CN114928374B - Multi-access interference resistant demodulation method, device, electronic equipment and storage medium - Google Patents
Multi-access interference resistant demodulation method, device, electronic equipment and storage medium Download PDFInfo
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- H04B1/69—Spread spectrum techniques
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Abstract
The embodiment of the application discloses an anti-multiple access interference demodulation method, an anti-multiple access interference demodulation device, electronic equipment and a storage medium. Determining a spread spectrum signal corresponding to a signal to be processed; determining signal correlation degree between spread spectrum signals and preset pseudo code signals corresponding to different addresses; selecting a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation degree; and according to the consistency of the standard pseudo code signals of the target baseband signals in the target pseudo code signals and the spread spectrum signals, controlling the spread spectrum signals to be demodulated to obtain the target baseband signals. The embodiment of the application improves the demodulation precision of the anti-multiple access interference.
Description
Technical Field
Embodiments of the present application relate to signal processing technologies, and in particular, to a method, an apparatus, an electronic device, and a storage medium for demodulating multiple access interference.
Background
The uplink signal system of the European loop system is code division multiple access (Code Division Multiple Access, CDMA), signals are modulated through different pseudo codes, spread spectrum communication is realized, and a receiver demodulates the spread spectrum signals through corresponding pseudo codes.
Multiple access interference exists in spread spectrum communication because multiple spread spectrum signals modulated by pseudo codes are transmitted in the same channel, and demodulation accuracy is low when the interference signal is strong.
Disclosure of Invention
The application provides an anti-multiple access interference demodulation method, an anti-multiple access interference demodulation device, electronic equipment and a storage medium, so as to improve the accuracy of the anti-multiple access interference demodulation.
In a first aspect, an embodiment of the present application provides an anti-multiple access interference demodulation method, where the anti-multiple access interference demodulation method includes:
determining a spread spectrum signal corresponding to a signal to be processed;
determining signal correlation degree between spread spectrum signals and preset pseudo code signals corresponding to different addresses;
selecting a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation degree;
and according to the consistency of the standard pseudo code signals of the target baseband signals in the target pseudo code signals and the spread spectrum signals, controlling the spread spectrum signals to be demodulated to obtain the target baseband signals.
In a second aspect, embodiments of the present application further provide an anti-multiple access interference demodulation apparatus, where the anti-multiple access interference demodulation apparatus includes:
the spread spectrum signal determining module is used for determining a spread spectrum signal corresponding to the signal to be processed;
the signal correlation determining module is used for determining the signal correlation between the spread spectrum signal and preset pseudo code signals corresponding to different addresses;
The target pseudo code signal selecting module is used for selecting a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation degree;
the target baseband signal acquisition module is used for controlling the spread spectrum signal to be demodulated according to the consistency of the standard pseudo code signal of the target baseband signal in the target pseudo code signal and the spread spectrum signal, so as to obtain the target baseband signal.
In a third aspect, embodiments of the present application further provide an electronic device, including:
one or more processors;
a storage means for storing one or more programs;
the one or more programs, when executed by the one or more processors, cause the one or more processors to implement any of the multiple access interference rejection demodulation methods as provided by embodiments of the present application.
In a fourth aspect, embodiments of the present application also provide a storage medium comprising computer-executable instructions, which when executed by a computer processor, are configured to perform any one of the multiple access interference resistant demodulation methods as provided by embodiments of the present application.
According to the method, the spread spectrum signal corresponding to the signal to be processed is determined, so that the spread spectrum signal needing pseudo code synchronization is obtained; the signal correlation degree between the spread spectrum signal and the preset pseudo code signals corresponding to different addresses is determined, so that the signal correlation degree of the spread spectrum signal and the different phases of the different preset pseudo code signals can be obtained, the target pseudo code signal can be determined, and the signal correlation degree can be used as the basis of pseudo code signal phase synchronization; selecting a target pseudo code signal from preset pseudo code signals according to the signal correlation degree; based on the consistency of the target pseudo code signal and the standard pseudo code signal of the target baseband signal in the spread spectrum signal, whether multiple access interference exists can be judged, and the spread spectrum signal is controlled to be demodulated to obtain the target baseband signal. Therefore, through the technical scheme of the application, the problem of multiple access interference in spread spectrum communication is solved, and when an interference signal is strong, the effect of the demodulation precision of the multiple access interference resistance is improved.
Drawings
Fig. 1 is a flowchart of a method for demodulating multiple access interference in accordance with a first embodiment of the present application;
fig. 2 is a flowchart of an anti-multiple access interference demodulation method in a second embodiment of the present application;
fig. 3 is a flowchart of an anti-multiple access interference demodulation method in a third embodiment of the present application;
fig. 4 is a flowchart of an anti-multiple access interference demodulation method in a fourth embodiment of the present application;
fig. 5 is a schematic structural diagram of an anti-multiple access interference demodulation device in a fifth embodiment of the present application;
fig. 6 is a schematic structural diagram of an electronic device in a sixth embodiment of the present application.
Detailed Description
In order to make the present application solution better understood by those skilled in the art, the following description will be made in detail and with reference to the accompanying drawings in the embodiments of the present application, it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, shall fall within the scope of the present application.
It should be noted that the terms "first" and "second" and the like in the description and claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that embodiments of the present application described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Example 1
Fig. 1 is a flowchart of an anti-multiple access interference demodulation method according to an embodiment of the present application, where the method may be performed by an anti-multiple access interference demodulation device, and the device may be implemented by software and/or hardware.
Referring to the multiple access interference resistant demodulation method shown in fig. 1, the method specifically includes the following steps:
s110, determining a spread spectrum signal corresponding to the signal to be processed.
The signal to be processed is a signal which can be processed by the anti-multiple access interference demodulation system. In a communication system, a demodulation system of a signal receiving party needs to demodulate a received signal to obtain a baseband signal, and the demodulation system demodulates a signal which can be processed in a certain range, for example, a signal with signal energy in a certain range, or a signal with signal bandwidth in a certain range, etc.
For example, when the signal receiver receives a signal, it needs to determine whether the signal is a signal within the processing range of the demodulation system; if yes, the received signal is used as a signal to be processed. The signal receiving party performs digital sampling on the received signal after receiving the signal, converts the analog signal into a digital signal, calculates the energy of the digital signal, and detects whether the energy of the digital signal is within the energy range preset by the demodulation system; if yes, the digital signal is used as a signal to be processed; otherwise, the digital signal is discarded.
The spread spectrum signal is a signal after the signal to be processed is processed by carrier synchronization, namely, the signal after the carrier is removed.
Carrier synchronization may be achieved by square transform, square loops, costas (Costas) loops, and the like, to obtain spread spectrum signals, for example. For example, the signal to be processed passes through a Costas loop to realize carrier synchronization, specifically, the output frequency of the numerical control oscillator is adjusted to adjust the phase error in real time, so that the signal to be processed can reach a locking state in an infinitely small way, and carrier synchronization is realized.
S120, determining the signal correlation degree between the spread spectrum signal and the preset pseudo code signals corresponding to different addresses.
The preset pseudo code signals are a group of pseudo code signals stored in a despreading system and are used for demodulating spread spectrum signals corresponding to different pseudo code signals. The number of bits of the preset pseudo code signals is the same, and all the preset pseudo code signals are mutually orthogonal.
The signal correlation degree is a result of performing correlation integration on the two signals and is used for determining a target pseudo code signal from preset pseudo code signals. Different addresses of the same pseudo code signal correspond to different phases of the pseudo code signal, and the preset pseudo code signals with different phases can be obtained by adjusting the addresses of the preset pseudo code signals.
When the preset pseudo code signals include N pseudo code signals, and each pseudo code signal is N bits, calculating correlation integration of the N pseudo codes and the spread spectrum signals under N addresses to obtain signal correlation between the spread spectrum signals and the pseudo code signals under N addresses corresponding to the N preset pseudo code signals, and obtaining n×n signal correlation.
S130, selecting a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation degree.
The target pseudo code signal may be a pseudo code signal determined according to the signal correlation degree, and a pseudo code signal most correlated with the spread spectrum signal may be understood as a pseudo code signal after phase synchronization. According to the signal correlation degree between the spread spectrum signal and the preset pseudo code signals corresponding to different addresses, a target pseudo code signal can be selected from at least one preset pseudo code signal.
In an alternative embodiment, selecting the target pseudo code signal from the at least one preset pseudo code signal according to the signal correlation degree includes: and taking the preset pseudo code signal with the highest signal correlation degree as a target pseudo code signal.
The closer the phase of the pseudo code signal is to the corresponding pseudo code signal in the spread spectrum signal, the higher the correlation degree between the pseudo code signal and the spread spectrum signal is, and the highest correlation degree is when the phase is synchronous. The correlation is also related to the baseband signal power in the spread spectrum signal, the greater the baseband signal power, the greater the correlation. The larger the signal correlation is, the closer the phase of the preset pseudo code signal corresponding to the signal correlation is to the phase of the pseudo code signal in the spread spectrum signal, and the larger the power of the modulated baseband signal in the spread spectrum signal corresponding to the preset pseudo code signal is. Therefore, the preset pseudo code signal with the highest signal correlation degree is used as the target pseudo code signal, the pseudo code synchronization effect can be realized, and the modulated baseband signal with the largest power in the spread spectrum signal can be obtained at the same time, so that the despreading of the modulated baseband signal with the largest power in the spread spectrum signal can be realized.
And S140, controlling the spread spectrum signal to be demodulated according to the consistency of the standard pseudo code signal of the target baseband signal in the target pseudo code signal and the spread spectrum signal, so as to obtain the target baseband signal.
The standard pseudo code signal is a pseudo code in the spread spectrum signal for modulating the target baseband signal. The target baseband signal is a target signal which needs to be obtained by the demodulation system through modulation. In the cdma communication method, a transmitting signal side transmits an identifier of a pseudo code signal modulating a target baseband signal to a signal receiving side, so that the receiving side demodulates a spread spectrum signal according to the corresponding pseudo code signal to obtain the target baseband signal.
The consistency may be understood as a result of determining whether the pseudo code identifier corresponding to the target pseudo code signal is the same as the pseudo code identifier corresponding to the standard pseudo code signal. For example, the pseudo-code identification may include at least one of a number, letter, character, or the like.
Specifically, if the target pseudo code signal is the same as the pseudo code identifier corresponding to the standard pseudo code signal, the standard pseudo code signal of the target baseband signal in the target pseudo code signal and the spread spectrum signal is consistent; if the target pseudo code signal is different from the pseudo code identification corresponding to the standard pseudo code signal, the standard pseudo code signals of the target baseband signal in the target pseudo code signal and the spread spectrum signal are inconsistent.
An interference signal may be present in the spread spectrum signal, which is a baseband signal modulated by other pseudo code signals than the standard pseudo code signal in the demodulation system. If the target pseudo code signal is consistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, the power of the target baseband signal in the demodulation system is considered to be larger than the power of the interference signal; if the target pseudo code signal is inconsistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, the power of the target baseband signal in the demodulation system is considered to be smaller than the power of the interference signal.
When the target pseudo code signal is inconsistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, the spread spectrum signal can be despread by the target pseudo code signal to obtain a despread interference signal, the interference signal in the spread spectrum signal can be removed, and then the spread spectrum signal after the despread interference signal is removed is used as the spread spectrum signal in S120 to continue to sequentially execute the rest steps until the target pseudo code signal is consistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, and the spread spectrum signal is despread at the moment to obtain the target baseband signal.
When the target baseband signal power is equal to the interference signal power, the consistency of the standard pseudo code signals of the target baseband signal in the target pseudo code signal and the spread spectrum signal obtained through demodulation may be consistent or inconsistent, and the probability of each signal is 50%, but the spread spectrum signal can still be demodulated according to consistency control, so that the target baseband signal is obtained, and the demodulation result is not affected.
According to the technical scheme, a spread spectrum signal which needs to be subjected to pseudo code synchronization is obtained by determining a spread spectrum signal corresponding to a signal to be processed; the signal correlation degree between the spread spectrum signal and the preset pseudo code signals corresponding to different addresses is determined, so that the signal correlation degree of the spread spectrum signal and the different phases of the different preset pseudo code signals can be obtained, the target pseudo code signal can be determined, and the signal correlation degree can be used as the basis of pseudo code signal phase synchronization; selecting a target pseudo code signal from preset pseudo code signals according to the signal correlation degree; based on the consistency of the target pseudo code signal and the standard pseudo code signal of the target baseband signal in the spread spectrum signal, whether multiple access interference exists can be judged, and the spread spectrum signal is controlled to be demodulated to obtain the target baseband signal. Therefore, through the technical scheme of the application, the problem of multiple access interference in spread spectrum communication is solved, and when an interference signal is strong, the effect of the demodulation precision of the multiple access interference resistance is improved.
Example two
Fig. 2 is a flowchart of a flow chart method of a multiple access interference resistant demodulation method according to a second embodiment of the present application, and the technical solution of the present embodiment is further refined on the basis of the technical solution.
Further, the method comprises the steps of demodulating the spread spectrum signal according to the consistency of the target pseudo code signal and the standard pseudo code signal of the target baseband signal in the spread spectrum signal to obtain the target baseband signal, and refining the target baseband signal as follows: if the target pseudo code signal is inconsistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, despreading the spread spectrum signal according to the target pseudo code signal to obtain a despread interference signal; and determining a target baseband signal according to the spread spectrum signal and the despread interference signal so as to realize a target baseband signal determining mechanism when the despread interference signal exists.
Referring to fig. 2, a method for demodulating multiple access interference includes:
s210, determining a spread spectrum signal corresponding to the signal to be processed.
S220, determining the signal correlation degree between the spread spectrum signal and the preset pseudo code signals corresponding to different addresses.
S230, selecting a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation degree.
S240, if the target pseudo code signal is inconsistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, the spread spectrum signal is despread according to the target pseudo code signal, and a despread interference signal is obtained.
The despread interference signal is a baseband signal modulated by other pseudo code signals except the standard pseudo code signal in the spread spectrum signal.
Specifically, the target pseudo code signal is a synchronous pseudo code signal of a pseudo code signal corresponding to a despreading interference signal in the spread spectrum signal, and symbol judgment is performed on a correlation value obtained by multiplying and accumulating every N numerical values of the spread spectrum signal and the target pseudo code signal, so as to obtain the despreading interference signal. If the target pseudo code signal is inconsistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, the power of the despread interference signal is larger than the power of the target baseband signal, if the spread spectrum signal is despread directly by the standard pseudo code signal, the obtained target baseband signal has a noise signal obtained by multiplying the spread spectrum interference signal corresponding to the despread signal and the standard pseudo code signal, and the noise signal has larger power, serious interference can be generated on the target baseband signal, the accuracy of the target baseband signal is seriously affected, and the accuracy of the target baseband signal obtained by despreading is greatly reduced. Therefore, when the target pseudo code signal is inconsistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, the despread interference signal is required to be obtained by despreading, so that the despread interference signal is removed later, and the anti-interference performance of demodulation is improved.
S250, determining a target baseband signal according to the spread spectrum signal and the despread interference signal.
After the despread interference signal is obtained, multiplying the despread interference signal with the target pseudo code signal to obtain a spread spectrum interference signal, subtracting the spread spectrum interference signal from the spread spectrum signal, updating the spread spectrum signal, and removing the corresponding signal of the despread interference signal in the spread spectrum signal. And (3) continuing to sequentially execute the step (S220) and the following steps on the updated spread spectrum signal until the target pseudo code signal is consistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, and despreading to obtain the target baseband signal.
In an alternative embodiment, determining the target baseband signal from the spread spectrum signal and the despread interference signal includes: obtaining an original interference signal according to the product of the despread interference signal and the target pseudo code signal; updating the spread spectrum signal according to the spread spectrum signal and the original interference signal; and determining a target baseband signal according to the updated spread spectrum signal.
And taking the pseudo code signal corresponding to the despreading interference signal as a target pseudo code signal, multiplying the despreading interference signal by the target pseudo code signal to obtain an original interference signal, namely a signal corresponding to the despreading interference signal in the spread spectrum signal. The original interference signal can be subtracted from the spread spectrum signal, the spread spectrum signal is updated, and the original interference signal in the spread spectrum signal is removed. And calculating the signal correlation degree between the updated spread spectrum signal and the preset pseudo code signals corresponding to different addresses. And selecting a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation degree, and despreading to obtain a target baseband signal when the target pseudo code signal is consistent with a standard pseudo code signal of a target baseband signal in the spread spectrum signal.
The original interference signal is obtained according to the product of the despreading interference signal and the target pseudo code signal, and the signal corresponding to the despreading interference signal in the spread spectrum signal can be determined so as to remove the original interference signal in the spread spectrum signal and update the spread spectrum signal. And according to the consistency of the standard pseudo code signals corresponding to the target pseudo code signals and the target baseband signals, controlling the demodulation of the updated spread spectrum signals to obtain the target baseband signals. And the original interference signals in the spread spectrum signals are removed, the spread spectrum signals are updated, and the accuracy of the target baseband signals obtained later is improved.
In an alternative embodiment, determining the target baseband signal from the updated spread spectrum signal includes: returning to execute signal correlation degree determining operation according to the updated spread spectrum signal until the target pseudo code signal is the same as the standard pseudo code signal; taking a spread spectrum signal when the target pseudo code signal is the same as the standard pseudo code signal as a target spread spectrum signal; and despreading the target spread spectrum signal according to the target pseudo code signal to obtain a target baseband signal.
And the signal correlation degree determining operation is to determine the signal correlation degree between the updated spread spectrum signal and the preset pseudo code signals corresponding to different addresses. And selecting a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation degree until the target pseudo code signal is identical to the standard pseudo code signal. And taking the spread spectrum signal when the target pseudo code signal is the same as the standard pseudo code signal as a target spread spectrum signal, considering that the power of a target baseband signal in the target spread spectrum signal is the largest at the moment, and despreading the target spread spectrum signal according to the target pseudo code signal to obtain the target baseband signal.
A plurality of de-spread interference signals in the spread spectrum signal can be removed by returning to execute signal correlation degree determining operation according to the updated spread spectrum signal until the target pseudo code signal is the same as the standard pseudo code signal; taking a spread spectrum signal when the target pseudo code signal is the same as the standard pseudo code signal as a target spread spectrum signal; and despreading the target spread spectrum signal according to the target pseudo code signal to obtain a target baseband signal, and improving the accuracy of the target baseband signal obtained by despreading.
According to the scheme of the embodiment, when the target pseudo code signal is inconsistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signals, the spread spectrum signals are despread according to the target pseudo code signals to obtain despread interference signals, signals corresponding to the despread interference signals in the spread spectrum signals can be removed, the target baseband signals are further obtained, and anti-interference performance of the target baseband signals obtained according to the spread spectrum signals is improved.
In an alternative embodiment, according to the consistency of the target pseudo code signal and the standard pseudo code signal of the target baseband signal in the spread spectrum signal, the method for demodulating the spread spectrum signal to obtain the target baseband signal comprises the following steps: and if the target pseudo code signal is consistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, despreading the spread spectrum signal according to the target pseudo code signal to obtain the target baseband signal.
If the target pseudo code signal is consistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, at the moment, the power of the target baseband signal in the despreading system is considered to be larger than the power of other despreading interference signals, and the spread spectrum signal is directly despread through the target pseudo code signal to obtain the target baseband signal. Specifically, the target pseudo code signal is a synchronous pseudo code signal after phase synchronization of the standard pseudo code signal, and symbol judgment is performed on a correlation value obtained by multiplying and accumulating each N numerical values of the spread spectrum signal and the target pseudo code to obtain a target baseband signal.
When the target pseudo code signal is consistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, the target pseudo code signal is the pseudo code signal after the phase synchronization adjustment of the standard pseudo code signal, namely, the target pseudo code signal is the synchronous pseudo code signal of the target baseband signal, the spread spectrum signal is despread according to the target pseudo code signal, the pseudo code synchronization adjustment is not needed, the target baseband signal can be quickly obtained, and the demodulation efficiency is improved.
Example III
Fig. 3 is a flowchart of a flowchart method of an anti-multiple access interference demodulation method provided in a third embodiment of the present application, where the technical solution of the present embodiment is further refined on the basis of the technical solution.
Further, the signal correlation degree between the spread spectrum signal and the preset pseudo code signal corresponding to different addresses is determined by the following steps: "for each preset pseudo code signal, according to the number of bits of the preset pseudo code signal, respectively performing shift processing on the preset pseudo code signal to obtain each reference pseudo code signal of the preset pseudo code signal; determining the correlation degree of each reference pseudo code signal and the spread spectrum signal to obtain a corresponding initial correlation degree; and determining the signal correlation' of the preset pseudo code signal according to the initial correlations of the preset pseudo code signal so as to determine the signal correlation of the preset pseudo code signal.
Referring to fig. 3, a method for demodulating multiple access interference includes:
s310, determining a spread spectrum signal corresponding to the signal to be processed.
S320, for each preset pseudo code signal, respectively performing shift processing on the preset pseudo code signal according to the bit number of the preset pseudo code signal to obtain each reference pseudo code signal of the preset pseudo code signal.
The number of bits of the preset pseudo code signal is the length of the pseudo code signal, and all pseudo code bits contained in the preset pseudo code signal are the same, for example, N bits. The preset pseudo code signal is stored in Rom (a memory in a computer) of the demodulation system, and the corresponding preset pseudo code signal is acquired by reading the address. And respectively carrying out shift processing on the preset pseudo code signals to obtain different phase signals of the preset pseudo code signals, wherein the different phase signals are used for obtaining synchronous pseudo code signals. Each reference pseudo code signal of the preset pseudo code signal, namely each pseudo code signal obtained after the shift of the preset pseudo code signal. The shift processing is to shift the preset pseudo code signal to a fixed direction by one bit to obtain each reference pseudo code signal of the preset pseudo code signal, the shifting times are the same as the bit number of the preset pseudo code signal, the shifting fixed direction can be left or right, the specific limitation is not made, and the consistency is only required.
For example, when the number of bits of the preset pseudo code signal is N, N shift processing is required on the preset pseudo code signal to obtain N reference pseudo code signals of the preset pseudo code signal. By carrying out shift processing on the preset pseudo code signals, each reference pseudo code signal under different phases of the preset pseudo code signals can be obtained, pseudo code synchronization adjustment is not needed in the subsequent despreading process, and despreading efficiency is improved.
S330, determining the correlation degree of each reference pseudo code signal and the spread spectrum signal, and obtaining a corresponding initial correlation degree.
The correlation degree is a numerical result obtained by performing correlation calculation on each reference pseudo-code signal and the spread spectrum signal, namely a result that the spread spectrum signal and each reference pseudo-code signal are multiplied in one pseudo-code period and accumulated. The correlation degree of each reference pseudo code signal and the spread spectrum signal, namely the correlation degree of the spread spectrum signal and the same preset pseudo code signal under different phases. And calculating the correlation degree of each reference pseudo code signal and the spread spectrum signal to obtain the corresponding initial correlation degree of each reference pseudo code signal.
S340, determining the signal correlation degree of the preset pseudo code signal according to the initial correlation degrees of the preset pseudo code signal.
And taking the maximum value in the initial correlation as the signal correlation of the preset pseudo code signal. For the same preset pseudo code signal, when the pseudo code in the spread spectrum signal is synchronous with the phase of the preset pseudo code signal, the correlation value is maximum, so that the maximum value in the correlation degree of each reference pseudo code signal and the spread spectrum signal is used as the signal correlation degree of the preset pseudo code signal.
S350, selecting a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation degree.
S360, according to the consistency of the standard pseudo code signals of the target baseband signals in the target pseudo code signals and the spread spectrum signals, the spread spectrum signals are controlled to be demodulated, and the target baseband signals are obtained.
According to the scheme of the embodiment, the phase adjustment is realized through the shift processing of the preset pseudo code signals, the corresponding initial correlation degree of each reference pseudo code signal is obtained through the correlation value calculation, the signal correlation degree of the preset pseudo code signal is determined through the initial correlation degree, the reference pseudo code signal of each preset pseudo code signal corresponding to the signal correlation degree of the preset pseudo code signal is the preset pseudo code signal after pseudo code synchronization, and the method can be used for despreading spread spectrum signals. The pseudo code synchronization and interference elimination are realized by adopting the sliding correlation method, the pseudo code synchronization by using multiple branches is avoided, the realization is simple, the mathematical calculation rate is high, the despreading interference signal or the target baseband signal can be rapidly obtained, and the demodulation efficiency is improved.
Example IV
Fig. 4 is a flowchart of a flowchart method of an anti-multiple access interference demodulation method according to a fourth embodiment of the present application, where the technical solution of the present embodiment is further refined on the basis of the technical solution described above.
Further, the "determining the spread spectrum signal corresponding to the signal to be processed" is thinned into: carrying out low-pass filtering on the signal to be processed to obtain a low-pass signal; and (3) carrying out downsampling on the low-pass signal according to the cascade filter to obtain a spread spectrum signal so as to improve the acquisition efficiency of the spread spectrum signal.
Referring to fig. 4, a method for demodulating multiple access interference includes:
s410, low-pass filtering is carried out on the signal to be processed, and a low-pass signal is obtained.
The numerically controlled oscillator outputs a single-frequency sinusoidal signal with a frequency fc, which is the carrier frequency, by setting a fixed frequency control word. The signal to be processed is multiplied by a single-frequency sinusoidal signal with the frequency fc, and after passing through a low-pass filter, a high-frequency component is filtered to obtain a low-pass signal. The low-pass signal is a signal obtained by removing the carrier signal from the signal to be processed.
S420, downsampling the low-pass signal according to a cascade filter to obtain a spread spectrum signal, wherein the cascade filter comprises a half-band filter and a comb filter which are sequentially connected.
The signal to be processed is a digital signal, the frequency being Fc, fc being typically an integer multiple of (rd×n), where Rd is the bit rate of the target baseband signal, N is the number of bits of the pseudo-code signal, and the rate of the low-pass signal being Fc. For subsequent despreading, the low-pass signal needs to be downsampled such that the rate of the low-pass signal will be Rd N. The downsampling factor is m=fc/(rd×n). Downsampling is the extraction of the corresponding data from the low-pass signal in steps of interval m as a spread spectrum signal. The down-sampling process can be performed in multiple steps to avoid signal distortion when performing the large-scale decimation filtering. For example, the downsampling process may be performed in two steps, where the half-band filter performs 2 times of decimating filtering on the low-pass signal, and then m/2 times of decimating filtering is performed by the cascaded comb filter, and after twice decimating filtering, the low-pass signal rate is reduced from Fc to Fc/m, that is, the spread-spectrum signal with rate rd×n; alternatively, the downsampling process may be performed in three steps, where the half-band filter performs 2 times of decimating filtering on the low-pass signal, the cascaded half-band filter performs 2 times of decimating filtering on the low-pass signal, and the cascaded comb filter performs m/4 times of decimating filtering, where after three times of decimating filtering, the low-pass signal rate is reduced from Fc to Fc/m, that is, the spread spectrum signal with rate rd×n.
S430, determining the signal correlation degree between the spread spectrum signal and the preset pseudo code signals corresponding to different addresses.
S440, selecting a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation degree.
S450, according to the consistency of the standard pseudo code signals of the target baseband signals in the target pseudo code signals and the spread spectrum signals, the spread spectrum signals are controlled to be demodulated, and the target baseband signals are obtained.
In the prior art, carrier synchronization during demodulation is typically performed by means of a costas loop. The costas loop comprises a multiplier, a numerical control oscillator, a low-pass filter and a loop filter. The signal to be processed is multiplied with the in-phase signal and the quadrature signal generated by the numerical control oscillator and the high-frequency component is filtered by the low-pass filter, the two paths of signals are multiplied to obtain a phase error signal, the phase error signal passes through the loop filter, and only the signal which approximates direct current is allowed to pass through because the cut-off frequency of the loop filter is very low, so that the output signal of the loop filter, namely the frequency control word of the numerical control oscillator, is used for adjusting the phase error in real time by controlling the output frequency of the numerical control oscillator, and the phase error is infinitely small, namely the phase error is locked, and carrier synchronization is realized. The carrier synchronization is carried out through the Kestes loop, so that the problem of loop instability caused by the asymmetry of two branches exists, the loop cannot enter a locking state, and the problem of high requirement on the clock speed is solved.
According to the scheme, the problem of loop instability caused by asymmetry of two branches when a loop is adopted to recover a carrier wave is effectively avoided by adopting a mode of cascading the single-branch digital down-conversion and the multi-stage filter, the part of spread spectrum signals with lower output rate have lower requirements on the subsequent processing clock rate, and meanwhile, the resource occupancy rate is relatively smaller.
Example five
Fig. 5 is a schematic structural diagram of an anti-multiple access interference demodulation device according to a fifth embodiment of the present application, where the embodiment is applicable to a case of demodulating a cdma signal when multiple access interference exists, and the specific structure of the anti-multiple access interference demodulation device is as follows:
a spread spectrum signal determining module 510, configured to determine a spread spectrum signal corresponding to the signal to be processed;
the signal correlation determining module 520 is configured to determine a signal correlation between the spread spectrum signal and a preset pseudo code signal corresponding to a different address;
a target pseudo code signal selecting module 530, configured to select a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation;
the target baseband signal obtaining module 540 is configured to control demodulation of the spread spectrum signal according to consistency of standard pseudo code signals of the target baseband signal in the target pseudo code signal and the spread spectrum signal, so as to obtain the target baseband signal.
According to the technical scheme, a spread spectrum signal which needs to be subjected to pseudo code synchronization is obtained by determining a spread spectrum signal corresponding to a signal to be processed; the signal correlation degree between the spread spectrum signal and the preset pseudo code signals corresponding to different addresses is determined, so that the signal correlation degree of the spread spectrum signal and the different phases of the different preset pseudo code signals can be obtained, the target pseudo code signal can be determined, and the signal correlation degree can be used as the basis of pseudo code signal phase synchronization; selecting a target pseudo code signal from preset pseudo code signals according to the signal correlation degree; based on the consistency of the target pseudo code signal and the standard pseudo code signal of the target baseband signal in the spread spectrum signal, whether multiple access interference exists can be judged, and the spread spectrum signal is controlled to be demodulated to obtain the target baseband signal. Therefore, through the technical scheme of the application, the problem of multiple access interference in spread spectrum communication is solved, and when an interference signal is strong, the effect of the demodulation precision of the multiple access interference resistance is improved.
Optionally, the target baseband signal acquisition module 540 includes:
the despreading interference signal acquisition unit is used for despreading the spread spectrum signal according to the target pseudo code signal if the target pseudo code signal is inconsistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, so as to obtain a despreading interference signal;
And the target baseband signal acquisition unit is used for determining the target baseband signal according to the spread spectrum signal and the despread interference signal.
Optionally, the target baseband signal acquisition unit includes:
the original interference signal acquisition subunit is used for acquiring an original interference signal according to the product of the despread interference signal and the target pseudo code signal;
a spread spectrum signal updating subunit, configured to update a spread spectrum signal according to the spread spectrum signal and an original interference signal;
and the target baseband signal determining subunit is used for determining the target baseband signal according to the updated spread spectrum signal.
Optionally, the target baseband signal determining subunit is specifically configured to: returning to execute signal correlation degree determining operation according to the updated spread spectrum signal until the target pseudo code signal is the same as the standard pseudo code signal; taking a spread spectrum signal when the target pseudo code signal is the same as the standard pseudo code signal as a target spread spectrum signal; and despreading the target spread spectrum signal according to the target pseudo code signal to obtain a target baseband signal.
Optionally, the target baseband signal acquisition module 540 includes:
and the spread spectrum signal despreading unit is used for despreading the spread spectrum signal according to the target pseudo code signal if the target pseudo code signal is consistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, so as to obtain the target baseband signal.
Optionally, the signal correlation determination module 520 includes:
the pseudo code signal shifting unit is used for shifting the preset pseudo code signals according to the digits of the preset pseudo code signals to obtain reference pseudo code signals of the preset pseudo code signals;
the initial correlation acquisition unit is used for determining the correlation between each reference pseudo code signal and the spread spectrum signal to obtain a corresponding initial correlation;
the device comprises a preset pseudo code signal correlation determining unit, a signal correlation determining unit and a signal correlation determining unit, wherein the preset pseudo code signal correlation determining unit is used for determining the signal correlation of the preset pseudo code signal according to each initial correlation of the preset pseudo code signal.
Optionally, the spread spectrum signal determining module 510 includes:
the low-pass signal acquisition unit is used for carrying out low-pass filtering on the signal to be processed to obtain a low-pass signal;
the low-pass signal downsampling unit is used for downsampling the low-pass signal according to the cascade filter to obtain a spread spectrum signal; the cascade filter comprises a half-band filter and a comb filter which are sequentially connected.
The anti-multiple access interference demodulation device provided by the embodiment of the application can execute the anti-multiple access interference demodulation method provided by any embodiment of the application, and has the corresponding functional modules and beneficial effects of the execution method.
Example six
Fig. 6 is a schematic structural diagram of an electronic device according to a sixth embodiment of the present application, as shown in fig. 6, the electronic device includes a processor 610, a memory 620, an input device 630, and an output device 640; the number of processors 610 in the electronic device may be one or more, one processor 610 being taken as an example in fig. 6; the processor 610, memory 620, input device 630, and output device 640 in the electronic device may be connected by a bus or other means, for example in fig. 6.
The memory 620 is a computer readable storage medium, and may be used to store software programs, computer executable programs, and modules, such as program instructions/modules (e.g., the spread spectrum signal determining module 510, the signal correlation determining module 520, the target pseudo code signal selecting module 530, and the target baseband signal obtaining module 540) corresponding to the multiple access interference resisting demodulation method in the embodiment of the present application. The processor 610 executes various functional applications of the electronic device and data processing by running software programs, instructions and modules stored in the memory 620, i.e., implements the above-described anti-multiple access interference demodulation method.
The input device 630 may be used to receive input character information and to generate key signal inputs related to user settings and function control of the electronic device. The output device 640 may include a display device such as a display screen.
Example seven
The seventh embodiment of the present application also provides a storage medium containing computer-executable instructions, which when executed by a computer processor, are configured to perform a multiple access interference rejection demodulation method, the method comprising: determining a spread spectrum signal corresponding to a signal to be processed; determining signal correlation degree between spread spectrum signals and preset pseudo code signals corresponding to different addresses; selecting a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation degree; and according to the consistency of the standard pseudo code signals of the target baseband signals in the target pseudo code signals and the spread spectrum signals, controlling the spread spectrum signals to be demodulated to obtain the target baseband signals.
Of course, the storage medium containing the computer executable instructions provided in the embodiments of the present application is not limited to the method operations described above, and may also perform the related operations in the multiple access interference resistant demodulation method provided in any embodiment of the present application.
From the above description of embodiments, it will be clear to a person skilled in the art that the present application may be implemented by means of software and necessary general purpose hardware, but of course also by means of hardware, but in many cases the former is a preferred embodiment. Based on such understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art in the form of a software product, which may be stored in a computer readable storage medium, such as a floppy disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a FLASH Memory (FLASH), a hard disk, or an optical disk of a computer, etc., including several instructions for causing an electronic device (which may be a personal computer, a server, or a network device, etc.) to perform the method described in the embodiments of the present application.
It should be noted that, in the above-mentioned embodiments of the search apparatus, each unit and module included are only divided according to the functional logic, but not limited to the above-mentioned division, as long as the corresponding functions can be implemented; in addition, the specific names of the functional units are also only for distinguishing from each other, and are not used to limit the protection scope of the present application.
Note that the above is only a preferred embodiment of the present application and the technical principle applied. Those skilled in the art will appreciate that the present application is not limited to the particular embodiments described herein, but is capable of numerous obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the present application. Therefore, while the present application has been described in connection with the above embodiments, the present application is not limited to the above embodiments, but may include many other equivalent embodiments without departing from the spirit of the present application, the scope of which is defined by the scope of the appended claims.
Claims (9)
1. A method of multiple access interference resistant demodulation comprising:
determining a spread spectrum signal corresponding to a signal to be processed;
determining the signal correlation degree between the spread spectrum signal and preset pseudo code signals corresponding to different addresses;
selecting a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation degree;
according to the consistency of the target pseudo code signal and the standard pseudo code signal of the target baseband signal in the spread spectrum signal, the spread spectrum signal is controlled to be demodulated to obtain the target baseband signal, and the method comprises the following steps:
If the target pseudo code signal is consistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, despreading the spread spectrum signal according to the target pseudo code signal to obtain the target baseband signal;
the signal correlation degree is a result of correlation integration of the two signals and is used for determining the target pseudo code signal from the preset pseudo code signal; the consistency is a judging result of whether the pseudo code identifier corresponding to the target pseudo code signal is the same as the pseudo code identifier corresponding to the standard pseudo code signal.
2. The method of claim 1, wherein the controlling the demodulating the spread spectrum signal to obtain the target baseband signal according to the consistency of the target pseudo code signal and the standard pseudo code signal of the target baseband signal in the spread spectrum signal, further comprises:
if the target pseudo code signal is inconsistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, despreading the spread spectrum signal according to the target pseudo code signal to obtain a despread interference signal;
and determining the target baseband signal according to the spread spectrum signal and the despread interference signal.
3. The method of claim 2, wherein said determining said target baseband signal from said spread spectrum signal and said despread interfering signal comprises:
obtaining an original interference signal according to the product of the despread interference signal and the target pseudo code signal;
updating the spread spectrum signal according to the spread spectrum signal and the original interference signal;
and determining the target baseband signal according to the updated spread spectrum signal.
4. The method of claim 3, wherein said determining the target baseband signal from the updated spread spectrum signal comprises:
returning to execute signal correlation degree determining operation according to the updated spread spectrum signal until the target pseudo code signal is the same as the standard pseudo code signal;
taking a spread spectrum signal when the target pseudo code signal is the same as the standard pseudo code signal as a target spread spectrum signal;
and despreading the target spread spectrum signal according to the target pseudo code signal to obtain the target baseband signal.
5. The method according to any one of claims 1-4, wherein determining a signal correlation between the spread spectrum signal and a preset pseudo code signal corresponding to a different address comprises:
For each preset pseudo code signal, respectively carrying out shift processing on the preset pseudo code signal according to the bit number of the preset pseudo code signal to obtain each reference pseudo code signal of the preset pseudo code signal;
determining the correlation degree of each reference pseudo code signal and the spread spectrum signal to obtain a corresponding initial correlation degree;
and determining the signal correlation degree of the preset pseudo code signal according to the initial correlation degree of the preset pseudo code signal.
6. The method according to any one of claims 1-4, wherein determining a spread spectrum signal corresponding to the signal to be processed comprises:
carrying out low-pass filtering on the signal to be processed to obtain a low-pass signal;
downsampling the low-pass signal according to a cascade filter to obtain the spread spectrum signal;
the cascade filter comprises a half-band filter and a comb filter which are sequentially connected.
7. An anti-multiple access interference demodulation apparatus, comprising:
the spread spectrum signal determining module is used for determining a spread spectrum signal corresponding to the signal to be processed;
the signal correlation determining module is used for determining the signal correlation between the spread spectrum signal and preset pseudo code signals corresponding to different addresses;
The target pseudo code signal selecting module is used for selecting a target pseudo code signal from at least one preset pseudo code signal according to the signal correlation degree;
the target baseband signal acquisition module is used for controlling the spread spectrum signal to be demodulated according to the consistency of the target pseudo code signal and the standard pseudo code signal of the target baseband signal in the spread spectrum signal so as to obtain the target baseband signal;
the spread spectrum signal despreading unit is used for despreading the spread spectrum signal according to the target pseudo code signal if the target pseudo code signal is consistent with the standard pseudo code signal of the target baseband signal in the spread spectrum signal, so as to obtain the target baseband signal;
the signal correlation degree is a result of correlation integration of the two signals and is used for determining the target pseudo code signal from the preset pseudo code signal; the consistency is a judging result of whether the pseudo code identifier corresponding to the target pseudo code signal is the same as the pseudo code identifier corresponding to the standard pseudo code signal.
8. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the multiple access interference resistant demodulation method according to any one of claims 1-6 when the program is executed by the processor.
9. A computer readable storage medium having stored thereon a computer program, which when executed by a processor implements a multiple access interference resistant demodulation method according to any one of claims 1-6.
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