CN112039613B - Processing method and device for asymmetric PCMA (pulse code division multiple Access) mixed signal - Google Patents
Processing method and device for asymmetric PCMA (pulse code division multiple Access) mixed signal Download PDFInfo
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
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- H04B17/345—Interference values
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- 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
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Abstract
The application discloses a processing method and a device for an asymmetric PCMA mixed signal, wherein the method comprises the following steps: performing parameter estimation on a to-be-processed PCMA mixed signal to obtain a channel parameter, wherein the to-be-processed PCMA mixed signal comprises a useful signal and an interference signal, and the channel parameter comprises a frequency offset parameter, a phase parameter and an amplitude parameter of the interference signal; carrying out digital signal processing on the PCMA mixed signal to be processed to obtain information bit data and check bit data; reconstructing according to the channel parameter, the information bit data and the check bit data to generate the interference signal, and subtracting the to-be-processed PCMA mixed signal from the interference signal to obtain the useful signal. The method and the device solve the technical problem that in the prior art, the effect of eliminating the interference signals in the PCMA mixed signals is poor.
Description
Technical Field
The present application relates to the field of signal processing technologies, and in particular, to a method and an apparatus for processing an asymmetric PCMA mixed signal.
Background
With the increasing demand of users, the development of centralized high-throughput satellite systems is limited. In order to solve the problems of large antenna aperture, high requirement on a radio frequency system, large equipment quantity and large occupied area of a gateway station in a centralized high-flux satellite system, high difficulty in site selection, land use and construction of the gateway station and high system construction, maintenance cost and operation cost, a distributed feed system is tried to be adopted in the industry.
In order to improve the frequency resource utilization of the distributed feed system, Paired Carrier Multiple Access (PCMA) technology has been developed. The PCMA mixed signal can be divided into a symmetrical PCMA mixed signal and an asymmetrical PCMA mixed signal according to the energy of two signal components in the PCMA mixed signal. From the use scene, the asymmetric PCMA mixed signal is more widely applied to a satellite communication system. In the asymmetric mode, signals sent by the ground station terminal are transmitted to the master station after being forwarded by the satellite transponder, and the master station mixes the ground station terminal signals with the master station self-interference signals after receiving the ground station terminal signals to obtain asymmetric PCMA mixed signals. Since the power of the ground station terminal signal (useful signal) received by the master station is much smaller than that of the master station self-interference signal, the self-interference signal in the asymmetric PCMA hybrid signal needs to be eliminated.
At present, the common process for eliminating the interference signal in the asymmetric PCMA hybrid signal is as follows: carrying out digital frequency conversion filtering processing on the asymmetric PCMA mixed signal to obtain a processed PCMA mixed signal, then storing the processed PCMA mixed signal, and carrying out parameter estimation according to the processed PCMA mixed signal to obtain a channel parameter; the method comprises the steps of carrying out LDPC decoding on a stored local sequence to obtain a decoded local sequence, modulating the decoded local sequence to obtain a modulated local sequence, carrying out frequency offset, phase and amplitude adjustment reconstruction on the modulated local sequence according to channel parameters to obtain an interference signal, and finally carrying out subtraction on an asymmetric PCMA mixed signal and the reconstructed interference signal to obtain a useful signal. Specifically, fig. 1 shows a flow diagram of a conventional asymmetric PCMA hybrid signal processing; referring to fig. 2, a diagram illustrating the effect of a conventional asymmetric PCMA hybrid signal processing is shown. Therefore, in the prior art, the interference signal is subjected to interference reconstruction based on the local sequence, the method based on the local sequence is difficult to obtain a higher signal-to-noise ratio and has higher implementation complexity, and the effect of eliminating the interference signal in the PCMA mixed signal is further reduced.
Disclosure of Invention
The technical problem that this application was solved is: in the scheme provided by the embodiment of the application, the interference signal is obtained by reconstructing according to information bit data and check bit data obtained by decoding the PCMA mixed signal and channel parameters estimated by the PCMA mixed signal, so that the interference signal is closer to an actual interference signal in the PCMA mixed signal, and the effect of eliminating the interference signal in the PCMA mixed signal is further improved.
In a first aspect, an embodiment of the present application provides a method for processing an asymmetric PCMA mixed signal, where the method includes:
performing parameter estimation on a to-be-processed PCMA mixed signal to obtain a channel parameter, wherein the to-be-processed PCMA mixed signal comprises a useful signal and an interference signal, and the channel parameter comprises a frequency offset parameter, a phase parameter and an amplitude parameter of the interference signal;
carrying out digital signal processing on the PCMA mixed signal to be processed to obtain information bit data and check bit data;
reconstructing according to the channel parameter, the information bit data and the check bit data to generate the interference signal, and subtracting the to-be-processed PCMA mixed signal from the interference signal to obtain the useful signal.
In the scheme provided by the embodiment of the application, parameter estimation is performed on a to-be-processed PCMA mixed signal to obtain a channel parameter, digital signal processing is performed on the to-be-processed PCMA mixed signal to obtain information bit data and check bit data, the interference signal is generated by reconstructing according to the channel parameter, the information bit data and the check bit data, and the to-be-processed PCMA mixed signal and the interference signal are subtracted to obtain the useful signal. Therefore, in the scheme provided by the embodiment of the application, the interference signal is obtained by reconstructing the information bit data and the check bit data obtained by decoding the PCMA mixed signal and the channel parameter estimated by the PCMA mixed signal, so that the interference signal is closer to the actual interference signal in the PCMA mixed signal, and the effect of eliminating the interference signal in the PCMA mixed signal is further improved.
Optionally, performing parameter estimation on the PCMA hybrid signal to be processed to obtain a channel parameter, including:
carrying out frequency offset estimation on the PCMA mixed signal to be processed to obtain the frequency offset parameter;
performing phase estimation on the PCMA mixed signal to be processed to obtain the phase parameter;
and carrying out amplitude estimation on the PCMA mixed signal to be processed to obtain the amplitude parameter.
Optionally, performing frequency offset estimation on the PCMA mixed signal to be processed to obtain the frequency offset parameter, where the frequency offset parameter includes:
setting frequency searching times and a searching frequency range, dividing the searching frequency range into a plurality of first sub-intervals, calculating a measurement parameter corresponding to each first sub-interval, and searching a maximum value of the measurement parameter and a frequency corresponding to the maximum value from the measurement parameters of the plurality of first sub-intervals;
narrowing the search frequency range to obtain a narrowed search frequency range, determining a new search frequency range according to the frequency and the narrowed search frequency range, and judging whether the current frequency search frequency is less than the frequency search frequency;
if the frequency offset parameter is less than the first frequency offset parameter, dividing the new search frequency range into a plurality of second sub-intervals, calculating a metric parameter corresponding to each second sub-interval, searching a maximum value of the metric parameter and a frequency corresponding to the maximum value from the metric parameters of the plurality of second sub-intervals until the current frequency search frequency is not less than the frequency search frequency, and taking the maximum value of the metric parameter searched for the last time and the frequency corresponding to the maximum value as the frequency offset parameter.
Optionally, performing phase estimation on the PCMA mixed signal to be processed to obtain the phase parameter includes:
carrying out frequency deviation removal processing on the PCMA mixed signal to be processed according to the frequency deviation parameters to obtain the PCMA mixed signal subjected to frequency deviation removal;
performing a quadratic operation on the PCMA mixed signal subjected to frequency offset removal according to a preset operation method, and simplifying an operation result to obtain a simplified operation result;
and calculating the phase value of the interference signal according to the simplified operation result.
Optionally, performing amplitude estimation on the PCMA mixed signal to be processed to obtain the amplitude parameter includes:
determining the mean value of the simplified operation result and the fourth power mean value of a preset local sequence;
and calculating the amplitude value of the interference signal according to the mean value of the simplified operation result and the fourth power mean value of the preset local sequence.
Optionally, performing digital signal processing on the PCMA mixed signal to be processed to obtain information bit data and check bit data, including:
carrying out down-conversion processing on the PCMA mixed signal to be processed to obtain a zero intermediate frequency signal, and carrying out rate conversion processing on the zero intermediate frequency signal to obtain a low-rate PCMA mixed signal;
Filtering the low-rate PCMA mixed signal to obtain a filtered signal, and converting the filtered signal into a digital baseband signal;
and decoding the digital baseband signal to obtain the information bit data and the check bit data.
Optionally, reconstructing according to the channel parameter, the information bit data, and the check bit data to generate the interference signal, includes:
generating an interference sequence according to the information bit data and the check bit data;
and demodulating the interference sequence to obtain a demodulated interference sequence, and adjusting frequency offset, phase and amplitude of the demodulated interference sequence according to the channel parameters to obtain the interference signal.
In the scheme provided by the embodiment of the application, the signal bit data and the check bit data obtained by decoding are directly utilized to reconstruct the interference sequence in the interference signal reconstruction process, so that encoding is not required in the interference sequence generation process, the difficulty of interference signal reconstruction is reduced, and the interference signal in the PCMA mixed signal is easier to eliminate.
In a second aspect, an embodiment of the present application provides an apparatus for processing an asymmetric PCMA mixed signal, the apparatus including:
The device comprises a parameter estimation unit, a channel estimation unit and a processing unit, wherein the parameter estimation unit is used for performing parameter estimation on a to-be-processed PCMA mixed signal to obtain a channel parameter, the to-be-processed PCMA mixed signal comprises a useful signal and an interference signal, and the channel parameter comprises a frequency offset parameter, a phase parameter and an amplitude parameter of the interference signal;
the digital signal processing unit is used for carrying out digital signal processing on the PCMA mixed signal to be processed to obtain information bit data and check bit data;
and the reconstruction unit is used for reconstructing according to the channel parameters, the information bit data and the check bit data to generate the interference signal, and subtracting the interference signal from the PCMA mixed signal to be processed to obtain the useful signal.
Optionally, the parameter estimation unit is specifically configured to:
carrying out frequency offset estimation on the PCMA mixed signal to be processed to obtain the frequency offset parameter;
performing phase estimation on the PCMA mixed signal to be processed to obtain the phase parameter;
and carrying out amplitude estimation on the PCMA mixed signal to be processed to obtain the amplitude parameter.
Optionally, the parameter estimation unit is specifically configured to:
setting frequency searching times and a searching frequency range, dividing the searching frequency range into a plurality of first sub-intervals, calculating a measurement parameter corresponding to each first sub-interval, and searching a maximum value of the measurement parameter and a frequency corresponding to the maximum value from the measurement parameters of the plurality of first sub-intervals;
Narrowing the search frequency range to obtain a narrowed search frequency range, determining a new search frequency range according to the frequency and the narrowed search frequency range, and judging whether the current frequency search frequency is less than the frequency search frequency;
if the frequency offset parameter is less than the first frequency offset parameter, dividing the new search frequency range into a plurality of second sub-intervals, calculating a metric parameter corresponding to each second sub-interval, searching a maximum value of the metric parameter and a frequency corresponding to the maximum value from the metric parameters of the plurality of second sub-intervals until the current frequency search frequency is not less than the frequency search frequency, and taking the maximum value of the metric parameter searched for the last time and the frequency corresponding to the maximum value as the frequency offset parameter.
Optionally, the parameter estimation unit is specifically configured to:
carrying out frequency deviation removal processing on the PCMA mixed signal to be processed according to the frequency deviation parameters to obtain the PCMA mixed signal subjected to frequency deviation removal;
performing a quadratic operation on the PCMA mixed signal subjected to frequency offset removal according to a preset operation method, and simplifying an operation result to obtain a simplified operation result;
And calculating the phase value of the interference signal according to the simplified operation result.
Optionally, the parameter estimation unit is specifically configured to:
determining the mean value of the simplified operation result and the fourth power mean value of a preset local sequence;
and calculating the amplitude value of the interference signal according to the mean value of the simplified operation result and the fourth power mean value of the preset local sequence.
Optionally, the digital signal processing unit is specifically configured to:
carrying out down-conversion processing on the PCMA mixed signal to be processed to obtain a zero intermediate frequency signal, and carrying out rate conversion processing on the zero intermediate frequency signal to obtain a low-rate PCMA mixed signal;
filtering the low-rate PCMA mixed signal to obtain a filtered signal, and converting the filtered signal into a digital baseband signal;
and decoding the digital baseband signal to obtain the information bit data and the check bit data.
Optionally, the reconstruction unit is specifically configured to:
generating an interference sequence according to the information bit data and the check bit data;
and demodulating the interference sequence to obtain a demodulated interference sequence, and adjusting frequency offset, phase and amplitude of the demodulated interference sequence according to the channel parameters to obtain the interference signal.
In a third aspect, the present application provides a computer device, comprising:
a memory for storing instructions for execution by at least one processor;
a processor for executing instructions stored in a memory to perform the method of the first aspect.
In a fourth aspect, the present application provides a computer readable storage medium having stored thereon computer instructions which, when run on a computer, cause the computer to perform the method of the first aspect.
Drawings
Fig. 1 is a schematic flowchart illustrating a conventional processing method for an asymmetric PCMA hybrid signal according to an embodiment of the present disclosure;
fig. 2 is a diagram illustrating an effect of a conventional asymmetric PCMA hybrid signal processing according to an embodiment of the present application;
fig. 3 is a flowchart illustrating a method for processing an asymmetric PCMA hybrid signal according to an embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of a processing apparatus for processing an asymmetric PCMA mixed signal according to an embodiment of the present disclosure;
fig. 5 is a schematic structural diagram of a computer device according to an embodiment of the present application.
Detailed Description
In the solutions provided in the embodiments of the present application, the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The following describes in further detail a method for processing an asymmetric PCMA mixed signal according to an embodiment of the present application with reference to the drawings in the specification, where the method may be implemented by the following steps (a method flow is shown in fig. 3):
step 301, performing parameter estimation on a to-be-processed PCMA mixed signal to obtain a channel parameter, where the to-be-processed PCMA mixed signal includes a useful signal and an interference signal, and the channel parameter includes a frequency offset parameter, a phase parameter, and an amplitude parameter of the interference signal.
In the solution provided in the embodiment of the present application, there are various ways to obtain channel parameters by performing parameter estimation on a PCMA hybrid signal to be processed, and a preferred way is described as an example below.
In one possible implementation manner, performing parameter estimation on the PCMA hybrid signal to be processed to obtain a channel parameter includes: performing frequency offset estimation on the PCMA mixed signal to be processed to obtain the frequency offset parameter; performing phase estimation on the PCMA mixed signal to be processed to obtain the phase parameter; and carrying out amplitude estimation on the PCMA mixed signal to be processed to obtain the amplitude parameter.
To facilitate understanding of the PCMA hybrid signal to be processed, a brief description is provided below.
Supposing that a ground station in a PCMA system receives two paths of MPSK or QAM modulation signals with the same symbol rate, wherein the two paths of signals comprise a first path of signals and a second path of signals, and the sampling interval of the modulation signals is T s T/L, L denotes the oversampling multiple, the PCMA mixed signal to be processed is:
wherein v is k Mean, v, representing white Gaussian noise k ＝0；h 1 Indicating a first letterThe magnitude of the number; f. of 1 Representing the frequency deviation of the first path of signal; theta 1 Representing the carrier phase of the first path of signal; h is 2 Representing the amplitude of the second path of signals; f. of 2 Representing the frequency deviation of the second path of signal; theta 2 Representing the carrier phase of the second path of signal; x is the number of 1,k A digital baseband modulated signal representing a desired signal; x is the number of 2,k A digital baseband modulated signal representing an interfering signal.
Further, assuming that the two paths of signals have the same modulation mode and are statistically independent to each other, the digital baseband modulation signal x 1,k Or x 2,j Can be represented by the following formula:
wherein x is i,k Represents the ith digital baseband modulation signal, i is 1 or 2, k is 0,1, …; n ═ {0,1,2, …, L-1 }; tau is i Indicating the timing deviation of the ith path signal; a is i,k The signal sequence of the ith path signal is represented, and the value of the signal sequence is related to the modulation mode; gi (-) denotes an equivalent channel filter comprising a shaping filter, a channel filter, a matched filter, etc., the filter having a continuous effective range of [ -L ] 1 T,L 1 T]，L 1 Representing half the order of the channel filter, m ∈ -L 1 ，L 1 ]。
In the scheme provided by the embodiment of the application, the parameter estimation of the PCMA mixed signal to be processed includes three parts, namely frequency offset estimation, phase estimation and amplitude estimation. For ease of understanding, the procedures for frequency offset estimation, phase estimation, and amplitude estimation are briefly described below.
First, frequency offset estimation
Specifically, there are various ways to obtain the frequency offset parameter by performing frequency offset estimation on the PCMA mixed signal to be processed, and a preferred way is described as an example below.
In a possible implementation manner, performing frequency offset estimation on the PCMA mixed signal to be processed to obtain the frequency offset parameter includes: setting frequency searching times and a searching frequency range, dividing the searching frequency range into a plurality of first sub-intervals, calculating a measurement parameter corresponding to each first sub-interval, and searching a maximum value of the measurement parameter and a frequency corresponding to the maximum value from the measurement parameters of the plurality of first sub-intervals; narrowing the search frequency range to obtain a narrowed search frequency range, determining a new search frequency range according to the frequency and the narrowed search frequency range, and judging whether the current frequency search frequency is less than the frequency search frequency; if the frequency offset parameter is less than the first frequency offset parameter, dividing the new search frequency range into a plurality of second sub-intervals, calculating a metric parameter corresponding to each second sub-interval, searching a maximum value of the metric parameter and a frequency corresponding to the maximum value from the metric parameters of the plurality of second sub-intervals until the current frequency search frequency is not less than the frequency search frequency, and taking the maximum value of the metric parameter searched for the last time and the frequency corresponding to the maximum value as the frequency offset parameter.
To facilitate an understanding of the above-described frequency offset estimation process, a brief description of the frequency offset estimation process is provided below. Specifically, the frequency offset estimation steps are as follows:
step 11, setting frequency searching times q and a frequency searching interval S, wherein q is a positive integer not less than 1; s has a value range of [ f l ，f r ]。
Step 12, uniformly dividing the frequency search interval S into M sub-intervals, wherein M is a positive integer not less than 1; denote the ith sub-interval as S i The frequency range of the ith sub-interval is
The central frequency point of the ith subinterval is marked as f (i) (ii) a Calculating R (f) corresponding to each subinterval according to the central frequency point of each subinterval (i) ) Value and take it as a subinterval S i A metric parameter of the correlation value.
Step 13, from R (f) for each subinterval (i) ) Finding the maximum value R max And R max And the corresponding frequency point is marked as f'.
Step 14, reducing the size of the interval S to 1/M to obtain a new search frequency interval S ', wherein the value range of S' is [ f l ′，f r ′]，
Step 15, judging whether the frequency searching times is less than q; if the value is less than the preset value, jumping to the step 12; otherwise, the process is ended, and the last determined R is max And f' is output as the final search result.
For the convenience of understanding the following pairs of R (f) (i) ) The calculation process is briefly described.
Assuming that the time delay estimation of the interference signal is finished for the PCMA mixed signal to be processed, the time delay estimation value is
And reconstructing the interference signal according to the local sequence locally transmitted by the master station. Specifically, the expression of the interference signal is as follows:
further, the time delay calibration is carried out on the mixed signal according to the time delay estimation value, and the following auxiliary signals are constructed:
according to the above-mentioned y k The expression can be found in k Expression:
further, z is expressed by the following formula k And s 2,k Is a conjugate function of
The calculation results in (2):
in the equation (5), the term 1 on the right side of the equation is ignored due to the fact that two paths of transmitted symbols are independent in statistics and have frequency offset, and the correlation is weak; the information sequences of the interference signal and the reconstructed signal in item 2 are retained because of the strong correlation. Let K denote the correlation symbol length, the correlation sampling point length N ═ LK, K ≦ 0 ≦ N-1, and we can obtain:
further, it is possible to obtain:
obviously, when f ═ f 2 When the value is larger than the predetermined value, the maximum value is expressed by the formula (7). Therefore, the frequency offset estimation result of the interference signal, i.e. the frequency offset estimation result of the interference signal, can be obtained by searching the peak position of equation (7)
Wherein the content of the first and second substances,
representing the frequency offset parameter.
Two, phase estimation
Specifically, there are various ways to obtain the phase parameter by performing phase estimation on the PCMA hybrid signal to be processed, and a preferred way is described as an example below.
In one possible implementation manner, performing phase estimation on the PCMA mixed signal to be processed to obtain the phase parameter includes: performing frequency deviation removal processing on the PCMA mixed signal to be processed according to the frequency deviation parameters to obtain the PCMA mixed signal subjected to frequency deviation removal; performing a fourth power operation on the PCMA mixed signal subjected to frequency offset removal according to a preset operation method, and performing simplification processing on an operation result to obtain a simplified operation result; and calculating the phase value of the interference signal according to the simplified operation result.
To facilitate understanding of the phase estimation process, the following description briefly describes the phase estimation process. Specifically, the phase estimation steps are as follows:
and step 21, performing frequency offset removal processing on the PCMA mixed signal to be processed according to the frequency offset parameter to obtain the PCMA mixed signal after frequency offset removal. Specifically, the PCMA mixed signal after frequency offset removal is as follows:
wherein, Δ f 2 ＝f 2 -f；Δf 1 ＝f 1 -f。
And step 22, performing a fourth power operation on the PCMA mixed signal subjected to frequency offset removal in the formula (8), and performing simplification processing on the cloud cut result to obtain a simplified operation result. Specifically, the simplified operation result is as follows:
Wherein E { (z' k ) 4 The simplified operation result is represented;
a fourth power mean representing a local sequence;
and step 23, performing phase estimation on the interference signal according to the simplified operation result to obtain a phase parameter. Specifically, the phase parameter is obtained by performing phase estimation on the interference signal according to the following formula:
wherein the content of the first and second substances,
representing a phase parameter; arg (a) represents the phase of complex number with the range of [ -pi, pi [ -pi [ ], pi ]]。
Amplitude estimation
Specifically, there are various ways to obtain the amplitude parameter by performing amplitude estimation on the PCMA hybrid signal to be processed, and a preferred way is described as an example below.
In one possible implementation manner, performing amplitude estimation on the PCMA hybrid signal to be processed to obtain the amplitude parameter includes: determining the mean value of the simplified operation result and the fourth power mean value of a preset local sequence; and calculating the amplitude value of the interference signal according to the mean value of the simplified operation result and the fourth power mean value of the preset local sequence.
To facilitate understanding of the above-described amplitude estimation process, a brief description of the process of amplitude estimation is provided below. Specifically, the steps of amplitude estimation are as follows:
And (3) completing mixed signal frequency deviation removal to obtain:
after removing frequency deviation of the mixed signal, performing fourth power operation and simplifying the calculation result to obtain
Step 31, the simplified operation result is obtained
Two-side modulus obtaining of simplified operation result mean value
Let the fourth power mean of the local sequence
Is a constant G.
Step 32, calculating the mean value of the result according to the simplified operation
And calculating the amplitude value of the interference signal by using the constant G. Specifically, the amplitude value of the interference signal is calculated by the following formula:
wherein the content of the first and second substances,
representing the amplitude value of the interference signal.
Step 302, performing digital signal processing on the PCMA mixed signal to be processed to obtain information bit data and check bit data.
In the solution provided in the embodiment of the present application, there are various ways of obtaining information bit data and check bit data by performing digital signal processing on the PCMA mixed signal to be processed, and a preferred way is described as an example below.
In a possible implementation manner, performing digital signal processing on the PCMA mixed signal to be processed to obtain information bit data and check bit data includes: carrying out down-conversion processing on the PCMA mixed signal to be processed to obtain a zero intermediate frequency signal, and carrying out rate conversion processing on the zero intermediate frequency signal to obtain a low-rate PCMA mixed signal; filtering the low-rate PCMA mixed signal to obtain a filtered signal, and converting the filtered signal into a digital baseband signal; and decoding the digital baseband signal to obtain the information bit data and the check bit data.
Specifically, a received PCMA mixed signal sent by a transmitter is down-converted to a zero intermediate frequency signal, then a Low-pass filter tap coefficient is generated through matlab, and a FIR of Xilinx is called to perform sampling rate conversion to obtain a Low-rate PCMA mixed signal, then the Low-rate PCMA mixed signal is filtered to obtain a filtered signal, the filtered signal is converted into a digital baseband signal, and then the digital baseband signal is subjected to Low Density Parity Check (LDPC) decoding to obtain information bit data and Check bit data.
Step 303, reconstructing according to the channel parameter, the information bit data, and the check bit data to generate the interference signal, and subtracting the to-be-processed PCMA mixed signal from the interference signal to obtain the useful signal.
In a possible implementation manner, reconstructing according to the channel parameter, the information bit data, and the check bit data to generate the interference signal includes: generating an interference sequence according to the information bit data and the check bit data; and demodulating the interference sequence to obtain a demodulated interference sequence, and adjusting frequency offset, phase and amplitude of the demodulated interference sequence according to the channel parameters to obtain the interference signal.
In the scheme provided by the embodiment of the application, the signal bit data and the check bit data obtained by decoding are directly utilized to reconstruct the interference sequence in the interference signal reconstruction process, so that encoding is not required in the interference sequence generation process, the difficulty of interference signal reconstruction is reduced, and the interference signal in the PCMA mixed signal is easier to eliminate.
Specifically, an interference sequence is generated according to the information bit data and the check bit data obtained by decoding, then the interference sequence is encoded and modulated, and the frequency offset, the phase and the amplitude of the interference sequence are adjusted and reconstructed according to the estimated channel parameters to generate an interference signal. And subtracting the interference signal from the PCMA mixed signal to be processed to obtain the useful signal.
In the scheme provided by the embodiment of the application, parameter estimation is performed on a to-be-processed PCMA mixed signal to obtain a channel parameter, digital signal processing is performed on the to-be-processed PCMA mixed signal to obtain information bit data and check bit data, the interference signal is generated by reconstructing according to the channel parameter, the information bit data and the check bit data, and the to-be-processed PCMA mixed signal and the interference signal are subtracted to obtain the useful signal. Therefore, in the scheme provided by the embodiment of the application, the interference signal is obtained by reconstructing the information bit data and the check bit data obtained by decoding the PCMA mixed signal and the channel parameter estimated by the PCMA mixed signal, so that the interference signal is closer to the actual interference signal in the PCMA mixed signal, and the effect of eliminating the interference signal in the PCMA mixed signal is further improved.
Based on the same inventive concept as the method shown in fig. 3, the embodiment of the present application provides an apparatus for processing an asymmetric PCMA mixed signal, referring to fig. 4, the apparatus including:
a parameter estimation unit 401, configured to perform parameter estimation on a to-be-processed PCMA mixed signal to obtain a channel parameter, where the to-be-processed PCMA mixed signal includes a useful signal and an interference signal, and the channel parameter includes a frequency offset parameter, a phase parameter, and an amplitude parameter of the interference signal;
a digital signal processing unit 402, configured to perform digital signal processing on the PCMA mixed signal to be processed to obtain information bit data and check bit data;
a reconstructing unit 403, configured to reconstruct according to the channel parameter, the information bit data, and the check bit data to generate the interference signal, and subtract the to-be-processed PCMA mixed signal from the interference signal to obtain the useful signal.
Optionally, the parameter estimation unit 401 is specifically configured to:
performing frequency offset estimation on the PCMA mixed signal to be processed to obtain the frequency offset parameter;
performing phase estimation on the PCMA mixed signal to be processed to obtain the phase parameter;
And carrying out amplitude estimation on the PCMA mixed signal to be processed to obtain the amplitude parameter.
Optionally, the parameter estimation unit 401 is specifically configured to:
setting frequency searching times and a searching frequency range, dividing the searching frequency range into a plurality of first sub-intervals, calculating a measurement parameter corresponding to each first sub-interval, and searching a maximum value of the measurement parameter and a frequency corresponding to the maximum value from the measurement parameters of the plurality of first sub-intervals;
narrowing the search frequency range to obtain a narrowed search frequency range, determining a new search frequency range according to the frequency and the narrowed search frequency range, and judging whether the current frequency search frequency is less than the frequency search frequency;
if the frequency offset parameter is less than the first frequency offset parameter, dividing the new search frequency range into a plurality of second sub-intervals, calculating a metric parameter corresponding to each second sub-interval, searching a maximum value of the metric parameter and a frequency corresponding to the maximum value from the metric parameters of the plurality of second sub-intervals until the current frequency search frequency is not less than the frequency search frequency, and taking the maximum value of the metric parameter searched for the last time and the frequency corresponding to the maximum value as the frequency offset parameter.
Optionally, the parameter estimation unit 401 is specifically configured to:
performing frequency deviation removal processing on the PCMA mixed signal to be processed according to the frequency deviation parameters to obtain the PCMA mixed signal subjected to frequency deviation removal;
performing a quadratic operation on the PCMA mixed signal subjected to frequency offset removal according to a preset operation method, and simplifying an operation result to obtain a simplified operation result;
and calculating the phase value of the interference signal according to the simplified operation result.
Optionally, the parameter estimation unit 401 is specifically configured to:
determining the mean value of the simplified operation result and the fourth power mean value of a preset local sequence;
and calculating the amplitude value of the interference signal according to the mean value of the simplified operation result and the fourth power mean value of the preset local sequence.
Optionally, the digital signal processing unit 402 is specifically configured to:
carrying out down-conversion processing on the PCMA mixed signal to be processed to obtain a zero intermediate frequency signal, and carrying out rate conversion processing on the zero intermediate frequency signal to obtain a low-rate PCMA mixed signal;
filtering the low-rate PCMA mixed signal to obtain a filtered signal, and converting the filtered signal into a digital baseband signal;
And decoding the digital baseband signal to obtain the information bit data and the check bit data.
Optionally, the reconstructing unit 403 is specifically configured to:
generating an interference sequence according to the information bit data and the check bit data;
and demodulating the interference sequence to obtain a demodulated interference sequence, and adjusting frequency offset, phase and amplitude of the demodulated interference sequence according to the channel parameters to obtain the interference signal.
Referring to fig. 5, the present application provides a computer device comprising:
a memory 501 for storing instructions for execution by at least one processor;
a processor 502 for executing instructions stored in memory to perform the method described in fig. 3.
A computer-readable storage medium having stored thereon computer instructions which, when executed on a computer, cause the computer to perform the method of fig. 3.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.
Claims (4)
1. A method for processing an asymmetric PCMA hybrid signal, comprising:
performing parameter estimation on a to-be-processed PCMA mixed signal to obtain a channel parameter, wherein the to-be-processed PCMA mixed signal comprises a useful signal and an interference signal, and the channel parameter comprises a frequency offset parameter, a phase parameter and an amplitude parameter of the interference signal;
carrying out digital signal processing on the PCMA mixed signal to be processed to obtain information bit data and check bit data;
Reconstructing according to the channel parameter, the information bit data and the check bit data to generate the interference signal, and subtracting the to-be-processed PCMA mixed signal from the interference signal to obtain the useful signal;
the method for obtaining the channel parameters by performing parameter estimation on the PCMA mixed signal to be processed comprises the following steps:
carrying out frequency offset estimation on the PCMA mixed signal to be processed to obtain the frequency offset parameter;
performing phase estimation on the PCMA mixed signal to be processed to obtain the phase parameter;
carrying out amplitude estimation on the PCMA mixed signal to be processed to obtain the amplitude parameter;
performing frequency offset estimation on the to-be-processed PCMA mixed signal to obtain the frequency offset parameter, including:
setting frequency searching times and a searching frequency range, dividing the searching frequency range into a plurality of first sub-intervals, calculating a measurement parameter corresponding to each first sub-interval, and searching out the maximum value of the measurement parameter and the frequency corresponding to the maximum value from the measurement parameters of the plurality of first sub-intervals;
narrowing the search frequency range to obtain a narrowed search frequency range, determining a new search frequency range according to the frequency and the narrowed search frequency range, and judging whether the current frequency search frequency is less than the frequency search frequency;
If the frequency offset parameter is less than the first frequency offset parameter, dividing the new search frequency range into a plurality of second sub-intervals, calculating a measurement parameter corresponding to each second sub-interval, searching a maximum value of the measurement parameter and a frequency corresponding to the maximum value from the measurement parameters of the plurality of second sub-intervals until the current frequency search frequency is not less than the frequency search frequency, and taking the maximum value of the measurement parameter searched for the last time and the frequency corresponding to the maximum value as the frequency offset parameter;
performing phase estimation on the PCMA mixed signal to be processed to obtain the phase parameter, including:
carrying out frequency deviation removal processing on the PCMA mixed signal to be processed according to the frequency deviation parameters to obtain the PCMA mixed signal subjected to frequency deviation removal;
performing a quadratic operation on the PCMA mixed signal subjected to frequency offset removal according to a preset operation method, and simplifying an operation result to obtain a simplified operation result;
calculating a phase value of the interference signal according to the simplified operation result;
performing amplitude estimation on the to-be-processed PCMA mixed signal to obtain the amplitude parameter, including:
determining the mean value of the simplified operation result and the fourth power mean value of a preset local sequence;
Calculating the amplitude value of the interference signal according to the mean value of the simplified operation result and the fourth power mean value of the preset local sequence;
performing digital signal processing on the PCMA mixed signal to be processed to obtain information bit data and check bit data, including:
carrying out down-conversion processing on the PCMA mixed signal to be processed to obtain a zero intermediate frequency signal, and carrying out rate conversion processing on the zero intermediate frequency signal to obtain a low-rate PCMA mixed signal;
filtering the low-rate PCMA mixed signal to obtain a filtered signal, and converting the filtered signal into a digital baseband signal;
decoding the digital baseband signal to obtain the information bit data and the check bit data;
reconstructing according to the channel parameter, the information bit data and the check bit data to generate the interference signal, including:
generating an interference sequence according to the information bit data and the check bit data;
and demodulating the interference sequence to obtain a demodulated interference sequence, and adjusting frequency offset, phase and amplitude of the demodulated interference sequence according to the channel parameters to obtain the interference signal.
2. An apparatus for processing an asymmetric PCMA hybrid signal, comprising:
the device comprises a parameter estimation unit, a channel estimation unit and a processing unit, wherein the parameter estimation unit is used for performing parameter estimation on a to-be-processed PCMA mixed signal to obtain a channel parameter, the to-be-processed PCMA mixed signal comprises a useful signal and an interference signal, and the channel parameter comprises a frequency offset parameter, a phase parameter and an amplitude parameter of the interference signal;
the digital signal processing unit is used for carrying out digital signal processing on the PCMA mixed signal to be processed to obtain information bit data and check bit data;
and the reconstruction unit is used for reconstructing according to the channel parameters, the information bit data and the check bit data to generate the interference signal, and subtracting the interference signal from the PCMA mixed signal to be processed to obtain the useful signal.
3. The apparatus of claim 2, wherein the parameter estimation unit is specifically configured to:
performing frequency offset estimation on the PCMA mixed signal to be processed to obtain the frequency offset parameter;
performing phase estimation on the PCMA mixed signal to be processed to obtain the phase parameter;
and carrying out amplitude estimation on the PCMA mixed signal to be processed to obtain the amplitude parameter.
4. The apparatus according to claim 3, wherein the reconstruction unit is specifically configured to:
generating an interference sequence according to the information bit data and the check bit data;
and demodulating the interference sequence to obtain a demodulated interference sequence, and adjusting frequency offset, phase and amplitude of the demodulated interference sequence according to the channel parameters to obtain the interference signal.
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