CN108200002B - Signal demodulation method and baseband receiver - Google Patents
Signal demodulation method and baseband receiver Download PDFInfo
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- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/38—Demodulator circuits; Receiver circuits
- H04L27/3845—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier
- H04L27/3854—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier using a non - coherent carrier, including systems with baseband correction for phase or frequency offset
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2657—Carrier synchronisation
- H04L27/2659—Coarse or integer frequency offset determination and synchronisation
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- H—ELECTRICITY
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- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2668—Details of algorithms
- H04L27/2669—Details of algorithms characterised by the domain of operation
- H04L27/2672—Frequency domain
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0024—Carrier regulation at the receiver end
- H04L2027/0026—Correction of carrier offset
- H04L2027/003—Correction of carrier offset at baseband only
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Abstract
The invention is suitable for the technical field of wireless communication, and provides a signal demodulation method and a baseband receiver, wherein the signal demodulation method comprises the following steps: acquiring a digital baseband signal; acquiring a leading domain of the digital baseband signal according to the digital baseband signal, wherein the leading domain comprises a leading training sequence and a leading information sequence; obtaining a public correction parameter and frame configuration information according to the leader domain, wherein the public correction parameter comprises an integer timing position, a frequency offset estimation value and a sampling clock deviation; processing the digital baseband signal according to the public correction parameter and the frame configuration information to obtain a first signal; obtaining a frequency domain signal according to the first signal; and demodulating and decoding the frequency domain signal to obtain data information carried by the frequency domain signal. The compensation and correction of the frequency offset estimation value, the timing position deviation and the sampling clock deviation are realized, so that the signal quality and the decoding performance are improved.
Description
Technical Field
The invention belongs to the technical field of wireless communication, and particularly relates to a signal demodulation method and a baseband receiver.
Background
The WLAN (wireless local area network) technology is a product of continuous development and integration of computer and communication technologies, and is also an important branch of wireless network technology, the IEEE 802.11a/g/n/ac protocol is one of the most influential wireless local area network protocol standards at present, and the IEE 802.11 a/g/n/ac-based WLAN system adopts the OFDM (Orthogonal Frequency Division Multiplexing) technology as its physical layer access technology, and has been widely applied at present.
Currently, WLAN protocols have evolved to 802.11ax over 802.11 a/g/n/ac. The physical layer Access technology is upgraded to OFDMA (Orthogonal Frequency Division Multiple Access). As a device for signal demodulation in wireless communication transmission, a baseband receiver for digital communication mainly aims to receive and process a modulated signal and acquire demodulated data information from the modulated signal. Under the new generation of WLAN protocols, the baseband receiver is required to be compatible with the new and old versions of the protocol standard.
In the prior art, when a plurality of user terminals access simultaneously, a baseband receiver is limited by factors such as user terminal hardware difference, distance and the like, and may have the problems of frequency deviation, sampling clock and timing position deviation.
Disclosure of Invention
In view of this, embodiments of the present invention provide a signal demodulation method and a baseband receiver to solve the problem in the prior art that there may be a frequency offset, a sampling clock, and a timing position deviation.
A first aspect of an embodiment of the present invention provides a signal demodulation method, including:
acquiring a digital baseband signal;
acquiring a leading domain of the digital baseband signal according to the digital baseband signal, wherein the leading domain comprises a leading training sequence and a leading information sequence;
obtaining a public correction parameter and frame configuration information according to the leader domain, wherein the public correction parameter comprises an integer timing position, a frequency offset estimation value and a sampling clock deviation;
processing the digital baseband signal according to the public correction parameter and the frame configuration information to obtain a first signal;
obtaining a frequency domain signal according to the first signal;
and demodulating and decoding the frequency domain signal to obtain data information carried by the frequency domain signal.
A second aspect of an embodiment of the present invention provides a baseband receiver, including:
the digital baseband signal acquisition module is used for acquiring a digital baseband signal;
a leading domain obtaining module, configured to obtain a leading domain of the digital baseband signal according to the digital baseband signal, where the leading domain includes a leading training sequence and a leading information sequence;
the parameter acquisition module is used for acquiring a public correction parameter and frame configuration information according to the preamble domain, wherein the public correction parameter comprises an integer timing position, a frequency offset estimation value and a sampling clock offset;
the first signal acquisition module is used for processing the digital baseband signal according to the common correction parameter and the frame configuration information to obtain a first signal;
the frequency domain signal acquisition module is used for obtaining a frequency domain signal according to the first signal;
and the data information acquisition module is used for demodulating and decoding the frequency domain signal to obtain the data information carried by the frequency domain signal.
A third aspect of the embodiments of the present invention provides a baseband receiver, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the steps of the signal demodulation method as described above when executing the computer program.
A fourth aspect of embodiments of the present invention provides a computer-readable storage medium storing a computer program which, when executed by a processor, implements the steps of the signal demodulation method described above.
Compared with the prior art, the embodiment of the invention has the following beneficial effects: by acquiring a digital baseband signal; acquiring a leading domain of the digital baseband signal according to the digital baseband signal, wherein the leading domain comprises a leading training sequence and a leading information sequence; obtaining a public correction parameter and frame configuration information according to the leader domain, wherein the public correction parameter comprises an integer timing position, a frequency offset estimation value and a sampling clock deviation; processing the digital baseband signal according to the public correction parameter and the frame configuration information to obtain a first signal; obtaining a frequency domain signal according to the first signal; and demodulating and decoding the frequency domain signal to obtain data information carried by the frequency domain signal. The compensation and correction of the frequency offset estimation value, the timing position deviation and the sampling clock deviation are realized, so that the signal quality and the decoding performance are improved.
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In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in 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 invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
Fig. 1 is a schematic flow chart illustrating an implementation of a signal demodulation method according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of an implementation of a signal demodulation method according to an embodiment of the present invention;
fig. 3 is a schematic flow chart of an implementation of step S203 in fig. 2 according to an embodiment of the present invention;
fig. 4 is a schematic flow chart of an implementation of step S103 in fig. 1 according to an embodiment of the present invention;
fig. 5 is a schematic flow chart of an implementation of step S104 in fig. 1 according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a baseband receiver provided in an embodiment of the present invention;
FIG. 7 is a schematic structural diagram of a baseband receiver according to an embodiment of the present invention
FIG. 8 is a schematic structural diagram of a bandwidth obtaining module in FIG. 7 according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of a baseband receiver according to an embodiment of the present invention.
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 embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention 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 invention with unnecessary detail.
The terms "comprises" and "comprising," and any variations thereof, in the description and claims of this invention and the above-described drawings are intended to cover non-exclusive inclusions. For example, a process, method, or system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus. Furthermore, the terms "first," "second," and "third," etc. are used to distinguish between different objects and are not used to describe a particular order.
In order to explain the technical means of the present invention, the following description will be given by way of specific examples.
Example 1:
fig. 1 shows a flow of implementing a signal demodulation method according to an embodiment of the present invention, where the signal demodulation method of the present embodiment is applied to a baseband receiver, and the process thereof is detailed as follows:
in step S101, a digital baseband signal is acquired.
In the present embodiment, an OFDMA signal modulation technique is adopted, where OFDMA is a multiple access technique, and the OFDMA is based on OFDM modulation, and multiple users are accessed by allocating a certain number of subcarriers to each user, so that multiple users share frequency band resources through the OFDMA.
In this embodiment, the baseband receiver includes a local oscillation module and an ADC analog-to-digital conversion module.
In this embodiment, a baseband receiver first obtains a modulation signal sent by a user terminal; generating a local coherent carrier through a local oscillation module, and mixing the modulation signal with the local coherent carrier to realize down-conversion to obtain a down-converted signal; and performing analog-to-digital conversion on the signal after the down-conversion through an ADC analog-to-digital conversion module to obtain a digital baseband signal, wherein the sampling rate of the ADC analog-to-digital conversion module is recorded as a preset second sampling rate.
In step S102, a preamble field of the digital baseband signal is obtained according to the digital baseband signal, where the preamble field includes a preamble training sequence and a preamble information sequence.
In this embodiment, the digital baseband signal includes a preamble field and a data field, where the preamble field includes a preamble training sequence and a preamble information sequence, the preamble training sequence is used to perform time synchronization and frequency synchronization on the digital baseband signal, the preamble information sequence is used to carry frame configuration information, and the data field is used to carry data information sent by a user.
In this embodiment, the preamble training sequences used by each user for time synchronization and frequency synchronization are the same, and the digital baseband signal of each user realizes preliminary time synchronization and frequency synchronization through the preamble training sequences, so as to obtain the common correction parameters.
In step S103, according to the preamble field, a common correction parameter and frame configuration information are obtained, where the common correction parameter includes an integer timing position, a frequency offset estimation value, and a sampling clock offset.
In this embodiment, according to the preamble training sequence, time synchronization and frequency synchronization are performed on the preamble training sequence to obtain a common correction parameter, and since the common correction parameter is obtained by performing time synchronization and frequency synchronization on the preamble training sequence and the preamble training sequences used by all users for performing time synchronization and frequency synchronization are the same, the common correction parameter is a correction parameter commonly used by all users, and the common correction parameter includes an integer timing position, a frequency offset estimation value, and a sampling clock offset.
In this embodiment, the frame configuration information is obtained by a preamble information sequence.
In step S104, the digital baseband signal is processed according to the common correction parameter and the frame configuration information to obtain a first signal.
In this embodiment, according to the frame configuration information, the length of a signal extracted from the digital baseband signal is obtained, the start position of the digital baseband signal is determined according to the integer timing position, the frequency of the digital baseband signal is adjusted according to the frequency offset estimation value, so that the digital baseband signal is accurately obtained, the data field in the digital baseband signal is extracted for serial-parallel conversion, a serial signal is obtained, and the serial signal is subjected to fast fourier transform, so that the frequency domain signal is obtained.
In step S105, the frequency domain signal is demodulated and decoded to obtain data information carried by the frequency domain signal.
As can be seen from the above embodiments, by obtaining a digital baseband signal; acquiring a leading domain of the digital baseband signal according to the digital baseband signal, wherein the leading domain comprises a leading training sequence and a leading information sequence; obtaining a public correction parameter and frame configuration information according to the leader domain, wherein the public correction parameter comprises an integer timing position, a frequency offset estimation value and a sampling clock deviation; processing the digital baseband signal according to the public correction parameter and the frame configuration information to obtain a first signal; obtaining a frequency domain signal according to the first signal; and demodulating and decoding the frequency domain signal to obtain data information carried by the frequency domain signal. The compensation and correction of the frequency offset estimation value, the timing position deviation and the sampling clock deviation are realized, so that the signal quality and the decoding performance are improved.
As shown in fig. 2, in an embodiment of the present invention, after the step S101, the signal demodulation method further includes:
in step S201, a first frame header position of the digital baseband signal is determined.
In this embodiment, when acquiring the digital baseband signal, it is necessary to first determine a first frame header position of the digital baseband signal.
In one embodiment, step S201 includes:
1) carrying out power detection on the digital baseband signal;
2) and when the jumping quantity of the power value of the digital baseband signal is detected to be larger than a first threshold value, acquiring a corresponding position in the digital baseband signal as a first frame header position.
In this embodiment, the power value of the digital baseband signal is detected by using the sliding window method, and the power values of the digital baseband signal that passes through are sequentially determined by using the sliding window method, so that the position of the power value jump of the digital baseband signal can be quickly and accurately found, and the position of the first frame header can be quickly found.
In an embodiment of the present invention, after finding the first frame header position of the digital baseband signal, the method further includes:
and performing direct current elimination on the digital baseband signal to obtain a direct current eliminated digital baseband signal.
In step S202, a first signal segment with a preset first length is extracted from a first frame header position in the digital baseband signal.
In this embodiment, the first frame header position is a preliminary estimated frame header position, and after the first frame header position is obtained, a first signal segment with a first length is preset after the first frame header position is extracted.
In this embodiment, the preset first length is greater than the length of the preamble field.
In step S203, the bandwidth of the first signal segment is obtained.
In step S204, the first signal segment is filtered to obtain a second signal.
In this embodiment, the first signal segment is filtered to suppress signals outside the bandwidth of the first signal segment.
In step S205, the second signal is decimated according to a preset first sampling rate to obtain a third signal, where a value of the preset first sampling rate is equal to a value of a bandwidth of the first signal segment.
Taking a specific application scenario as an example, assuming that the sampling rate of the ADC analog-to-digital conversion module is 240MHz, and the bandwidth of the second signal is 20MHz, the first sampling rate is preset to be 20MHz, and the second signal is extracted according to the preset first sampling rate, that is, one of the samples is extracted from the second signal every 12 samples, so as to form a third signal.
In this embodiment, the second signal is down-sampled and decimated according to a preset first sampling rate, where the preset first sampling rate is set to a value equal to the bandwidth of the first signal segment, and a third signal is obtained by decimation.
As shown in fig. 3, in an embodiment of the present invention, fig. 3 shows a specific implementation flow of step S203, which includes:
in step S301, it is determined whether the bandwidth of the first signal segment meets a preset protocol requirement.
In this embodiment, it is determined whether the first signal segment meets a preset protocol requirement, and a bandwidth of the first signal segment needs to be detected, and since wireless communication needs to meet a WLAN protocol standard, the current WLAN protocol includes an 802.11a/g/n/ac/ax protocol, the bandwidth of the first signal segment needs to meet one of 20/40/80/160MHz, so that the first signal segment can be demodulated by the baseband receiver.
In step S302, when the bandwidth of the first signal segment does not meet the preset protocol requirement, the digital baseband signal is acquired again.
In this embodiment, when the bandwidth of the first signal segment meets the requirement of the preset protocol, the bandwidth of the first signal segment is obtained, and the steps after S203 are performed; and when the bandwidth of the first signal segment does not meet the requirement of the preset protocol, the modulation signal sent by the transmitting terminal is obtained again.
As shown in fig. 4, in an embodiment of the present invention, fig. 4 shows a specific flow of the step S103, which includes:
in step S401, time synchronization and frequency synchronization are performed on the third signal according to the correlation peak characteristic of the preamble training sequence, so as to obtain a correlation peak value.
In step S402, it is determined whether the correlation peak value is greater than a preset peak threshold value.
In step S403, when the correlation peak value is greater than the preset peak threshold value, a common correction parameter is obtained.
In this embodiment, the method for performing time synchronization and frequency synchronization on the third signal according to the correlation peak characteristic of the preamble training sequence includes the following two methods:
the first method comprises the following steps: and obtaining a correlation peak value through the autocorrelation characteristic of the preamble training sequence, and realizing time synchronization and frequency synchronization of the third signal when the correlation peak value is greater than a preset correlation peak threshold value, thereby obtaining a common correction parameter.
And the second method comprises the following steps: and generating a local training sequence, performing cross correlation with a preamble training sequence to obtain a correlation peak value, detecting the size of the correlation peak value and the preset correlation peak threshold value, and when the correlation peak value is greater than the preset correlation peak threshold value, realizing time synchronization and frequency synchronization of a third signal to obtain a common correction parameter.
In this embodiment, the digital baseband signal is filtered and extracted, and the preamble training sequence is used to perform time synchronization and frequency synchronization, so as to obtain a common correction parameter, and further correct the timing position deviation, the frequency deviation, and the sampling clock deviation of the obtained baseband received signal, thereby improving the quality of the frequency signal.
In step S404, the position of the first frame header is adjusted according to the integer timing position to obtain a standard frame header position.
In step S405, the preamble information sequence is parsed and decoded according to the standard frame header position, so as to obtain frame configuration information.
In this embodiment, the preamble information sequence in the preamble domain is accurately found according to the position of the standard frame header.
In this embodiment, the preamble information sequence is parsed and decoded, and the preamble information sequence includes frame configuration information in the digital baseband signal, and the frame configuration information includes information such as a frame type, a frame length, a resource allocation method, the number of users, a coding method, a modulation order, and a GI (Guard Interval) length.
In an embodiment of the present invention, parsing and decoding the preamble information sequence to obtain frame configuration information specifically includes:
1) carrying out bit check on the information of the leading information sequence, wherein the bit check comprises cyclic redundancy check;
2) and when the information of the preamble information sequence passes bit check, acquiring frame configuration information.
In an embodiment of the present invention, a specific implementation flow of the step S104 includes:
in step S501, a complete frame signal is extracted from the digital baseband signal according to the frame configuration information and the standard frame header position, so as to obtain a second signal segment.
In this embodiment, a complete one-frame signal may be extracted from the digital baseband signal by using the frame length and the standard frame header position in the frame configuration information, and the complete one-frame signal may be defined as the second signal segment.
In step S502, the second signal segment is filtered to obtain a fourth signal.
In this embodiment, the obtained second signal segment is filtered to filter out signals outside the bandwidth of the second signal segment, and suppress out-of-band noise, so as to obtain a fourth signal.
In step S503, the sampling clock of the fourth signal is compensated according to the sampling clock deviation, and a fifth signal is obtained.
In step S504, the amplitudes and phases of the in-phase component and the quadrature component of the fifth signal are estimated and compensated to obtain a sixth signal.
In this embodiment, the amplitude and the phase of the in-phase component and the quadrature component of the fifth signal are estimated to obtain an amplitude deviation value and a phase deviation value, and the amplitude and the phase are compensated according to the amplitude deviation value and the phase deviation value, so that the amplitudes of the in-phase component and the quadrature component are kept consistent, and the phases are kept orthogonal.
In step S505, the frequency of the sixth signal is compensated according to the frequency offset estimation value, so as to obtain the first signal.
In an embodiment of the present invention, step S105 in fig. 1 specifically includes:
step S601: and extracting the first signal according to a preset first sampling rate to obtain a seventh signal.
Step S602: and performing channel estimation on the seventh signal to obtain a channel matrix.
Step S603: and obtaining the fraction timing position according to the channel matrix.
In this embodiment, the preamble training sequence of the seventh signal is extracted, channel estimation is performed through the local training sequence and the preamble training sequence to obtain a channel matrix, and the fractional timing position is obtained through the channel matrix. When the local training sequence is used for channel estimation, only the pilot frequency symbol of the subcarrier where the specific user is located is generated, so that the obtained fraction timing position is the timing position of the specific user; that is, for a specific user, after the frequency offset estimation value, the sampling clock offset and the frequency of the digital baseband signal are once compensated by the common correction parameter to obtain a first signal, channel estimation is performed on the first signal to obtain the fractional timing position of the specific user, so that the timing position is more accurate.
Step S604: and according to the fraction timing position, extracting the first signal according to the preset first sampling rate to obtain an eighth signal.
In this embodiment, the first signal is down-sampled according to the fractional timing position, thereby obtaining a more accurate eighth signal.
In an embodiment of the present invention, after obtaining the eighth signal, the method further includes:
and performing channel estimation on the eighth signal to obtain a second channel matrix.
In this embodiment, after obtaining the frequency domain signal, channel equalization is performed on the frequency domain signal according to the obtained second channel matrix.
Step S605, converting the eighth signal from the time domain to the frequency domain to obtain a frequency domain signal
In this embodiment, a data field of an eighth signal is first extracted, the data field of the eighth signal is subjected to serial-to-parallel conversion to obtain a serial signal, and then the serial signal is converted from a time domain to a frequency domain through fast fourier transform to obtain a frequency domain signal.
In an embodiment of the present invention, after step S605, the method further includes:
step S701: a user specific frequency domain signal of the frequency domain signals is obtained.
In this embodiment, the user-specific frequency domain signal is obtained according to the resource allocation information in the obtained frame configuration information.
Step S702: and acquiring the pilot frequency subcarrier in the user specific frequency domain signal.
Step S703: and performing residual frequency offset estimation on the pilot frequency subcarrier to obtain a residual frequency offset estimation value.
Step S704: and carrying out sampling clock estimation on the pilot frequency sub-carrier to obtain a residual sampling clock estimation value.
Step S705: and obtaining user correction parameters based on the fractional timing position, the residual frequency offset estimation value and the residual sampling clock estimation value, wherein the user correction parameters comprise the fractional timing position, the residual frequency offset estimation value and the residual sampling clock estimation value.
Step S706: and correspondingly correcting and updating the public correction parameters according to the user correction parameters.
In this embodiment, the common correction parameter is corrected and updated correspondingly according to the user correction parameter. The method specifically comprises the following steps:
1) correcting and updating the integral timing position based on the fractional timing position;
2) and correcting and updating the frequency offset estimation value based on the residual frequency offset estimation value.
3) Based on the residual sampling clock bias, the sampling clock bias is corrected and updated.
In this embodiment, the integer timing positions of all users are obtained through the common correction parameter, and the frequency deviation and the sampling clock deviation are compensated, but since the frequency and the sampling clock of each user have a certain deviation, the corresponding accurate compensation cannot be performed for different users well only through the common correction parameter.
In this embodiment, the user-specific frequency domain signal includes a pilot subcarrier, OFDMA allocates a certain number of pilot subcarriers to each user, and after the data domain is converted from the time domain to the frequency domain to obtain a frequency domain signal, extracts the pilot subcarriers in the user-specific frequency domain signal, and performs correlation calculation with the locally stored pilot subcarriers using training characteristics of the pilot subcarriers to obtain a residual frequency offset estimation value and a residual sampling clock estimation value.
In this embodiment, the user modification parameters are specific modification parameters for each user, and the user modification parameters include fractional timing position, residual frequency offset estimation value, and residual sampling clock offset.
In this embodiment, the fractional timing position is obtained, the integer timing position is corrected by the fractional timing position to obtain the precise timing position, the integer timing position is updated by the precise timing position, and the steps S104 to S106 are executed again by the precise timing position to obtain a more precise frequency domain signal.
In this embodiment, taking an application scenario as an example, the modifying and updating the integer timing position based on the fractional timing position includes:
suppose that the signal bandwidth of the digital baseband signal is fBWMHz, preset second sampling rate fsMHZ. First, f is carried out on the second signals/fBWMultiple decimation, the sampling rate of the third signal is fBWMHz, then estimatedTo integer timing position Np. From integer timing position NpThen the seventh signal is extracted according to a preset first sampling rate to obtain a first signal, and the first signal is subjected to channel estimation to obtain a fraction timing position NfAssuming the precise timing position is NrealThe precise timing position obtained after the residual frequency offset estimation is performed on the pilot frequency subcarrier
Where round (. cndot.) is rounded.
In this embodiment, the frequency offset estimation value is corrected according to the obtained residual frequency offset estimation value, and step S104 to step S106 are executed again according to the corrected frequency offset estimation value, so as to obtain a more accurate frequency domain signal.
In this embodiment, the sampling clock bias is corrected according to the obtained residual sampling clock bias, and step S104 to step S106 are executed according to the corrected sampling clock bias, so that the sampling clock is more accurate, and a more accurate frequency domain signal is obtained.
In an embodiment of the present invention, after step S704, the method further includes:
and performing residual phase estimation on the pilot frequency sub-carrier to obtain a residual phase, and compensating the phase of the frequency domain signal.
It can be known from the foregoing embodiment that, by obtaining the pilot subcarriers, and performing residual frequency offset estimation and sampling clock estimation on the pilot subcarriers, fractional timing positions, residual frequency offset estimation values, and residual sampling clock deviations are obtained, and further, feedback compensation is performed on integer timing positions, frequency offset estimation values, and sampling clock deviations of each user, so as to obtain frequency domain signals with higher quality.
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 to the implementation process of the embodiments of the present invention.
Example 2:
as shown in fig. 6, an embodiment of the present invention provides a baseband receiver 1000 for performing the method steps in the embodiment corresponding to fig. 1, which includes:
a digital baseband signal obtaining module 1010, configured to obtain a digital baseband signal.
A preamble field obtaining module 1020, configured to obtain a preamble field of the digital baseband signal according to the digital baseband signal, where the preamble field includes a preamble training sequence and a preamble information sequence.
A parameter obtaining module 1030, configured to obtain a common correction parameter and frame configuration information according to the preamble domain, where the common correction parameter includes an integer timing position, a frequency offset estimation value, and a sampling clock offset.
The first signal obtaining module 1040 is configured to process the digital baseband signal according to the common correction parameter and the frame configuration information, so as to obtain a first signal.
A frequency domain signal obtaining module 1050, configured to obtain a frequency domain signal according to the first signal.
A data information obtaining module 1060, configured to demodulate and decode the frequency domain signal to obtain data information carried by the frequency domain signal.
As can be seen from the above embodiments, by obtaining a digital baseband signal; acquiring a leading domain of the digital baseband signal according to the digital baseband signal, wherein the leading domain comprises a leading training sequence and a leading information sequence; obtaining a public correction parameter and frame configuration information according to the leader domain, wherein the public correction parameter comprises an integer timing position, a frequency offset estimation value and a sampling clock deviation; processing the digital baseband signal according to the public correction parameter and the frame configuration information to obtain a first signal; obtaining a frequency domain signal according to the first signal; and demodulating and decoding the frequency domain signal to obtain data information carried by the frequency domain signal. The compensation and correction of the frequency offset estimation value, the timing position deviation and the sampling clock deviation are realized, so that the signal quality and the decoding performance are improved.
As shown in fig. 7, in an embodiment of the present invention, after the digital baseband signal acquisition module 1010, a structure for performing the method steps in the embodiment corresponding to fig. 2 is further included, which includes:
a first frame header position obtaining module 1070 is configured to determine a first frame header position of the digital baseband signal.
A first signal segment obtaining module 1080, configured to extract a first signal segment with a preset first length from the first frame header position in the digital baseband signal.
A bandwidth obtaining module 1090, configured to obtain a bandwidth of the first signal segment.
A second signal obtaining module 1100, configured to filter the first signal segment to obtain a second signal.
The third signal obtaining module 1110 is configured to extract the second signal according to a preset first sampling rate to obtain a third signal, where a value of the preset first sampling rate is equal to a value of a bandwidth of the first signal segment.
As shown in fig. 8, in an embodiment of the present invention, a structure of the bandwidth obtaining module 1090 in the embodiment corresponding to fig. 7 is configured to perform the method steps in the embodiment corresponding to fig. 3, and includes:
a bandwidth determining unit 1091, configured to determine whether a bandwidth of the first signal segment meets a preset protocol requirement.
A digital baseband signal reacquisition unit 1092, configured to reacquire the digital baseband signal when the bandwidth of the first signal segment does not meet the preset protocol requirement.
In an embodiment of the present invention, the parameter obtaining module 1030 corresponding to fig. 6 is further configured to execute the structure of the method step in the embodiment corresponding to fig. 4, and specifically includes:
and the correlation peak value acquisition unit is used for carrying out time synchronization and frequency synchronization on the third signal according to the correlation peak characteristics of the preamble training sequence to obtain a correlation peak value.
And the peak value judging unit is used for judging whether the related peak value is larger than a preset peak threshold value or not.
And the public correction parameter acquisition unit is used for acquiring a public correction parameter when the correlation peak value is larger than a preset peak threshold value.
And the standard frame header position obtaining unit is used for adjusting the position of the first frame header according to the integer timing position to obtain the position of the standard frame header.
And the frame configuration information acquisition unit is used for analyzing and decoding the leading information sequence according to the position of the standard frame head to obtain the frame configuration information.
In an embodiment of the present invention, the first signal obtaining module 1040 in fig. 6 specifically includes:
and the second signal segment acquisition unit is used for extracting a complete frame signal from the digital baseband signal according to the frame configuration information and the position of the standard frame header to obtain a second signal segment.
And the fourth signal acquisition unit is used for filtering the second signal segment to obtain a fourth signal.
And the fifth signal acquisition unit is used for compensating the sampling clock of the fourth signal according to the sampling clock deviation to obtain a fifth signal.
And the sixth signal acquisition unit is used for estimating and compensating the amplitude and the phase of the in-phase component and the quadrature component of the fifth signal to obtain a sixth signal.
And the first signal acquisition unit is used for compensating the frequency of the sixth signal according to the frequency offset estimation value to obtain a first signal.
In an embodiment of the present invention, the frequency domain signal obtaining module 1050 in fig. 6 specifically includes:
and the seventh signal acquisition unit is used for extracting the first signal according to a preset first sampling rate to obtain a seventh signal.
And the channel matrix calculation unit is used for carrying out channel estimation on the seventh signal to obtain a channel matrix.
And the fraction timing position acquisition unit is used for calculating to obtain the fraction timing position according to the channel matrix.
And the eighth signal acquisition unit is used for extracting the first signal according to the preset first sampling rate according to the fraction timing position to obtain an eighth signal.
And the frequency domain signal acquisition unit is used for converting the eighth signal from a time domain to a frequency domain to obtain a frequency domain signal.
In an embodiment of the present invention, after the frequency domain signal obtaining module 1050 in fig. 6, the method further includes:
and the user specific frequency domain signal acquisition module is used for acquiring the user specific frequency domain signal in the frequency domain signals.
And the pilot frequency subcarrier acquisition module is used for acquiring the pilot frequency subcarriers in the user specific frequency domain signals.
And the residual frequency offset estimation value acquisition module is used for performing residual frequency offset estimation on the pilot frequency subcarrier to obtain a residual frequency offset estimation value.
And the residual sampling clock estimation value acquisition module is used for carrying out sampling clock estimation on the pilot frequency subcarrier to obtain a residual sampling clock estimation value.
And the user correction parameter acquisition module is used for obtaining user correction parameters based on the fraction timing position, the residual frequency offset estimation value and the residual sampling clock estimation value, wherein the user correction parameters comprise the fraction timing position, the residual frequency offset estimation value and the residual sampling clock estimation value.
And the feedback correction module is used for correspondingly correcting and updating the public correction parameter according to the user correction parameter.
It can be known from the foregoing embodiment that, by obtaining the pilot subcarriers, and performing residual frequency offset estimation and sampling clock estimation on the pilot subcarriers, user correction parameters are obtained, and further, corresponding feedback compensation is performed on integer timing positions, frequency offset estimation values, and sampling clock offsets of each user, so as to obtain a frequency domain signal with higher quality.
Example 3:
as shown in fig. 9, an embodiment of the present invention further provides a baseband receiver 1000, which includes a memory 91, a processor 90, and a computer program 92 stored in the memory and executable on the processor, where the processor 90 executes the computer program 92 to implement steps in embodiments as described in embodiment 1, such as steps S101 to S106 shown in fig. 1. Alternatively, the processor 90, when executing the computer program 92, implements the functions of the modules in the device embodiments as described in embodiment 2, for example, the functions of the modules 1010 to 1060 shown in fig. 6.
The Processor 90 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, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory 91 may be an internal storage unit of the baseband receiver, such as a hard disk or a memory of the baseband receiver. The memory 91 may also be an external storage device of the baseband receiver, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), etc. provided on the baseband receiver. Further, the memory 91 may also include both a baseband receiver internal storage unit and an external storage device. The memory 91 is used for storing the computer program 92 and other programs and data required by the baseband receiver. The memory 91 may also be used to temporarily store data that has been output or is to be output.
Example 4:
an embodiment of the present invention further provides a computer-readable storage medium, in which a computer program 92 is stored, and when being executed by the processor 90, the computer program 92 implements the steps in the embodiments described in embodiment 1, such as step S101 to step S106 shown in fig. 1. Alternatively, the computer program 92 realizes the functions of the respective modules in the respective device embodiments as described in embodiment 2, for example, the functions of the modules 1010 to 1060 shown in fig. 6, when executed by the processor 90.
The computer program 92 may be stored in a computer readable storage medium, and the computer program 82 may implement the steps of the above-described method embodiments when executed by the processor 90. Wherein the computer program 92 comprises computer program code, which may be in source code form, object code form, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain other components which may be suitably increased or decreased as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media which may not include electrical carrier signals and telecommunications signals in accordance with legislation and patent practice.
The steps in the method of the embodiment of the invention can be sequentially adjusted, combined and deleted according to actual needs.
The modules or units in the system of the embodiment of the invention can be combined, divided and deleted according to actual needs.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (12)
1. A method for demodulating a signal, comprising:
acquiring a digital baseband signal;
acquiring a leading domain of the digital baseband signal according to the digital baseband signal, wherein the leading domain comprises a leading training sequence and a leading information sequence;
obtaining a public correction parameter and frame configuration information according to the preamble domain, wherein the public correction parameter comprises an integer timing position, a frequency offset estimation value and a sampling clock offset;
processing the digital baseband signal according to the common correction parameter and the frame configuration information to obtain a first signal;
obtaining a frequency domain signal according to the first signal, and obtaining a user specific frequency domain signal in the frequency domain signal;
calculating a user correction parameter according to the pilot frequency subcarrier in the user specific frequency domain signal, and correspondingly correcting and updating the public correction parameter according to the user correction parameter;
correcting and updating the frequency domain signal according to the corrected and updated common correction parameter;
and demodulating and decoding the corrected and updated frequency domain signal to obtain data information carried by the frequency domain signal.
2. A signal demodulation method as claimed in claim 1, further comprising, after said acquiring the digital baseband signal:
determining a first frame header position of the digital baseband signal;
extracting a first signal segment with a preset first length from the position of the first frame header in the digital baseband signal;
acquiring the bandwidth of the first signal segment;
filtering the first signal segment to obtain a second signal;
and extracting the second signal according to a preset first sampling rate to obtain a third signal, wherein the value of the preset first sampling rate is equal to the value of the bandwidth of the first signal segment.
3. The signal demodulation method as claimed in claim 2, wherein obtaining the bandwidth of the first signal segment specifically comprises:
judging whether the bandwidth of the first signal segment meets the requirement of a preset protocol or not;
and when the bandwidth of the first signal segment does not meet the requirement of a preset protocol, the digital baseband signal is obtained again.
4. The signal demodulation method as claimed in claim 2, wherein said obtaining the common modification parameter and the frame configuration information according to the preamble field comprises:
performing time synchronization and frequency synchronization on the third signal according to the correlation peak characteristics of the preamble training sequence to obtain a correlation peak value;
judging whether the correlation peak value is larger than a preset peak threshold value or not;
when the correlation peak value is larger than the preset peak threshold value, obtaining the public correction parameter;
adjusting the position of the first frame header according to the integer timing position to obtain a standard frame header position;
and analyzing and decoding the leading information sequence according to the position of the standard frame header to obtain frame configuration information.
5. The signal demodulation method of claim 4 wherein said processing said digital baseband signal based on said common correction parameter and said frame configuration information to obtain a first signal comprises:
extracting a complete frame signal from the digital baseband signal according to the frame configuration information and the position of the standard frame header to obtain a second signal segment;
filtering the second signal segment to obtain a fourth signal;
according to the sampling clock deviation, compensating the sampling clock of the fourth signal to obtain a fifth signal;
estimating and compensating the amplitude and the phase of the in-phase component and the quadrature component of the fifth signal to obtain a sixth signal;
and compensating the frequency of the sixth signal according to the frequency deviation estimated value to obtain a first signal.
6. A signal demodulation method as claimed in claim 1, wherein said obtaining a frequency domain signal from said first signal comprises:
extracting the first signal according to a preset first sampling rate to obtain a seventh signal;
performing channel estimation on the seventh signal to obtain a channel matrix;
calculating to obtain a fraction timing position according to the channel matrix;
according to the fraction timing position, the first signal is extracted according to the preset first sampling rate to obtain an eighth signal;
and converting the eighth signal from the time domain to the frequency domain to obtain a frequency domain signal.
7. The signal demodulation method of claim 6 wherein said calculating user correction parameters based on pilot subcarriers in said user-specific frequency domain signal further comprises:
performing residual frequency offset estimation on the pilot frequency subcarrier to obtain a residual frequency offset estimation value;
carrying out sampling clock estimation on the pilot frequency sub-carrier to obtain a residual sampling clock estimation value;
and obtaining the user correction parameter based on the fraction timing position, the residual frequency offset estimation value and the residual sampling clock estimation value, wherein the user correction parameter comprises the fraction timing position, the residual frequency offset estimation value and the residual sampling clock estimation value.
8. A baseband receiver, comprising:
the digital baseband signal acquisition module is used for acquiring a digital baseband signal;
a leading domain obtaining module, configured to obtain a leading domain of the digital baseband signal according to the digital baseband signal, where the leading domain includes a leading training sequence and a leading information sequence;
a parameter obtaining module, configured to obtain a common correction parameter and frame configuration information according to the preamble domain, where the common correction parameter includes an integer timing position, a frequency offset estimation value, and a sampling clock offset;
a first signal obtaining module, configured to process the digital baseband signal according to the common correction parameter and the frame configuration information to obtain a first signal;
the frequency domain signal acquisition module is used for obtaining a frequency domain signal according to the first signal;
a pilot frequency subcarrier acquiring module, configured to acquire a pilot frequency subcarrier in a user-specific frequency domain signal and calculate a user correction parameter according to the pilot frequency subcarrier in the user-specific frequency domain signal;
the feedback correction module is used for correspondingly correcting and updating the public correction parameter according to the user correction parameter;
and the data information acquisition module is used for demodulating and decoding the corrected and updated frequency domain signal to obtain the data information carried by the frequency domain signal.
9. The baseband receiver of claim 8, further comprising, after said digital baseband signal acquisition module:
a first frame header position obtaining module, configured to determine a first frame header position of the digital baseband signal;
a first signal segment obtaining module, configured to extract a first signal segment with a preset first length from the position of the first frame header in the digital baseband signal;
a bandwidth obtaining module, configured to obtain a bandwidth of the first signal segment;
the second signal acquisition module is used for filtering the first signal segment to obtain a second signal;
and the third signal acquisition module is used for extracting the second signal according to a preset first sampling rate to obtain a third signal, wherein the numerical value of the preset first sampling rate is equal to the numerical value of the bandwidth of the first signal segment.
10. The baseband receiver of claim 9, wherein said bandwidth acquisition module comprises:
the bandwidth judging unit is used for judging whether the bandwidth of the first signal segment meets the requirement of a preset protocol or not;
and the digital baseband signal reacquiring unit is used for reacquiring the digital baseband signal when the bandwidth of the first signal segment does not meet the requirement of a preset protocol.
11. A baseband receiver comprising a memory, a processor and a computer program stored in said memory and executable on said processor, characterized in that said processor implements the steps of the signal demodulation method according to any one of claims 1 to 7 when executing said computer program.
12. 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 signal demodulation method according to any one of claims 1 to 7.
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