CN115208734B - Method and device for fine signal synchronization - Google Patents
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Abstract
The disclosure relates to the technical field of communication, and provides a method and a device for fine signal synchronization. The method comprises the following steps: determining a first starting position of a received target signal in a non-high-flux short training sequence domain, and performing signal coarse synchronization on the target signal based on the first starting position; determining a phase error value by performing cross-correlation calculation on a target signal subjected to signal coarse synchronization, and determining coarse frequency offset according to the phase error value; inquiring a communication standard protocol, determining a reference symbol in a non-high-flux long training sequence domain, and performing frequency offset compensation on the reference symbol based on coarse frequency offset; and determining a second initial position of the target signal in the non-high-flux long training sequence domain by performing sliding correlation calculation on the target signal and the reference symbol subjected to frequency offset compensation, and performing signal fine synchronization on the target signal based on the second initial position. By adopting the technical means, the problem that error detection is easy to occur when fine synchronization is carried out in an orthogonal frequency division multiplexing system in the prior art is solved.
Description
Technical Field
The present disclosure relates to the field of communications technologies, and in particular, to a method and an apparatus for fine signal synchronization.
Background
OFDM (Orthogonal Frequency Division Multiplexing), which converts high-speed serial data into low-speed parallel data for transmission and converts a Frequency selective channel into a Frequency flat fading channel, overcomes inter-symbol interference (ISI) caused by high-speed data communication, and improves transmission performance of a communication system, is widely used. In OFDM systems under local area networks, the transmitted signals often need to be frequency synchronized. The frequency synchronization is divided into coarse frequency synchronization and fine frequency synchronization. The coarse synchronization is mainly to eliminate a relatively large frequency offset, and the fine synchronization is mainly to eliminate a relatively small frequency offset. Because of the low accuracy of coarse synchronization, fine synchronization is often used. Regarding fine synchronization, in the prior art, a method for directly performing cross-correlation calculation on a correlation peak value by using a reference signal of a non-high-throughput long training sequence domain (an initial position of a signal can be judged according to the correlation peak value, and then fine synchronization of the signal is realized), and due to the low success rate of limitation of frequency offset and phase offset, when a detected signal has a certain frequency offset, the correlation peak value is weakened, and false detection is caused.
In the process of implementing the disclosed concept, the inventors found that at least the following technical problems exist in the related art: the error detection is easy to occur when the fine synchronization is performed in the orthogonal frequency division multiplexing system under the local area network.
Disclosure of Invention
In view of this, the embodiments of the present disclosure provide a method and an apparatus for fine synchronization of signals, an electronic device, and a computer-readable storage medium, so as to solve the problem that a false detection is easily performed when fine synchronization is performed in an orthogonal frequency division multiplexing system in a local area network.
In a first aspect of the embodiments of the present disclosure, a method for fine signal synchronization is provided, which is applied to an orthogonal frequency division multiplexing system in a local area network, and includes: determining a first starting position of a received target signal in a non-high-flux short training sequence domain, and performing signal coarse synchronization on the target signal based on the first starting position; determining a phase error value by performing cross-correlation calculation on a target signal subjected to signal coarse synchronization, and determining coarse frequency offset according to the phase error value; inquiring a communication standard protocol, determining a reference symbol in a non-high-flux long training sequence domain, and performing frequency offset compensation on the reference symbol based on coarse frequency offset; and performing sliding correlation calculation on the target signal and the reference symbol subjected to frequency offset compensation, determining a second initial position of the target signal in a non-high-flux long training sequence domain, and performing signal fine synchronization on the target signal based on the second initial position.
In a second aspect of the embodiments of the present disclosure, a device for fine signal synchronization is provided, which is applied to an orthogonal frequency division multiplexing system in a local area network, and includes: the coarse synchronization module is configured to determine a first starting position of the received target signal in a non-high-flux short training sequence domain, and perform signal coarse synchronization on the target signal based on the first starting position; the determining module is configured to determine a phase error value by performing cross-correlation calculation on the target signal subjected to signal coarse synchronization, and determine a coarse frequency offset according to the phase error value; the compensation module is configured to query a communication standard protocol, determine a reference symbol in a non-high-flux long training sequence domain, and perform frequency offset compensation on the reference symbol based on coarse frequency offset; and the fine synchronization module is configured to determine a second starting position of the target signal in the non-high-flux long training sequence domain by performing sliding correlation calculation on the target signal and the frequency offset compensated reference symbol, and perform signal fine synchronization on the target signal based on the second starting position.
In a third aspect of the disclosed embodiments, an electronic device is provided, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the above method when executing the computer program.
In a fourth aspect of the embodiments of the present disclosure, a computer-readable storage medium is provided, which stores a computer program, which when executed by a processor, implements the steps of the above-mentioned method.
Compared with the prior art, the embodiment of the disclosure has the following beneficial effects: determining a first starting position of a received target signal in a non-high-flux short training sequence domain, and performing signal coarse synchronization on the target signal based on the first starting position; determining a phase error value by performing cross-correlation calculation on a target signal subjected to signal coarse synchronization, and determining coarse frequency offset according to the phase error value; inquiring a communication standard protocol, determining a reference symbol in a non-high-flux long training sequence domain, and performing frequency offset compensation on the reference symbol based on coarse frequency offset; and performing sliding correlation calculation on the target signal and the reference symbol subjected to frequency offset compensation, determining a second initial position of the target signal in a non-high-flux long training sequence domain, and performing signal fine synchronization on the target signal based on the second initial position. By adopting the technical means, the problem that error detection is easy to occur when fine synchronization is carried out in an orthogonal frequency division multiplexing system under a local area network in the prior art is solved, and a fine synchronization method with high accuracy is further provided.
Drawings
To more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed for the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without inventive efforts.
FIG. 1 is a scenario diagram of an application scenario of an embodiment of the present disclosure;
fig. 2 is a schematic flow chart of a method for fine signal synchronization provided by an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of an apparatus for fine signal synchronization provided in an embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of an electronic device provided in an embodiment of the present disclosure.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the disclosed embodiments. However, it will be apparent to one skilled in the art that the present disclosure may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present disclosure with unnecessary detail.
A group delay estimation method and apparatus according to an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.
Fig. 1 is a scene schematic diagram of an application scenario of an embodiment of the present disclosure. The application scenario may include terminal devices 101, 102, and 103, server 104, and network 105.
The terminal apparatuses 101, 102, and 103 may be hardware or software. When terminal devices 101, 102, and 103 are hardware, they may be various electronic devices having a display screen and supporting communication with server 104, including but not limited to smart phones, tablets, laptop portable computers, desktop computers, and the like; when the terminal apparatuses 101, 102, and 103 are software, they can be installed in the electronic apparatus as above. The terminal devices 101, 102, and 103 may be implemented as a plurality of software or software modules, or may be implemented as a single software or software module, which is not limited by the embodiment of the present disclosure. Further, various applications, such as a data processing application, an instant messaging tool, social platform software, a search type application, a shopping type application, and the like, may be installed on the terminal devices 101, 102, and 103.
The server 104 may be a server providing various services, for example, a backend server receiving a request sent by a terminal device establishing a communication connection with the server, and the backend server may receive and analyze the request sent by the terminal device, and generate a processing result. The server 104 may be a server, may also be a server cluster composed of a plurality of servers, or may also be a cloud computing service center, which is not limited in this disclosure.
The server 104 may be hardware or software. When the server 104 is hardware, it may be various electronic devices that provide various services to the terminal devices 101, 102, and 103. When the server 104 is software, it may be multiple software or software modules providing various services for the terminal devices 101, 102, and 103, or may be a single software or software module providing various services for the terminal devices 101, 102, and 103, which is not limited by the embodiment of the present disclosure.
The network 105 may be a wired network connected by a coaxial cable, a twisted pair cable, and an optical fiber, or may be a wireless network that can interconnect various Communication devices without wiring, for example, bluetooth (Bluetooth), near Field Communication (NFC), infrared (Infrared), and the like, which is not limited in the embodiment of the present disclosure.
A user can establish a communication connection with the server 104 via the network 105 through the terminal apparatuses 101, 102, and 103 to receive or transmit information or the like. It should be noted that specific types, numbers, and combinations of the terminal devices 101, 102, and 103, the server 104, and the network 105 may be adjusted according to actual needs of an application scenario, which is not limited in this disclosure.
Fig. 2 is a schematic flowchart of a method for fine signal synchronization according to an embodiment of the present disclosure. The method of fine synchronization of signals of fig. 2 may be performed by the terminal device or the server of fig. 1. As shown in fig. 2, the method for fine synchronization of signals includes:
s201, determining a first initial position of a received target signal in a non-high-flux short training sequence domain, and performing signal coarse synchronization on the target signal based on the first initial position;
s202, performing cross-correlation calculation on the target signal subjected to signal coarse synchronization to determine a phase error value, and determining coarse frequency offset according to the phase error value;
s203, inquiring a communication standard protocol, determining a reference symbol in a non-high-flux long training sequence domain, and performing frequency offset compensation on the reference symbol based on coarse frequency offset;
s204, determining a second initial position of the target signal in the non-high-flux long training sequence domain by performing sliding correlation calculation on the target signal and the reference symbol subjected to frequency offset compensation, and performing signal fine synchronization on the target signal based on the second initial position.
Non-HT Short Training field Non-high-throughput Short Training sequence domain L-STF, non-HT Long Training field Non-high-throughput Long Training sequence domain L-LTF. The target signal is a signal transmitted in an orthogonal frequency division multiplexing system in a local area network, and the embodiment of the disclosure is applied to a signal receiving end of the orthogonal frequency division multiplexing system. The coarse synchronization mainly eliminates larger frequency deviation, the coarse synchronization has low precision or accuracy, the fine synchronization mainly eliminates smaller frequency deviation, and the fine synchronization has high precision or accuracy. The communication standard protocol is queried to directly determine the reference symbols in the non-high-throughput long training sequence domain, which is not described herein again. The reference symbol may be a ZC sequence, which is a sequence transmitted by a communication signal.
According to the technical scheme provided by the embodiment of the disclosure, a first starting position of a received target signal in a non-high-flux short training sequence domain is determined, and signal coarse synchronization is carried out on the target signal based on the first starting position; determining a phase error value by performing cross-correlation calculation on a target signal subjected to signal coarse synchronization, and determining coarse frequency offset according to the phase error value; inquiring a communication standard protocol, determining a reference symbol in a non-high-flux long training sequence domain, and performing frequency offset compensation on the reference symbol based on coarse frequency offset; and performing sliding correlation calculation on the target signal and the reference symbol subjected to frequency offset compensation, determining a second initial position of the target signal in a non-high-flux long training sequence domain, and performing signal fine synchronization on the target signal based on the second initial position. By adopting the technical means, the problem that in the prior art, the error detection is easy to occur when the synchronization is carried out in the orthogonal frequency division multiplexing system under the local area network is solved, and a high-accuracy fine synchronization method is further provided.
In step 201, determining a first starting position of the received target signal in the non-high-throughput short training sequence domain, including: intercepting N data from a target position of a target signal, and recording the currently intercepted N data as a first data sequence, wherein N is a positive integer; moving back N data from the target position of the target signal to intercept N data, and recording the currently intercepted N data as a second data sequence; calculating the total power of a first sequence corresponding to the first data sequence, calculating the total power of a second sequence corresponding to the second data sequence, and calculating the total power of a third sequence corresponding to the first data sequence and the second data sequence; determining a target value corresponding to the target position according to the first sequence total power, the second sequence total power and the third sequence total power; and when the target value is greater than a preset threshold value, taking the target position as a first starting position.
And when the target value corresponding to the target position is less than or equal to a preset threshold value, the target position is updated by moving the target position backwards by one data position.
The above method for determining the first starting position of the received target signal in the non-high-throughput short training sequence domain can be understood as performing the following loop: intercepting N data from a target position of a target signal, and recording the currently intercepted N data as a first data sequence, wherein N is a positive integer, and an initial value of the target position is a data header of the target signal; moving N data backwards from the target position of the target signal to intercept N data, and recording the currently intercepted N data as a second data sequence; calculating the total power of a first sequence corresponding to the first data sequence, calculating the total power of a second sequence corresponding to the second data sequence, and calculating the total power of a third sequence corresponding to the first data sequence and the second data sequence; determining a target value corresponding to the target position according to the first sequence total power, the second sequence total power and the third sequence total power; when the target value is less than or equal to the preset threshold value, the target position is updated by moving the target position backwards by one data position, and the circulation is continued; and when the target value is greater than the preset threshold value, taking the target position as a first initial position, and ending the circulation.
The header of the target signal is the foremost position in the target signal. The first data sequence has N data, all the power carried by the N data is the total power of the first sequence, and the total power of the second sequence is similar.
Let the total power of the first sequence be P1, the total power of the second sequence be P2, and the total power of the third sequence be P0, S1 represents the first data sequence, and S2 represents the second data sequence.
P0 = S1’ * conj(S2)
Where' denotes transpose, conj denotes conjugate calculation;
M = (|P0|^2)/P，P = max(P1，P2)；
the formula normalizes P0 to obtain a target value M, judges whether the target value is larger than a preset threshold value, wherein | | represents an absolute value, ^2 represents a square, and max () is a large function.
In step 202, determining a phase error value by performing a cross-correlation calculation on the target signal after the coarse synchronization of the signals, includes: dividing a target signal subjected to signal coarse synchronization into data sequences with preset number, wherein the number of data in each group of data sequences is N, and N is a positive integer; performing cross-correlation calculation on each two groups of adjacent data sequences to obtain a first correlation value corresponding to each two groups of adjacent data sequences; and determining the phase angle of each first correlation value, averaging a plurality of phase angles, and taking the average value as a phase error value.
For example, the preset number is 10, that is, the target signal after coarse synchronization is divided into 10 sets of data sequences, the first set of data sequences and the second set of data sequences are adjacent data sequences, the second set of data sequences and the third set of data sequences are adjacent data sequences \8230, and the cross-correlation calculation of the first set of data sequences and the second set of data sequences is to multiply the conjugate of the second set of data sequences by the first set of data sequences, wherein one set of data sequences can be regarded as a vector, and the multiplication of the two sets of data sequences is a dot multiplication of two vectors to finally obtain a first correlation value, and finally, 9 first correlation values can be obtained. The phase angle at which the first correlation value is determined can be expressed as an angle (H) function, H being a first correlation value. The averaging of the plurality of phase angles may be performed by discarding the first two first correlations and the last two first correlations and averaging the third first correlation to the seventh first correlation (which may reduce interference).
In step 202, determining a coarse frequency offset from the phase error value includes: determining a sampling rate corresponding to the target signal according to the bandwidth of the target signal; and determining a coarse frequency offset according to the sampling rate and the phase error value.
The coarse frequency offset may be calculated by the following equation:
Ferr = PhErr * Fs / (2 * pi)
ferr is the coarse frequency offset, phErr is the phase error value, pi is the circumference rate, fs is the sampling rate, typically twice the bandwidth of the signal.
In step 204, determining a second starting position of the target signal in the non-high-flux long training sequence domain by performing a sliding correlation calculation on the target signal and the frequency offset compensated reference symbol, including: acquiring a plurality of groups of third data sequences by intercepting N data from a target signal for a plurality of times, wherein N is a positive integer, the initial position of intercepting the N data for the first time is a first initial position, and the initial position of intercepting the N data every time is sequentially moved back by one data from the first initial position; performing cross-correlation calculation on the reference symbols subjected to frequency offset compensation and each group of third data sequences to obtain second correlation values corresponding to each group of third data sequences, wherein the sliding correlation calculation comprises cross-correlation calculation; and taking the starting position of the intercepted N data corresponding to the maximum value in the second correlation values as a second starting position.
The above method for determining the second starting position of the target signal in the non-high-flux long training sequence domain by performing sliding correlation calculation on the target signal and the frequency offset compensated reference symbol may be understood as performing the following loop:
intercepting N data from a target position in the target signal to obtain a third data sequence, wherein N is a positive integer; performing the cross-correlation calculation on the reference symbol subjected to the frequency offset compensation and a third data sequence to obtain a second correlation value corresponding to the third data sequence, wherein the sliding correlation calculation comprises the cross-correlation calculation; updating the target position by moving the target position backward by the position of one datum, and continuing circulation;
and ending the circulation until the target position is smaller than the Nth data of the target signal from the last time, and taking the initial position of the intercepted N data corresponding to the maximum value in the second correlation values as a second initial position.
The method comprises the steps of firstly intercepting N data, wherein the initial position of the first intercepted N data is a first initial position, the initial position of the second intercepted N data is a first initial position and is shifted backward by one data position, the initial position of the third intercepted N data is a first initial position and is shifted backward by two data positions, namely, one datum is shifted backward for 82308230on the basis of the initial position of the second intercepted N data, and the method can be called sliding correlation calculation because the method sequentially shifts backward by one datum from the first initial position.
Performing cross-correlation calculation on the reference symbol subjected to the frequency offset compensation and each group of third data sequences to obtain a second correlation value corresponding to each group of third data sequences, wherein the second correlation value can be calculated by the following formula:
G i = sum(S i，j * conj(R j ))
wherein conj represents the conjugate calculation, R j Is j (maximum of N, S) data in the reference symbol subjected to frequency offset compensation i，j Taking the maximum of the ith data in the ith intercepted third data sequence as A, wherein A is the times of intercepting N data and G i And sum () is a summation function for a second correlation value corresponding to the ith truncated third data sequence.
It should be noted that "first" and "second" in the embodiments of the present disclosure have no special meaning, and are indicated for distinction. For example the first starting position is one of the starting positions. When the initial position of the signal is determined, performing coarse signal synchronization or fine signal synchronization on the target signal is a common technical means, and is not described herein again.
All the above optional technical solutions may be combined arbitrarily to form optional embodiments of the present application, and are not described in detail herein.
The following are embodiments of the disclosed apparatus that may be used to perform embodiments of the disclosed methods. For details not disclosed in the embodiments of the apparatus of the present disclosure, refer to the embodiments of the method of the present disclosure.
Fig. 3 is a schematic diagram of an apparatus for fine signal synchronization according to an embodiment of the present disclosure. As shown in fig. 3, the apparatus for fine synchronization of signals includes:
a coarse synchronization module 301 configured to determine a first start position of the received target signal in the non-high-throughput short training sequence domain, and perform signal coarse synchronization on the target signal based on the first start position;
a determining module 302 configured to determine a phase error value by performing a cross-correlation calculation on the target signal subjected to the signal coarse synchronization, and determine a coarse frequency offset according to the phase error value;
a compensation module 303, configured to query a communication standard protocol, determine a reference symbol in a non-high-throughput long training sequence domain, and perform frequency offset compensation on the reference symbol based on coarse frequency offset;
and a fine synchronization module 304 configured to determine a second start position of the target signal in the non-high-flux long training sequence domain by performing a sliding correlation calculation on the target signal and the frequency offset compensated reference symbol, and perform signal fine synchronization on the target signal based on the second start position.
Non-high-throughput Short Training sequence field is Non-high-throughput Long Training sequence field is L-STF. The target signal is a signal transmitted in an orthogonal frequency division multiplexing system in a local area network, and the embodiment of the disclosure is applied to a signal receiving end of the orthogonal frequency division multiplexing system. The coarse synchronization mainly eliminates larger frequency deviation, the coarse synchronization precision or accuracy is low, the fine synchronization mainly eliminates smaller frequency deviation, and the fine synchronization precision or accuracy is high.
According to the technical scheme provided by the embodiment of the disclosure, a first starting position of a received target signal in a non-high-flux short training sequence domain is determined, and signal coarse synchronization is carried out on the target signal based on the first starting position; determining a phase error value by performing cross-correlation calculation on a target signal subjected to signal coarse synchronization, and determining coarse frequency offset according to the phase error value; inquiring a communication standard protocol, determining a reference symbol in a non-high-flux long training sequence domain, and performing frequency offset compensation on the reference symbol based on coarse frequency offset; and performing sliding correlation calculation on the target signal and the reference symbol subjected to frequency offset compensation, determining a second initial position of the target signal in a non-high-flux long training sequence domain, and performing signal fine synchronization on the target signal based on the second initial position. By adopting the technical means, the problem that in the prior art, the error detection is easy to occur when the synchronization is carried out in the orthogonal frequency division multiplexing system under the local area network is solved, and a high-accuracy fine synchronization method is further provided.
Optionally, the coarse synchronization module 301 is further configured to intercept N data from a target position of the target signal, and record the currently intercepted N data as a first data sequence, where N is a positive integer; moving N data backwards from the target position of the target signal to intercept N data, and recording the currently intercepted N data as a second data sequence; calculating the total power of a first sequence corresponding to the first data sequence, calculating the total power of a second sequence corresponding to the second data sequence, and calculating the total power of a third sequence corresponding to the first data sequence and the second data sequence; determining a target value corresponding to the target position according to the first sequence total power, the second sequence total power and the third sequence total power; and when the target value is greater than a preset threshold value, taking the target position as a first starting position.
And when the target value corresponding to the target position is less than or equal to a preset threshold value, the target position is updated by moving the target position backwards by one data position.
Optionally, the coarse synchronization module 301 is further configured to intercept N data from a target position of the target signal, and record the currently intercepted N data as a first data sequence, where N is a positive integer, and an initial value of the target position is a data header of the target signal; moving N data backwards from the target position of the target signal to intercept N data, and recording the currently intercepted N data as a second data sequence; calculating the total power of a first sequence corresponding to the first data sequence, calculating the total power of a second sequence corresponding to the second data sequence, and calculating the total power of a third sequence corresponding to the first data sequence and the second data sequence; determining a target value corresponding to the target position according to the first sequence total power, the second sequence total power and the third sequence total power; when the target value is less than or equal to the preset threshold value, the target position is updated by moving the target position backwards by one data position, and the circulation is continued; and when the target value is larger than the preset threshold value, taking the target position as a first starting position, and ending the circulation.
The header of the target signal is the foremost position in the target signal. The first data sequence has N data, all the power carried by the N data is the total power of the first sequence, and the total power of the second sequence is similar.
Let the total power of the first sequence be P1, the total power of the second sequence be P2, and the total power of the third sequence be P0, S1 represents the first data sequence, and S2 represents the second data sequence.
P0 = S1’ * conj(S2)
Where' denotes transpose, conj denotes conjugate calculation;
M = (|P0|^2)/P，P = max(P1，P2)；
the formula normalizes P0 to obtain a target value M, judges whether the target value is larger than a preset threshold value, wherein | | represents an absolute value, ^2 represents a square, and max () is a large function.
Optionally, the determining module 302 is further configured to divide the target signal subjected to signal coarse synchronization into a preset number of data sequences, where the number of data in each group of data sequences is N, and N is a positive integer; performing cross-correlation calculation on each two groups of adjacent data sequences to obtain a first correlation value corresponding to each two groups of adjacent data sequences; and determining the phase angle of each first correlation value, averaging a plurality of phase angles, and taking the average value as a phase error value.
For example, the preset number is 10, that is, the target signal after coarse synchronization is divided into 10 sets of data sequences, the first set of data sequences and the second set of data sequences are adjacent data sequences, the second set of data sequences and the third set of data sequences are adjacent data sequences \8230, and the cross-correlation calculation of the first set of data sequences and the second set of data sequences is to multiply the conjugate of the second set of data sequences by the first set of data sequences, wherein one set of data sequences can be regarded as a vector, and the multiplication of the two sets of data sequences is a dot multiplication of two vectors to finally obtain a first correlation value, and finally, 9 first correlation values can be obtained. The phase angle at which the first correlation value is determined can be expressed as an angle (H) function, H being a first correlation value. The averaging of the plurality of phase angles may be performed by discarding the first two first correlations and the last two first correlations and averaging the third first correlation to the seventh first correlation (which may reduce interference).
Optionally, the determining module 302 is further configured to determine a sampling rate corresponding to the target signal according to the bandwidth of the target signal; and determining coarse frequency offset according to the sampling rate and the phase error value.
The coarse frequency offset may be calculated by the following equation:
Ferr = PhErr * Fs / (2 * pi)
ferr is the coarse frequency offset, phErr is the phase error value, pi is the circumference rate, fs is the sampling rate, typically twice the bandwidth of the signal.
Optionally, the fine synchronization module 304 is further configured to obtain a plurality of sets of third data sequences by intercepting N data from the target signal for a plurality of times, where N is a positive integer, a start position of the first interception of the N data is a first start position, and then start positions of each interception of the N data are sequentially shifted backward by one data from the first start position; performing cross-correlation calculation on the reference symbol subjected to frequency offset compensation and each group of third data sequences to obtain second correlation values corresponding to each group of third data sequences, wherein the sliding correlation calculation comprises cross-correlation calculation; and taking the starting position of the intercepted N data corresponding to the maximum value in the second correlation values as a second starting position.
Optionally, fine synchronization module 304 is further configured to perform the following loop: intercepting N data from a target position in the target signal to obtain a third data sequence, wherein N is a positive integer; performing the cross-correlation calculation on the reference symbol subjected to the frequency offset compensation and a third data sequence to obtain a second correlation value corresponding to the third data sequence, wherein the sliding correlation calculation comprises the cross-correlation calculation; updating the target position by moving the target position backward by the position of one datum, and continuing circulation; and ending the circulation until the target position is smaller than the Nth data of the target signal from the last time, and taking the initial position of the intercepted N data corresponding to the maximum value in the second correlation values as a second initial position.
The initial position of intercepting N data for the first time is a first initial position, the initial position of intercepting N data for the second time is a position of shifting back by one data from the first initial position, the initial position of intercepting N data for the third time is a position of shifting back by two data from the first initial position, namely, shifting back by one data on the basis of the initial position of intercepting N data for the second time \8230, and since the embodiment of the disclosure sequentially shifts back by one data from the first initial position, the method can be called sliding correlation calculation.
Performing cross-correlation calculation on the reference symbol subjected to the frequency offset compensation and each group of third data sequences to obtain a second correlation value corresponding to each group of third data sequences, wherein the second correlation value can be calculated by the following formula:
G i = sum(S i，j * conj(R j ))
wherein conj represents the conjugate calculation, R j J is the j data in the reference symbol after frequency offset compensation, wherein j is maximum N, S i，j For the jth data in the ith intercepted third data sequence, i is the maximum A, A is the times of intercepting N data, G i And sum () is a summation function for a second correlation value corresponding to the ith truncated third data sequence.
It should be noted that "first" and "second" in the embodiments of the present disclosure have no special meaning, and are indicated for distinction. For example the first starting position is one of the starting positions. When the initial position of the signal is determined, performing coarse signal synchronization or fine signal synchronization on the target signal is a common technical means, and is not described herein again.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure.
Fig. 4 is a schematic diagram of an electronic device 4 provided by the embodiment of the present disclosure. As shown in fig. 4, the electronic apparatus 4 of this embodiment includes: a processor 401, a memory 402 and a computer program 403 stored in the memory 402 and executable on the processor 401. The steps in the various method embodiments described above are implemented when the processor 401 executes the computer program 403. Alternatively, the processor 401 implements the functions of the respective modules/units in the above-described respective apparatus embodiments when executing the computer program 403.
Illustratively, the computer program 403 may be partitioned into one or more modules/units, which are stored in the memory 402 and executed by the processor 401 to accomplish the present disclosure. One or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution of the computer program 403 in the electronic device 4.
The electronic device 4 may be a desktop computer, a notebook, a palm computer, a cloud server, or other electronic devices. The electronic device 4 may include, but is not limited to, a processor 401 and a memory 402. Those skilled in the art will appreciate that fig. 4 is merely an example of the electronic device 4, and does not constitute a limitation of the electronic device 4, and may include more or less components than those shown, or combine certain components, or different components, e.g., the electronic device may also include input-output devices, network access devices, buses, etc.
The Processor 401 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, discrete hardware component, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The storage 402 may be an internal storage unit of the electronic device 4, for example, a hard disk or a memory of the electronic device 4. The memory 402 may also be an external storage device of the electronic device 4, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like provided on the electronic device 4. Further, the memory 402 may also include both internal storage units of the electronic device 4 and external storage devices. The memory 402 is used for storing computer programs and other programs and data required by the electronic device. The memory 402 may also be used to temporarily store data that has been output or is to be output.
It should be clear to those skilled in the art that, for convenience and simplicity of description, the foregoing division of the functional units and modules is only used for illustration, and in practical applications, the above function distribution may be performed by different functional units and modules as needed, that is, the internal structure of the device is divided into different functional units or modules, so as to perform all or part of the above described functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.
In the embodiments provided in the present disclosure, it should be understood that the disclosed apparatus/electronic device and method may be implemented in other ways. For example, the above-described apparatus/electronic device embodiments are merely illustrative, and for example, a module or a unit may be divided into only one logical function, and may be implemented in other ways, and multiple units or components may be combined or integrated into another system, or some features may be omitted or not implemented. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
Units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present disclosure may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, the present disclosure may implement all or part of the flow of the method in the above embodiments, and may also be implemented by a computer program to instruct related hardware, where the computer program may be stored in a computer readable storage medium, and when the computer program is executed by a processor, the computer program may implement the steps of the above methods and embodiments. The computer program may comprise computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer readable medium may include: any entity or device capable of carrying computer program code, recording medium, U.S. disk, removable hard disk, magnetic diskette, optical disk, computer Memory, read-Only Memory (ROM), random Access Memory (RAM), electrical carrier wave signal, telecommunications signal, software distribution medium, etc. It should be noted that the computer readable medium may contain suitable additions or additions that may be required in accordance with legislative and patent practices within the jurisdiction, for example, in some jurisdictions, computer readable media may not include electrical carrier signals or telecommunications signals in accordance with legislative and patent practices.
The above examples are only intended to illustrate the technical solutions of the present disclosure, not to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present disclosure, and are intended to be included within the scope of the present disclosure.
Claims (9)
1. A method for fine synchronization of signals is applied to an orthogonal frequency division multiplexing system under a local area network, and is characterized by comprising the following steps:
determining a first starting position of a received target signal in a non-high-flux short training sequence domain, and performing signal coarse synchronization on the target signal based on the first starting position;
performing cross-correlation calculation on the target signal subjected to the signal coarse synchronization to determine a phase error value, and determining coarse frequency offset according to the phase error value;
inquiring a communication standard protocol, determining a reference symbol in a non-high-flux long training sequence domain, and performing frequency offset compensation on the reference symbol based on the coarse frequency offset;
determining a second starting position of the target signal in the non-high-flux long training sequence domain by performing sliding correlation calculation on the target signal and the reference symbol subjected to the frequency offset compensation, and performing signal fine synchronization on the target signal based on the second starting position;
wherein, determining a second starting position of the target signal in the non-high-throughput long training sequence domain by performing sliding correlation calculation on the target signal and the reference symbol subjected to the frequency offset compensation comprises: acquiring a plurality of groups of third data sequences by intercepting N data from the target signal for a plurality of times, wherein N is a positive integer, the initial position of intercepting the N data for the first time is the first initial position, and the initial position of intercepting the N data each time is sequentially shifted back by one data from the first initial position; performing the cross-correlation calculation on the reference symbols subjected to the frequency offset compensation and each group of third data sequences to obtain second correlation values corresponding to each group of third data sequences, wherein the sliding correlation calculation comprises the cross-correlation calculation; and taking the starting position of the intercepted N data corresponding to the maximum value in the second correlation values as the second starting position.
2. The method of claim 1, wherein determining a first starting position of the received target signal in a non-high-throughput short training sequence domain comprises:
intercepting N data from the target position of the target signal, and recording the currently intercepted N data as a first data sequence, wherein N is a positive integer;
moving back N data from the target position of the target signal to intercept N data, and marking the currently intercepted N data as a second data sequence;
calculating the total power of a first sequence corresponding to the first data sequence, calculating the total power of a second sequence corresponding to the second data sequence, and calculating the total power of a third sequence corresponding to the first data sequence and the second data sequence;
determining a target value corresponding to the target position according to the first sequence total power, the second sequence total power and the third sequence total power;
and when the target value is greater than a preset threshold value, taking the target position as the first starting position.
3. The method according to claim 2, wherein the initial value of the target position is a data header of the target signal, and when the target value corresponding to the target position is less than or equal to the preset threshold, the target position is updated by moving the target position backward by one data position.
4. The method of claim 1, wherein determining a phase error value by performing a cross-correlation calculation on a target signal that is coarsely synchronized with the signal comprises:
dividing the target signals subjected to the signal coarse synchronization into data sequences with preset number, wherein the number of data in each group of data sequences is N, and N is a positive integer;
performing the cross-correlation calculation on each two groups of adjacent data sequences to obtain a first correlation value corresponding to each two groups of adjacent data sequences;
and determining the phase angle of each first correlation value, averaging a plurality of phase angles, and taking the averaged value as the phase error value.
5. The method of claim 1, wherein determining a coarse frequency offset based on the phase error value comprises:
determining a sampling rate corresponding to the target signal according to the bandwidth of the target signal;
and determining the coarse frequency offset according to the sampling rate and the phase error value.
6. The method of claim 1, wherein determining a first starting position of the received target signal in a non-high-throughput short training sequence domain comprises:
the following loop is executed:
intercepting N data from a target position of the target signal, and recording the currently intercepted N data as a first data sequence, wherein N is a positive integer, and an initial value of the target position is a data header of the target signal;
moving back N data from the target position of the target signal to intercept N data, and marking the currently intercepted N data as a second data sequence;
calculating a first sequence total power corresponding to the first data sequence, calculating a second sequence total power corresponding to the second data sequence, and calculating a third sequence total power corresponding to the first data sequence and the second data sequence;
determining a target value corresponding to the target position according to the first sequence total power, the second sequence total power and the third sequence total power;
when the target value is less than or equal to a preset threshold value, the target position is updated by moving the target position backwards by one data position, and circulation is continued;
and when the target value is greater than the preset threshold value, taking the target position as the first starting position, and ending the cycle.
7. A signal fine synchronization device is applied to an orthogonal frequency division multiplexing system under a local area network, and is characterized by comprising:
a coarse synchronization module configured to determine a first starting position of a received target signal in a non-high-throughput short training sequence domain and perform signal coarse synchronization on the target signal based on the first starting position;
the determining module is configured to determine a phase error value by performing cross-correlation calculation on the target signal subjected to the signal coarse synchronization, and determine a coarse frequency offset according to the phase error value;
the compensation module is configured to query a communication standard protocol, determine a reference symbol in a non-high-flux long training sequence domain, and perform frequency offset compensation on the reference symbol based on the coarse frequency offset;
a fine synchronization module configured to determine a second start position of the target signal in the non-high-flux long training sequence domain by performing sliding correlation calculation on the target signal and the frequency offset-compensated reference symbol, and perform signal fine synchronization on the target signal based on the second start position;
the fine synchronization module is further configured to obtain a plurality of groups of third data sequences by intercepting N data from the target signal for a plurality of times, where N is a positive integer, the initial position of intercepting N data for the first time is the first initial position, and then the initial positions of intercepting N data each time are sequentially shifted backward by one data from the first initial position; performing the cross-correlation calculation on the reference symbols subjected to the frequency offset compensation and each group of third data sequences to obtain second correlation values corresponding to each group of third data sequences, wherein the sliding correlation calculation comprises the cross-correlation calculation; and taking the starting position of the intercepted N data corresponding to the maximum value in the second correlation values as the second starting position.
8. An electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor realizes the steps of the method according to any one of claims 1 to 6 when executing the computer program.
9. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 6.
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