A nonlinear orthogonal mode parallel channel estimation method and its implementation system

Abstract

The present invention discloses a parallel channel estimation method of a nonlinear orthogonal mode and its implementation system, belonging to the technical field of channel estimation. The method comprises: at the transmitting end, inserting a group of orthogonal codes in front of each data code of multiple parallel data codes containing nonlinear orthogonal mode signals, and inserting multiple groups of pilots B and a group of pilots A in front of the orthogonal code of the first channel, forming multiple parallel data frames, and sending them to the receiving end through a parallel channel; wherein the pilots A and pilots B are a group of mutually correlated pseudo-random sequences; at the receiving end, based on the received multiple parallel data frames, using pilots A for frame positioning, using multiple groups of pilots B for carrier synchronization based on Costas loops, and realizing parallel channel estimation of nonlinear orthogonal mode signals according to the carrier synchronization results and orthogonal codes. The method can use very little time domain resource overhead, and use Costas loops to realize high-precision carrier synchronization in a nonlinear orthogonal base beam transmission system.

Description

Technical Field

[0001] The invention belongs to the technical field of channel estimation, and in particular relates to a nonlinear orthogonal mode parallel channel estimation method and an implementation system thereof. Background Art

[0002] Nonlinear orthogonal base beam transmission is a highly promising part of the future 6G technology trend. It can generate theoretically infinite orthogonal beams under limited channels and improve channel transmission efficiency. However, the traditional nonlinear orthogonal base beam transmission system faces problems such as "divergence in the middle of the air". It is necessary to use channel estimation and carrier synchronization technology in the actual system to achieve "alignment" of transmission and reception at the signal level, so as to construct a channel quasi-cyclic matrix and suppress interference between signals.

[0003] The Costas loop method is also known as the in-phase orthogonal loop method or the edge loop method. It mainly uses a phase-locked loop to extract the carrier frequency, and the carrier frequency output can be obtained without performing a square operation on the received signal. The error signal of this method is provided by multiplying two signals and a low-pass filter. The Costas loop can generally be used for carrier recovery in coherent demodulation of suppressed carrier modulation signals (such as double-sideband suppressed carrier modulation) and traditional phase modulation signals (such as BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying)). Since the amplitudes of the i-path and the q-path in the nonlinear orthogonal base beam transmission system are not equal, the Costas loop method cannot be used for parallel and efficient channel estimation.

[0004] At present, for channel estimation and carrier synchronization of nonlinear orthogonal basis beam transmission systems, the antenna face alignment method at the physical level is usually used. By constructing a quasi-cyclic matrix at the physical level, the mutual interference introduced in the nonlinear orthogonal basis beam transmission can be suppressed, which can be used in short-distance transmission systems. However, for future large-scale and long-distance nonlinear orthogonal basis beam transmission systems, an efficient and physically feasible channel estimation method is required. In addition, future nonlinear orthogonal basis beam transmission systems need to be connected to high-mobility scenarios, while the antenna face alignment method at the physical level is limited to transmission at fixed positions and cannot be applied to nonlinear orthogonal basis beam transmission in high-mobility scenarios. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a parallel channel estimation method of nonlinear orthogonal mode and its implementation system. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0006] In a first aspect, the present invention proposes a parallel channel estimation method for nonlinear orthogonal modes, comprising:

[0007] At the transmitting end, a group of orthogonal codes are inserted before each data code of multiple parallel data codes containing nonlinear orthogonal mode signals, and multiple groups of pilots B and a group of pilots A are inserted before the first orthogonal code to form multiple parallel data frames, which are sent to the receiving end through parallel channels; wherein pilots A and pilots B are a group of mutually correlated pseudo-random sequences;

[0008] At the receiving end, based on the received multi-channel parallel data frames, pilot A is used for frame positioning, and multiple groups of pilot B are used for carrier synchronization based on Costas loops, and parallel channel estimation of nonlinear orthogonal mode signals is achieved based on the carrier synchronization results and orthogonal codes.

[0009] In a second aspect, the present invention proposes a system for implementing the method proposed in the first aspect of the present invention, the system comprising a transmitting end and a receiving end, the transmitting end comprising a plurality of transmitting antennas and configured with a frame format generating module;

[0010] The frame format generation module is used to insert a group of orthogonal codes in front of each data code of the multi-channel parallel data code containing nonlinear orthogonal mode signals, and insert multiple groups of pilots B and a group of pilots A in front of the first orthogonal code to form a multi-channel parallel data frame; wherein the pilots A and pilots B are a group of mutually correlated pseudo-random sequences;

[0011] Multiple transmitting antennas, used to send multiple parallel data frames to a receiving end through parallel channels;

[0012] The receiving end includes multiple receiving antennas and is equipped with a positioning module, a carrier synchronization module and a channel estimation module;

[0013] The multiple receiving antennas are used to receive the multi-channel parallel data frames sent by the transmitting end, and obtain pilot A, multiple groups of pilot B, orthogonal codes and multi-channel parallel data codes;

[0014] A positioning module, used for frame positioning using pilot A;

[0015] A carrier synchronization module, used for performing carrier synchronization based on a Costas loop using multiple groups of pilot signals B;

[0016] The channel estimation module is used to realize parallel channel estimation of nonlinear orthogonal mode signals according to carrier synchronization results and orthogonal codes.

[0017] Beneficial effects of the present invention:

[0018] 1. The parallel channel estimation method of nonlinear orthogonal mode provided by the present invention first redesigns the frame format at the transmitting end, inserts a group of orthogonal codes in front of each data code of multiple parallel data codes containing nonlinear orthogonal mode signals, and inserts multiple groups of pilots B and a group of pilots A only in front of the first orthogonal code to form multiple parallel data frames; then, at the receiving end, pilot A is used for frame positioning, and multiple groups of pilots B are used for carrier synchronization based on Costas loops, and parallel channel estimation of nonlinear orthogonal mode signals is realized based on the carrier synchronization results and orthogonal codes. This method can use very little time domain resource overhead, and uses Costas loops to realize carrier synchronization in a nonlinear orthogonal base beam transmission system, so that the nonlinear orthogonal base beam transmission is no longer affected by the transmission distance, so as to be suitable for nonlinear orthogonal base beam transmission in high mobility scenarios;

[0019] 2. The present invention uses Walsh code to implement multi-path parallel channel estimation. Compared with the existing single-transmit multiple-receive channel estimation, while ensuring accuracy, it only needs to use the original time of estimating one transmitting antenna to estimate all transmitting antennas, which greatly reduces the time consumption;

[0020] 3. After the first carrier synchronization is achieved using the Costas loop, the present invention also uses a dual pilot method to estimate the fixed frequency deviation that occurs after the Costas loop stops locking, and performs phase compensation on the subsequent part, thereby improving the data accuracy of the carrier synchronization.

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of a parallel channel estimation method of a nonlinear orthogonal mode provided by an embodiment of the present invention;

[0023] Figure 2 It is a schematic diagram of the structural design of a multi-channel parallel data frame provided by an embodiment of the present invention;

[0024] Figure 3 It is a structural block diagram of a nonlinear orthogonal mode parallel channel estimation implementation system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The first aspect of the present invention provides a parallel channel estimation method for nonlinear orthogonal modes. The method is mainly aimed at the carrier recovery in the coherent demodulation of the traditional phase modulation signal in the Costas loop in the traditional second-order digital loop. When other phase modulation signals cannot use the second-order digital loop for carrier synchronization, the frame format is redesigned at the transmitting end: a group of pilots A and multiple groups of pilots B are added, and pilots A and pilots B are a group of pseudo-random sequences with excellent mutual correlation performance; wherein pilot A is used for frame positioning, and pilot B can provide the operating environment of the second-order digital loop, so that the Costas loop can be used in the nonlinear orthogonal base beam transmission system. Since the Costas loop method uses very few transistor resources at both ends of the transmitter and receiver when performing carrier synchronization, it provides a lower transistor consumption cost in the nonlinear orthogonal base beam transmission system than using other carrier synchronization methods. At the same time, an orthogonal code is added to the redesigned frame format at the transmitting end, and the orthogonal code can be used to realize parallel efficient channel estimation.

[0027] For details, see Figure 1 , Figure 1 1 is a flow chart of a parallel channel estimation method for nonlinear orthogonal modes provided by an embodiment of the present invention, which mainly includes the following two steps:

[0028] Step 1: At the transmitting end, a group of orthogonal codes are inserted in front of each data code of multiple parallel data codes containing nonlinear orthogonal mode signals, and multiple groups of pilot B and a group of pilot A are inserted in front of the first orthogonal code to form multiple parallel data frames, which are sent to the receiving end through parallel channels; wherein pilot A and pilot B are a group of pseudo-random sequences with excellent mutual correlation performance, which can be recorded as Pilot A and Pilot B.

[0029] Step 2: At the receiving end, based on the received multi-channel parallel data frames, frame positioning is performed using pilot A, and carrier synchronization based on Costas loops is performed using multiple groups of pilot B. Parallel channel estimation of nonlinear orthogonal mode signals is implemented based on the carrier synchronization results and orthogonal codes.

[0030] The parallel channel estimation method of the nonlinear orthogonal mode provided by the present invention first redesigns the frame format at the transmitting end, inserts a group of orthogonal codes before each data code of the multi-channel parallel data code containing the nonlinear orthogonal mode signal, and inserts multiple groups of pilots B and a group of pilots A only before the orthogonal code of the first channel to form a multi-channel parallel data frame; then, at the receiving end, the pilot A is used for frame positioning, and the multiple groups of pilots B are used for carrier synchronization based on the Costas loop, and the parallel channel estimation of the nonlinear orthogonal mode signal is realized according to the carrier synchronization result and the orthogonal code. The method can use very little time domain resource overhead, and realizes carrier synchronization using the Costas loop in the nonlinear orthogonal base beam transmission system, so that the nonlinear orthogonal base beam transmission is no longer affected by the transmission distance, so as to be suitable for nonlinear orthogonal base beam transmission in high mobility scenarios.

[0031] Optionally, this embodiment is illustrated by taking four parallel channels, that is, both the transmitting end and the receiving end include four antennas, and the communication frequency between the transmitting end and the receiving end can be 5.5 GHz. The four parallel data codes containing nonlinear orthogonal mode signals can be recorded as DATA A, DATA B, DATA C, and DATA D, and their length can be designed to be 1000 bits.

[0032] In the process of implementing step 1, this embodiment designs the following at the transmitting end: Figure 2 The frame structure shown in the figure, wherein pilot A and pilot B can be designed as 32-bit m-sequences or other pseudo-random sequences, and pilot B can specifically include 15 groups.

[0033] Furthermore, in order to achieve high accuracy, general nonlinear orthogonal mode channel estimation will choose to use a time-division-based "single-transmit multiple-receive" pilot sequence for channel estimation. The time consumed by the channel estimation part will increase linearly with the number of transmit antennas M. When the number of transmit antennas M increases, the time consumption of the entire channel estimation system will become very large. Based on this, this embodiment designs orthogonal codes in different channels of the frame format and uses Walsh codes for implementation.

[0034] Walsh code is an orthogonal code mainly used to achieve orthogonality between different channels, i.e., orthogonal modulation. Walsh code does not have the function of spreading spectrum, so its ability to resist channel interference is not strong. Walsh code is often used as an address code or spread spectrum code in CDMA (Code Division Multiple Access) mobile communication systems. The autocorrelation value of Walsh code is sharp and the cross-correlation value is 0. Therefore, this embodiment selects Walsh code as the orthogonal sequence for channel estimation.

[0035] The present invention adopts Walsh code to realize multi-path parallel channel estimation. Compared with the existing single-transmit multiple-receive channel estimation, it only needs to use the original estimation time of one transmitting antenna to estimate all transmitting antennas while ensuring the accuracy, which greatly reduces the time consumption.

[0036] Optionally, in this embodiment, the number of Walsh codes is set according to the number of antennas at the transmitting end and the receiving end, and all orthogonal codes added in the multiple parallel channels can form a group of orthogonal code groups, which are recorded as , is the number of antennas at the transmitting and receiving ends, where The value can be 4, corresponding to four parallel channels, so the number of Walsh codes can be 4 accordingly.

[0037] Exemplarily, in this embodiment, each orthogonal code in the orthogonal code group including four Walsh codes can be recorded as Walsh code A, Walsh code B, Walsh code C, and Walsh code D, such as Figure 2 As shown, the length can be 128 bits.

[0038] It should be noted that Figure 2 The data format used by the entire nonlinear orthogonal basis beam transmission system is exemplarily shown below, including a sign bit, an integer part, a decimal part, etc. The data format can also be changed according to actual needs.

[0039] At this point, the frame format design of the transmitter is completed.

[0040] Then, the frame format including pilot A, pilot B, Walsh code and effective information DATA of the nonlinear orthogonal mode signal is sent to the receiving end through a parallel channel.

[0041] according to Figure 2 From the frame format design shown, it can be seen that the pilot A used to achieve frame synchronization and the pilot B used to achieve carrier synchronization can only transmit one channel, preferably the first channel, to reduce the power required to transmit; and when transmitting pilot A and pilot B, the remaining channels do not send data to avoid interference.

[0042] It should be noted that after the transmitting end designs the frame format, the pilot A, pilot B, and orthogonal code (Walsh code in this embodiment) are stored in the receiving end in a copy so that the receiving end can perform signal processing. It can be understood that the pilot A copy, pilot B copy, and orthogonal code copy pre-stored at the receiving end are exactly the same as the pilot A, pilot B, and orthogonal code at the transmitting end.

[0043] Furthermore, the specific implementation process of step 2 mainly includes the following steps 21)-24):

[0044] 21) Use pilot A to perform frame positioning, and after the frame positioning is successful, open the Costas loop.

[0045] Specifically, when the receiving end receives the pilot A, it can use the pre-stored copy of the pilot A to perform a complex conjugate correlation operation, thereby achieving frame positioning; and after completing the frame positioning, the Costas loop is immediately opened.

[0046] 22) Using the header sequences of the multiple groups of pilot signals B, the first carrier synchronization based on the Costas loop is performed, and after the first carrier synchronization is completed, the Costas loop is closed.

[0047] Specifically, the header sequences of multiple groups of pilot signals B are used to simultaneously perform the first carrier synchronization of the Costas loop in the second-order digital loop and estimate the frequency deviation of the receiving and transmitting signals, so that the frequency deviation is continuously reduced during the second-order digital loop tracking process and eventually becomes stable.

[0048] The frequency deviation eventually tends to be stable mainly refers to the frequency deviation fluctuating within a very small amplitude range, which can be customized according to actual conditions.

[0049] When the frequency deviation tends to be stable, the first carrier synchronization is completed and the Costas loop is closed.

[0050] After the traditional Costas loop is locked in the second-order digital loop, it will cause certain frequency oscillations due to the delay of the loop parameter setting and the loop feedback part; after the Costas loop is stopped, the synchronized carrier frequency will randomly select a frequency in the frequency oscillation range and fix it, which will cause a certain fixed frequency difference. Therefore, this embodiment chooses to use the head sequence of multiple groups of pilots B to perform the first carrier synchronization of the Costas loop in the second-order digital loop, and uses the tail sequence of multiple groups of pilots B to perform the second carrier synchronization based on dual pilots, estimates the fixed frequency deviation that occurs after the Costas loop lock stops, and performs phase compensation on the subsequent part of the digital code to improve the data accuracy of carrier synchronization.

[0051] The head sequences of the multiple groups of pilots B can be understood as the first several groups of sequences of the multiple groups of pilots B, and the corresponding tail sequences of the multiple groups of pilots B can be understood as the last several groups of sequences remaining after removing the head sequences from the multiple groups of pilots B. For example, when there are 15 groups of pilots B, the first 9 groups of sequences can be selected as the head sequences for the first carrier synchronization based on the Costas loop in the second-order digital loop, and the last 6 groups of sequences can be selected as the tail sequences for the second carrier synchronization based on the dual pilots.

[0052] 23) The tail sequences of the multiple groups of pilot signals B are used to perform a second carrier synchronization based on dual pilot signals to achieve frequency compensation of the carrier at the receiving end.

[0053] 23-1) Estimating the phase offset per unit time based on any two sequences in the tail sequences of the multiple groups of pilot signals B to obtain an average phase difference between adjacent sequences.

[0054] First, two sequences are randomly selected from the tail sequences of multiple groups of pilot signals B; for example, the 11th and 14th sequences may be selected from the last 6 groups of sequences.

[0055] Then, the pilot B replica stored in the receiving end is used to perform complex conjugate correlation operation on the two selected sequences to extract two phase deviation information, wherein the phase deviation information corresponding to the 11th group can be recorded as the first phase deviation information , the phase deviation information corresponding to the 14th group of sequences can be recorded as the second phase deviation information .

[0056] Next, based on the interval between the two selected sequences (also called adjacent symbols), the average phase difference between the adjacent sequences is calculated.

[0057] Since the signal frequency difference is approximately fixed at this time, and considering the influence of estimation accuracy, it is impossible to make the phase difference exactly the same, the phase difference between adjacent sequences of the signal can be considered as a constant value, and the average phase difference of adjacent sequences can be calculated by the following formula:

[0058] ;

[0059] In the formula, represents the average phase difference of adjacent sequences, Indicates the interval between the two selected sequences.

[0060] 23-2) The frequency compensation of the subsequent part of the received multi-channel parallel data frame is performed using the average phase difference value of the adjacent sequences, thereby realizing the frequency compensation of the carrier at the receiving end.

[0061] The average phase difference After that, the frequency difference of the subsequent parts can be compensated according to the sequence interval n bits.

[0062] After the first carrier synchronization is achieved by using the Costas loop, the present invention also uses a dual pilot method to estimate a fixed frequency deviation that occurs after the Costas loop stops locking, and performs phase compensation on the subsequent part, thereby improving the data accuracy of the carrier synchronization.

[0063] 24) Using orthogonal codes, parallel channel estimation is performed on the frequency compensated channel based on nonlinear orthogonal mode signals to obtain a channel matrix.

[0064] In the embodiment, the orthogonal code copies pre-stored at the receiving end are used to perform complex conjugate correlation calculation on the orthogonal codes received by different receiving ends, and the channel information from different transmitting ends to different receiving ends is extracted to obtain a channel matrix.

[0065] Specifically, the receiving end uses the different Walsh code copies corresponding to each transmission channel pre-stored, and performs complex conjugate correlation calculations on the composite signals from different transmission ports received by the receiving end. Because of the orthogonality of the Walsh code itself, the value obtained by performing complex conjugate correlation calculations on the Walsh code of a specific transmission port and the corresponding Walsh code copy used by the receiving port is close to the Walsh code element length, while the value obtained by performing complex conjugate correlation calculations on the non-corresponding Walsh code copies in the composite signal composed by the transmitting end is close to 0. Therefore, when different receiving ends receive the composite signal composed by the transmitting end, they can extract the channel information from different transmitting ends to different receiving ends by performing complex conjugate correlation operations on different Walsh code copies at the same time. ,in, are the numbers of different transmitters. is the number of different receiving ends, which together form the estimated channel matrix. For example, with 4 transmitting ends and 4 receiving ends, the estimated four-way parallel channel matrix is It can be expressed as:

[0066] .

[0067] After obtaining the channel matrix, it also includes:

[0068] Based on the channel matrix, complex multiplication operation is performed on the received multi-channel parallel data codes at the receiving end, and the data obtained by the operation is decoded to obtain a nonlinear orthogonal mode signal.

[0069] Specifically, the multi-channel parallel data code received by the receiving end can be recorded as , You can take 4; use complex multiplication to calculate the required nonlinear orthogonal mode signal data , Express Find the conjugate operation, Indicates a transposition operation; the data information is then decoded to obtain decoded data.

[0070] So far, the transmission, channel estimation and decoding of one frame of data have been realized. When the nonlinear orthogonal mode signal is continuously transmitted, the information can be repeatedly sent according to the above steps, and only the data code DATA containing the nonlinear orthogonal mode signal needs to be modified and replaced with the required valid information.

[0071] In summary, the nonlinear orthogonal mode parallel channel estimation method provided by the present invention has the following advantages:

[0072] 1. By redesigning the frame format at the transmitter, carrier synchronization can be achieved by using a Costas loop in a nonlinear orthogonal basis beam transmission system with little time domain resource overhead.

[0073] 2. The introduction of Walsh codes to achieve parallel MIMO channel estimation greatly reduces the time consumption. While ensuring accuracy, it only takes the time to estimate one transmitting antenna to estimate all transmitting antennas.

[0074] 3. The dual pilot method is used to estimate the fixed frequency deviation that occurs after the Costas loop stops locking, and phase compensation is performed on the subsequent part, thereby improving the data accuracy of carrier synchronization.

[0075] The second aspect of the present invention further provides an implementation system for implementing a nonlinear orthogonal mode parallel channel estimation method provided by the first aspect of the present invention. Figure 3 , Figure 3 The present invention provides a block diagram of a nonlinear orthogonal mode parallel channel estimation implementation system. The system includes a transmitting end and a receiving end, the transmitting end includes multiple transmitting antennas and is equipped with a frame format generation module;

[0076] The frame format generation module is used to insert a group of orthogonal codes in front of each data code of the multi-channel parallel data code containing nonlinear orthogonal mode signals, and insert multiple groups of pilots B and a group of pilots A in front of the first orthogonal code to form a multi-channel parallel data frame; wherein the pilots A and pilots B are a group of mutually correlated pseudo-random sequences;

[0077] A plurality of transmitting antennas are used to send multiple parallel data frames to a receiving end according to the formed parallel channels;

[0078] The receiving end includes multiple receiving antennas and is equipped with a positioning module, a carrier synchronization module and a channel estimation module;

[0079] Multiple receiving antennas are used to receive multiple parallel data frames sent by the transmitting end, and obtain pilot A, multiple groups of pilot B, orthogonal codes and multiple parallel data codes;

[0080] A positioning module, used for frame positioning using pilot A;

[0081] A carrier synchronization module, used for performing carrier synchronization based on a Costas loop using multiple groups of pilot signals B;

[0082] The channel estimation module is used to realize parallel channel estimation of nonlinear orthogonal mode signals according to carrier synchronization results and orthogonal codes.

[0083] Therefore, the system can perform nonlinear orthogonal basis beam transmission and achieve carrier synchronization by using Costas loop.

[0084] Although the present application is described herein in conjunction with various embodiments, in the process of implementing the claimed application, those skilled in the art may understand and implement other changes to the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "one" or "an" does not exclude multiple situations. A single processor or other unit may implement several functions listed in the claims. Certain measures are recorded in different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0085] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, devices (equipment), or computer program products. Therefore, the present application may adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware, which are collectively referred to as "modules" or "systems" herein. Moreover, the present application may adopt the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program codes. The computer program is stored / distributed in a suitable medium, provided together with other hardware or as a part of hardware, or may adopt other distribution forms, such as by Internet or other wired or wireless telecommunication systems.

[0086] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A parallel channel estimation method for nonlinear orthogonal modes, characterized in that: include: At the transmitting end, a group of orthogonal codes are inserted before each data code of multiple parallel data codes containing nonlinear orthogonal mode signals, and multiple groups of pilots B and a group of pilots A are inserted before the first orthogonal code to form multiple parallel data frames, which are sent to the receiving end through parallel channels; wherein the pilots A and the pilots B are a group of mutually correlated pseudo-random sequences; At the receiving end, based on the received multi-channel parallel data frames, the pilot A is used to perform frame positioning, multiple groups of the pilot B are used to perform carrier synchronization based on the Costas loop, and parallel channel estimation of the nonlinear orthogonal mode signal is realized according to the carrier synchronization result and the orthogonal code; Among them, at the receiving end, based on the received multi-channel parallel data frames, the pilot A is used to perform frame positioning, multiple groups of the pilot B are used to perform carrier synchronization based on the Costas loop, and parallel channel estimation of the nonlinear orthogonal mode signal is realized according to the carrier synchronization result and the orthogonal code, specifically including: Perform frame positioning using the pilot signal A, and after the frame positioning is successful, open the Costas loop; Using multiple groups of header sequences of the pilot signals B to simultaneously perform the first carrier synchronization of the Costas loop in the second-order digital loop and the frequency deviation estimation of the receiving and transmitting signals, so that the frequency deviation is continuously reduced during the second-order digital loop tracking process and eventually tends to be stable; When the frequency deviation tends to be stable, the first carrier synchronization is completed and the Costas loop is closed; Performing a phase offset estimation per unit time based on any two sequences in the tail sequences of the multiple groups of pilot signals B to obtain an average phase difference value of adjacent sequences; Performing frequency compensation on the subsequent part of the received multi-channel parallel data frame by using the average phase difference value of the adjacent sequences, thereby realizing frequency compensation of the carrier at the receiving end; The orthogonal code is used to perform parallel channel estimation based on nonlinear orthogonal mode signals on the frequency compensated channel to obtain a channel matrix.

2. The parallel channel estimation method of a nonlinear orthogonal mode according to claim 1, characterized in that: The pilot A and the pilot B are both 32-bit m-sequences; and the pilot B specifically includes 15 groups.

3. The parallel channel estimation method of a nonlinear orthogonal mode according to claim 1, characterized in that: The orthogonal code is implemented by Walsh code, and the number of the Walsh codes is set according to the number of antennas at the transmitting end and the receiving end.

4. The parallel channel estimation method of a nonlinear orthogonal mode according to claim 1, characterized in that: Estimating the phase offset per unit time based on any two sequences in the tail sequences of the multiple groups of pilot signals B to obtain an average phase difference value of adjacent sequences; comprising: Select any two sequences from a plurality of groups of tail sequences of the pilot signal B; Performing a complex conjugate correlation operation on the two selected sequences using the pilot signal B replica pre-stored at the receiving end to extract the first phase deviation information pream1 and the second phase deviation information pream2; Based on the interval between the two selected sequences, the average phase difference of adjacent sequences is calculated using the following formula: fbit=(pream1-pream2)÷PilotLength; Wherein, fbit represents the average phase difference between adjacent sequences, and PilotLength represents the interval between two selected sequences.

5. The parallel channel estimation method of a nonlinear orthogonal mode according to claim 1, characterized in that: The orthogonal code is used to perform parallel channel estimation based on nonlinear orthogonal mode signals on the frequency compensated channel to obtain a channel matrix, including: By using the orthogonal code copies pre-stored at the receiving end, complex conjugate correlation calculation is performed on the orthogonal codes received by different receiving ends, channel information from different transmitting ends to different receiving ends is extracted, and a channel matrix is ​​obtained.

6. The method for parallel channel estimation of nonlinear orthogonal modes according to claim 5, characterized in that: After obtaining the channel matrix, it also includes: Based on the channel matrix, complex multiplication operation is performed on the received multi-path parallel data codes at the receiving end, and the data obtained by the operation is decoded to obtain a nonlinear orthogonal mode signal.

7. A system for implementing a parallel channel estimation method of a nonlinear orthogonal mode according to any one of claims 1 to 6, the system comprising a transmitting end and a receiving end, characterized in that: The transmitting end includes a plurality of transmitting antennas and is configured with a frame format generating module; The frame format generation module is used to insert a group of orthogonal codes in front of each data code of the multiple parallel data codes containing nonlinear orthogonal mode signals, and insert multiple groups of pilots B and a group of pilots A in front of the first orthogonal code to form a multiple parallel data frame; wherein the pilots A and the pilots B are a group of mutually correlated pseudo-random sequences; The multiple transmitting antennas are used to send the multiple parallel data frames to the receiving end through parallel channels; The receiving end includes multiple receiving antennas and is equipped with a positioning module, a carrier synchronization module and a channel estimation module; The multiple receiving antennas are used to receive multiple parallel data frames sent by the transmitting end, and obtain pilot A, multiple groups of pilot B, orthogonal codes and multiple parallel data codes; The positioning module is used to perform frame positioning using the pilot A; The carrier synchronization module is used to perform carrier synchronization based on the Costas loop using multiple groups of pilot signals B; The channel estimation module is used to realize parallel channel estimation of nonlinear orthogonal mode signals according to the carrier synchronization result and the orthogonal code.

Images