Correlation operation method based on XNOR polarization and acquisition algorithm thereof

Abstract

The invention belongs to the technical field of communication systems, and relates to a correlation operation method based on XNOR polarization and a capture algorithm thereof. The correlation operation method comprises the following steps: respectively carrying out {0, 1} polarization on a real part and an imaginary part of a vector X and a real part and an imaginary part of a vector Y according to a definition of {0, 1} polarization; replacing a multiplier in a correlation calculation formula (3) of the vector X and the vector Y with an XNOR; on the basis of XNOR operation, performing {1,-1} polarization on all XNOR operation results; through the above steps, the correlation calculation formula (3) is simplified into a new correlation formula (9), and according to the new correlation formula (9), summation is carried out on data after XNOR polarization to obtain a final correlation operation result. According to the method, a multiplier is abandoned, only 4N times of XNOR and 2 times of data polarization need to be carried out, and particularly when the number of signal paths is large, such as a thousand-path / ten-thousand-path receiver, resource consumption of an FPGA is reduced, and the operation speed is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of communication systems, relates to a signal acquisition algorithm, and in particular to a correlation operation method based on co-OR polarization and a acquisition algorithm thereof. Background Art

[0002] In the design of multi-channel signal reception and detection, the signal synchronization capture algorithm is one of the core contents. It is a capture algorithm with excellent performance and low complexity. It is very important for backpack shortwave / ultra-shortwave radio stations produced in actual projects and with high power consumption requirements.

[0003] The synchronization capture algorithm of the signal can be mainly divided into two categories: data-assisted synchronization algorithm and non-data-assisted synchronization algorithm. Among them, the synchronization algorithm based on data assistance is more applicable in actual engineering projects due to its low implementation complexity. Among the synchronization algorithms based on data assistance, the sliding correlation algorithm is a more commonly used and less complex method. The essence of sliding correlation is to perform matched filtering operations on the signal, and the value of the local synchronization preamble sequence PN is the tap coefficient of the matched filter. When the received signal and the local synchronization preamble sequence PN are aligned with each other, due to the excellent autocorrelation characteristics of the synchronization preamble sequence PN, the correlation result will show a significant peak. At this time, it can be judged that the signal has been captured successfully, and the position of the correlation peak is the position of the signal arrival point.

[0004] Traditional correlation calculation methods cannot do without multipliers. In multi-channel signal reception, once the number of signal channels is large, such as thousands or tens of thousands of receivers, and the synchronization sequence is relatively long, the resource consumption required for FPGA (Field Programmable Gate Array) implementation is extremely large. Therefore, it is urgent to improve the correlation algorithm to reduce FPGA resource consumption and increase the calculation speed. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a correlation operation method based on co-OR polarization and its capture algorithm to reduce the resource consumption of FPGA and improve the operation speed.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] This correlation operation method based on XOR polarization uses XOR logic operation and data polarization operation to replace the multiplier, so as to reduce the resource consumption of FPGA and improve the operation speed.

[0008] Specifically, the steps are as follows:

[0009] Step A1, according to the definition of {0, 1} polarization, the real part and imaginary part of vector X and the real part and imaginary part of vector Y are respectively {0, 1} polarized;

[0010] Step A2, replacing the multiplier in the calculation formula (3) related to vector X and vector Y with an XOR device;

[0011] Step A3: Based on the XOR operation, all XOR operation results are polarized to {1, -1};

[0012] Step A4: Through the above steps A1 to A3, the correlation calculation formula (3) is simplified to a new correlation formula (9), and according to the new correlation formula (9), the data after co-or polarization are summed to obtain the final correlation operation result.

[0013] Specifically, in step A1, the expression (1) of vector X, the expression (2) of vector Y, and the calculation formula (3) related to vector X and vector Y are specifically:

[0014] X=[x1,x2,…,x N ]=[a1+b1i,a2+b2i,…,a N +b N i] Formula (1)

[0015] Y=[y1,y2,…,y N ]=[c1+d1i,c2+d2i,…,c N +d N i] Formula (2)

[0016]

[0017] Specifically, the definition of {0, 1} polarization in step A1 is as follows:

[0018]

[0019] In formula (4), is the {0, 1} polarization value of a.

[0020] Specifically, the polarized vector in step A1 is and vector as follows:

[0021]

[0022] Specifically, the definition of the XOR logic operation used by the XOR device in step A2 is as follows:

[0023]

[0024] In formula (7), ⊙ is the exclusive OR logical operator symbol.

[0025] Specifically, the {1, -1} polarization in step A3 is defined as follows:

[0026]

[0027] In formula (8), is the {1, -1} polarization value of a.

[0028] Specifically, the formula for the final relevant calculation result in step A4 is as follows:

[0029]

[0030] In formula (9), They are respectively n , b n 、c n ,d n {0, 1} polarization; ⊙ is the exclusive OR logical operator symbol; They are The {1, -1} polarization value of .

[0031] In addition, the present invention also provides a capture algorithm based on part or all of the above related operation methods, and the specific implementation process is:

[0032] Step B1, obtaining a received signal Y(n): the length of the receiving window r(n) is L*sps, where L is the symbol length of the preamble sequence PN, sps is the upsampling multiple, and a sampling point is slid each time to obtain a signal r(n), and r(n) is decimated by sps times to obtain a received sequence Y(n) of length L;

[0033] Step B2, correlation operation: using the co-or polarization correlation algorithm, the received sequence Y(n) and the leading sequence PN are subjected to co-or polarization correlation operation to obtain the correlation value Then take the absolute value of the relevant value to get

[0034] Step B3, FIFO processing: put the relevant result |R(n)| into a cache FIFO with a length of M;

[0035] Step B4, judgment: use the specified algorithm to determine whether the correlation peak appears. If it appears, it is determined that the signal is captured successfully and the signal arrival point position is returned; otherwise, if it does not appear, return to step B1 to continue the next sliding correlation.

[0036] Specifically, the current time n is defined, when n>M and n·mod·N=0, the data in the FIFO is processed and judged; wherein M is the total length of the FIFO, N is the length of the new value in the FIFO, and MN is the length of the old value; the step B4 specifically includes:

[0037] Step B4.1, calculate the maximum value of N new value data in FIFO to obtain the maximum value Max_new;

[0038] Step B4.2, calculate the maximum value of MN old value data in FIFO, and obtain the maximum value Max_old and the maximum value position P1;

[0039] Step B4.3, set the threshold REL=3, and the judgment condition is Max_old>(Max_new*REL); if it is satisfied, it is determined that the correlation peak has appeared, and the arrival point position is P=P1+(nM); if it is not satisfied, it is considered that the correlation peak has not appeared, and return to step B1 to continue the next sliding correlation.

[0040] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0041] The correlation operation method based on XOR polarization provided by the present invention abandons the multiplier and no longer needs to perform 4N times (N is the data length of the leading sequence PN) multiplication, but only needs to perform 4N times of XOR and 2 times of data polarization. Especially when there are many signal paths, such as a thousand-path / ten-path receiver, when the PN sequence is relatively long, the FPGA resource consumption is too large, and the correlation operation is no longer implemented by multiplication but by logical XOR operation and data polarization, thereby reducing the resource consumption of the FPGA and greatly improving the operation speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the present invention.

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0044] Figure 1 A flowchart of a correlation operation method based on co-OR polarization provided in Embodiment 1 of the present invention;

[0045] Figure 2 A flowchart of a capture algorithm provided in Example 2 of the present invention;

[0046] Figure 3A schematic diagram of data sliding provided in Example 2 of the present invention;

[0047] Figure 4 A schematic diagram of FIFO data length division provided by Embodiment 2 of the present invention;

[0048] Figure 5 It is a line graph showing the variation of the detection threshold signal-to-noise ratio (SNR) captured in Example 2 of the present invention with the length of the preamble sequence PN. DETAILED DESCRIPTION

[0049] Here, exemplary embodiments will be described in detail, and the embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples consistent with some aspects of the present invention described in detail in the appended claims.

[0050] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0051] Example 1

[0052] This embodiment provides a correlation operation method based on XOR polarization, which uses XOR logic operation and data polarization operation to replace the multiplier, so as to reduce the resource consumption of FPGA and improve the operation speed.

[0053] See also Figure 1 As shown, in this embodiment, the correlation calculation method based on co-OR polarization has the following specific steps:

[0054] Step A1, according to the definition of {0, 1} polarization, the real part and imaginary part of vector X and the real part and imaginary part of vector Y are respectively {0, 1} polarized;

[0055] Step A2, replacing the multiplier in the calculation formula (3) related to vector X and vector Y with an XOR device;

[0056] Step A3: Based on the XOR operation, all XOR operation results are polarized to {1, -1};

[0057] Step A4: Through the above steps A1 to A3, the correlation calculation formula (3) is simplified to a new correlation formula (9), and according to the new correlation formula (9), the data after co-or polarization are summed to obtain the final correlation operation result.

[0058] Here, we take the correlation between vector X and vector Y as an example to introduce the co- or polarization correlation calculation method in detail. Let vector X and vector Y be expressed as follows:

[0059] X=[x1,x2,…,x N ]=[a1+b1i,a2+b2i,…,aN +b N i] Formula (1)

[0060] Y=[y1,y2,…,y N ]=[c1+d1i,c2+d2i,…,c N +d N i] Formula (2)

[0061] The conventional calculation formula (3) for vector X and vector Y is:

[0062]

[0063] Based on the above formula (3), the co-or polarization correlation algorithm operates as follows:

[0064] 1) {0, 1} polarization

[0065] The definition of {0, 1} polarization in step A1 is as follows:

[0066]

[0067] In formula (4), is the {0, 1} polarization value of a.

[0068] According to the definition of {0, 1} polarization, the real and imaginary parts of vector X and vector Y are polarized by {0, 1} to obtain the polarized vector and vector as follows:

[0069]

[0070] 2) XOR logical operation

[0071] The XOR logic operation used by the XOR device in step A2 is defined as follows:

[0072]

[0073] In formula (4), ⊙ is the symbol of the XOR logical operation. After this step, replace the multiplication with XOR, that is, replace the a in the relevant calculation formula (3) with n *c n become b n *d n become b n *c n become a n *d n become

[0074] 3) {1, -1} polarization

[0075] The {1, -1} polarization in step A3 is defined as follows:

[0076]

[0077] In formula (8), is the {1, -1} polarization value of a. After this step, the a in the relevant calculation formula (3) n *c n Eventually becomes b n *d n Eventually becomes b n *c n Eventually becomes a n *d n become

[0078] All the above XOR operation results are polarized to {1, -1}, and the formula for the final correlation calculation result is as follows:

[0079]

[0080] In formula (9), They are respectively n , b n 、c n ,d n {0, 1} polarization; ⊙ is the XOR logic operation; They are The {1, -1} polarization value of .

[0081] In summary, the correlation operation method of the same or polarization provided in this embodiment abandons the multiplier, and no longer needs to perform 4N multiplications (N is the data length of the leading sequence PN). Only 4N same or polarizations and 2 data polarizations are required, which greatly reduces the amount of calculation and resource consumption.

[0082] Example 2

[0083] Based on Example 1, this embodiment also provides a capture algorithm based on the co-or polarization correlation operation method, see Figure 2 As shown, the specific implementation process is as follows:

[0084] Step B1, obtain the received signal Y(n): Combine Figure 3, the length of the receiving window r(n) is L*sps, where L is the symbol length of the leading sequence PN, sps is the upsampling multiple, and each time a sampling point is slid, the signal r(n) is obtained, and r(n) is decimated by sps times to obtain the receiving sequence Y(n) of length L;

[0085] Step B2, correlation operation: using the co-or polarization correlation algorithm, the received sequence Y(n) and the leading sequence PN are subjected to co-or polarization correlation operation to obtain the correlation value Then take the absolute value of the relevant value to get

[0086] Step B3, FIFO processing: put the relevant result |R(n)| into a cache FIFO with a length of M;

[0087] Step B4, judgment: use the specified algorithm to determine whether the correlation peak appears. If it appears, it is determined that the signal is captured successfully and the signal arrival point position is returned; otherwise, if it does not appear, return to step B1 to continue the next sliding correlation.

[0088] Furthermore, the step B4 specifically includes:

[0089] Define the current time n, when n>M and n·mod·N=0, process and judge the data in FIFO; Figure 4 , M is the total length of FIFO, N is the length of the new value in FIFO, and MN is the length of the old value;

[0090] Step B4.1, calculate the maximum value of N new value data in FIFO to obtain the maximum value Max_new;

[0091] Step B4.2, calculate the maximum value of MN old value data in FIFO, and obtain the maximum value Max_old and the maximum value position P1;

[0092] Step B4.3, set the threshold REL=3, and the judgment condition is Max_old>(Max_new*REL); if it is satisfied, it is determined that the correlation peak has appeared, and the arrival point position is P=P1+(nM); if it is not satisfied, it is considered that the correlation peak has not appeared, and return to step B1 to continue the next sliding correlation.

[0093] In order to further verify the effectiveness of the technical solution provided by the present invention, this embodiment specifically performs the following synchronous capture simulation, and the specific simulation conditions are as follows:

[0094] (1)Signal bandwidth: 20MHz;

[0095] (2) Transmission channel: Gaussian channel;

[0096] (3) Background noise: additive Gaussian white noise;

[0097] (4) Frequency deviation setting: Randomly changes within the range of [-10kHz, 10kHz];

[0098] (5) Number of simulation repetitions: 10 5 Second-rate;

[0099] (6) Detection conditions: Synchronous detection position - real synchronous position < one symbol point;

[0100] (7) Capture success rate: 99.99%.

[0101] Combination Figure 5 The simulation results show that the detection threshold decreases with the increase of PN length until it reaches the minimum detection threshold of the algorithm. After reaching the minimum detection threshold of -9dB, the detection threshold does not change when the PN length is increased. From the simulation diagram, it can be seen that the PN length only needs 450 symbols to reach the minimum detection threshold of -9dB, which can fully meet the current communication product needs.

[0102] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0103] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A correlation operation method based on co-OR polarization, characterized in that: The XOR logic operation and data polarization operation are used to replace the multiplier to reduce the resource consumption of FPGA and improve the operation speed.

2. The correlation operation method based on co-OR polarization according to claim 1, characterized in that: The specific steps are as follows: Step A1, according to the definition of {0, 1} polarization, the real part and imaginary part of vector X and the real part and imaginary part of vector Y are respectively {0, 1} polarized; Step A2, replacing the multiplier in the calculation formula (3) related to vector X and vector Y with an XOR device; Step A3: Based on the XOR operation, all XOR operation results are polarized to {1, -1}; Step A4: Through the above steps A1 to A3, the correlation calculation formula (3) is simplified to a new correlation formula (9), and according to the new correlation formula (9), the data after co-or polarization are summed to obtain the final correlation operation result.

3. The correlation operation method based on co-OR polarization according to claim 2, characterized in that: In step A1, the expression (1) of vector X, the expression (2) of vector Y, and the calculation formula (3) related to vector X and vector Y are specifically: X = [x1, x2, …, x N = [a1 + b1i, a2 + b2i, …, a N + b N i] Equation (1) Y = [y1, y2, …, y N = [c1 + d1i, c2 + d2i, …, c N + d N i] Equation (2) 4. The correlation operation method based on co-OR polarization according to claim 3, characterized in that: The definition of {0, 1} polarization in step A1 is as follows: In formula (4), is the {0, 1} polarization value of a.

5. The correlation operation method based on co-OR polarization according to claim 4, characterized in that: The polarized vector in step A1 and vector as follows:

6. The correlation operation method based on co-OR polarization according to claim 2, characterized in that: The XOR logic operation used by the XOR device in step A2 is defined as follows: In formula (7), ⊙ is the exclusive OR logical operator.

7. The correlation operation method based on co-OR polarization according to claim 6, characterized in that: The {1, -1} polarization in step A3 is defined as follows: In formula (8), is the {1, -1} polarization value of a.

8. The correlation operation method based on co-OR polarization according to claim 2, characterized in that: The formula for the final correlation operation result in step A4 is as follows: In formula (9), They are respectively n , b n 、c n ,d n {0, 1} polarization; ⊙ is the NOR operator symbol; They are The {1, -1} polarization value of .

9. A capture algorithm based on the correlation operation method according to any one of claims 1 to 8, characterized in that: The specific implementation process is: Step B1, obtaining a received signal Y(n): the length of the receiving window r(n) is L*sps, where L is the symbol length of the preamble sequence PN, sps is the upsampling multiple, and a sampling point is slid each time to obtain a signal r(n), and r(n) is decimated by sps times to obtain a received sequence Y(n) of length L; Step B2, correlation operation: using the co-or polarization correlation algorithm, the received sequence Y(n) and the leading sequence PN are subjected to co-or polarization correlation operation to obtain the correlation value Then take the absolute value of the relevant value to get Step B3, FIFO processing: put the relevant result |R(n)| into a cache FIFO with a length of M; Step B4, judgment: use the specified algorithm to determine whether the correlation peak appears. If it does, it is determined that the signal is captured successfully and the signal arrival point position is returned; Otherwise, if it does not appear, return to step B1 to continue the next sliding correlation.

10. The capture algorithm according to claim 9, characterized in that: Define the current time n, when n>M and n·mod·N=0, process and judge the data in the FIFO; wherein M is the total length of the FIFO, N is the length of the new value in the FIFO, and MN is the length of the old value; the step B4 specifically includes: Step B4.1, calculate the maximum value of N new value data in FIFO to obtain the maximum value Max_new; Step B4.2, calculate the maximum value of MN old value data in FIFO, and obtain the maximum value Max_old and the maximum value position P1; Step B4.3, set the threshold REL=3, and the judgment condition is Max_old>(Max_new*REL); if it is satisfied, it is determined that the correlation peak has appeared, and the arrival point position is P=P1+(nM); if it is not satisfied, it is considered that the correlation peak has not appeared, and return to step B1 to continue the next sliding correlation.

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