Joint time-frequency domain equalization method under PSK and QAM modulation

Abstract

The application provides a joint time-frequency domain equalization method under PSK and QAM modulation, which comprises the following steps: receiving an initial signal, sampling, obtaining an initial head scattered pilot, processing the initial head scattered pilot, realizing time domain cross-correlation and autocorrelation, respectively performing fast Fourier transform on a first processed signal and a second processed signal to obtain a third processed signal and a fourth processed signal, taking the third processed signal as a numerator and the fourth processed signal as a denominator to obtain a channel estimation frequency response, estimating a signal-to-noise ratio of the second processed signal to obtain a signal-to-noise ratio curve, calculating a signal-to-noise ratio estimation value according to a peak value in the signal-to-noise ratio curve and data variance calculated according to other data, combining the channel estimation frequency response to obtain a frequency domain equalization coefficient, processing second data and a tail scattered pilot in the initial signal to obtain a fifth processed signal, and combining the frequency domain equalization coefficient to obtain a time domain signal.

Description

Technical Field

[0001] This application relates to the field of single-carrier equalization technology, specifically to a joint time-frequency domain equalization method under PSK and QAM modulation. Background Technology

[0002] With the continuous expansion of wireless communication application scenarios, long-distance networking communication has become a key application of wireless communication. Its main characteristics are long transmission distance, limited transmission power, extremely high receiver sensitivity, and complex operating environment. In order to improve its reliability, long-distance networking communication usually adopts PSK (Phase Shift Keying) or QAM (Quadrature Amplitude Modulation) modulation methods. However, under low signal-to-noise ratio, some noise exists in the transmission environment, which causes the signal to be interfered with during transmission, that is, there is a serious inter-symbol interference problem. As a result, traditional single-carrier equalization technology cannot work properly under PSK or QAM modulation methods, ultimately causing the signal received by the receiver to be inconsistent with the signal transmitted by the transmitter. Summary of the Invention

[0003] The purpose of this application is to address the above problems by providing a joint time-frequency domain equalization method under PSK and QAM modulation, including:

[0004] Receive an initial signal, the initial signal including bit synchronization information, the bit synchronization information being used to characterize the start and end markers of data bits in the initial signal;

[0005] At each first preset time interval, the initial signal is sampled according to the bit synchronization information;

[0006] Based on the bit synchronization information, obtain the first data stored locally, the first data including the initial header dispersion pilot;

[0007] The initial head-dispersive pilot is subjected to a first processing to obtain a first processed signal, so as to realize the time-domain cross-correlation of the initial head-dispersive pilot;

[0008] The initial head-dispersive pilot is subjected to a second processing to obtain a second processed signal, thereby realizing the time-domain autocorrelation of the initial head-dispersive pilot;

[0009] The frequency domain equalization coefficient is calculated based on the first processed signal and the second processed signal;

[0010] The initial signal also includes second data and tail-dispersed pilot. A fast Fourier transform is performed on the second data and the tail-dispersed pilot to obtain the fifth processed signal.

[0011] Calculate the product of the fifth processed signal and the frequency domain equalization coefficient, perform an inverse fast Fourier transform, and extract the first Nd symbols to obtain the time domain signal after single-carrier equalization, where Nd represents the number of symbols of the second data.

[0012] According to the technical solution provided in the embodiments of this application, the method further includes:

[0013] Obtain the length of the first sequence corresponding to the initial head dispersion pilot;

[0014] The first processing of the initial head-dispersed pilot to obtain a first processed signal includes:

[0015] When it is determined that the length of the first sequence conforms to the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the initial head-dispersed pilot to obtain the first signal;

[0016] If the length of the first sequence does not conform to the Fast Fourier Transform rule, the length of the first sequence is padded and a Fast Fourier Transform is performed to obtain the first signal.

[0017] The initial signal also includes a head-dispersion pilot, and the second sequence length corresponding to the head-dispersion pilot is obtained;

[0018] When it is determined that the length of the second sequence conforms to the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the head-dispersed pilot to obtain the second signal;

[0019] If the length of the second sequence does not conform to the Fast Fourier Transform, the length of the second sequence is padded and a Fast Fourier Transform is performed to obtain the second signal;

[0020] The first signal and the second signal are multiplied by their conjugate to obtain the third signal;

[0021] The third signal is subjected to a fast Fourier inverse transform to obtain the first processed signal.

[0022] According to the technical solution provided in the embodiments of this application, the method further includes:

[0023] Obtain the first signal and the third signal;

[0024] The second processing of the initial head-dispersed pilot signal to obtain a second processed signal includes:

[0025] The fourth signal is obtained by multiplying the first signal and the third signal.

[0026] The fourth signal is subjected to a fast Fourier inverse transform to obtain the second processed signal.

[0027] According to the technical solution provided in the embodiments of this application, the method further includes:

[0028] The step of calculating the frequency domain equalization coefficient based on the first processed signal and the second processed signal specifically includes:

[0029] Perform a Fast Fourier Transform on the first processed signal to obtain a third processed signal; perform a Fast Fourier Transform on the second processed signal to obtain a fourth processed signal;

[0030] Using the third processed signal as the numerator and the fourth processed signal as the denominator, the estimated channel frequency response is calculated.

[0031] The signal-to-noise ratio (SNR) of the second processed signal is estimated to obtain the SNR curve;

[0032] Based on the signal-to-noise ratio curve, the peak value is obtained, and the data variance of other data besides the peak value is calculated.

[0033] The signal-to-noise ratio estimate is calculated by using the square of the peak value as the numerator and the variance of the data as the denominator.

[0034] The frequency domain equalization coefficients are calculated based on the estimated channel frequency response and the estimated signal-to-noise ratio.

[0035] According to the technical solution provided in the embodiments of this application, the method further includes:

[0036] Obtain the length of the third sequence corresponding to the first processed signal;

[0037] Perform a Fast Fourier Transform on the first processed signal to obtain a third processed signal, including:

[0038] When it is determined that the length of the third sequence satisfies the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the first processed signal to obtain the third processed signal;

[0039] If the length of the third sequence does not meet the Fast Fourier Transform rule, the third sequence is padded and subjected to Fast Fourier Transform to obtain the third processed signal.

[0040] According to the technical solution provided in the embodiments of this application, the method further includes:

[0041] Obtain the length of the fourth sequence corresponding to the second processed signal;

[0042] Perform a Fast Fourier Transform on the second processed signal to obtain a fourth processed signal, including:

[0043] When it is determined that the length of the fourth sequence satisfies the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the second processed signal to obtain the fourth processed signal;

[0044] If the length of the fourth sequence does not meet the Fast Fourier Transform rule, the length of the fourth sequence is padded and a Fast Fourier Transform is performed to obtain the fourth processed signal.

[0045] According to the technical solution provided in the embodiments of this application, the method further includes:

[0046] The channel estimation frequency response is conjugate-processed to obtain a first value;

[0047] The step of calculating the frequency domain equalization coefficient based on the estimated channel frequency response and the estimated signal-to-noise ratio includes:

[0048] The second value is obtained by multiplying the estimated channel frequency response by the first value.

[0049] The third value is obtained by summing the second value with the estimated signal-to-noise ratio value.

[0050] The frequency domain equalization coefficient is obtained by multiplying the first value as the numerator and the third value as the denominator.

[0051] According to the technical solution provided in the embodiments of this application, the method further includes:

[0052] Obtain the fifth sequence length of the second data and the sixth sequence length of the tail-dispersed pilot;

[0053] Perform a Fast Fourier Transform on the second data and the tail-dispersed pilot to obtain a fifth processed signal, including:

[0054] The length of the seventh sequence is obtained by summing the length of the fifth sequence and the length of the sixth sequence.

[0055] When it is determined that the length of the seventh sequence satisfies the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the second data and the tail-dispersed pilot to obtain the fifth processed signal;

[0056] If the length of the seventh sequence does not meet the Fast Fourier Transform rule, the length of the seventh sequence is padded and a Fast Fourier Transform is performed to obtain the fifth processed signal.

[0057] Compared with the prior art, the beneficial effects of this application are as follows: This application receives an initial signal with bit synchronization information, and samples the initial signal according to the bit synchronization information at a first preset time interval, and obtains the first data including the initial header dispersion pilot stored locally. The initial header dispersion pilot is subjected to a first processing to achieve time-domain cross-correlation, and the initial header dispersion pilot is subjected to a second processing to achieve time-domain autocorrelation. The frequency domain equalization coefficient is calculated based on the first and second processed signals. The second data and the tail dispersion pilot in the initial signal are subjected to a fast Fourier transform to obtain a fifth processed signal. The product of the fifth processed signal and the frequency domain equalization coefficient is calculated, and an inverse fast Fourier transform is performed. The first Nd symbols are truncated to obtain the time domain signal after single-carrier equalization, where Nd represents the number of symbols of the second data.

[0058] During use, an initial signal is first received, sampled, and first data identical to the initial signal is obtained based on bit synchronization information. The initial header dispersed pilot in the first data is processed in the first process to achieve time-domain cross-correlation. The initial header dispersed pilot is processed in the second process to achieve time-domain autocorrelation. The third processed signal is used as the numerator, and the frequency domain equalization coefficient is calculated based on the first and second processed signals. The second data and the tail dispersed pilot in the initial signal are subjected to a fast Fourier transform to obtain a fifth processed signal. The product of the fifth processed signal and the frequency domain equalization coefficient is calculated, and an inverse fast Fourier transform is performed. The first Nd symbols are truncated to obtain the time-domain signal after single-carrier equalization. The signal obtained at this time is consistent with the signal transmitted by the transmitter.

[0059] This application extracts bit synchronization information from the initial signal, ensuring that the receiver can accurately sample at the beginning and end of data bits, thus guaranteeing signal integrity. By performing a series of processes on the initial header pilot, including time-domain cross-correlation and autocorrelation, as well as Fast Fourier Transform, channel estimation frequency response and signal-to-noise ratio (SNR) estimates are obtained. These processes help extract and utilize information from the signal and improve the quality of the estimated signal. When calculating the equalization coefficients, they help adjust the signal in the frequency domain to eliminate or reduce the impact of channel distortion. A Fast Fourier Transform is performed on the fifth signal, and the first Nd symbols are truncated to obtain the time-domain signal after single-carrier equalization. This process converts the fifth processed signal from the frequency domain to the time domain, further optimizing the received signal quality. Simultaneously, by performing time-domain correlation on the received initial signal, this application obtains correlation gain, which can be used to improve the detection SNR, ensuring more accurate estimation of channel parameters in low SNR environments and guaranteeing the consistency between the signal received by the receiver and the signal transmitted by the transmitter. Attached Figure Description

[0060] Figure 1A flowchart of a joint time-frequency domain equalization method under PSK and QAM modulation provided in an embodiment of this application;

[0061] Figure 2 A signal structure diagram of a joint time-frequency domain equalization method under PSK and QAM modulation provided in an embodiment of this application;

[0062] Figure 3 A constellation diagram before equalization in a multipath channel under BPSK modulation, provided as an embodiment of this application, for a joint time-frequency domain equalization method under PSK and QAM modulation.

[0063] Figure 4 A simulation diagram of the constellation diagram after equalization in a multipath channel under BPSK modulation, provided by an embodiment of this application, for a joint time-frequency domain equalization method under PSK and QAM modulation.

[0064] Figure 5 The simulation comparison results of the bit error rate before and after equalization in a multipath channel under BPSK modulation using a joint time-frequency domain equalization method under PSK and QAM modulation provided in the embodiments of this application. Detailed Implementation

[0065] To enable those skilled in the art to better understand the technical solution of this application, the application will be described in detail below with reference to the accompanying drawings. The description in this section is only exemplary and explanatory, and should not be used to limit the scope of protection of this application.

[0066] Symbol crosstalk caused by frequency-selective fading due to multipath in wireless channels seriously affects the reliability of broadband wireless communication.

[0067] Single-carrier frequency domain equalization technology can effectively suppress frequency-selective fading and avoid the high complexity of single-carrier time domain equalization and the high peak-to-average power ratio of OFDM (Orthogonal Frequency Division Multiplexing) technology. Therefore, single-carrier frequency domain equalization technology has become a key technology in broadband wireless communication systems.

[0068] With the continuous expansion of wireless communication application scenarios, long-distance networking communication has become a key application of wireless communication. Its main characteristics are long transmission distance, limited transmission power, extremely high receiver sensitivity, and complex operating environment. In order to improve its reliability, long-distance networking communication usually adopts PSK (Phase Shift Keying) or QAM (Quadrature Amplitude Modulation) modulation methods. However, under low signal-to-noise ratio, some noise exists in the transmission environment, which causes the signal to be interfered with during transmission, that is, there is a serious inter-symbol interference problem. As a result, traditional single-carrier equalization technology cannot work properly under PSK or QAM modulation methods, ultimately causing the signal received by the receiver to be inconsistent with the signal transmitted by the transmitter.

[0069] Therefore, in order to overcome the problem that traditional single-carrier equalization techniques cannot function properly under low signal-to-noise ratio (SNR) PSK (Phase Shift Keying) or QAM (Quadrature Amplitude Modulation) modulation, this application provides a joint time-frequency domain equalization method for PSK and QAM modulation. By using joint time-frequency domain equalization techniques, the detection SNR is improved, ensuring the accuracy of parameter estimation under low SNR, and enabling reliable wireless transmission of PSK and QAM modulation in multipath environments (where interference exists in the transmission environment). That is, in such environments, the signal received by the receiver is consistent with the signal transmitted by the transmitter.

[0070] The joint time-frequency domain equalization method under PSK and QAM modulation provided in this application is as follows: Figure 1 As shown:

[0071] S1. Receive an initial signal, wherein the initial signal includes bit synchronization information, and the bit synchronization information is used to characterize the start and end markers of data bits in the initial signal;

[0072] S2. At each first preset time interval, the initial signal is sampled according to the bit synchronization information;

[0073] S3. Based on the bit synchronization information, obtain the first data stored locally, wherein the first data includes the initial head dispersion pilot;

[0074] S4. Perform a first processing on the initial head-dispersive pilot to obtain a first processed signal, so as to realize the time-domain cross-correlation of the initial head-dispersive pilot;

[0075] S5. Perform a second processing on the initial head-dispersive pilot to obtain a second processed signal, so as to realize the time-domain autocorrelation of the initial head-dispersive pilot;

[0076] Perform a Fast Fourier Transform on the first processed signal to obtain a third processed signal; perform a Fast Fourier Transform on the second processed signal to obtain a fourth processed signal;

[0077] Using the third processed signal as the numerator and the fourth processed signal as the denominator, the estimated channel frequency response is calculated.

[0078] The signal-to-noise ratio (SNR) of the second processed signal is estimated to obtain the SNR curve;

[0079] Based on the signal-to-noise ratio curve, the peak value is obtained, and the data variance of other data besides the peak value is calculated.

[0080] The signal-to-noise ratio estimate is calculated by using the square of the peak value as the numerator and the variance of the data as the denominator.

[0081] S6. Calculate the frequency domain equalization coefficient based on the estimated channel frequency response and the estimated signal-to-noise ratio.

[0082] S7. The initial signal also includes second data and tail-dispersed pilot. A fast Fourier transform is performed on the second data and the tail-dispersed pilot to obtain the fifth processed signal.

[0083] S8. Calculate the product of the fifth processed signal and the frequency domain equalization coefficient, and perform a fast Fourier transform to extract the first Nd symbols to obtain the time domain signal after single-carrier equalization, where Nd represents the number of symbols of the second data.

[0084] Specifically, in this embodiment, the receiving end first receives the initial signal emitted by the transmitting end, and the structure diagram of the initial signal is as follows. Figure 2 As shown, the initial signal includes bit synchronization information, a head scatter pilot, second data, and a tail scatter pilot. The bit synchronization information is used to characterize the start and end markers of the data bits in the initial signal. Every first preset time interval, the received initial signal is sampled according to the bit synchronization information, and the first data stored locally is obtained according to the bit synchronization information. The first data includes an initial head scatter pilot, such that the initial head scatter pilot in the first data is consistent with that in the initial signal. The initial head scatter pilot is subjected to a first processing to obtain a first processed signal, thereby realizing the time-domain cross-correlation of the initial head scatter pilot.

[0085] The expression for the initial signal after sampling is as follows:

[0086] r(n) = [C(n)] c1 t s -τ0) D(n d t s C(n)c2 t s -τ0)],n=0,1,...,N-1

[0087] Where: N is the total number of sampling points;

[0088] ts is the time-domain sampling interval, which is the first preset duration, and its value is the duration of a symbol;

[0089] C(n c1 t s ) represents n c1 t s Initial head-spread pilot at sampling time, n c1 =0,1,...,N c -1;

[0090] Nc represents the initial dispersed pilot length;

[0091] τ0 represents the initial phase of the head-spread pilot;

[0092] D(n d t s ) represents n d t s Data at sampling time n d =N c N c +1,...,N c +N d -1, where Nd represents the length of the second data;

[0093] C(n c2 t s ) represents n c2 t s Tail-dispersed pilot at sampling time, n c2 =N c +N d N c +N d +1,...,N-1.

[0094] Furthermore, the method also includes:

[0095] Obtain the length of the first sequence corresponding to the initial head dispersion pilot;

[0096] The first processing of the initial head-dispersed pilot to obtain a first processed signal includes:

[0097] When it is determined that the length of the first sequence conforms to the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the initial head-dispersed pilot to obtain the first signal;

[0098] If the length of the first sequence does not conform to the Fast Fourier Transform rule, the length of the first sequence is padded and a Fast Fourier Transform is performed to obtain the first signal.

[0099] The initial signal also includes a head-dispersion pilot, and the second sequence length corresponding to the head-dispersion pilot is obtained;

[0100] When it is determined that the length of the second sequence conforms to the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the head-dispersed pilot to obtain the second signal;

[0101] If the length of the second sequence does not conform to the Fast Fourier Transform, the length of the second sequence is padded and a Fast Fourier Transform is performed to obtain the second signal;

[0102] The first signal and the second signal are multiplied by their conjugate to obtain the third signal;

[0103] The third signal is subjected to a fast Fourier inverse transform to obtain the first processed signal.

[0104] Specifically, in this embodiment, the first processing of the initial head-spreading pilot to obtain a first processed signal, and the specific steps for realizing the time-domain cross-correlation of the initial head-spreading pilot, are as follows:

[0105] Obtain the length of the first sequence corresponding to the initial head-dispersed pilot, and determine whether the length of the first sequence satisfies the Fast Fourier Transform (FFT) rule. The FFT rule is that the length processed must be a multiple of N, that is, an integer power of 2 greater than the minimum length of the first sequence. If it does not satisfy the rule, the length of the first sequence needs to be padded. For example, if the length of the first sequence is 10, then the processing length of the FFT is 2. 4 That is, 16, which need to be padded with 6 zeros based on the length of the first sequence to satisfy the FFT processing rules; when it is determined that the length of the first sequence is a multiple of N, that is, when the fast Fourier transform rule is satisfied, the fast Fourier transform is directly performed on the initial head dispersed pilot to obtain the first signal;

[0106] When the length of the first sequence does not satisfy the Fast Fourier Transform (FFT) rule, it needs to be padded to satisfy the FFT rule to ensure the correctness and accuracy of the calculation. After padding, an FFT is performed on the padded initial head-dispersion pilot to obtain the first signal. The initial signal also includes the head-dispersion pilot. The second sequence length corresponding to the head-dispersion pilot is obtained, and it is determined whether the second sequence length satisfies the FFT rule. If the second sequence length satisfies the FFT rule, an FFT is directly performed on the head-dispersion pilot to obtain the second signal. If the second sequence length does not satisfy the FFT rule, it needs to be padded to satisfy the FFT rule, and an FFT is performed on the padded head-dispersion pilot to obtain the second signal. The first signal and the second signal are multiplied by their conjugates to obtain the first processed signal. The expression of the first processed signal is as follows:

[0107]

[0108] Where: r xx The result represents the cross-correlation in the time domain;

[0109] FFT(·) represents performing FFT processing on a time-domain signal; its FFT processing length is the smallest integer power of 2 greater than Nc;

[0110] IFFT(·) represents performing IFFT processing on a frequency domain signal;

[0111] (·)* indicates that the signal is conjugate;

[0112] This indicates the header dispersion pilot of the local storage.

[0113] After achieving the time-domain cross-correlation of the initial head-spreading pilot, a second processing step is required to obtain a second processed signal, which then achieves the time-domain autocorrelation of the initial head-spreading pilot. The expression for the second processed signal is as follows:

[0114]

[0115] In the formula: r xx This represents the time-domain autocorrelation result.

[0116] Furthermore, the first signal and the third signal are acquired;

[0117] The second processing of the initial head-dispersed pilot signal to obtain a second processed signal includes:

[0118] The fourth signal is obtained by multiplying the first signal and the third signal.

[0119] The fourth signal is subjected to a fast Fourier inverse transform to obtain the second processed signal.

[0120] Specifically, in this embodiment, the steps for implementing the time-domain autocorrelation of the initial head-dispersive pilot are as follows:

[0121] The first signal and the third signal are obtained, the product of the first signal and the third signal is calculated to obtain the fourth signal, and the fourth signal is subjected to a fast Fourier inverse transform to obtain the second processed signal, thereby realizing the time-domain autocorrelation of the head-dispersed pilot.

[0122] The specific steps for performing a Fast Fourier Transform on the first processed signal to obtain the third processed signal are as follows:

[0123] Furthermore, the method also includes:

[0124] Obtain the length of the third sequence corresponding to the first processed signal;

[0125] Perform a Fast Fourier Transform on the first processed signal to obtain a third processed signal, including:

[0126] When it is determined that the length of the third sequence satisfies the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the first processed signal to obtain the third processed signal;

[0127] If the length of the third sequence does not meet the Fast Fourier Transform rule, the third sequence is padded and subjected to Fast Fourier Transform to obtain the third processed signal.

[0128] Specifically, in this embodiment, the length of the third sequence corresponding to the first processed signal is first obtained, and it is determined whether the length of the third sequence satisfies the Fast Fourier Transform rule.

[0129] If the length of the third sequence satisfies the Fast Fourier Transform rule, then the first processed signal is directly subjected to Fast Fourier Transform to obtain the third processed signal.

[0130] If the length of the third sequence does not meet the Fast Fourier Transform (FFT) rules, it is necessary to pad the length of the third sequence to make it meet the FFT rules, and then perform a FFT on the padded first processed signal to obtain the third processed signal.

[0131] Its specific expression can be represented as follows:

[0132] R sx =FFT([rsx z i1 ])

[0133] Where: z i1 This represents the number of zeros used to fill the length of the third sequence.

[0134] Furthermore, the specific steps for performing a Fast Fourier Transform on the second processed signal to obtain the fourth processed signal are as follows:

[0135] Obtain the length of the fourth sequence corresponding to the second processed signal;

[0136] Perform a Fast Fourier Transform on the second processed signal to obtain a fourth processed signal, including:

[0137] When it is determined that the length of the fourth sequence satisfies the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the second processed signal to obtain the fourth processed signal;

[0138] If the length of the fourth sequence does not meet the Fast Fourier Transform rule, the length of the fourth sequence is padded and a Fast Fourier Transform is performed to obtain the fourth processed signal.

[0139] Specifically, in this embodiment, the length of the fourth sequence corresponding to the second processed signal is obtained, and it is determined whether the length of the fourth sequence satisfies the Fast Fourier Transform rule;

[0140] If the length of the fourth sequence satisfies the Fast Fourier Transform rule, then the second processed signal is directly subjected to Fast Fourier Transform to obtain the fourth processed signal;

[0141] If the length of the fourth sequence does not meet the Fast Fourier Transform (FFT) rules, it is necessary to pad the length of the fourth sequence to make it meet the FFT rules, and then perform a FFT on the padded second processed signal to obtain the fourth processed signal.

[0142] Its specific expression can be represented as follows:

[0143] R xx =FFT([r xx z i2 ])

[0144] Where: z i2 This represents the number of zeros used to fill the length of the third sequence.

[0145] Using the third processed signal as the numerator and the fourth processed signal as the denominator, the product yields the channel estimation frequency response Λ, the specific expression of which is as follows:

[0146] Λ=R sx / R xx .

[0147] By performing signal-to-noise ratio (SNR) estimation on the second processed signal, an SNR estimation curve can be obtained.

[0148] In the signal-to-noise ratio (SNR) estimation curve, the peak value is obtained and recorded as Asx. Simultaneously, the variance of all data points in the SNR curve other than the peak value is calculated and recorded as σ. sx And by solving for the square of the peak value, the signal-to-noise ratio (SNR) estimate can be obtained based on the peak value and the data variance, and its expression is as follows:

[0149]

[0150] Furthermore, the channel estimation frequency response is subjected to conjugate processing to obtain a first value;

[0151] The step of calculating the frequency domain equalization coefficient based on the estimated channel frequency response and the estimated signal-to-noise ratio includes:

[0152] The second value is obtained by multiplying the estimated channel frequency response by the first value.

[0153] The third value is obtained by summing the second value with the estimated signal-to-noise ratio value.

[0154] The frequency domain equalization coefficient is obtained by multiplying the first value as the numerator and the third value as the denominator.

[0155] Specifically, in this embodiment, the steps for calculating the frequency domain equalization coefficient H based on the estimated channel frequency response and the estimated signal-to-noise ratio are as follows:

[0156] The channel estimation frequency response is conjugate-processed to obtain a first value;

[0157] Then, the product of the first value and the estimated channel frequency response is calculated to obtain the second value. The sum of the second value and the estimated signal-to-noise ratio is calculated to obtain the third value. The frequency domain equalization coefficient is obtained by multiplying the first value as the numerator and the third value as the denominator. The specific expression is as follows:

[0158]

[0159] Where H represents the frequency domain equalization coefficient;

[0160] Λ * This represents the first value, which is the result after performing conjugate processing on the estimated frequency response of the channel.

[0161] Furthermore, the method also includes:

[0162] Obtain the fifth sequence length of the second data and the sixth sequence length of the tail-dispersed pilot;

[0163] Perform a Fast Fourier Transform on the second data and the tail-dispersed pilot to obtain a fifth processed signal, including:

[0164] The length of the seventh sequence is obtained by summing the length of the fifth sequence and the length of the sixth sequence.

[0165] When it is determined that the length of the seventh sequence satisfies the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the second data and the tail-dispersed pilot to obtain the fifth processed signal;

[0166] If the length of the seventh sequence does not meet the Fast Fourier Transform rule, the length of the seventh sequence is padded and a Fast Fourier Transform is performed to obtain the fifth processed signal.

[0167] Specifically, in this embodiment, the fifth sequence length of the second data and the sixth sequence length of the tail-dispersed pilot are obtained, the sum of the fifth sequence length and the sixth sequence length is calculated to obtain the seventh sequence length, and it is determined whether the seventh sequence length satisfies the Fast Fourier Transform rule. If the seventh sequence length satisfies the Fast Fourier Transform rule, the second data and the tail-dispersed pilot are directly subjected to Fast Fourier Transform, and the fifth processed signal is obtained.

[0168] If the length of the seventh sequence does not satisfy the Fast Fourier Transform (FFT) rule, the length of the seventh sequence needs to be padded to satisfy the FFT rule. Then, a FFT is performed on the second data after satisfying the FFT rule and the tail-dispersed pilot signal to obtain the fifth processed signal, which can be specifically expressed as follows:

[0169] R = FFT([rz) k ])

[0170] z k The number of zeros that fill the length of the seventh sequence;

[0171] r represents the second data after merging and the tail-dispersed pilot.

[0172] Specifically, the steps are as follows: calculate the product of the fifth processed signal and the frequency domain equalization coefficient, perform an inverse Fast Fourier Transform on the result of the product, and truncate the first Nd symbols of the result obtained after the inverse Fast Fourier Transform as the time domain signal after single-carrier equalization. The time-domain signal obtained at this time It is consistent with the signal emitted by the transmitting end, where Nd represents the number of symbols in the second data; its specific expression can be represented as follows:

[0173] r h =IFFT(R×H)

[0174]

[0175] r h This represents the result of performing a fast Fourier inverse transform on the product of the fifth processed signal and the frequency domain equalization coefficient.

[0176] like Figure 3 The image shown is a constellation diagram simulation diagram of the "joint time-frequency domain equalization method under PSK and QAM modulation" provided in the embodiments of this application, before equalization in a multipath channel under BPSK modulation.

[0177] like Figure 4 The image shown is a simulation diagram of the constellation after equalization in a multipath channel under BPSK modulation, based on the "joint time-frequency domain equalization method under PSK and QAM modulation" provided in this application embodiment. This is after comparison with... Figure 3 The comparison shows that the constellation chart was scattered before balancing, and was corrected to the correct position after balancing.

[0178] like Figure 5 The figure shows the simulation comparison results of the bit error rate before and after equalization of the "joint time-frequency domain equalization method under PSK and QAM modulation" provided in the embodiment of this application under BPSK modulation and multipath channel. The comparison shows that the bit error rate is extremely high before equalization, and the bit error rate is significantly reduced after equalization. The demodulation threshold is reduced by about 7dB compared with the theoretical bit error rate.

[0179] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. A joint time-frequency domain equalization method under PSK and QAM modulation, characterized in that, include: Receive an initial signal, the initial signal including bit synchronization information, the bit synchronization information being used to characterize the start and end markers of data bits in the initial signal; At each first preset time interval, the initial signal is sampled according to the bit synchronization information; Based on the bit synchronization information, obtain the first data stored locally, the first data including the initial header dispersion pilot; The initial head-dispersive pilot is subjected to a first processing to obtain a first processed signal, so as to realize the time-domain cross-correlation of the initial head-dispersive pilot; The initial head-dispersive pilot is subjected to a second processing to obtain a second processed signal, thereby realizing the time-domain autocorrelation of the initial head-dispersive pilot; The frequency domain equalization coefficient is calculated based on the first processed signal and the second processed signal; The initial signal also includes second data and tail-dispersed pilot. A fast Fourier transform is performed on the second data and the tail-dispersed pilot to obtain the fifth processed signal. Calculate the product of the fifth processed signal and the frequency domain equalization coefficient, perform an inverse fast Fourier transform, and extract the first Nd symbols to obtain the time domain signal after single-carrier equalization, where Nd represents the number of symbols of the second data.

2. The joint time-frequency domain equalization method under PSK and QAM modulation according to claim 1, characterized in that, The method further includes: Obtain the length of the first sequence corresponding to the initial head dispersion pilot; The first processing of the initial head-dispersed pilot to obtain a first processed signal includes: When it is determined that the length of the first sequence conforms to the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the initial head dispersed pilot to obtain the first signal; If the length of the first sequence does not conform to the Fast Fourier Transform rule, the length of the first sequence is padded and a Fast Fourier Transform is performed to obtain the first signal. The initial signal also includes a head-dispersion pilot, and the second sequence length corresponding to the head-dispersion pilot is obtained; When it is determined that the length of the second sequence conforms to the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the head-dispersed pilot to obtain the second signal; If the length of the second sequence does not conform to the Fast Fourier Transform, the length of the second sequence is padded and a Fast Fourier Transform is performed to obtain the second signal; The third signal is obtained by performing a conjugate multiplication of the first signal and the second signal. The third signal is subjected to a fast Fourier inverse transform to obtain the first processed signal.

3. The joint time-frequency domain equalization method under PSK and QAM modulation according to claim 2, characterized in that, The method further includes: Obtain the first signal and the third signal; The second processing of the initial head-dispersed pilot signal to obtain a second processed signal includes: The fourth signal is obtained by multiplying the first signal and the third signal. The fourth signal is subjected to a fast Fourier inverse transform to obtain the second processed signal.

4. The joint time-frequency domain equalization method under PSK and QAM modulation according to claim 1, characterized in that, The step of calculating the frequency domain equalization coefficient based on the first processed signal and the second processed signal specifically includes: Perform a Fast Fourier Transform on the first processed signal to obtain a third processed signal; perform a Fast Fourier Transform on the second processed signal to obtain a fourth processed signal. Using the third processed signal as the numerator and the fourth processed signal as the denominator, the estimated channel frequency response is calculated. The signal-to-noise ratio (SNR) of the second processed signal is estimated to obtain the SNR curve; Based on the signal-to-noise ratio curve, the peak value is obtained, and the data variance of other data besides the peak value is calculated. The signal-to-noise ratio estimate is calculated by using the square of the peak value as the numerator and the variance of the data as the denominator. The frequency domain equalization coefficients are calculated based on the estimated channel frequency response and the estimated signal-to-noise ratio.

5. The joint time-frequency domain equalization method under PSK and QAM modulation according to claim 4, characterized in that, The method further includes: Obtain the length of the third sequence corresponding to the first processed signal; Perform a Fast Fourier Transform on the first processed signal to obtain a third processed signal, including: When it is determined that the length of the third sequence satisfies the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the first processed signal to obtain the third processed signal; If the length of the third sequence does not meet the Fast Fourier Transform rule, the third sequence is padded and subjected to Fast Fourier Transform to obtain the third processed signal.

6. The joint time-frequency domain equalization method under PSK and QAM modulation according to claim 4, characterized in that, The method further includes: Obtain the length of the fourth sequence corresponding to the second processed signal; Perform a Fast Fourier Transform on the second processed signal to obtain a fourth processed signal, including: When it is determined that the length of the fourth sequence satisfies the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the second processed signal to obtain the fourth processed signal; If the length of the fourth sequence does not meet the Fast Fourier Transform rule, the length of the fourth sequence is padded and a Fast Fourier Transform is performed to obtain the fourth processed signal.

7. The joint time-frequency domain equalization method under PSK and QAM modulation according to claim 4, characterized in that, The method further includes: The channel estimation frequency response is conjugate-processed to obtain a first value; The step of calculating the frequency domain equalization coefficient based on the estimated channel frequency response and the estimated signal-to-noise ratio includes: The second value is obtained by multiplying the estimated channel frequency response by the first value. The third value is obtained by summing the second value with the estimated signal-to-noise ratio value. The frequency domain equalization coefficient is obtained by multiplying the first value as the numerator and the third value as the denominator.

8. The joint time-frequency domain equalization method under PSK and QAM modulation according to claim 1, characterized in that, The method further includes: Obtain the fifth sequence length of the second data and the sixth sequence length of the tail-dispersed pilot; Perform a Fast Fourier Transform on the second data and the tail-dispersed pilot to obtain a fifth processed signal, including: The length of the seventh sequence is obtained by summing the length of the fifth sequence and the length of the sixth sequence. When it is determined that the length of the seventh sequence satisfies the Fast Fourier Transform rule, a Fast Fourier Transform is performed on the second data and the tail-dispersed pilot to obtain the fifth processed signal; If the length of the seventh sequence does not meet the Fast Fourier Transform rule, the length of the seventh sequence is padded and a Fast Fourier Transform is performed to obtain the fifth processed signal.

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