A pilot compression transmission method for frequency-selective channels based on extended weighted fractional Fourier transform

Abstract

A method for pilot compression transmission in a frequency-selective channel based on an extended weighted fractional Fourier transform belongs to the field of wireless communication technology. The purpose of the present invention is to solve the problem that the channel estimation method of the existing frequency-selective channel cannot take into account both the channel estimation accuracy and the communication effectiveness. The present invention can improve the spectrum efficiency by reducing the number of pilots, thereby improving the effectiveness of the communication system. After the signal is fast Fourier transformed at the receiving end, the extended weighted fractional inverse Fourier transform corresponding to the transmitting end is performed. Since the extended weighted inverse Fourier transform has an averaging effect on the channel response, the channel response amplitude change of the equivalent channel in the fractional domain is much smaller than the channel response in the frequency domain. The accurate channel response at the data position can still be obtained by interpolation, ultimately achieving the goal of reducing the number of pilot insertions and ensuring that the channel estimation performance does not decrease. The method of the present invention can be applied to pilot compression transmission in a frequency-selective channel.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to a frequency-selective channel pilot compression transmission method based on extended weighted fractional Fourier transform. Background Art

[0002] System reliability and effectiveness are two key optimization objectives for wireless transmission systems. These two objectives are generally contradictory: improving reliability often comes at the expense of effectiveness, and vice versa. This is particularly evident in frequency-selective channel estimation. When inserting comb-shaped pilots, the accuracy of the channel estimation results is related to the number of inserted pilots. A large number of inserted pilots ensures channel estimation accuracy, further guaranteeing reliability, but the pilots occupy valid data positions, reducing system communication effectiveness. A small number of inserted pilots increases the proportion of valid data, improving system communication effectiveness. However, due to large channel estimation errors, system reliability decreases.

[0003] In summary, the current channel estimation method based on frequency-selective channel interpolation is difficult to balance channel estimation accuracy and communication effectiveness. Proposing a method that can reduce the number of pilot insertions and improve communication effectiveness while ensuring channel estimation performance is an urgent problem that needs to be solved. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem that the existing frequency-selective channel channel estimation method cannot take into account both channel estimation accuracy and communication effectiveness, and to propose a frequency-selective channel pilot compression transmission method based on extended weighted fractional Fourier transform.

[0005] The technical solution adopted by the present invention to solve the above technical problems is:

[0006] According to one aspect of the present invention, a frequency-selective channel pilot compression transmission method based on extended weighted fractional Fourier transform, the method specifically comprises the following steps:

[0007] On the sending side

[0008] Step S1: Perform digital baseband modulation on the 0 and 1 bit data streams generated by the signal source to obtain the modulation result after constellation mapping. The modulation result is the transform domain data X to be sent. 1d ;

[0009] Step S2: Generate transform domain pilot data X to be inserted 1p , pilot data X 1p The number of data in is N p ; For pilot data X 1p Perform extended weighted fractional Fourier transform to obtain pilot data X 1pThe output data X obtained by extended weighted fractional Fourier transform 2p ;

[0010] Step S3: Transform domain data X to be sent 1d Perform serial-to-parallel conversion, that is, transform domain data X 1d Divided into 2 a-b -1 group, each of which contains 2 b data, and a>>b, a and b are positive integers;

[0011] Then perform extended weighted fractional Fourier transform on each group of data to obtain the transformed data X 2d ;

[0012] Step S4: Transformed data X 2d and data X 2p After the pilot data is mapped, the mapped data is parallel-to-serial converted to obtain frequency domain data X3 after parallel-to-serial conversion;

[0013] Then the frequency domain data X3 is processed by IFFT, up-conversion and digital-to-analog conversion in sequence, and the processed data is sent through the channel; at the receiving end

[0014] Step R1: The receiver performs down-conversion, analog-to-digital conversion, and FFT processing on the received signal in sequence, and records the processed signal as the baseband digital sampling signal Y0;

[0015] Step R2, perform serial-to-parallel conversion on the baseband digital sampling signal Y0 to obtain 2 a-b Then, each group of data obtained by serial-to-parallel conversion is subjected to an extended weighted fractional inverse Fourier transform to obtain an inverse transform result of each group of data;

[0016] Perform parallel-to-serial conversion on the data of each group of inverse transformation results, and extract the transform domain data Y from the parallel-to-serial conversion results. 1d and pilot data Y 1p ;

[0017] Step R3: Using pilot data Y 1p Estimate the channel response h at the pilot under the transform domain equivalent channel p ;

[0018] Step R4: Channel response h at the pilot p Interpolate and get the transform domain data Y 1d The channel response at position h d , that is, the transform domain data Y is obtained 1d Channel estimation result at position;

[0019] Step R5: According to the transformed domain data Y 1d and transform domain data Y 1dThe channel estimation result at the position is used to obtain the bit data sent by the transmitter.

[0020] Furthermore, the modulation mode is QPSK.

[0021] Furthermore, the pilot X 1p The number of data N in p =N OFDM / N, N is the pilot data compression ratio, N OFDM is the amount of data in the pilot of the OFDM system.

[0022] Furthermore, the pilot X 1p The number of data in satisfies: N p =2 b ;

[0023] N d =N all -N p

[0024] Among them, N d Indicates the amount of data sent in the transmission block, N all is the length of a complete transmission block, N all =2 a .

[0025] Furthermore, the pair of pilots X 1p Perform extended weighted fractional Fourier transform, specifically:

[0026]

[0027] Among them, the superscript T represents the transpose, and Π[·] represents the transformation iteration matrix F j Perform cumulative multiplication and transform the iterative matrix F j is of size N p *N p A block diagonal matrix, j = 0, 1, ..., N p -1;

[0028] The transformation iteration matrix F j The kth sub-block is represented as:

[0029]

[0030] Among them, [F j ] k is the transformation iteration matrix F j The kth sub-block, N p =log2B, is of size 2 j+1 *2 j+1 The identity matrix, is of size 2 j+1 *2 j+1 The Fourier transform matrix of is the permutation matrix, is the weighting coefficient;

[0031] The weighting coefficient for:

[0032]

[0033] in, is the transformation parameter, and i is the imaginary unit.

[0034] Furthermore, the transformed data X 2d and data X 2p Perform pilot data mapping, specifically:

[0035] The data X 2p As a set of data, and add this set of data to the transformed data X 2d Before the first set of data, the mapped data is obtained;

[0036] The mapped data is converted into parallel-to-serial data to obtain the frequency domain data X3 after parallel-to-serial conversion; specifically:

[0037] The first data of each group in the mapped data is used as the first to second data of the frequency domain data X3. a-b data, and the second data of each group in the mapped data is used as the second data of the frequency domain data X3. a-b +1 to 2nd a-b+1 data, and so on, to obtain the frequency domain data X3 after parallel-to-serial conversion.

[0038] According to another aspect of the present invention, a frequency-selective channel pilot compression transmission method based on extended weighted fractional Fourier transform, the working process of the method at the transmitting end is as follows:

[0039] Step S1: Perform digital baseband modulation on the 0 and 1 bit data streams generated by the signal source to obtain the modulation result after constellation mapping. The modulation result is the transform domain data X to be sent. 1d ;

[0040] Step S2: Generate transform domain pilot data X to be inserted 1p , pilot data X 1p The number of data in is N p ; For pilot data X 1p Perform extended weighted fractional Fourier transform to obtain pilot data X 1p The output data X obtained by extended weighted fractional Fourier transform 2p ;

[0041] Step S3: Transform domain data X to be sent 1d Perform serial-to-parallel conversion, that is, transform domain data X 1d Divided into 2 a-b -1 group, each of which contains 2 b data, and a>>b, a and b are positive integers;

[0042] Then perform extended weighted fractional Fourier transform on each group of data to obtain the transformed data X 2d ;

[0043] Step S4: Transformed data X 2d and data X 2p After the pilot data is mapped, the mapped data is parallel-to-serial converted to obtain frequency domain data X3 after parallel-to-serial conversion;

[0044] The frequency domain data X3 is then processed in sequence with IFFT, up-conversion, and digital-to-analog conversion, and the processed data is sent via the channel.

[0045] The beneficial effects of the present invention are:

[0046] Compared to conventional orthogonal frequency division multiplexing systems, the method of the present invention reduces the number of pilots by 1:N. That is, in conventional orthogonal frequency division multiplexing systems, M*N pilot data are inserted into each block of data, while in the extended weighted fractional Fourier system of the present invention, only M pilot data are used, thereby improving spectrum efficiency and the effectiveness of the communication system. At the receiving end, after performing a fast Fourier transform on the signal, an extended weighted fractional Fourier inverse transform corresponding to the transmitting end is performed. Since the extended weighted fractional Fourier inverse transform has an averaging effect on the channel response, the channel response amplitude variation of the equivalent channel in the fractional domain is much smaller than the channel response in the frequency domain. Therefore, even if the number of pilots is reduced by 1:N, an accurate channel response at the data position can still be obtained through interpolation, ultimately achieving the goal of reducing the number of pilot insertions while ensuring that the channel estimation performance does not degrade. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a flowchart of the method of the present invention in a transmitter;

[0048] Where: EWFRFT stands for Extended Weighted Fractional Fourier Transform, IFFT stands for Inverse Fast Fourier Transform;

[0049] Figure 2 It is a schematic diagram of the pilot data mapping of the transmitter and the parallel-to-serial conversion process after mapping;

[0050] Where: d1~d 24 Represents X 2d , p1~p8 represent X 2p;

[0051] Figure 3 This is a flowchart of the method of the present invention in a receiver;

[0052] Where: IEWFRFT stands for Inverse Extended Weighted Fractional Fourier Transform, and FFT stands for Fast Fourier Transform. DETAILED DESCRIPTION

[0053] Specific implementation method 1: Combination Figure 1 and Figure 3 This embodiment describes a frequency-selective channel pilot compression transmission method based on extended weighted fractional Fourier transform, and the method specifically includes the following steps:

[0054] On the sending side

[0055] Step S1: Perform digital baseband modulation on the 0 and 1 bit data streams generated by the signal source to obtain the modulation result after constellation mapping. The modulation result is the transform domain data X to be sent. 1d ;

[0056] Step S2: Generate transform domain pilot data X to be inserted 1p , pilot data X 1p The number of data in is N p ; For pilot data X 1p Perform extended weighted fractional Fourier transform to obtain pilot data X 1p The output data X obtained by extended weighted fractional Fourier transform 2p ;

[0057] Step S3: Transform domain data X to be sent 1d Perform serial-to-parallel conversion, that is, transform domain data X 1d Divided into 2 a-b -1 group, each of which contains 2 b data, and a>>b, a and b are positive integers;

[0058] Then perform extended weighted fractional Fourier transform on each group of data to obtain the transformed data X 2d ;

[0059] Step S4: Transformed data X 2d and data X 2p After the pilot data is mapped, the mapped data is parallel-to-serial converted to obtain frequency domain data X3 after parallel-to-serial conversion;

[0060] The frequency domain data X3 is then processed sequentially by IFFT, up-conversion, and digital-to-analog conversion, and the processed data is sent via the channel;

[0061] On the receiving end

[0062] Step R1: The receiver performs down-conversion, analog-to-digital conversion, and FFT processing on the received signal in sequence, and records the processed signal as the baseband digital sampling signal Y0;

[0063] Step R2, perform serial-to-parallel conversion on the baseband digital sampling signal Y0 to obtain 2 a-b Then, each group of data obtained by serial-to-parallel conversion is subjected to an extended weighted fractional inverse Fourier transform to obtain an inverse transform result of each group of data;

[0064] Perform parallel-to-serial conversion on the data of each group of inverse transformation results, and extract the transform domain data Y from the parallel-to-serial conversion results. 1d and pilot data Y 1p ;

[0065] Step R3: Using pilot data Y 1p Estimate the channel response h at the pilot under the transform domain equivalent channel p ;

[0066] Step R4: Channel response h at the pilot p Interpolate and get the transform domain data Y 1d The channel response at position h d , that is, the transform domain data Y is obtained 1d Channel estimation result at position;

[0067] Step R5: According to the transformed domain data Y 1d and transform domain data Y 1d The channel estimation result at the position is used to obtain the bit data sent by the transmitter.

[0068] When a signal passes through a multipath channel, the time dispersion characteristic causes the channel to become a frequency-selective channel in the frequency domain. The longer the maximum delay of the channel, the more dramatic the gain change of the frequency-selective channel, which can lead to distortion of the channel response at the data obtained by interpolating the channel response at the pilot, further causing a decrease in the accuracy of the channel estimation result. The present invention utilizes the power averaging characteristics of the extended weighted fractional Fourier transform. At the transmitting end, the extended weighted fractional Fourier transform is first used to perform the same transformation on the pilot and signal, respectively, to obtain a precoded signal and pilot, which can achieve averaging of the changing channel. Therefore, using a small amount of pilot data, accurate channel estimation results can be obtained through interpolation.

[0069] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the modulation mode is QPSK.

[0070] Other steps and parameters are the same as those in the first embodiment.

[0071] The modulation methods that can be used in this embodiment include but are not limited to QPSK, and are compatible with various modulation methods.

[0072] Specific implementation method three: This implementation method is different from specific implementation methods one or two in that: the pilot X 1p The number of data N in p =N OFDM / N, N is the pilot data compression ratio, N OFDM It is the amount of data in the pilot of the OFDM system (ie, the traditional OFDM system).

[0073] Other steps and parameters are the same as those in the first or second embodiment.

[0074] The present invention takes an orthogonal frequency division multiplexing system as an example and supports other systems using fast Fourier transform, for example, it can be used in combination with a single carrier system.

[0075] Specific embodiment 4: This embodiment differs from any one of the specific embodiments 1 to 3 in that: the pilot X 1p The number of data in satisfies: N p =2 b ;

[0076] N d =N all -N p

[0077] Among them, N d Indicates the amount of data sent in the transmission block, N all is the length of a complete transmission block, N all =2 a .

[0078] The other steps and parameters are the same as those in the first to third embodiments.

[0079] Specific embodiment 5: This embodiment differs from any one of the specific embodiments 1 to 4 in that: the pilot X 1p Perform extended weighted fractional Fourier transform, specifically:

[0080]

[0081] Among them, the superscript T represents the transpose, and Π[·] represents the transformation iteration matrix F j Perform cumulative multiplication and transform the iterative matrix F j is of size N p *N p A block diagonal matrix, j = 0, 1, ..., N p -1;

[0082] The transformation iteration matrix F jThe kth sub-block is represented as:

[0083]

[0084] Among them, [F j ] k is the transformation iteration matrix F j The kth sub-block, N p =log2B, is of size 2 j+1 *2 j+1 The identity matrix, is of size 2 j+1 *2 j+1 The Fourier transform matrix of is the permutation matrix, is the weighting coefficient;

[0085] The weighting coefficient for:

[0086]

[0087] in, is the transformation parameter, and i is the imaginary unit.

[0088] The other steps and parameters are the same as those in the first to fourth embodiments.

[0089] Similarly, an extended weighted fractional Fourier transform may be performed on each packet of transform domain data to be transmitted.

[0090] Specific implementation method six: combination Figure 2 The difference between this embodiment and any one of the specific embodiments 1 to 5 is that: the transformed data X 2d and data X 2p Perform pilot data mapping, specifically:

[0091] The data X 2p As a set of data, and add this set of data to the transformed data X 2d Before the first set of data, the mapped data is obtained;

[0092] Because before performing the extended weighted fractional Fourier transform, the transformed domain data X 1d The data are grouped, so after the extended weighted fractional Fourier transform, the transformation results corresponding to each group of data are used as the transformed data X 2d A row, and finally the data X 2p Add to the transformed data X 2d Before the first row of data, get the mapped data;

[0093] The mapped data is converted into parallel-to-serial data to obtain the frequency domain data X3 after parallel-to-serial conversion; specifically:

[0094] The first data of each group in the mapped data is used as the first to second data of the frequency domain data X3. a-b data, and the second data of each group in the mapped data is used as the second data of the frequency domain data X3. a-b +1 to 2nd a-b+1 data, and so on, to obtain the frequency domain data X3 after parallel-to-serial conversion.

[0095] If the mapped data is regarded as a matrix, the first column of the matrix is ​​the first to second frequency domain data X3. a-b data, the second column of data is the second column of frequency domain data X3 a-b +1 to 2nd a-b+1 data.

[0096] The other steps and parameters are the same as those in the first to fifth embodiments.

[0097] The present invention proposes a method for estimating an equivalent channel with higher precision by interpolating a small number of pilots. In the traditional frequency domain channel estimation method, when the pilot spacing is large, even if a relatively accurate channel response at the pilot is obtained, the channel response at the data will cause a large error due to the drastic change of the channel. In order to achieve the flattening of the channel response and reduce the channel estimation error caused by interpolation, the method of the present invention applies the extended weighted fractional Fourier transform. Due to its power averaging capability, the degree of transformation of the equivalent channel response in the transform domain is reduced compared to the frequency domain channel. This allows the channel estimation in the transform domain to utilize the relatively small number of pilots at the transmitting end (1 / N of the traditional system) and the same interpolation method as the traditional system to achieve a higher precision channel estimation result, that is, one pilot point in the transform domain plays the role of N pilot points in the frequency domain.

[0098] In a communication system employing the method of the present invention, the signal undergoes an extended weighted fractional Fourier transform at both the transmitting and receiving ends, which is equivalent to undergoing a transform domain equivalent channel. The amplitude of the change is relatively gentle, and when interpolating in the transform domain, significant interpolation errors are not caused by drastic changes in the channel. This allows for high channel estimation accuracy when compressing pilot signals, i.e., low interpolation errors. The method of the present invention is applicable to frequency-selective channels or slowly varying channels and is highly compatible with systems that currently employ pilot insertion for channel estimation. While ensuring high-quality channel estimation results, it reduces pilot overhead, thereby improving communication effectiveness.

[0099] Specific implementation method seven: combination Figure 1This embodiment describes a frequency-selective channel pilot compression transmission method based on extended weighted fractional Fourier transform, and the working process of the method at the transmitting end is as follows:

[0100] Step S1: Perform digital baseband modulation on the 0 and 1 bit data streams generated by the signal source to obtain the modulation result after constellation mapping (the modulation method that can be used includes but is not limited to QPSK). The modulation result is the transform domain data X to be sent. 1d ;

[0101] Step S2: Generate transform domain pilot data X to be inserted 1p , pilot data X 1p The number of data in is N p ; For pilot data X 1p Perform extended weighted fractional Fourier transform to obtain pilot data X 1p The output data X obtained by extended weighted fractional Fourier transform 2p ;

[0102] Step S3: Transform domain data X to be sent 1d Perform serial-to-parallel conversion, that is, transform domain data X 1d Divided into 2 a-b -1 group, each of which contains 2 b data, and a>>b, a and b are positive integers;

[0103] Then perform extended weighted fractional Fourier transform on each group of data to obtain the transformed data X 2d ;

[0104] Step S4: Transformed data X 2d and data X 2p After the pilot data is mapped, the mapped data is parallel-to-serial converted to obtain frequency domain data X3 after parallel-to-serial conversion;

[0105] The frequency domain data X3 is then processed in sequence with IFFT, up-conversion, and digital-to-analog conversion, and the processed data is sent via the channel.

[0106] Specific embodiment eight: This embodiment differs from specific embodiment seven in that: the pilot X 1p The number of data N in p =N OFDM / N, N is the pilot data compression ratio, N OFDM It is the amount of data in the pilot of the OFDM system (ie, the traditional OFDM system).

[0107] Other steps and parameters are the same as those in the seventh embodiment.

[0108] The present invention takes an orthogonal frequency division multiplexing system as an example and supports other systems using fast Fourier transform, for example, it can be used in combination with a single carrier system.

[0109] Specific embodiment 9: This embodiment differs from specific embodiment 7 or 8 in that: the pilot X 1p The number of data in satisfies: N p =2 b ;

[0110] N d =N all -N p

[0111] Among them, N d Indicates the amount of data sent in the transmission block, N all is the length of a complete transmission block, N all =2 a .

[0112] Other steps and parameters are the same as those in the seventh or eighth embodiment.

[0113] Specific embodiment 10: This embodiment differs from any one of specific embodiments 7 to 9 in that: the pilot X 1p Perform extended weighted fractional Fourier transform, specifically:

[0114]

[0115] Among them, the superscript T represents the transpose, and Π[·] represents the transformation iteration matrix F j Perform cumulative multiplication and transform the iterative matrix F j is of size N p *N p A block diagonal matrix, j = 0, 1, ..., N p -1;

[0116] The transformation iteration matrix F j The kth sub-block is represented as:

[0117]

[0118] Among them, [F j ] k is the transformation iteration matrix F j The kth sub-block, N p =log2B, is of size 2 j+1 *2 j+1 The identity matrix, is of size 2 j+1 *2 j+1 The Fourier transform matrix of is the permutation matrix, is the weighting coefficient;

[0119] The weighting coefficient for:

[0120]

[0121] in, is the transformation parameter, and i is the imaginary unit.

[0122] The other steps and parameters are the same as those in any one of the seventh to ninth embodiments.

[0123] Similarly, an extended weighted fractional Fourier transform may be performed on each packet of transform domain data to be transmitted.

[0124] The above examples are merely illustrative of the calculation model and process of the present invention and are not intended to limit the embodiments of the present invention. Persons skilled in the art will readily appreciate that other variations or modifications based on the above description are possible. This list of embodiments is not exhaustive; however, any obvious variations or modifications derived from the technical solution of the present invention remain within the scope of protection of the present invention.

Claims

1. A frequency-selective channel pilot compression transmission method based on extended weighted fractional Fourier transform, characterized in that: The method specifically comprises the following steps: On the sending side Step S1: Perform digital baseband modulation on the 0 and 1 bit data streams generated by the signal source to obtain the modulation result after constellation mapping. The modulation result is the transform domain data X to be sent. 1d ; Step S2: Generate transform domain pilot data X to be inserted 1p , pilot data X 1p The number of data in is N p ; For pilot data X 1p Perform extended weighted fractional Fourier transform to obtain pilot data X 1p The output data X obtained by extended weighted fractional Fourier transform 2p ; Pilot X 1p Perform extended weighted fractional Fourier transform, specifically: Among them, the superscript T represents the transpose, and Π[·] represents the transformation iteration matrix F j Perform cumulative multiplication and transform the iterative matrix F j is of size N p *N p A block diagonal matrix, j = 0, 1, ..., N p -1; The transformation iteration matrix F j The kth sub-block is represented as: Among them, [F j ] k is the transformation iteration matrix F j The kth sub-block, N p =log2B, is of size 2 j+1 *2 j+1 The identity matrix, is of size 2 j+1 *2 j+1 The Fourier transform matrix of is the permutation matrix, is the weighting coefficient; The weighting coefficient for: in, is the transformation parameter, i is the imaginary unit; Step S3: Transform domain data X to be sent 1d Perform serial-to-parallel conversion, that is, transform domain data X 1d Divided into 2 a-b -1 group, each of which contains 2 b data, and a>>b, a and b are positive integers; Then perform extended weighted fractional Fourier transform on each group of data to obtain the transformed data X 2d ; Step S4: Transformed data X 2d and data X 2p After the pilot data is mapped, the mapped data is parallel-to-serial converted to obtain frequency domain data X3 after parallel-to-serial conversion; The frequency domain data X3 is then processed sequentially by IFFT, up-conversion, and digital-to-analog conversion, and the processed data is sent via the channel; On the receiving end Step R1: The receiver performs down-conversion, analog-to-digital conversion, and FFT processing on the received signal in sequence, and records the processed signal as the baseband digital sampling signal Y0; Step R2, perform serial-to-parallel conversion on the baseband digital sampling signal Y0 to obtain 2 a-b Then, each group of data obtained by serial-to-parallel conversion is subjected to an extended weighted fractional inverse Fourier transform to obtain an inverse transform result of each group of data; Perform parallel-to-serial conversion on the data of each group of inverse transformation results, and extract the transform domain data Y from the parallel-to-serial conversion results. 1d and pilot data Y 1p ; Step R3: Using pilot data Y 1p Estimate the channel response h at the pilot under the transform domain equivalent channel p ; Step R4: Channel response h at the pilot p Interpolate and get the transform domain data Y 1d The channel response at position h d , that is, the transform domain data Y is obtained 1d Channel estimation result at position; Step R5: According to the transformed domain data Y 1d and transform domain data Y 1d The channel estimation result at the position is used to obtain the bit data sent by the transmitter.

2. The method for frequency-selective channel pilot compression transmission based on extended weighted fractional Fourier transform according to claim 1, characterized in that: The modulation mode is QPSK.

3. The method for frequency-selective channel pilot compression transmission based on extended weighted fractional Fourier transform according to claim 1, characterized in that: The pilot X 1p The number of data N in p =N OFDM / N, N is the pilot data compression ratio, N OFDM is the amount of data in the pilot of the OFDM system.

4. The method for frequency-selective channel pilot compression transmission based on extended weighted fractional Fourier transform according to claim 3, characterized in that: The pilot X 1p The number of data in satisfies: N p =2 b ; N d =N all -N p Among them, N d Indicates the amount of data sent in the transmission block, N all is the length of a complete transmission block, N all =2 a .

5. The method for frequency-selective channel pilot compression transmission based on extended weighted fractional Fourier transform according to claim 1, characterized in that: The transformed data X 2d and data X 2p Perform pilot data mapping, specifically: The data X 2p As a set of data, and add this set of data to the transformed data X 2d Before the first set of data, the mapped data is obtained; The mapped data is converted into parallel-to-serial data to obtain the frequency domain data X3 after parallel-to-serial conversion; specifically: The first data of each group in the mapped data is used as the first to second data of the frequency domain data X3. a-b data, and the second data of each group in the mapped data is used as the second data of the frequency domain data X3. a-b +1 to 2nd a-b+1 data, and so on, to obtain the frequency domain data X3 after parallel-to-serial conversion.

6. A frequency-selective channel pilot compression transmission method based on extended weighted fractional Fourier transform, characterized in that: The working process of the method at the sending end is: Step S1: Perform digital baseband modulation on the 0 and 1 bit data streams generated by the signal source to obtain the modulation result after constellation mapping. The modulation result is the transform domain data X to be sent. 1d ; Step S2: Generate transform domain pilot data X to be inserted 1p , pilot data X 1p The number of data in is N p ; For pilot data X 1p Perform extended weighted fractional Fourier transform to obtain pilot data X 1p The output data X obtained by extended weighted fractional Fourier transform 2p ; Pilot X 1p Perform extended weighted fractional Fourier transform, specifically: Among them, the superscript T represents the transpose, and Π[·] represents the transformation iteration matrix F j Perform cumulative multiplication and transform the iterative matrix F j is of size N p *N p A block diagonal matrix, j = 0, 1, ..., N p -1; The transformation iteration matrix F j The kth sub-block is represented as: Among them, [F j ] k is the transformation iteration matrix F j The kth sub-block, N p =log2B, is of size 2 j+1 *2 j+1 The identity matrix, is of size 2 j+1 *2 j+1 The Fourier transform matrix, π 2j+1 is the permutation matrix, is the weighting coefficient; The weighting coefficient for: in, is the transformation parameter, i is the imaginary unit; Step S3: Transform domain data X to be sent 1d Perform serial-to-parallel conversion, that is, transform domain data X 1d Divided into 2 a-b -1 group, each of which contains 2 b data, and a>>b, a and b are positive integers; Then perform extended weighted fractional Fourier transform on each group of data to obtain the transformed data X 2d ; Step S4: Transformed data X 2d and data X 2p After the pilot data is mapped, the mapped data is parallel-to-serial converted to obtain frequency domain data X3 after parallel-to-serial conversion; The frequency domain data X3 is then processed in sequence with IFFT, up-conversion, and digital-to-analog conversion, and the processed data is sent via the channel.

7. The method for frequency-selective channel pilot compression transmission based on extended weighted fractional Fourier transform according to claim 6, characterized in that: The pilot X 1p The number of data N in p =N OFDM / N, N is the pilot data compression ratio, N OFDM is the amount of data in the pilot of the OFDM system.

8. The method for frequency-selective channel pilot compression transmission based on extended weighted fractional Fourier transform according to claim 7, characterized in that: The pilot X 1p The number of data in satisfies: N p =2 b ; N d =N all -N p Among them, N d Indicates the amount of data sent in the transmission block, N all is the length of a complete transmission block, N all =2 a .

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