CN111212004B - Symbol modulation mode detection method and device in OFDM system - Google Patents
Symbol modulation mode detection method and device in OFDM system Download PDFInfo
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Abstract
The embodiment of the invention provides a method and a device for detecting a symbol modulation mode in an OFDM system, which relate to the technical field of communication, wherein the method comprises the following steps: the method comprises the steps of obtaining signals transmitted within a time period of preset duration from signals transmitted by a channel, using the signals as signals to be detected, carrying out Orthogonal Frequency Division Multiplexing (OFDM) demodulation on the signals to be detected to obtain demodulated signals, calculating the ratio of the amplitude of frequency domain symbols located on adjacent subcarriers in the demodulated signals within each sub-time period aiming at each sub-time period contained in the time period, and detecting the symbol modulation mode of the signals to be detected according to each calculated ratio. By applying the scheme provided by the embodiment of the invention to detect the symbol modulation mode of the signal, the accuracy of the detection result of the symbol modulation mode in the OFDM system can be improved.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a method and an apparatus for detecting a symbol modulation scheme in an OFDM system.
Background
When a signal transmitting end transmits a signal to a signal receiving end, symbol modulation in an OFDM (Orthogonal Frequency Division Multiplexing) system is performed on an original signal, OFDM modulation is performed again, and the modulated signal is transmitted to the signal receiving end through a channel. After receiving the signal, the signal receiving end demodulates the received signal in an OFDM demodulation mode corresponding to the OFDM modulation mode adopted in the modulation process to obtain a demodulated signal, and performs symbol demodulation on the demodulated signal in a symbol demodulation mode corresponding to the symbol modulation mode to obtain an original signal. Thus, the signals transmitted in the channel are all modulated signals.
In addition, when the channel transmits signals, the transmitted signals may be illegal signals, and therefore, the detection device needs to detect the signals transmitted in the channel, so as to prevent the illegal signals from occupying the channel, which results in a shortage of channel resources. Since the signal obtained from the channel by the detection device is a signal subjected to symbol modulation and OFDM modulation, the detection device needs to detect a symbol modulation scheme adopted by the signal subjected to symbol modulation after OFDM demodulation of the signal, perform symbol demodulation on the signal subjected to symbol modulation by using a symbol demodulation scheme corresponding to the detected symbol modulation scheme, and then detect whether the signal subjected to symbol demodulation is an illegal signal.
However, signals transmitted in the channel are susceptible to channel interference such as signal reflection, refraction, fading, etc., so that the detected symbol modulation scheme in the OFDM system has low accuracy.
Disclosure of Invention
An object of the embodiments of the present invention is to provide a method and an apparatus for detecting a symbol modulation scheme in an OFDM system, so as to improve accuracy of a detection result of the symbol modulation scheme in the OFDM system. The specific technical scheme is as follows:
in a first aspect, an embodiment of the present invention provides a method for detecting a symbol modulation mode in an OFDM system, where the method includes:
acquiring signals transmitted within a time period of preset duration from the signals transmitted by the channel as signals to be detected;
carrying out OFDM demodulation on the signal to be detected to obtain a demodulated signal;
calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in the demodulation signal in each sub-time period contained in the time period in the sub-time period;
and detecting the symbol modulation mode of the signal to be detected according to each calculated ratio.
In an embodiment of the present invention, the detecting the symbol modulation mode of the signal to be detected according to the calculated ratios includes:
inputting each calculated ratio into a pre-trained modulation mode detection model to obtain a symbol modulation mode of the signal to be detected;
the modulation mode detection model is as follows: a model for detecting a symbol modulation scheme of a signal, obtained by training a first initial model with a first sample set, the first sample set including: and for each sub-period, the sample ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in the first sample signal in the sub-period, and the symbol modulation mode of the first sample signal.
In an embodiment of the present invention, the calculating, for each sub-period included in the time period, a ratio of amplitudes of frequency-domain symbols located on each adjacent subcarrier in the demodulated signal in the sub-period includes:
determining each PRB (Physical Resource Block) in the demodulated signal;
and calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in each PRB in each sub-time period contained in the time period in the sub-time period.
In an embodiment of the present invention, the calculating, for each sub-period included in the time period, a ratio of an amplitude of a frequency-domain symbol located on each adjacent subcarrier in each PRB in the sub-period includes:
determining PRBs occupied by signals in each PRB as occupied resource blocks;
and calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in each occupied resource block in each sub-time period contained in the time period in the sub-time period.
In an embodiment of the present invention, the determining, as occupied resource blocks, PRBs occupied by signals in each PRB includes:
inputting each PRB into a pre-trained resource block occupation detection model, and determining occupied resource blocks;
the resource block occupation detection model comprises the following steps: a model obtained by training a second initial model by using a second sample set and used for detecting whether the PRB is occupied by a signal, wherein the second sample set comprises: and marking whether the sample PRB is occupied or not.
In a second aspect, an embodiment of the present invention provides a symbol modulation scheme detection apparatus in an OFDM system, where the apparatus includes:
the signal acquisition module is used for acquiring signals transmitted within a time period of preset duration from the signals transmitted by the channel as signals to be detected;
the signal demodulation module is used for carrying out OFDM demodulation on the signal to be detected to obtain a demodulated signal;
a ratio calculation module, configured to calculate, for each sub-period included in the period, a ratio of an amplitude of a frequency domain symbol located on each adjacent subcarrier in the demodulated signal in the sub-period;
and the modulation mode detection module is used for detecting the symbol modulation mode of the signal to be detected according to each calculated ratio.
In an embodiment of the present invention, the modulation scheme detecting module is specifically configured to:
inputting each calculated ratio into a pre-trained modulation mode detection model to obtain a symbol modulation mode of the signal to be detected;
the modulation mode detection model is as follows: a model for detecting a symbol modulation scheme of a signal, obtained by training a first initial model with a first sample set, the first sample set including: and for each sub-period, the sample ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in the first sample signal in the sub-period, and the symbol modulation mode of the first sample signal.
In an embodiment of the present invention, the ratio calculating module includes:
a physical resource block determining submodule: for determining individual PRBs in the demodulated signal;
a ratio operator module: and the method is used for calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in each PRB in each sub-time period contained in the time period within the sub-time period.
In an embodiment of the present invention, the ratio operator module includes:
an occupied resource block determining unit, configured to determine a PRB occupied by a signal in each PRB, as an occupied resource block;
and a ratio calculation unit, configured to calculate, for each sub-time segment included in the time segment, a ratio of the amplitude of the frequency domain symbol located on each adjacent subcarrier in each occupied resource block in the sub-time segment.
In an embodiment of the present invention, the occupied resource block determining unit is specifically configured to:
inputting each PRB into a pre-trained resource block occupation detection model, and determining occupied resource blocks;
the resource block occupation detection model comprises the following steps: a model obtained by training a second initial model by using a second sample set and used for detecting whether the PRB is occupied by a signal, wherein the second sample set comprises: and marking whether the sample PRB is occupied or not.
In a third aspect, an embodiment of the present invention provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, where the processor and the communication interface complete communication between the memory and the processor through the communication bus;
a memory for storing a computer program;
a processor adapted to perform the method steps of any of the above first aspects when executing a program stored in the memory.
In a fourth aspect, the present invention provides a computer-readable storage medium, in which a computer program is stored, and the computer program, when executed by a processor, implements the method steps of any one of the above first aspects.
In a fifth aspect, embodiments of the present invention also provide a computer program product comprising instructions, which when run on a computer, cause the computer to perform the method steps of any of the first aspects described above.
The embodiment of the invention has the following beneficial effects:
when the scheme provided by the embodiment of the invention is applied to symbol modulation mode detection in an OFDM system, a signal transmitted in a time period with preset time duration is obtained from a signal transmitted by a channel and is used as a signal to be detected, OFDM demodulation is carried out on the signal to be detected, a demodulated signal is obtained, the ratio of frequency domain symbols positioned on each adjacent subcarrier in the demodulated signal in the sub-time period is calculated aiming at each sub-time period contained in the time period, and the symbol modulation mode of the signal to be detected is detected according to each calculated ratio. Since the time duration of each sub-period is generally shorter after the time period is divided into the sub-periods, it can be considered that the interference of the channel to the signal in the sub-periods is the same in the adjacent subcarriers, and in addition, in the case of the interference of the channel to the signal, the interference of the gaussian white noise to the signal is smaller and can be ignored within the error tolerance range compared with the interference of the channel to the signal. In addition, in the frequency domain dimension, the frequency domain symbol of the channel is superimposed on the signal in a manner of multiplying the frequency domain symbol of the signal, so that in the range that the duration of the sub-period is short enough and the error is allowed, the interference superimposed on the signal by the channel can be removed by calculating the ratio of the amplitudes of the frequency domain symbols positioned on the adjacent subcarriers in the demodulated signal in the same time period, and thus the symbol modulation mode in the OFDM system is detected by using the ratio of the amplitudes of the frequency domain symbols positioned on the adjacent subcarriers from which the channel interference is removed, and the accuracy of the detection result of the symbol modulation mode in the OFDM system can be improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flowchart of a symbol modulation scheme detection method in a first OFDM system according to an embodiment of the present invention;
fig. 2A is a schematic flowchart of a symbol modulation scheme detection method in a second OFDM system according to an embodiment of the present invention;
fig. 2B is a schematic structural diagram of a first neural network model according to an embodiment of the present invention;
FIG. 2C is a schematic structural diagram of a first machine learning model according to an embodiment of the present disclosure;
fig. 3 is a schematic flowchart of a symbol modulation scheme detection method in a third OFDM system according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a physical resource block according to an embodiment of the present invention;
fig. 5A is a schematic flowchart of a symbol modulation scheme detection method in a fourth OFDM system according to an embodiment of the present invention;
FIG. 5B is a schematic structural diagram of a second neural network model according to an embodiment of the present invention;
FIG. 5C is a schematic structural diagram of a second machine learning model according to an embodiment of the present disclosure;
fig. 6 is a schematic flowchart of a symbol modulation scheme detection method in a fifth OFDM system according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a symbol modulation scheme detection apparatus in a first OFDM system according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of a symbol modulation scheme detection apparatus in a second OFDM system according to an embodiment of the present invention;
fig. 9 is a schematic structural diagram of a symbol modulation scheme detection apparatus in a third OFDM system according to an embodiment of the present invention;
fig. 10 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, 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 invention.
In order to solve the problem that a detection result is influenced by channel interference when a symbol modulation mode in an OFDM system is detected in the prior art, the embodiment of the present invention provides a method and an apparatus for detecting a symbol modulation mode in an OFDM system.
In an embodiment of the present invention, a method for detecting a symbol modulation scheme in an OFDM system is provided, where the method includes:
and acquiring the signals transmitted within a time period of preset duration from the signals transmitted by the channel as the signals to be detected.
And carrying out OFDM demodulation on the signal to be detected to obtain a demodulated signal.
And calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in the demodulation signal in each sub-time section contained in the time section in the sub-time section.
And detecting the symbol modulation mode of the signal to be detected according to each calculated ratio.
When the scheme provided by this embodiment is applied to the modulation scheme detection in the OFDM system, since the time period is divided into sub-time periods, and the duration of each sub-time period is generally short, it can be considered that the interference of the channel to the signal in the sub-time period is the same in adjacent subcarriers, and in addition, in the case that the channel interferes with the signal, the interference of the gaussian white noise to the signal is smaller and can be ignored in the error allowable range compared with the interference of the channel to the signal. In addition, in the frequency domain dimension, the frequency domain symbol of the channel is superimposed on the signal in a manner of multiplying the frequency domain symbol of the signal, so that in the range that the duration of the sub-period is short enough and the error is allowed, the interference superimposed on the signal by the channel can be removed by calculating the ratio of the amplitudes of the frequency domain symbols positioned on the adjacent subcarriers in the demodulated signal in the same time period, and thus the symbol modulation mode in the OFDM system is detected by using the ratio of the amplitudes of the frequency domain symbols positioned on the adjacent subcarriers from which the channel interference is removed, and the accuracy of the detection result of the symbol modulation mode in the OFDM system can be improved.
The following describes in detail a symbol modulation scheme detection method and apparatus in an OFDM system according to embodiments of the present invention, respectively, with reference to specific embodiments.
Referring to fig. 1, an embodiment of the present invention provides a flowchart of a method for detecting a symbol modulation scheme in an OFDM system, where the method includes the following steps S101 to S104.
S101: and acquiring the signals transmitted within a time period of preset duration from the signals transmitted by the channel as the signals to be detected.
In the field of wireless communication, such as 4G or 5G communication, the signal is transmitted in the air, the medium for signal transmission is called a channel, and the channel is the air during the signal transmission. During the transmission of signals in the air channel, the signals may be reflected, refracted, and faded, that is, the signals are affected by the channel during the transmission process.
The preset time duration may be a time duration set by a user or a default time duration, such as 50ms, 100ms, or the like.
S102: and carrying out OFDM demodulation on the signal to be detected to obtain a demodulated signal.
When a signal sending end sends a signal, symbol modulation is performed on an original signal first, and then OFDM modulation is performed, so that when demodulation is performed, OFDM demodulation is performed first, and then a symbol modulation mode of the signal is determined according to a symbol modulation mode detection result.
For example, in the field of wireless communication, when a 4G or 5G signal is generated, the signal is modulated by an OFDM modulation method, and when the signal is demodulated, the signal is demodulated by a corresponding OFDM demodulation method to obtain a demodulated signal.
S103: and calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in the demodulation signal in each sub-time section contained in the time section in the sub-time section.
When the demodulated signal is a signal demodulated by OFDM, the demodulated signal has a frame structure, the demodulated signal may be composed of different frames, the duration of 1 frame is 10ms, each frame includes 10 subframes, the duration of 1 subframe is 1ms, each subframe includes 2 slots, the duration of 1 slot is 0.5ms, and each slot includes multiple sub-slots. For example, 3, 6, 7 sub-periods may be included.
Since the sub-period is short enough, the demodulated signal is considered to remain unchanged in the sub-period.
The demodulation signal includes a plurality of subcarriers for each of the sub-periods, and each of the subcarriers corresponds to a different frequency bin. For example, the subcarrier 1, the subcarrier 2 and the subcarrier 3 may respectively correspond to different frequency intervals f1-f2, f2-f3 and f3-f4, and the frequency intervals f1-f2, f2-f3 and f3-f4 are sequentially adjacent and have the same size. When calculating the ratio of the amplitudes of the frequency domain symbols located on the adjacent subcarriers within a certain sub-period, the ratio of the amplitudes of the frequency domain symbols located on the subcarrier 3 and the frequency domain symbols located on the subcarrier 2, and the ratio of the amplitudes of the frequency domain symbols located on the subcarrier 2 and the frequency domain symbols located on the subcarrier 1 may be calculated for the sub-period, respectively.
Based on the above, if the number of subcarriers in the demodulated signal is 12, the ratio calculated for each of the sub-periods is 11, and if the number of subcarriers in the demodulated signal is 24, the ratio calculated for each of the sub-periods is 23.
The frequency domain symbol on the subcarrier is obtained by performing OFDM demodulation on a signal to be detected to obtain a demodulated signal and simultaneously performing Fourier transform calculation.
If the OFDM demodulation method is used in step S102 to demodulate the signal to be detected to obtain a demodulated signal, the frequency domain symbol is a frequency domain OFDM symbol.
The amplitude of the frequency domain symbol may be the amplitude of the frequency domain symbol at the sampling time point in the sub-period.
The principle of removing channel interference by ratio proposed in the embodiment of the present invention is analyzed by the following formula:
wherein, | | is an operation of taking an amplitude value, Yk+1,nIs the frequency domain symbol of the (k + 1) th subcarrier in the nth sub-period, | Yk+1,nL is Yk+1,nAmplitude of (A), Yk,nIs the frequency domain symbol of the kth sub-carrier in the nth sub-period, | Yk,nL is Yk,nAmplitude of (H)k+1Frequency domain symbol of channel interference suffered by the k +1 th subcarrier, Xk+1,nIs Y not interfered by channelk+1,n，wk+1Is Gaussian white noise on the k +1 th subcarrier, HkFrequency domain symbol, X, for channel interference experienced by the k-th subcarrierk,nIs Y not interfered by channelk,n，wkIs gaussian white noise on the k-th subcarrier.
Since the gaussian white noise has less interference to the signal than the channel interference in the presence of the channel interference, the gaussian white noise can be ignored within the error tolerance. In addition, in the nth sub-period, since the nth sub-period is short enough to consider that the channel is not changed in the nth sub-period and the interference to each sub-carrier is the same, the influence of the channel interference can be cancelled between frequency domain symbols located on adjacent sub-carriers through ratio calculation, so that the interference of the channel to the sub-carriers is removed.
Specifically, the ratio of the amplitudes of the frequency domain symbols located on the adjacent subcarriers in the demodulated signal in each sub-period can be calculated through steps S103A-S103B, which will not be detailed here.
S104: and detecting the symbol modulation mode of the signal to be detected according to each calculated ratio.
The amplitudes of the frequency domain symbols on the subcarriers of the signals obtained by different symbol modulation modes are different, so that the ratios obtained by calculating the amplitudes of the frequency domain symbols on the adjacent subcarriers are different for different symbol modulation modes, and the modulation mode of the signal to be detected can be judged according to the calculated ratios.
Specifically, the Modulation method of the signal to be detected may be determined by detecting the signal to be detected in which the Modulation method is QPSK (Quadrature Phase Shift Keying), 16QAM (16Quadrature Amplitude Modulation), 64QAM (64Quadrature Amplitude Modulation), 256QAM (256Quadrature Amplitude Modulation), or other Modulation methods.
In an embodiment of the present invention, the symbol modulation mode of the signal to be detected may be detected through step S104A, which will not be described in detail herein.
When the scheme provided by the embodiment is applied to symbol modulation mode detection in an OFDM system, a signal transmitted in a time period of a preset duration is obtained from a signal transmitted by a channel and is used as a signal to be detected, OFDM demodulation is performed on the signal to be detected to obtain a demodulated signal, for each sub-time period included in the time period, a ratio of a frequency domain symbol located on each adjacent subcarrier in the demodulated signal in the sub-time period is calculated, and the symbol modulation mode of the signal to be detected is detected according to each calculated ratio. Since the time duration of each sub-period is generally shorter after the time period is divided into the sub-periods, it can be considered that the interference of the channel to the signal in the sub-periods is the same in the adjacent subcarriers, and in addition, in the case of the interference of the channel to the signal, the interference of the gaussian white noise to the signal is smaller and can be ignored within the error tolerance range compared with the interference of the channel to the signal. In addition, in the frequency domain dimension, the frequency domain symbol of the channel is superimposed on the signal in a manner of multiplying the frequency domain symbol of the signal, so that in the range of short enough time duration and allowable error of the sub-time period, the interference superimposed on the signal by the channel can be removed by calculating the ratio of the amplitudes of the frequency domain symbols on the adjacent subcarriers in the demodulated signal in the same time period, and thus the symbol modulation mode in the OFDM system is detected by using the ratio of the amplitudes of the frequency domain symbols on the adjacent subcarriers from which the channel interference is removed, and the accuracy of the detection result of the symbol modulation mode in the OFDM system can be improved.
In an embodiment of the present invention, referring to fig. 2A, a flowchart of a symbol modulation scheme detection method in a second OFDM system is provided, and compared with the foregoing embodiment shown in fig. 1, in this embodiment, the foregoing step S104 may be implemented by step S104A.
S104A: and inputting each calculated ratio into a pre-trained modulation mode detection model to obtain the symbol modulation mode of the signal to be detected.
The modulation mode detection model is as follows: a model for detecting a symbol modulation scheme of a signal, obtained by training a first initial model using a first sample set, the first sample set including: and for each sub-period, the sample ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in the first sample signal in the sub-period, and the symbol modulation mode of the first sample signal.
Specifically, the first initial model may be a neural network model, and referring to fig. 2B, a schematic structural diagram of the first neural network model is provided, where the first initial model includes two convolutional layers, two pooling layers, and two full-link layers.
The first convolution layer inputs convolution processing results into a first pooling layer after convolution processing is carried out on input specific values, the first pooling layer carries out pooling processing on data after receiving the data input by the first convolution layer and inputs the pooling processing results into a second convolution layer, the second pooling layer inputs processing results into a second pooling layer after convolution processing is carried out on the received data, the second pooling layer carries out pooling processing on the received data and inputs the processing results into a first full-connection layer, the first full-connection layer carries out full-connection processing on the data and inputs the processing results into a second full-connection layer, and the second full-connection layer carries out full-connection processing on the received data to obtain a detected modulation mode.
For example, the convolution kernel dimension of the first convolution layer may be 5 × 5, the convolution layer depth may be 32, the pooled cell size of the first pooling layer may be 2 × 2, the convolution kernel dimension of the second convolution layer may be 5 × 5, the convolution layer depth may be 64, the pooled cell size of the second pooling layer may be 2 × 2, and both the first fully-connected layer and the second fully-connected layer may contain 512 neurons.
In addition, the first initial model may be a machine learning model, and the modulation scheme detection model may be obtained by training the machine learning model.
Referring to fig. 2C, a schematic structural diagram of a first machine learning model is provided, where in a case that the first initial model is a machine learning model, before data in the first sample set is input into the first initial model, a high-order accumulation amount of each sample ratio in the first sample set based on each high-order time for different orders is calculated, feature extraction is implemented, and the calculated high-order accumulation amount is input into the first initial model to train the first initial model.
For example, the high-order accumulation amount based on each high-order time instant for each sample ratio value in the first sample set described above for 9 different orders may be calculated.
Specifically, the machine learning model may be a decision tree model, a random forest model, a k-nearest neighbor model, an SVM (Support Vector machine) model, or the like.
Before a modulation mode detection model with an initial model as a machine learning model is used for detecting the symbol modulation mode of the signal to be detected, feature extraction is carried out on each calculated ratio, high-order accumulation quantities of each ratio based on each high-order moment are obtained for different orders, and each obtained high-order accumulation quantity is input into the modulation mode detection model so as to obtain a detection result of the symbol modulation mode.
When the scheme provided by the embodiment is applied to the symbol modulation mode detection in the OFDM system, the calculated ratio is input into a modulation mode detection model trained in advance, and the modulation mode detection model detects the symbol modulation mode of the signal. The modulation mode detection model is obtained by learning a large number of samples based on a neural network model or a machine learning model, so that the modulation mode detection model can learn the characteristics of different symbol modulation modes in the large number of samples, and the symbol modulation mode of the signal to be detected can be detected by applying the modulation mode detection model.
In an embodiment of the present invention, referring to fig. 3, a flowchart of a symbol modulation scheme detection method in a third OFDM system is provided, and compared with the embodiment shown in fig. 1, in this embodiment, the step S103 may be implemented by steps S103A-S103B.
S103A: determining each PRB in the demodulated signal.
The demodulation signal includes a plurality of PRBs, one PRB may correspond to the demodulation signal in one time slot, the duration of one time slot may be 0.5ms, and the modulation modes adopted by the PRBs may be different.
In addition, the OFDM system includes an LTE signal, a WLAN signal, a 5G signal, and the like, and performs OFDM demodulation on a signal to be detected to obtain a demodulated signal, where the demodulated signal includes a plurality of resource blocks, where a PRB is a resource block for the LTE signal, and other signals, such as the WLAN signal and the 5G signal, have resource blocks with different structures + corresponding to the respective resource blocks.
S103B: and calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in each PRB in each sub-time period contained in the time period in the sub-time period.
One PRB may correspond to multiple sub-periods in a time dimension, and each sub-period corresponds to multiple different subcarriers. For example, one PRB may correspond to 7 sub-periods and 12 subcarriers per sub-period in the time dimension, one PRB may also correspond to 6 sub-periods and 12 subcarriers per sub-period in the time dimension, one PRB may also correspond to 3 sub-periods and 24 subcarriers per sub-period in the time dimension.
Each PRB may correspond to multiple sub-time segments in the time dimension, and each sub-time segment includes multiple different subcarriers, so that it is necessary to perform ratio calculation on the amplitudes of every two frequency domain symbols located on adjacent subcarriers in each PRB for each sub-time segment.
In an embodiment of the present invention, referring to fig. 4, a physical resource block diagram is provided.
The left block diagram in fig. 4 shows, for each row, one sub-period for each block, which contains 7 sub-periods. For each column, each square corresponds to the amplitude of a frequency domain symbol on a different subcarrier during a certain sub-period, and the diagram contains 12 frequency domain symbols on different subcarriers.
The square at the top left corner corresponds to a frequency domain symbol located on the 12 th subcarrier corresponding to the frequency interval with the highest frequency in the 1 st sub-period in each PRB, and the square below the frequency domain symbol sequentially corresponds to a frequency domain symbol on the 11 th subcarrier in the 1 st sub-period in each PRB, a frequency domain symbol on the 10 th subcarrier in the 1 st sub-period in each PRB, and so on.
After the ratios are calculated, a diagram of the right side box in fig. 4 is obtained, for each row, each block corresponds to one sub-period, the diagram includes 7 sub-periods, for each column, each block corresponds to a ratio of amplitudes of frequency domain symbols located on adjacent subcarriers in a certain sub-period, the diagram includes 11 different calculated ratios, and for each PRB, the calculated ratio is 77.
The square in the upper left corner is the ratio of the amplitude of the frequency domain symbol on the 12 th subcarrier to the amplitude of the frequency domain symbol on the 11 th subcarrier for the 1 st sub-period in each PRB, the square in the lower corner is the ratio of the amplitude of the frequency domain symbol on the 11 th subcarrier to the amplitude of the frequency domain symbol on the 10 th subcarrier for the 1 st sub-period in each PRB, and so on.
The above calculated ratio may be stored in the form of a matrix, for example, the following matrix:
wherein, for each PRB, p1,1Is the amplitude ratio of the frequency domain symbols on the 2 nd subcarrier and the 1 st subcarrier in the 1 st sub-period, p11,1Is the 12 th sub-carrier and the 11 th sub-carrier in the 1 st sub-periodAmplitude ratio of frequency domain symbols on a carrier, p1,7Is the amplitude ratio of the frequency domain symbols on the 2 nd subcarrier and the 1 st subcarrier in the 7 th sub-period, p11,7Is the amplitude ratio of the frequency domain symbols on the 12 th subcarrier and the 11 th subcarrier in the 7 th subcarrier.
Specifically, the ratio of the amplitudes of the frequency-domain symbols located on the adjacent subcarriers in each PRB in each sub-period may be calculated through steps S103B1-S103B2, which will not be detailed here for the moment.
When the scheme provided by this embodiment is applied to symbol modulation mode detection in an OFDM system, because different symbol modulation modes may be used when performing symbol modulation on signals transmitted to different users, the signals transmitted to the same user may adopt the same symbol modulation mode, the signals transmitted to different users are transmitted simultaneously, and a PRB is the smallest user scheduling unit in the signals, each PRB corresponds to only one symbol modulation mode, and the symbol modulation modes corresponding to different PRBs may be different, so that determining each PRB in the signal and performing symbol modulation mode detection on each PRB respectively can remove mutual interference between multiple symbol modulation modes, and under the condition that multiple different symbol modulation modes are used during signal modulation, the accuracy of symbol modulation mode detection is improved.
In an embodiment of the present invention, referring to fig. 5A, a flowchart of a symbol modulation scheme detection method in a fourth OFDM system is provided, and compared with the foregoing embodiment shown in fig. 3, the step S103B in this embodiment can be implemented by steps S103B1-S103B 2.
S103B 1: and determining the PRBs occupied by the signals in each PRB as occupied resource blocks.
Specifically, the PRB includes a PRB occupied by a signal and a PRB not occupied by the signal, the PRB occupied by the signal includes an effective signal, and the PRB not occupied by the signal does not include an effective signal.
In an embodiment of the present invention, the occupied resource block may be determined through the following step C.
And C: and inputting each PRB into a pre-trained resource block occupation detection model to determine occupied resource blocks.
The resource block occupation detection model comprises the following steps: a model obtained by training a second initial model by using a second sample set and used for detecting whether the PRB is occupied by a signal, wherein the second sample set comprises: and marking whether the sample PRB is occupied or not.
Specifically, the second initial model may be a neural network model, and referring to fig. 5B, a schematic structural diagram of the second neural network model is provided, where the second initial model includes two convolutional layers, two pooling layers, and two full-link layers.
After the third convolutional layer performs convolutional processing on input data, a convolutional processing result is input into a third pooling layer, the third pooling layer performs pooling processing on the data after receiving the data input by the third convolutional layer, and inputs a pooling processing result into a fourth convolutional layer, the fourth convolutional layer performs convolutional processing on the received data and inputs a processing result into a fourth pooling layer, the fourth pooling layer performs pooling processing on the received data and inputs the processing result into a third full-link layer, the third full-link layer performs full-link processing on the data and inputs the processing result into a fourth full-link layer, and the fourth full-link layer performs full-link processing on the received data to obtain a result of whether detected PRBs are occupied or not.
For example, the convolution kernel dimension of the third convolution layer may be 5 × 5, the convolution layer depth may be 32, the pooled cell size of the third pooling layer may be 2 × 2, the convolution kernel dimension of the fourth convolution layer may be 5 × 5, the convolution layer depth may be 64, the pooled cell size of the fourth pooling layer may be 2 × 2, and the third and fourth fully-connected layers may each contain 512 neurons.
The data of the input resource block occupation detection model may be stored in a matrix form, for example, the following matrix:
wherein, for each PRB, x1,1Is the amplitude, x, of the 1 st subcarrier frequency domain symbol in the 1 st sub-period12,1Is the amplitude, x, of the frequency domain symbol of the 12 th sub-carrier in the 1 st sub-period1,7Is the amplitude, x, of the frequency domain symbol of the 1 st subcarrier in the 7 th sub-period12,7Is the amplitude of the frequency domain symbol of the 12 th subcarrier in the 7 th sub-period.
In addition, the second initial model may be a machine learning model, and the resource block occupation detection model is obtained by training the machine learning model.
Specifically, referring to fig. 5C, a schematic structural diagram of a second machine learning model is provided, where in a case that the second initial model is a machine learning model, before data in the second sample set is input into the second initial model, a high-order accumulation amount of each data in the second sample set based on each high-order time for different orders is calculated, feature extraction is implemented, and the calculated high-order accumulation amount is input into the second initial model to train the second initial model.
For example, a higher order accumulation amount based on each higher order time instant for each data in the second sample set for 9 different orders may be calculated.
The machine learning model may be a decision tree model, a random forest model, a k-nearest neighbor model, an SVM (Support Vector Machines) model, or the like.
S103B 2: and calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in each occupied resource block in each sub-time period contained in the time period in the sub-time period.
Specifically, the PRB not occupied by the signal does not include an effective signal, and therefore symbol modulation mode detection may not be performed on the PRB not occupied by the signal, and only ratio calculation needs to be performed on the occupied resource block and symbol modulation mode detection needs to be further performed.
Each occupied resource block can correspond to a plurality of sub-time periods in the time dimension, and for each sub-time period, the occupied resource block comprises a plurality of sub-carriers respectively corresponding to different frequency intervals, so that for each sub-time period, ratio calculation needs to be performed on the amplitude of every two frequency domain symbols located on adjacent sub-carriers in each occupied resource block.
When the scheme provided by the embodiment is applied to the detection of the symbol modulation mode in the OFDM system, because not every PRB is occupied by the signal, and the PRB not occupied by the signal does not contain an effective signal, whether the PRB is occupied by the signal or not is detected, and only the occupied resource block occupied by the signal is subjected to the detection of the symbol modulation mode, so that the workload of the detection of the symbol modulation mode in the OFDM system can be reduced, and the detection speed is accelerated.
Next, referring to fig. 6, a method for detecting a symbol modulation scheme in an OFDM system according to an embodiment of the present invention is described by way of specific example with reference to fig. 6.
Fig. 6 is a flowchart illustrating a symbol modulation scheme detection method in a fifth OFDM system according to an embodiment of the present invention.
Taking the example that the signal to be detected is an LTE signal,
s601: and after the LTE signal to be detected is obtained, OFDM demodulation is carried out on the LTE signal, and each PRB in the signal to be detected is determined.
S602: and determining occupied resource blocks occupied by the signals in each PRB, and not performing further processing on the resource blocks not occupied by the signals.
S603: and calculating the ratio of the amplitude of each frequency domain symbol positioned on the adjacent subcarrier in each occupied resource block in each sub-time period contained in the time period in the sub-time period.
S604: and detecting the symbol modulation mode of the LTE signal to be detected according to the calculated ratio, and determining that the modulation mode of the LTE signal to be detected is QPSK, 16QAM, 64QAM or 256 QAM.
Corresponding to the method for detecting the symbol modulation mode in the OFDM system, the embodiment of the invention also provides a device for detecting the symbol modulation mode in the OFDM system.
In an embodiment of the present invention, referring to fig. 7, a schematic structural diagram of a symbol modulation scheme detection apparatus in a first OFDM system is provided, specifically, the apparatus includes:
a signal obtaining module 701, configured to obtain, from signals transmitted through a channel, a signal transmitted within a time period of a preset duration as a signal to be detected;
a signal demodulation module 702, configured to perform OFDM demodulation on the signal to be detected to obtain a demodulated signal;
a ratio calculating module 703, configured to calculate, for each sub-period included in the time period, a ratio of the amplitude of the frequency domain symbol located on each adjacent subcarrier in the demodulated signal in the sub-period;
a modulation mode detection module 704, configured to detect a symbol modulation mode of the signal to be detected according to each calculated ratio.
When the scheme provided by the above embodiment is applied to the symbol modulation mode detection in the OFDM system, since the time duration of each sub-period is generally short after the time period is divided into the sub-periods, it can be considered that the interference of the channel to the signal in the sub-periods is the same in the adjacent subcarriers, and in addition, in the case of the interference of the channel to the signal, the interference of the gaussian white noise to the signal is smaller and can be ignored within the error allowable range compared with the interference of the channel to the signal. In addition, in the frequency domain dimension, the frequency domain symbol of the channel is superimposed on the signal in a manner of multiplying the frequency domain symbol of the signal, so that in the range that the duration of the sub-period is short enough and the error is allowed, the interference superimposed on the signal by the channel can be removed by calculating the ratio of the amplitudes of the frequency domain symbols positioned on the adjacent subcarriers in the demodulated signal in the same time period, and thus the symbol modulation mode in the OFDM system is detected by using the ratio of the amplitudes of the frequency domain symbols positioned on the adjacent subcarriers from which the channel interference is removed, and the accuracy of the detection result of the symbol modulation mode in the OFDM system can be improved.
In an embodiment of the present invention, the modulation scheme detecting module 704 is specifically configured to:
inputting each calculated ratio into a pre-trained modulation mode detection model to obtain a symbol modulation mode of the signal to be detected;
the modulation mode detection model is as follows: a model for detecting a symbol modulation scheme of a signal, obtained by training a first initial model with a first sample set, the first sample set including: and for each sub-period, the sample ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in the first sample signal in the sub-period, and the symbol modulation mode of the first sample signal.
When the scheme provided by the embodiment is applied to the symbol modulation mode detection in the OFDM system, the calculated ratio is input into a modulation mode detection model trained in advance, and the modulation mode detection model detects the symbol modulation mode of the signal. The modulation mode detection model is obtained by learning a large number of samples by adopting a neural network or a machine learning mode, so that the modulation mode detection model can learn the characteristics of different symbol modulation modes in the large number of samples, and the symbol modulation mode of the signal to be detected can be detected by applying the modulation mode detection model.
In an embodiment of the present invention, referring to fig. 8, which is a schematic structural diagram of a symbol modulation scheme detection apparatus in a second OFDM system according to an embodiment of the present invention, compared with the embodiment shown in fig. 7, in this embodiment, the ratio calculation module 703 includes:
physical resource block determination submodule 703A: for determining each physical resource block, PRB, in the demodulated signal;
ratio calculation submodule 703B: and the method is used for calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in each PRB in each sub-time period contained in the time period within the sub-time period.
When the scheme provided by this embodiment is applied to detect the symbol modulation mode in the OFDM system, because different symbol modulation modes may be used when modulating signals transmitted to different users, the signals transmitted to the same user may adopt the same symbol modulation mode, the signals transmitted to different users are transmitted simultaneously, and the PRB is the minimum user scheduling unit in the signals, each PRB only corresponds to one symbol modulation mode, and the symbol modulation modes corresponding to different PRBs may be different, so that determining each PRB in the signal and performing symbol modulation mode detection on each PRB respectively can remove mutual interference between multiple symbol modulation modes, and under the condition that multiple different symbol modulation modes are used during signal modulation, the accuracy of symbol modulation mode detection is improved.
In an embodiment of the present invention, referring to fig. 9, which is a schematic structural diagram of a symbol modulation scheme detection apparatus in a third OFDM system according to an embodiment of the present invention, compared with the embodiment shown in fig. 7, in this embodiment, the ratio calculation sub-module 703B includes:
an occupied resource block determining unit 703B1, configured to determine a PRB occupied by a signal in each PRB, as an occupied resource block;
a ratio calculating unit 703B2, configured to calculate, for each sub-period included in the time period, a ratio of the amplitude of the frequency domain symbol located on each adjacent subcarrier in each occupied resource block in the sub-period.
In an embodiment of the present invention, the occupied resource block determining unit 703B1 is specifically configured to:
inputting each PRB into a pre-trained resource block occupation detection model, and determining occupied resource blocks;
the resource block occupation detection model comprises the following steps: a model obtained by training a second initial model by using a second sample set and used for detecting whether the PRB is occupied by a signal, wherein the second sample set comprises: and marking whether the sample PRB is occupied or not.
When the scheme provided by the embodiment is applied to the detection of the symbol modulation mode in the OFDM system, because not every PRB is occupied by the signal, and the PRB not occupied by the signal does not contain an effective signal, whether the PRB is occupied by the signal or not is detected, and only the occupied resource block occupied by the signal is subjected to the detection of the symbol modulation mode, so that the workload of the detection of the symbol modulation mode in the OFDM system can be reduced, and the detection speed is accelerated.
Corresponding to the symbol modulation scheme detection method in the OFDM system, an embodiment of the present invention further provides an electronic device, as shown in fig. 10, including a processor 1001, a communication interface 1002, a memory 1003, and a communication bus 1004, where the processor 1001, the communication interface 1002, and the memory 1003 complete mutual communication through the communication bus 1004,
a memory 1003 for storing a computer program;
the processor 1001 is configured to implement the method steps of any of the above embodiments of the symbol modulation scheme detection method in the OFDM system when executing the program stored in the memory 1003.
When the electronic device provided in this embodiment is applied to detect the symbol modulation mode in the OFDM system, a signal transmitted within a time period of a preset duration is obtained from a signal transmitted through a channel and is used as a signal to be detected, the signal to be detected is OFDM-demodulated to obtain a demodulated signal, for each sub-time period included in the time period, a ratio of a frequency domain symbol located on each adjacent subcarrier in the demodulated signal within the sub-time period is calculated, and the symbol modulation mode of the signal to be detected is detected according to each calculated ratio. Since the time duration of each sub-period is generally shorter after the time period is divided into the sub-periods, it can be considered that the interference of the channel to the signal in the sub-periods is the same in the adjacent subcarriers, and in addition, in the case of the interference of the channel to the signal, the interference of the gaussian white noise to the signal is smaller and can be ignored within the error tolerance range compared with the interference of the channel to the signal. In addition, in the frequency domain dimension, the frequency domain symbol of the channel is superimposed on the signal in a manner of multiplying the frequency domain symbol of the signal, so that in the range that the duration of the sub-period is short enough and the error is allowed, the interference superimposed on the signal by the channel can be removed by calculating the ratio of the amplitudes of the frequency domain symbols positioned on the adjacent subcarriers in the demodulated signal in the same time period, and thus the symbol modulation mode in the OFDM system is detected by using the ratio of the amplitudes of the frequency domain symbols positioned on the adjacent subcarriers from which the channel interference is removed, and the accuracy of the detection result of the symbol modulation mode in the OFDM system can be improved.
The communication bus mentioned in the electronic device may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The communication bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown, but this does not mean that there is only one bus or one type of bus.
The communication interface is used for communication between the electronic equipment and other equipment.
The Memory may include a Random Access Memory (RAM) or a Non-Volatile Memory (NVM), such as at least one disk Memory. Optionally, the memory may also be at least one memory device located remotely from the processor.
The Processor may be a general-purpose Processor, including a Central Processing Unit (CPU), a Network Processor (NP), and the like; but also Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components.
In another embodiment of the present invention, a computer-readable storage medium is further provided, which stores a computer program, and the computer program is executed by a processor to implement the method steps of any of the above embodiments of the symbol modulation scheme detection method in the OFDM system.
When the symbol modulation mode in the OFDM system is detected by applying the computer program stored in the computer-readable storage medium provided in this embodiment, a signal transmitted in a time period of a preset duration is obtained from signals transmitted through a channel and is used as a signal to be detected, OFDM demodulation is performed on the signal to be detected to obtain a demodulated signal, for each sub-time period included in the time period, ratios of frequency domain symbols located on each adjacent subcarrier in the demodulated signal in the sub-time period are calculated, and the symbol modulation mode of the signal to be detected is detected according to the calculated ratios. Since the time duration of each sub-period is generally shorter after the time period is divided into the sub-periods, it can be considered that the interference of the channel to the signal in the sub-periods is the same in the adjacent subcarriers, and in addition, in the case of the interference of the channel to the signal, the interference of the gaussian white noise to the signal is smaller and can be ignored within the error tolerance range compared with the interference of the channel to the signal. In addition, in the frequency domain dimension, the frequency domain symbol of the channel is superimposed on the signal in a manner of multiplying the frequency domain symbol of the signal, so that in the range that the duration of the sub-period is short enough and the error is allowed, the interference superimposed on the signal by the channel can be removed by calculating the ratio of the amplitudes of the frequency domain symbols positioned on the adjacent subcarriers in the demodulated signal in the same time period, and thus the symbol modulation mode in the OFDM system is detected by using the ratio of the amplitudes of the frequency domain symbols positioned on the adjacent subcarriers from which the channel interference is removed, and the accuracy of the detection result of the symbol modulation mode in the OFDM system can be improved.
In a further embodiment of the present invention, corresponding to the method for detecting a symbol modulation scheme in the OFDM system, a computer program product is provided, which comprises instructions, when the computer program product runs on a computer, causes the computer to perform the method steps of any one of the above embodiments of the method for detecting a symbol modulation scheme in the OFDM system.
When the computer program product provided in this embodiment is executed to perform symbol modulation mode detection in an OFDM system, a signal transmitted within a time period of a preset duration is obtained from a signal transmitted through a channel and is used as a signal to be detected, the signal to be detected is OFDM-demodulated to obtain a demodulated signal, for each sub-time period included in the time period, a ratio of a frequency domain symbol located on each adjacent subcarrier in the demodulated signal within the sub-time period is calculated, and a symbol modulation mode of the signal to be detected is detected according to each calculated ratio. Since the time duration of each sub-period is generally shorter after the time period is divided into the sub-periods, it can be considered that the interference of the channel to the signal in the sub-periods is the same in the adjacent subcarriers, and in addition, in the case of the interference of the channel to the signal, the interference of the gaussian white noise to the signal is smaller and can be ignored within the error tolerance range compared with the interference of the channel to the signal. In addition, in the frequency domain dimension, the frequency domain symbol of the channel is superimposed on the signal in a manner of multiplying the frequency domain symbol of the signal, so that in the range that the duration of the sub-period is short enough and the error is allowed, the interference superimposed on the signal by the channel can be removed by calculating the ratio of the amplitudes of the frequency domain symbols positioned on the adjacent subcarriers in the demodulated signal in the same time period, and thus the symbol modulation mode in the OFDM system is detected by using the ratio of the amplitudes of the frequency domain symbols positioned on the adjacent subcarriers from which the channel interference is removed, and the accuracy of the detection result of the symbol modulation mode in the OFDM system can be improved.
In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the apparatus, the electronic device, the computer-readable storage medium and the computer program product, since they are substantially similar to the method embodiments, the description is relatively simple, and in relation to them, reference may be made to the partial description of the method embodiments.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (10)
1. A method for detecting a symbol modulation mode in an OFDM system, the method comprising:
acquiring signals transmitted within a time period of preset duration from the signals transmitted by the channel as signals to be detected;
carrying out Orthogonal Frequency Division Multiplexing (OFDM) demodulation on the signal to be detected to obtain a demodulated signal;
calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in the demodulation signal in each sub-time period contained in the time period in the sub-time period; the demodulation signal is kept unchanged in each sub-period;
and detecting the symbol modulation mode of the signal to be detected according to each calculated ratio.
2. The method according to claim 1, wherein the detecting the symbol modulation scheme of the signal to be detected according to the calculated ratios comprises:
inputting each calculated ratio into a pre-trained modulation mode detection model to obtain a symbol modulation mode of the signal to be detected;
the modulation mode detection model is as follows: a model for detecting a symbol modulation scheme of a signal, obtained by training a first initial model with a first sample set, the first sample set including: and for each sub-period, the sample ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in the first sample signal in the sub-period, and the symbol modulation mode of the first sample signal.
3. The method according to claim 1 or 2, wherein the calculating, for each sub-period included in the period, a ratio of amplitudes of frequency-domain symbols located on each adjacent subcarrier in the demodulated signal within the sub-period comprises:
determining each physical resource block PRB in the demodulation signal;
and calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in each PRB in each sub-time period contained in the time period in the sub-time period.
4. The method according to claim 3, wherein the calculating, for each sub-period included in the time period, a ratio of amplitudes of frequency-domain symbols located on each adjacent subcarrier in each PRB in the sub-period comprises:
determining PRBs occupied by signals in each PRB as occupied resource blocks;
and calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in each occupied resource block in each sub-time period contained in the time period in the sub-time period.
5. The method according to claim 4, wherein the determining the PRBs occupied by the signal in each PRB as occupied resource blocks comprises:
inputting each PRB into a pre-trained resource block occupation detection model, and determining occupied resource blocks;
the resource block occupation detection model comprises the following steps: a model obtained by training a second initial model by using a second sample set and used for detecting whether the PRB is occupied by a signal, wherein the second sample set comprises: and marking whether the sample PRB is occupied or not.
6. An apparatus for detecting a symbol modulation scheme in an OFDM system, the apparatus comprising:
the signal acquisition module is used for acquiring signals transmitted within a time period of preset duration from the signals transmitted by the channel as signals to be detected;
the signal demodulation module is used for carrying out Orthogonal Frequency Division Multiplexing (OFDM) demodulation on the signal to be detected to obtain a demodulated signal;
a ratio calculation module, configured to calculate, for each sub-period included in the period, a ratio of an amplitude of a frequency domain symbol located on each adjacent subcarrier in the demodulated signal in the sub-period; the demodulation signal is kept unchanged in each sub-period;
and the modulation mode detection module is used for detecting the symbol modulation mode of the signal to be detected according to each calculated ratio.
7. The apparatus of claim 6, wherein the modulation scheme detection module is specifically configured to:
inputting each calculated ratio into a pre-trained modulation mode detection model to obtain a symbol modulation mode of the signal to be detected;
the modulation mode detection model is as follows: a model for detecting a symbol modulation scheme of a signal, obtained by training a first initial model with a first sample set, the first sample set including: and for each sub-period, the sample ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in the first sample signal in the sub-period, and the symbol modulation mode of the first sample signal.
8. The apparatus of claim 6 or 7, wherein the ratio calculation module comprises:
a physical resource block determining submodule: for determining each physical resource block, PRB, in the demodulated signal;
a ratio operator module: and the method is used for calculating the ratio of the amplitude of the frequency domain symbol positioned on each adjacent subcarrier in each PRB in each sub-time period contained in the time period within the sub-time period.
9. An electronic device is characterized by comprising a processor, a communication interface, a memory and a communication bus, wherein the processor and the communication interface are used for realizing mutual communication by the memory through the communication bus;
a memory for storing a computer program;
a processor for implementing the method steps of any one of claims 1 to 5 when executing a program stored in the memory.
10. A computer-readable storage medium, characterized in that a computer program is stored in the computer-readable storage medium, which computer program, when being executed by a processor, carries out the method steps of any one of the claims 1-5.
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| US9794093B1 (en) * | 2017-02-08 | 2017-10-17 | Harris Corporation | Passive classification of radio frequency signals |
| CN107454032A (en) * | 2017-09-02 | 2017-12-08 | 中国人民解放军国防科技大学 | OFDM frequency offset estimation method based on amplitude product between subcarriers |
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