Signal transmission method, system and device based on generalized chirp division multiplexing and medium

Abstract

The application discloses a signal transmission method, system, device and medium based on generalized chirp sub-multiplexing, which uses a specific pulse shaping window for each chirp sub-carrier at the sending end and uses a matching filter window for each chirp matching sub-carrier at the receiving end, so as to suppress the fractional time delay and fractional Doppler effect introduced by the double dispersion channel in the communication system, that is, the diffusion of the received symbol, improve the sparsity of the equivalent channel of the system, and greatly reduce the interference between the symbols received by the communication receiving end. The diffusion degree of the received pilot symbol for channel estimation is slowed down, so that the channel estimation is more accurate, the number of guard symbols required by the sending end is reduced, the reachable capacity of the communication system is improved, the equivalent channel is more sparse, the interference between the pilot symbol and the data symbol of the receiving end is reduced, the pilot-data separation of the system is higher, and both of them make the signal detection complexity of the communication system lower and the detection effect better.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and more specifically, to a signal transmission method, system, device, and medium based on generalized chirp multiplexing. Background Technology

[0002] Pulse shaping is a crucial part of communication systems, determining the time and frequency resources used and reflecting the interference between users occupying adjacent time and frequency resources under that modulation scheme. Traditional pseudo-RF multiplexing systems do not perform specific pulse shaping, resulting in problems such as low channel estimation accuracy, high overhead, and high signal detection complexity in real-world fast-changing channel scenarios. Summary of the Invention

[0003] To overcome the above-mentioned defects, this invention provides a signal transmission method, system, device, and medium based on generalized chirped multiplexing, which improves the sparsity of the equivalent channel of the system and greatly reduces the interference between symbols received by the communication receiver.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0005] This invention provides a signal transmission method based on generalized chirped multiplexing, the method comprising:

[0006] Acquire several discrete pulse shaping windows, discrete matched filter windows, discrete chirped subcarriers, and information symbols to be transmitted;

[0007] The transmission time-domain signal is generated based on several discrete pulse shaping windows, discrete chirped subcarriers, and the information symbols to be transmitted;

[0008] A cyclic prefix is ​​added before the transmitted time domain signal and up-conversion processing is performed. The processed transmitted time domain signal is transmitted to the receiving end through a dual-dispersion wireless channel to obtain the first received time domain signal.

[0009] The received time-domain signal is down-converted and the cyclic prefix is ​​removed, and then filtered using a discrete matched filter window to obtain the second received time-domain signal.

[0010] Preferably, the method further includes:

[0011] The filtered second received time-domain signal is converted and calculated to obtain the demodulated received time-domain signal.

[0012] Preferably, the transmission of the time-domain signal specifically includes:

[0013]

[0014] Where t is a continuous time variable; m is the subcarrier index; For the pulse shaping window acting on the m-th chirped subcarrier; φ m (t) is the time delay form of the m-th subcarrier.

[0015] Preferably, the dual-dispersion wireless channel specifically comprises:

[0016]

[0017] Among them, h i τ is the fading coefficient of the i-th path segment; i v is the time delay of the i-th path segment; i δ(t) represents the Doppler frequency shift of the i-th path segment; δ(t) is the Dirichlet function.

[0018] Preferably, after the transmitted time-domain signal is transmitted through the dual-dispersion wireless channel to the receiving end, the receiving end first extracts the received time-domain signal from the frequency band corresponding to the transmitted time-domain signal, performs down-conversion on the received time-domain signal to obtain the baseband received time-domain signal, and removes the cyclic prefix. The second received time-domain signal is specifically:

[0019]

[0020] Where r(t) is the second received time-domain signal; w time (t) is the received time-domain Gaussian white noise; τ i v is the time delay of the i-th path segment; i Let be the Doppler frequency shift of the i-th path segment, (.) T This represents a modulo-T operation, where j is the first parameter and t represents the time variable.

[0021] Preferably, the demodulated received time-domain signal is specifically:

[0022]

[0023] Among them, w chirp [m] represents chirp domain noise; ε i (m,m′) is a complex exponential factor; For the integrated pulse shaping window; For pulse shaping window; For the matched filter window; N is the number of subcarriers; m′ is the transmit subcarrier index; m is the receive subcarrier index; c1 is the slope of the digital chirp signal; c2 is the auxiliary phase of the chirp signal; Δt is the sampling interval; T is the total duration of the transmitted signal; l i The integer part of the normalized delay in the digital field; ι i For the fractional part of the normalized delay in the digital domain, (.) N This represents a modulo N operation.

[0024] The present invention also provides a signal transmission system based on generalized chirp multiplexing for implementing the above method, the system comprising:

[0025] The data acquisition module acquires the discrete pulse shaping window, the discrete matched filter window, several discrete chirped subcarriers, and the information symbols to be transmitted;

[0026] The signal generation module generates a transmission time-domain signal based on a discrete pulse shaping window, several discrete chirped subcarriers, and the information symbols to be transmitted.

[0027] The signal transmission module adds a cyclic prefix to the transmitted time domain signal and performs up-conversion processing, then transmits the processed transmitted time domain signal to the receiving end through a dual-dispersion wireless channel to obtain the first received time domain signal.

[0028] The signal processing module performs down-conversion processing on the received time-domain signal, removes the cyclic prefix, and then performs filtering processing using a discrete matched filter window to obtain the second received time-domain signal.

[0029] Preferably, the system further includes:

[0030] The signal demodulation module performs conversion calculations on the filtered second received time-domain signal to obtain the demodulated received time-domain signal.

[0031] The present invention also provides an electronic device, comprising:

[0032] One or more processors;

[0033] Memory, used to store one or more programs;

[0034] When the one or more programs are executed by the one or more processors, the processors implement the methods described above.

[0035] The present invention also provides a computer-readable storage medium containing a computer program, wherein the computer program is stored thereon and, when executed by one or more processors, implements the above-described method.

[0036] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0037] This invention suppresses the fractional delay and fractional Doppler effect (i.e., the spread of received symbols) introduced by the dual-dispersion channel in the communication system by using specific pulse shaping windows for each chirped subcarrier at the transmitting end and matched filtering windows for each chirped matched subcarrier at the receiving end. This improves the sparsity of the equivalent channel and significantly reduces interference between symbols received at the communication receiver. The reduced spread of received pilot symbols used for channel estimation makes channel estimation more accurate, reduces the number of guard symbols required at the transmitting end, and increases the achievable capacity of the communication system. The sparser equivalent channel and reduced interference between pilot and data symbols at the receiving end result in higher pilot-data separation of the system. Both of these factors contribute to lower signal detection complexity and better detection performance in the communication system. Attached Figure Description

[0038] Figure 1 This is a flowchart of the signal transmission method based on generalized chirped multiplexing described in Example 1;

[0039] Figure 2 This is a flowchart of the signal transmission method based on generalized chirped multiplexing described in Example 2;

[0040] Figure 3 This is a schematic diagram of the time-frequency distribution of the chirped subcarriers described in Example 2;

[0041] Figure 4 The flowchart shows the high robustness and low complexity implementation of the signal transmission method based on generalized chirped multiplexing described in Example 3.

[0042] Figure 5 The flowchart shows the extremely low-complexity implementation of the signal transmission method based on generalized chirped multiplexing described in Example 3.

[0043] Figure 6 This is a schematic diagram of the signal transmission system based on generalized chirped multiplexing described in Example 4;

[0044] Figure 7 This is a schematic diagram illustrating the effect of different transmission pulse shaping window spacing factors on the pilot energy leakage ratio as described in Example 4.

[0045] Figure 8 This is a schematic diagram illustrating the effect of the signal-to-noise ratio under different transmit pulse shaping windows on the normalized mean square error of the estimated equivalent channel matrix, as described in Example 4. Detailed Implementation

[0046] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent.

[0047] To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions;

[0048] It will be understood by those skilled in the art that certain well-known structures and their descriptions may be omitted in the accompanying drawings.

[0049] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0050] Example 1

[0051] This embodiment provides a signal transmission method based on generalized chirped multiplexing, such as... Figure 1 As shown, the method includes:

[0052] Acquire several discrete pulse shaping windows, discrete matched filter windows, discrete chirped subcarriers, and information symbols to be transmitted;

[0053] The transmission time-domain signal is generated based on several discrete pulse shaping windows, discrete chirped subcarriers, and the information symbols to be transmitted;

[0054] A cyclic prefix is ​​added before the transmitted time domain signal and up-conversion processing is performed. The processed transmitted time domain signal is transmitted to the receiving end through a dual-dispersion wireless channel to obtain the first received time domain signal.

[0055] The received time-domain signal is down-converted and the cyclic prefix is ​​removed, and then filtered using a discrete matched filter window to obtain the second received time-domain signal.

[0056] The working principle of this embodiment is as follows: N quadrature amplitude modulation (QAM) information symbols are modulated onto discrete chirped subcarriers under the action of N discrete pulse shaping windows. These are then summed, a cyclic prefix is ​​added, and the signal is converted from digital to analog using a common filter to obtain a continuous transmit signal. This signal is then up-converted after passing through a bandwidth-limiting filter and finally transmitted into the channel. At the receiving end, the received continuous time-domain signal is first down-converted, then subjected to equal-interval sampling analog-to-digital conversion, the cyclic prefix is ​​removed, multiplied by a discrete matched filter window, and then multiplied by the corresponding discrete conjugate chirped subcarrier. The resulting discrete sequence is summed to obtain the demodulated received information symbols, which are then subjected to traditional channel estimation and signal detection.

[0057] Example 2

[0058] This embodiment provides a signal transmission method based on generalized chirped multiplexing, the method comprising:

[0059] Acquire several discrete pulse shaping windows, discrete matched filter windows, discrete chirped subcarriers, and information symbols to be transmitted;

[0060] The transmission time-domain signal is generated based on several discrete pulse shaping windows, discrete chirped subcarriers, and the information symbols to be transmitted;

[0061] A cyclic prefix is ​​added before the transmitted time domain signal and up-conversion processing is performed. The processed transmitted time domain signal is transmitted to the receiving end through a dual-dispersion wireless channel to obtain the first received time domain signal.

[0062] The received time-domain signal is down-converted and the cyclic prefix is ​​removed, and then filtered using a discrete matched filter window to obtain the second received time-domain signal.

[0063] The method further includes:

[0064] The filtered second received time-domain signal is converted and calculated to obtain the demodulated received time-domain signal.

[0065] like Figure 2 As shown, suppose x is a vector of information symbols to be transmitted, consisting of N quadrature amplitude modulation (QAM) information symbols. The transmitter first modulates these N information symbols x[m], m=0,...,N-1 onto N chirped subcarriers using shaping windows. Its mathematical expression is:

[0066]

[0067] Where t is a continuous time variable; m is the subcarrier index; For the pulse shaping window acting on the m-th chirped subcarrier; φ m (t) is the time delay form of the m-th subcarrier.

[0068] Where s(t) represents the transmitted time-domain signal, t represents a continuous time variable, and m = 0, ..., N-1 represents the subcarrier index. It acts on the m-th chirped subcarrier φ m The pulse shaping window on (t), φ m (t) represents the time delay of the m-th subcarrier, specifically expressed as:

[0069]

[0070] The subcarrier segmentation time point, Δt is the sampling interval, and T = NΔt is the total duration of the transmitted signal. c1 and c2 are two fundamental parameters of a generalized chirped multiplexing system. Parameter c1 is the slope of the digital chirped signal, and its value satisfies the following conditions: is a positive integer; parameter c2 is the auxiliary phase of the chirped signal, and its value is unrestricted; N is the number of subcarriers, m′ and m are the transmit and receive subcarrier indices respectively; c1 and c2 are two fundamental parameters of the generalized chirped multiplexing system; parameter c1 is the slope of the digital chirped signal, and its value satisfies It is a positive integer, parameter c2 is the auxiliary phase of the chirped signal, and its value is unrestricted. Δt is the sampling interval, T = NΔt is the total duration of the transmitted signal, and q is the segment index.

[0071] like Figure 3 As shown, a graph illustrating the time-frequency distribution of chirped subcarriers is presented, with the vertical axis variable f representing frequency. C=3. It can be seen that the bandwidth occupied by the chirped subcarrier is... Its instantaneous frequency increases linearly with time. When its instantaneous frequency reaches B, it jumps to 0 at the next moment, and then continues to increase linearly with time, repeating this cycle until the total signal duration T. Before transmitting to the channel, a duration of l needs to be added before the transmitted time-domain signal s(t). max The cyclic prefix of Δt, where l is max The maximum normalized delay spread of the channel is calculated by dividing the maximum delay spread of the channel by Δt and then rounding up. After adding the cyclic prefix, the baseband transmitted signal is filtered to limit the signal bandwidth, and then up-converted to shift the baseband signal to the target frequency band before transmission.

[0072] The dual-dispersion wireless channel is modeled in the time-delay-Doppler domain as follows:

[0073]

[0074] Among them, h i τ is the fading coefficient of the i-th path segment; i v is the time delay of the i-th path segment; i δ(t) represents the Doppler frequency shift of the i-th path segment; δ(t) is the Dirichlet function. and It is the digital domain normalized time delay and normalized Doppler frequency shift sum, l i and k i Represents the integer part, ι i and Represents the fractional part.

[0075] After the transmitted time-domain signal is transmitted through the dual-dispersion wireless channel to the receiving end, the receiving end first extracts the received time-domain signal from the frequency band corresponding to the transmitted time-domain signal, performs down-conversion on the received time-domain signal to obtain the baseband received time-domain signal, and removes the cyclic prefix. The second received time-domain signal is specifically:

[0076]

[0077] Where r(t) is the second received time-domain signal; w time (t) is the received time-domain Gaussian white noise; τ i v is the time delay of the i-th path segment;i Let be the Doppler frequency shift of the i-th path segment, (.) T This represents a modulo-T operation, where j is the first parameter and t represents the time variable.

[0078] Preferably, the demodulated received time-domain signal is specifically:

[0079]

[0080] Among them, w chir [m] represents chirp domain noise; ε i (m,m′) is a complex exponential factor; For the integrated pulse shaping window; For pulse shaping window; For the matched filter window; N is the number of subcarriers; m′ is the transmit subcarrier index; m is the receive subcarrier index; c1 is the slope of the digital chirp signal; c2 is the auxiliary phase of the chirp signal; Δt is the sampling interval; T is the total duration of the transmitted signal; l i The integer part of the normalized delay in the digital field; ι i For the fractional part of the normalized delay in the digital domain, (.) N This represents a modulo N operation.

[0081] in, It is chirp domain noise, and its statistical properties depend on the matched filter window used.

[0082]

[0083] gather The symbol indicates rounding down; N is the number of subcarriers, m′ and m are the transmit and receive subcarrier indices respectively, and parameter c1 is the slope of the digital chirp signal, whose value satisfies It is a positive integer, l i and ι i These are the integer and fractional parts of the normalized delay in the digital field, respectively. i and κ i These are the integer and fractional parts of the normalized Doppler in the digital field, respectively. Discrete functions... Defined as:

[0084]

[0085] Discrete function Defined as:

[0086]

[0087] The formula reveals that the effects of pulse shaping windows and matched filtering windows in generalized chirp demultiplexing are manifested in the integrated pulse shaping window.

[0088] The matrix representation of the formula is as follows:

[0089]

[0090] Where the matrix It is the equivalent channel matrix of a generalized chirped multiplexing system, with a size of N×N, and matrix H. i It is the sub-channel matrix corresponding to the i-th path, with a size of N×N; vector x=[x[0],...,x[N-1]] T It is the vector of transmitted information symbols from the sending end, with a size of N×1; vector y = [y[0],...,y[N-1]]. T is the received information symbol vector at the receiver, with a size of N×1. The operator T denotes transpose; w is the chirped domain noise vector, with a size of N×1. From the formula, we can see that matrix H... i The value of satisfies

[0091]

[0092] Where the factor ε i (m,m′) and factors The expression is shown in the formula. Due to the factor ε i (m,m′) is a complex exponent, so its absolute value is 1, therefore we have Observe the factors in the formula It takes the form of the classic discrete Fourier transform, i.e., |H i The values ​​of [m,m′]| are discrete sequences. The first discrete Fourier transform The amplitude of each value. Therefore, by the pulse shaping window and matched filter window The resulting integrated pulse shaping window Decision made | H i The energy distribution of [m,m′]| can be chosen such that |H i The energy concentration distribution of [m,m′]| and Further let the equivalent channel matrix H eff More sparse.

[0093] Specifically, the generalized chirped multiplexing system proposed in this patent has N pulse shaping windows at the transmitting end. N matched filter windows at the receiving end The choice of is not restricted; the above formula derivation and conclusions apply to any pulse shaping window and matched filter window, such as rectangular windows, Hamming windows, Dolph-Chebyshev windows, raised cosine windows, Gaussian windows, etc. It can be observed that when... When all B pulse shaping windows and N matched filter windows are identical rectangular windows, the generalized chirped demultiplexing system is essentially a traditional analog RF demultiplexing system. Therefore, the traditional analog RF demultiplexing system is a simple special case of the generalized chirped demultiplexing system proposed in this patent. Subsequent detailed implementations will provide the performance of windows with superior performance beyond rectangular waves.

[0094] Example 3

[0095] This embodiment provides a signal transmission method based on generalized chirped multiplexing, the method comprising:

[0096] Acquire several discrete pulse shaping windows, discrete matched filter windows, discrete chirped subcarriers, and information symbols to be transmitted;

[0097] The transmission time-domain signal is generated based on several discrete pulse shaping windows, discrete chirped subcarriers, and the information symbols to be transmitted;

[0098] A cyclic prefix is ​​added before the transmitted time domain signal and up-conversion processing is performed. The processed transmitted time domain signal is transmitted to the receiving end through a dual-dispersion wireless channel to obtain the first received time domain signal.

[0099] The received time-domain signal is down-converted and the cyclic prefix is ​​removed, and then filtered using a discrete matched filter window to obtain the second received time-domain signal.

[0100] The method further includes:

[0101] The filtered second received time-domain signal is converted and calculated to obtain the demodulated received time-domain signal.

[0102] Suppose x is a vector of information symbols to be transmitted, consisting of N quadrature amplitude modulation (QAM) information symbols. The transmitter first divides these N information symbols x[m], m=

[0103] The modulation of 0,...,N-1 onto N chirped subcarriers using shaping windows can be mathematically expressed as follows:

[0104]

[0105] Where t is a continuous time variable; m is the subcarrier index; For the pulse shaping window acting on the m-th chirped subcarrier; φ m (t) is the time delay form of the m-th subcarrier.

[0106] Where s(t) represents the transmitted time-domain signal, t represents a continuous time variable, and m = 0, ..., N-1 represents the subcarrier index. It acts on the m-th chirped subcarrier φ m The pulse shaping window on (t), φ m (t) represents the time delay of the m-th subcarrier, specifically expressed as:

[0107]

[0108] t m,q The subcarrier segmentation time point, Δt is the sampling interval, and T = NΔt is the total duration of the transmitted signal. c1 and c2 are two fundamental parameters of a generalized chirped multiplexing system. Parameter c1 is the slope of the digital chirped signal, and its value satisfies the following conditions: is a positive integer; parameter c2 is the auxiliary phase of the chirped signal, and its value is unrestricted; N is the number of subcarriers, m′ and m are the transmit and receive subcarrier indices respectively; c1 and c2 are two fundamental parameters of the generalized chirped multiplexing system; parameter c1 is the slope of the digital chirped signal, and its value satisfies It is a positive integer, parameter c2 is the auxiliary phase of the chirped signal, and its value is unrestricted. Δt is the sampling interval, T = NΔt is the total duration of the transmitted signal, and q is the segment index.

[0109] This shows that the vertical axis variable f represents frequency. C=3. It can be seen that the bandwidth occupied by the chirped subcarrier is... Its instantaneous frequency increases linearly with time. When its instantaneous frequency reaches B, it jumps to 0 at the next moment, and then continues to increase linearly with time, repeating this cycle until the total signal duration T. Before transmitting to the channel, a duration of l needs to be added before the transmitted time-domain signal s(t). max The cyclic prefix of Δt, where l is max The maximum normalized delay spread of the channel is calculated by dividing the maximum delay spread of the channel by Δt and then rounding up. After adding the cyclic prefix, the baseband transmitted signal is filtered to limit the signal bandwidth, and then up-converted to shift the baseband signal to the target frequency band before transmission.

[0110] Modeling the dual-dispersion wireless channel in the time-delay-Doppler domain yields:

[0111]

[0112] Among them, h i τ is the fading coefficient of the i-th path segment; i v is the time delay of the i-th path segment; i δ(t) represents the Doppler frequency shift of the i-th path segment; δ(t) is the Dirichlet function. and It is the digital domain normalized time delay and normalized Doppler frequency shift sum, l i and k i Represents the integer part, ι i and Represents the fractional part.

[0113] After the transmitted time-domain signal is transmitted through the dual-dispersion wireless channel to the receiving end, the receiving end first extracts the received time-domain signal from the frequency band corresponding to the transmitted time-domain signal, performs down-conversion on the received time-domain signal to obtain the baseband received time-domain signal, and removes the cyclic prefix. The second received time-domain signal is specifically:

[0114]

[0115] Where r(t) is the second received time-domain signal; w time (t) is the received time-domain Gaussian white noise; τ i v is the time delay of the i-th path segment; i Let be the Doppler frequency shift of the i-th path segment, (.) T This represents a modulo-T operation, where j is the first parameter and t represents the time variable.

[0116] Preferably, the demodulated received time-domain signal is specifically:

[0117]

[0118] Among them, w chirp [m] represents chirp domain noise; ε i (m,m′) is a complex exponential factor; For the integrated pulse shaping window; For pulse shaping window; For the matched filter window; N is the number of subcarriers; m′ is the transmit subcarrier index; m is the receive subcarrier index; c1 is the slope of the digital chirp signal; c2 is the auxiliary phase of the chirp signal; Δt is the sampling interval; T is the total duration of the transmitted signal; l i The integer part of the normalized delay in the digital field; ι i For the fractional part of the normalized delay in the digital domain, (.) N This represents a modulo N operation.

[0119] in, It is chirp domain noise, and its statistical properties depend on the matched filter window used.

[0120]

[0121] gather The symbol indicates rounding down; N is the number of subcarriers, m′ and m are the transmit and receive subcarrier indices respectively, and parameter c1 is the slope of the digital chirp signal, whose value satisfies It is a positive integer, l i and ι i These are the integer and fractional parts of the normalized delay in the digital field, respectively. i and k i These are the integer and fractional parts of the normalized Doppler in the digital field, respectively. Discrete functions... Defined as:

[0122]

[0123] Discrete function Defined as:

[0124]

[0125] The formula reveals that the effects of pulse shaping windows and matched filtering windows in generalized chirp demultiplexing are manifested in the integrated pulse shaping window.

[0126] The matrix representation of the formula is as follows:

[0127]

[0128] Where the matrix It is the equivalent channel matrix of a generalized chirped multiplexing system, with a size of N×N, and matrix H. i It is the sub-channel matrix corresponding to the i-th path, with a size of N×N; vector x=[x[0],...,x[N-1]] T It is the vector of transmitted information symbols from the sending end, with a size of N×1; vector y = [y[0],...,y[N-1]]. T is the received information symbol vector at the receiver, with a size of N×1. The operator T denotes transpose; w is the chirp domain noise vector, with a size of N×1. From the formula, we can see that matrix H... i The value of satisfies

[0129]

[0130] Where the factor ε i (m,m′) and factors The expression is shown in the formula. Due to the factor ε i (m,m′) is a complex exponent, so its absolute value is 1, therefore we have Observe the factors in the formula It takes the form of the classic discrete Fourier transform, i.e., |H i The values ​​of [m,m′]| are discrete sequences. The first discrete Fourier transform The amplitude of each value. Therefore, by the pulse shaping window and matched filter window The resulting integrated pulse shaping window Decision made | H i The energy distribution of [m,m′]| can be chosen such that |H i The energy concentration distribution of [m,m′]| and Further let the equivalent channel matrix H eff More sparse.

[0131] Specifically, the generalized chirped multiplexing system proposed in this patent has N pulse shaping windows at the transmitting end. N matched filter windows at the receiving end The choice of is not restricted; the above formula derivation and conclusions apply to any pulse shaping window and matched filter window, such as rectangular windows, Hamming windows, Dolph-Chebyshev windows, raised cosine windows, Gaussian windows, etc. It can be observed that when... When all N pulse shaping windows and N matched filtering windows are identical rectangular windows, the generalized chirped demultiplexing system is the traditional RF-like demultiplexing system. Therefore, the traditional RF-like demultiplexing system is a simple special case of the generalized chirped demultiplexing system proposed in this patent.

[0132] The following section further proposes a specific method for implementing a generalized chirped submultiplexing system in the digital domain with low complexity. Different implementation methods exist when the pulse shaping window and matched filter window used meet different requirements, and the implementation complexity also varies. First, a highly robust generalized chirped submultiplexing system is presented, in which each chirped subcarrier uses an arbitrary pulse shaping window at the transmitting end and an arbitrary matched filter window at the receiving end.

[0133] like Figure 4 The diagram shows a flow chart illustrating the high robustness and low complexity of a generalized chirped demultiplexing system's digital implementation. The discrete pulse shaping window is one example. It is obtained by equal-interval sampling from a continuous pulse shaping window, and a discrete matched filter window. It is obtained by equal-interval sampling of a continuous matched filter window. Discrete chirped subcarrier φ m [n]=φ m (t)| t＝nΔtIt is obtained by equally spaced sampling of continuous chirped subcarriers. The specific process involves modulating N quadrature amplitude modulation (QAM) information symbols onto N discrete chirped subcarriers under discrete pulse shaping windows, summing the results, adding a cyclic prefix, and then performing digital-to-analog conversion using a common filter to obtain a continuous transmit signal. This signal is then up-converted after passing through a bandwidth-limiting filter and finally transmitted into the channel. At the receiving end, the received continuous time-domain signal is first down-converted, then equally spaced sampled and converted from analog to digital. The cyclic prefix is ​​removed, multiplied by a discrete matched filter window, and then multiplied by the corresponding discrete conjugate chirped subcarriers. The summation of the resulting discrete sequences yields the demodulated received information symbol y, which is then subjected to traditional channel estimation and signal detection.

[0134] If only one transmit pulse shaping window and one receive matched filter window are used, i.e. Modulation at the transmitting end can be implemented using the low-complexity Inverse Discrete Affine Fourier Transform (IDAFT), and demodulation at the receiving end can be implemented using the low-complexity Discrete Affine Fourier Transform (DAFT), as follows: Figure 5 As shown, the matrix It is an N×N diagonal matrix, and multiplying it by a vector is equivalent to multiplying it by N points. The Inverse Fast Fourier Transform (IFT) has been widely used in modern mobile communication systems. Its specific process involves performing an N-point IFT on N orthogonal amplitude modulation (QAM) information symbols, multiplying the resulting discrete sequence by a discrete pulse shaping window, adding a cyclic prefix, and then performing digital-to-analog conversion through a common filter to obtain a continuous transmit signal. This signal is then up-converted after passing through a bandwidth-limiting filter and finally transmitted into the channel. At the receiving end, the received continuous time-domain signal is first down-converted, then subjected to equally spaced sampling analog-to-digital conversion, the cyclic prefix is ​​removed, multiplied by a discrete matched filter window, and then subjected to an N-point IFT to obtain the demodulated received information symbol y. Traditional channel estimation and signal detection are then performed. This system is highly backward compatible with the orthogonal frequency division multiplexing (OFDM) systems used in current mobile communication systems. It is worth mentioning that when the parameters of the generalized chirped multiplexing system satisfy c1 = c2 = 0, the inverse discrete affine Fourier transform becomes the common inverse discrete Fourier transform, and the generalized chirped multiplexing system degenerates into the orthogonal frequency division multiplexing system used in fifth-generation mobile communication. Therefore, the proposed generalized chirped multiplexing system has high backward compatibility.

[0135] Example 4

[0136] This embodiment also provides a signal transmission system based on generalized chirped multiplexing to implement the above method, such as... Figure 6 As shown, the system includes:

[0137] The data acquisition module acquires the discrete pulse shaping window, the discrete matched filter window, several discrete chirped subcarriers, and the information symbols to be transmitted;

[0138] The signal generation module generates a transmission time-domain signal based on a discrete pulse shaping window, several discrete chirped subcarriers, and the information symbols to be transmitted.

[0139] The signal transmission module adds a cyclic prefix to the transmitted time domain signal and performs up-conversion processing, then transmits the processed transmitted time domain signal to the receiving end through a dual-dispersion wireless channel to obtain the first received time domain signal.

[0140] The signal processing module performs down-conversion processing on the received time-domain signal, removes the cyclic prefix, and then performs filtering processing using a discrete matched filter window to obtain the second received time-domain signal.

[0141] The system also includes:

[0142] The signal demodulation module performs conversion calculations on the filtered second received time-domain signal to obtain the demodulated received time-domain signal.

[0143] Numerical simulations verified the proposed generalized chirped multiplexing system. The most classic embedded pilot channel estimation method was employed, with the energy leakage ratio of the pilot symbols used for channel estimation at the receiver and the normalized mean square error of the estimated equivalent channel matrix serving as the evaluation criteria for system communication performance. Receiving matched filters were all rectangular windows, while the transmitting end used only one shaped filter window. The effects of the traditional rectangular window were compared with two superior classic window functions—the Hamming window and the Dolph-Chebyshev DC window. The normalized delay and Doppler shift of the split path followed a uniform distribution between [0,3] and [-2,2], respectively. At a carrier frequency of 4 GHz, a subcarrier number of 512, and a spacing of 1000 Hz, the corresponding maximum moving speed was 540 km / h. The ratio of the received data signal power to the noise power in the time domain is denoted as SNR.

[0144] like Figure 7As shown, the effect of the spacing factor on the pilot energy leakage ratio under three different transmit pulse shaping windows is illustrated. The spacing factor determines the number of guard symbols used for channel estimation at the transmitter. A higher spacing factor results in less interference between receive-end pilot symbols, but also requires more guard symbols at the transmitter, leading to fewer data symbols that the system can transmit and a smaller effective capacity for the communication system. The receive-end pilot energy leakage ratio directly reflects the interference of receive-end pilot symbols on receive-end data symbols. It can be seen that using Hamming windows and DC windows can significantly reduce the receive-end pilot energy leakage ratio and decrease pilot interference on data symbols, which is beneficial for improving the accuracy of signal detection.

[0145] like Figure 8 As shown, the influence of the signal-to-noise ratio (SNR) on the normalized mean square error (MSE) of the estimated equivalent channel matrix is ​​illustrated under different transmit pulse shaping windows. A smaller MSE indicates more accurate channel estimation and subsequent detection. It can be seen that when the interval factor is greater than 0, the MSE of the equivalent channel matrix using the Hamming window and DC window is approximately smaller than that using the traditional rectangular window, demonstrating the advantage of the proposed generalized chirped demultiplexing system over the traditional pseudo-RF demultiplexing system.

[0146] This embodiment also provides an electronic device, including:

[0147] One or more processors;

[0148] Memory, used to store one or more programs;

[0149] When the one or more programs are executed by the one or more processors, the processors implement the methods described above.

[0150] This embodiment also provides a computer-readable storage medium containing a computer program, on which the computer program is stored, and which, when executed by one or more processors, implements the above-described method.

[0151] The same or similar labels correspond to the same or similar parts;

[0152] The terms used to describe positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent.

[0153] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A signal transmission method based on generalized chirped multiplexing, characterized in that, include: Acquire several discrete pulse shaping windows, discrete matched filter windows, discrete chirped subcarriers, and information symbols to be transmitted; The transmission time-domain signal is generated based on several discrete pulse shaping windows, discrete chirped subcarriers, and the information symbols to be transmitted; A cyclic prefix is ​​added before the transmitted time domain signal and up-conversion processing is performed. The processed transmitted time domain signal is transmitted to the receiving end through a dual-dispersion wireless channel to obtain the first received time domain signal. The received time-domain signal is down-converted and the cyclic prefix is ​​removed before being filtered using a discrete matched filter window. Obtain the second received time-domain signal; The filtered second received time-domain signal is converted and calculated to obtain the demodulated received time-domain signal. The transmission of the time-domain signal specifically refers to: in, It is a continuous-time variable; For subcarrier indexing; For pulse shaping window applied to the m-th chirped subcarrier; It is the first The time delay form of each subcarrier; The dual-dispersion wireless channel is specifically: in, For the first The fading coefficient of the slice path; For the first The time delay of the segmented path; For the first Doppler shift of the segmented path; It is the Dirichlet function; After the transmitted time-domain signal is transmitted through the dual-dispersion wireless channel to the receiving end, the receiving end first extracts the received time-domain signal from the frequency band corresponding to the transmitted time-domain signal, performs down-conversion on the received time-domain signal to obtain the baseband received time-domain signal, and removes the cyclic prefix. The second received time-domain signal is specifically: in, This is the second received time-domain signal; It receives time-domain Gaussian white noise; For the first The time delay of the segmented path; For the first The Doppler frequency shift of the segmented path, where j is the first parameter and t represents the time variable; The demodulated received time-domain signal is specifically: in, For chirp domain noise; It is a complex exponential factor; For the integrated pulse shaping window; For pulse shaping window; This represents the matched filter window; N is the number of subcarriers. Subcarrier index; For receiving subcarrier index; The slope of the digital chirped signal; It is the auxiliary phase of the chirped signal; The sampling interval; This is the total duration of the transmitted signal; For the integer part of the normalized delay in the digital field; This is the fractional part of the normalized delay in the digital domain.

2. A signal transmission system based on generalized chirped multiplexing, characterized in that, include: The data acquisition module acquires the discrete pulse shaping window, the discrete matched filter window, several discrete chirped subcarriers, and the information symbols to be transmitted; The signal generation module generates a transmission time-domain signal based on a discrete pulse shaping window, several discrete chirped subcarriers, and the information symbols to be transmitted. The signal transmission module adds a cyclic prefix to the transmitted time domain signal and performs up-conversion processing, then transmits the processed transmitted time domain signal to the receiving end through a dual-dispersion wireless channel to obtain the first received time domain signal. The signal processing module performs down-conversion processing on the received time-domain signal, removes the cyclic prefix, and then performs filtering processing using a discrete matched filter window; Obtain the second received time-domain signal.

3. The signal transmission system based on generalized chirped multiplexing according to claim 2, characterized in that, The system also includes: The signal demodulation module performs conversion calculations on the filtered second received time-domain signal to obtain the demodulated received time-domain signal.

4. An electronic device, characterized in that, include: One or more processors; Memory, used to store one or more programs; When the one or more programs are executed by the one or more processors, the processors cause the processors to implement the method as described in claim 1.

5. A computer-readable storage medium containing a computer program, wherein the computer program is stored thereon, characterized in that, When the program is executed by one or more processors, it implements the method as described in claim 1.

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