wherein the signals to be detected correspond to an originating signal of a transmitting end of the OFDM system, and the originating signal is transmitted to the receiving end through the channel;

Performing time synchronization on the sampling signals to obtain target sampling signals corresponding to the sampling signals;

compensating the target sampling signal according to the estimated value to correct the sampling frequency offset of the sampling signal;

the receiving, in real time, a plurality of signals to be detected through a channel, and taking the signals to be detected including the preamble symbol as sampling signals includes:

for any one received signal to be detected, selecting N signal data which are arranged in front in the signal to be detected, wherein N is a natural number;

performing fast Fourier transform on the N signal data to determine frequency domain data corresponding to the N signal data;

acquiring frequency domain data of a preset preamble sequence;

Conjugate multiplying the frequency domain data corresponding to the N signal data with the frequency domain data of the preset preamble sequence and performing inverse Fourier transform to determine a power delay spectrum;

determining a maximum value of expected power in a power delay spectrum corresponding to each signal to be detected;

for any signal to be detected, under the condition that the maximum value of the expected power is larger than a preset threshold value, determining that a leading symbol exists in the signal to be detected, and taking the signal to be detected comprising the leading symbol as a sampling signal;

and determining that no preamble symbol exists in any signal to be detected under the condition that the maximum value of the expected power is smaller than or equal to the preset threshold value.

2. The signal compensation method of claim 1, wherein time synchronizing the sampled signals to obtain target sampled signals corresponding to the sampled signals comprises:

for any one sampling signal, determining the signal position of the signal data corresponding to the maximum value of the expected power as the time delay point of the sampling signal;

and carrying out time synchronization on the sampling signals according to the time delay value of the time delay point so as to obtain target sampling signals corresponding to the sampling signals.

3. The signal compensation method of claim 2 wherein the sampled signal comprises a preamble symbol, a frame control symbol, and a data payload symbol, and wherein compensating the target sampled signal based on the estimate to correct a sampling frequency offset of the sampled signal comprises:

determining a first initial value, a second initial value and a third initial value of each preamble symbol, each frame control symbol and each data load symbol according to the time delay value;

determining a first frequency domain compensation phase and a second frequency domain compensation phase of each preamble symbol and each frame control symbol under each subcarrier number according to the first initial value, the second initial value and the estimated value respectively;

after each leading symbol and each frame control symbol are respectively compensated according to the first frequency domain compensation phase and the second frequency domain compensation phase, an estimated average value of sampling frequency offset is determined according to the compensated leading symbol and the compensated frame control symbol;

determining a third frequency domain compensation phase of each data load symbol under each subcarrier number according to the third initial value and the estimated average value;

And after compensating each data load symbol according to the third frequency domain compensation phase, obtaining a compensated target sampling signal so as to correct the sampling frequency offset of the sampling signal.

4. The signal compensation method of claim 3 wherein the determining of the first, second and third starting values for each preamble symbol, each frame control symbol and each data payload symbol starting sample point, respectively, based on the delay values comprises:

the first starting value is determined by formula (1):

symstart(1)＝TA+l·N (1)

wherein symstart (1) refers to a first initial value, TA refers to a delay value of a delay point, l refers to a position index of a preamble symbol, and N refers to the number of points of fast Fourier transform;

the second starting value is determined by formula (2):

symstart(m)＝TA+(L _preamble +0.5)*N+m*(N+N _CP ) (2)

wherein symstart (m) refers to a second initial value, TA refers to a delay value of a delay point, L _preamble Refers to the number of leading symbols in the target sampling signal, m is the position index of the frame control symbol, N is the number of points of the fast Fourier transform, N _CP Is the cyclic prefix length of the frame control symbol;

the third starting value is determined by formula (3):

wherein symstart (p) refers to a third initial value, TA refers to a delay value of a delay point, L _preamble Refers to the number of leading symbols in the target sampling signal, N refers to the number of points of the fast Fourier transform, N _CP Is the cyclic prefix length of the frame control symbol,is the cyclic prefix length of the data payload symbol, p is the position index of the data payload symbol, L _FC Refers to the number of frame control symbols in the target sample signal.

5. The signal compensation method of claim 3 wherein said determining an estimated average value of the sampling frequency offset from the frequency domain data of the compensated preamble symbol and the frequency domain data of the compensated frame control symbol comprises:

performing channel estimation on the frequency domain data of the compensated preamble symbol to determine a second equalization coefficient;

equalizing and demodulating the frequency domain data of the compensated frame control symbol according to the second equalizing coefficient to determine control information in the frame control symbol, wherein the control information comprises a terminal ID of the transmitting end;

determining historical estimation times of historical sampling frequency offset in a storage memory corresponding to the terminal ID, and a historical estimation value corresponding to each historical estimation time;

under the condition that the history estimation times exceeds a preset value, determining the sum of all history estimation values corresponding to the history estimation times;

A sum of all historical estimates and an estimated average of the estimates is determined.

6. The signal compensation method of claim 1 wherein said equalizing all of the first preamble symbols included in the target sample signal to determine first preamble field data corresponding to the first preamble symbols comprises:

determining a total number of first preamble symbols comprised by the target sampled signal;

selecting first preamble symbols which are arranged in front and have the number of first preset numbers from the total number, and performing fast Fourier transform to determine initial frequency domain data of each selected first preamble symbol;

selecting first preamble symbols which are arranged in front and have a second preset number from the total number, and determining a first equalization coefficient according to initial frequency domain data of each selected first preamble symbol, wherein the first preset number and the second preset number are natural numbers, and the first preset number is larger than the second preset number;

and carrying out equalization processing on all first preamble symbols included in the target sampling signal according to the first equalization coefficient so as to determine first preamble pilot frequency domain data corresponding to each first preamble symbol.

7. The signal compensation method of claim 1 wherein the number of the first preamble symbols is plural, the subcarrier number of the first preamble symbol is the same as the subcarrier number of the second preamble symbol, and the subcarrier number is determined according to the position of each subcarrier within the effective bandwidth;

the determining the estimated value of the sampling frequency offset of the sampling signal according to the first front pilot frequency domain data and the second front pilot frequency domain data comprises:

taking each first preamble symbol and a second preamble symbol corresponding to each first preamble symbol as a symbol group;

performing conjugate multiplication on the first pilot frequency domain data of the first pilot symbol and the second pilot frequency domain data of the second pilot symbol included in each symbol group to determine target frequency domain data of each symbol group corresponding to each subcarrier number;

determining target frequency domain total data corresponding to all subcarrier numbers according to the target frequency domain data corresponding to each subcarrier number;

determining the phase angle of the target frequency domain total data, and determining a sampling frequency offset estimation value of each symbol group according to the phase angle;

and determining the average value of the sampling frequency offset estimation values of all the symbol groups as the estimation value of the sampling frequency offset of the sampling signal.

8. The signal compensation method according to claim 1, wherein the preset distance is any value of a symbol interval distance of 4 to 8.

9. A processor configured to perform the signal compensation method according to any one of claims 1 to 8.

10. An OFDM system, the system comprising:

a channel;

the transmitting end is used for transmitting an originating signal through the channel;

the receiving end is used for acquiring a signal to be detected, wherein the signal to be detected corresponds to an originating signal of a transmitting end of the OFDM system, and the originating signal is transmitted to the receiving end through a channel; and

the processor of claim 9.

11. A machine-readable storage medium having instructions stored thereon, which when executed by a processor cause the processor to be configured to perform the signal compensation method according to any of claims 1 to 8.