Low signal-to-noise ratio signal processing method and device based on multi-symbol coherent waveform matching

Abstract

The application provides a low signal-to-noise ratio signal processing method and device based on multi-symbol coherent waveform matching, and relates to the technical field of wireless signal communication. The method comprises the following steps: converting an original template for performing waveform matching on a spread spectrum signal of a wireless local area network signal into a waveform template corresponding to an orthogonal frequency division multiplexing system; performing cyclic cross-correlation processing on the spread spectrum signal sent after being modulated by the orthogonal frequency division multiplexing system according to the waveform template to obtain a corresponding frequency domain waveform matching result; performing multi-symbol coherent waveform matching on the frequency domain waveform matching result in the time dimension to obtain a multi-symbol waveform matching result; and performing threshold judgment on the multi-symbol waveform matching result to obtain a signal demodulation result corresponding to the spread spectrum signal. Through the application, the defects that the orthogonal frequency division multiplexing system processes traditional wireless local area network waveform signals and the signal-to-noise ratio is lower than a demodulation threshold due to path loss in long-distance transmission are overcome.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless signal communication, in particular to a low signal-to-noise ratio signal processing method and device based on multi-symbol coherent waveform matching. BACKGROUND

[0002] Camouflage communication is a kind of covert communication paradigm based on biological mimicry or environmental signal simulation, which realizes information concealment by simulating natural signal characteristics (such as electromagnetic spectrum, time-frequency structure) or biological behavior patterns (such as insect vibration frequency), and its core features include signal mimicry, environmental integration and anti-detection.

[0003] Orthogonal frequency division multiplexing (OFDM) technology has become the physical layer core scheme of wireless local area network waveform signal system. By dividing the wideband channel into multiple groups of orthogonal subcarriers, combining with the cyclic prefix technology, it effectively suppresses the inter-symbol interference and frequency selective fading caused by multipath effect, and significantly improves the spectrum utilization. However, OFDM system is highly sensitive to carrier synchronization error, and carrier frequency offset and symbol timing error will destroy the orthogonality of subcarriers, resulting in serious inter-subcarrier interference, and thus requiring the receiver to have sub-microsecond synchronization accuracy, which constitutes a serious challenge in high dynamic or low signal-to-noise ratio scenarios.

[0004] On the other hand, the transmission power of commercial wireless local area network waveform signal equipment is constrained by antenna gain. When the transmission antenna gain Gt is less than 10dBi, the maximum allowed equivalent isotropically radiated power is 20dBm (100mW), which is typically used in indoor home routers. When the antenna gain Gt is greater than or equal to 10dBi, the maximum allowed equivalent isotropically radiated power is increased to 27dBm (500mW), which is commonly used in outdoor access points. Limited by this power threshold, the traditional wireless local area network waveform signal has a signal-to-noise ratio lower than the demodulation threshold due to path loss when transmitting at a long distance. SUMMARY

[0005] The present application provides a low signal-to-noise ratio signal processing method and device based on multi-symbol coherent waveform matching, which overcomes the defects of the prior art that the orthogonal frequency division multiplexing system processes traditional wireless local area network waveform signals, and the signal-to-noise ratio is lower than the demodulation threshold due to path loss when transmitting at a long distance.

[0006] The present application provides a low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching, comprising:

[0007] Receiving the spread spectrum signal obtained after the wireless local area network signal is modulated by the orthogonal frequency division multiplexing system;

[0008] convert the original template for waveform matching of the spread spectrum signal into a waveform template corresponding to an orthogonal frequency division multiplexing system;

[0009] perform cyclic cross-correlation processing on the spread spectrum signal according to the waveform template to obtain a corresponding frequency domain waveform matching result;

[0010] perform multi-symbol coherent waveform matching on the frequency domain waveform matching result in a time dimension to obtain a multi-symbol waveform matching result, and perform threshold judgment on the multi-symbol waveform matching result to obtain a signal demodulation result corresponding to the spread spectrum signal.

[0011] In some embodiments, the converting the original template for waveform matching of the spread spectrum signal into a waveform template corresponding to an orthogonal frequency division multiplexing system comprises:

[0012] serial-parallel conversion is performed on a spread spectrum code of the original template for waveform matching of the spread spectrum signal to obtain a plurality of spread spectrum sub-sequences;

[0013] channel processing is performed on each spread spectrum sub-sequence through subcarriers divided by the orthogonal frequency division multiplexing system;

[0014] the spread spectrum sequences after channel processing of each subcarrier are summed to obtain a corresponding spread spectrum sequence template;

[0015] an oversampling coefficient corresponding to the spread spectrum signal is determined, and sampling multiple conversion is performed on the spread spectrum sequence template through the oversampling coefficient to obtain a waveform template corresponding to the orthogonal frequency division multiplexing system.

[0016] In some embodiments, the performing cyclic cross-correlation processing on the spread spectrum signal according to the waveform template to obtain a corresponding frequency domain waveform matching result comprises:

[0017] fast Fourier transform is performed on the waveform template, and frequency domain shift processing is performed on a transform result to obtain reference template signals of a plurality of frequency offset channels;

[0018] fast Fourier transform is performed on a direct processing part divided from the spread spectrum signal to obtain a corresponding frequency domain signal;

[0019] waveform matching is performed on the frequency domain signal and the reference template signals of each frequency offset channel to obtain a corresponding frequency domain waveform matching result.

[0020] In some embodiments, the performing multi-symbol coherent waveform matching on the frequency domain waveform matching result in a time dimension to obtain a multi-symbol waveform matching result comprises:

[0021] The frequency domain waveform matching result of each frequency offset channel is subjected to multi-symbol accumulation processing according to the time dimension, and the multi-symbol waveform matching result corresponding to each frequency offset channel is obtained.

[0022] In some embodiments, the multi-symbol accumulation processing process of the frequency domain waveform matching result comprises:

[0023] The frequency domain waveform matching result of each frequency offset channel is subjected to vectorization processing according to the template length of the reference template signal, and a vector composition matrix is obtained.

[0024] The vector composition matrix is subjected to fast Fourier transform processing according to the time dimension.

[0025] The transformed processing result output from each frequency offset channel is removed from the part existing in the frequency domain overlap, and the corresponding multi-symbol waveform matching result is obtained.

[0026] In some embodiments, the multi-symbol waveform matching result comprises the multi-symbol waveform matching result obtained by the direct processing part of the spread spectrum signal division and the waveform matching result obtained by the bias processing part, and the threshold judgment on the multi-symbol waveform matching result to obtain the signal demodulation result corresponding to the spread spectrum signal comprises:

[0027] The modulus square value is calculated for the multi-symbol waveform matching result obtained by the direct processing part of the division.

[0028] The modulus square value and the waveform matching result obtained by the bias processing part are screened according to a preset threshold value, and the signal demodulation result corresponding to the spread spectrum signal is obtained.

[0029] The application also provides a low signal-to-noise ratio signal processing device based on multi-symbol coherent waveform matching, comprising:

[0030] The signal receiving module is configured to receive a spread spectrum signal obtained by modulating a wireless local area network signal by an orthogonal frequency division multiplexing system.

[0031] The template conversion module is configured to convert an original template for waveform matching of the spread spectrum signal into a waveform template corresponding to the orthogonal frequency division multiplexing system.

[0032] The cross-correlation processing module is configured to perform cyclic cross-correlation processing on the spread spectrum signal according to the waveform template to obtain a corresponding frequency domain waveform matching result.

[0033] The coherent waveform matching module is configured to perform multi-symbol coherent waveform matching on the frequency domain waveform matching result according to the time dimension to obtain a multi-symbol waveform matching result, and perform threshold judgment on the multi-symbol waveform matching result to obtain a signal demodulation result corresponding to the spread spectrum signal.

[0034] The application further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the low SNR signal processing method based on multi-symbol coherent waveform matching according to any one of the above when executing the computer program.

[0035] The application further provides a non-transitory computer readable storage medium, which stores a computer program, wherein the computer program is executed by a processor to implement the low SNR signal processing method based on multi-symbol coherent waveform matching according to any one of the above.

[0036] The application further provides a computer program product, comprising a computer program, wherein the computer program is executed by a processor to implement the low SNR signal processing method based on multi-symbol coherent waveform matching according to any one of the above.

[0037] The low SNR signal processing method and device based on multi-symbol coherent waveform matching have the following beneficial effects:

[0038] (1) The original template for waveform matching of a spread spectrum signal is converted into a waveform template corresponding to an OFDM system, and the spread spectrum signal sent after modulation by the OFDM system is directly subjected to cyclic cross-correlation processing, thereby reducing the process of multi-carrier combination, solving the problem of serious inter-subcarrier interference caused by the OFDM system, reducing the computational complexity, and reducing the design complexity of the signal receiving device.

[0039] (2) The result of waveform correlation matching is subjected to multi-symbol coherent waveform matching, further improving the frequency offset search accuracy, facilitating threshold decision, and improving the communication reliability under low SNR. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description one by one. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0041] Figure 1 is a flowchart of the low SNR signal processing method based on multi-symbol coherent waveform matching provided by the present application.

[0042] Figure 2 is a principle diagram of the low SNR signal processing method based on multi-symbol coherent waveform matching provided by the present application.

[0043] Figure 3 is a generation diagram of the waveform template provided by the present application.

[0044] Figure 4 Figure 1 is a structural schematic diagram of a low signal-to-noise ratio signal processing device based on multi-symbol coherent waveform matching provided by the present application.

[0045] Figure 5 Figure 2 is a structural schematic diagram of an electronic device provided by the present application. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0047] The execution subject of the low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching of the present application can be a receiving end or receiving device of a wireless local area network physical layer signal. The low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching of the present application will be described below with reference to the drawings. Figure 1 Figure 3 is a flow schematic diagram of the low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching provided by the present application, as shown in Figure 3, the method comprises the following steps 101 to 104, which will be described in detail below. Figure 1

[0048] Step 101, receiving a spread spectrum signal obtained after a wireless local area network signal is modulated by an orthogonal frequency division multiplexing system.

[0049] The wireless local area network signal here is specifically a wireless local area network physical layer signal, and the orthogonal frequency division multiplexing (OFDM) system is used to make the signal quasi-state, and the signal quasi-state WIFI waveform is needed. Therefore, the received signal is the spread spectrum signal sent after OFDM modulation.

[0050] Step 102, converting an original template for waveform matching of the spread spectrum signal into a waveform template corresponding to the orthogonal frequency division multiplexing system.

[0051] Since the spread spectrum signal is modulated by the orthogonal frequency division multiplexing system, the original template used when the signal is received cannot perform waveform matching of the spread spectrum signal. Therefore, the original template for waveform matching of the spread spectrum signal needs to be converted into a waveform template corresponding to the orthogonal frequency division multiplexing system.

[0052] The original template is essentially a signal spread spectrum sequence, that is, the signal spread spectrum sequence corresponding to the original signal template is modulated by the orthogonal frequency division multiplexing system to obtain a template modulated by the orthogonal frequency division multiplexing system, so as to match the spread spectrum signal modulated by the orthogonal frequency division multiplexing system.​

[0053] Step 103: Perform cyclic cross-correlation processing on the spread spectrum signal according to the waveform template to obtain the corresponding frequency domain waveform matching result.

[0054] The waveform template obtained by template modulation through an orthogonal frequency division multiplexing (OFDM) system can be used to perform matched filtering. That is, the waveform template is used to perform cyclic cross-correlation processing on the spread spectrum signal to obtain the corresponding frequency domain waveform matching result. Since the waveform template has already used OFDM modulation, Direct Sequence Spread Spectrum (DSSS) can be used here. Matched filtering can be directly performed on the spread spectrum signal to realize an OFDM-DSSS signal processing framework.

[0055] Furthermore, it should be noted that only a portion of the spread spectrum signal is used here in direct sequence spread spectrum. For example... Figure 2 As shown, before direct sequence spread spectrum (DSS), the spread spectrum signal needs to be divided into a direct processing part and an offset processing part. The offset processing part enters the offset frequency offset search channel. Before entering the offset frequency offset search channel, it undergoes matched filtering through orthogonal frequency division multiplexing (OFDM), then downsamples to a Q-fold chip rate and compensates for half the symbol rate. Then it enters the offset frequency offset search channel, where it is vectorized into a matrix of corresponding vectors. Finally, it undergoes fast Fourier transform (FFT) to obtain the corresponding waveform matching result, which is used for threshold judgment.

[0056] The spread spectrum signal for direct processing is processed using the waveform template obtained in step 102 above. Multiple frequency offset channels of reference template signals are generated from the waveform template using a frequency domain shifting method. After waveform matching of the spread spectrum signal, the frequency domain waveform matching results of multiple frequency offset channels are finally obtained.

[0057] Step 104: Perform multi-symbol coherent waveform matching on the frequency domain waveform matching results according to the time dimension to obtain multi-symbol waveform matching results, and perform threshold judgment on the multi-symbol waveform matching results to obtain the signal demodulation results corresponding to the spread spectrum signal.

[0058] Because the actual power of wireless LAN waveform signals is relatively low, insufficient signal-to-noise ratio (SNR) can occur during distance communication. Therefore, multi-symbol coherent waveform matching is performed after the frequency domain waveform matching result is output to obtain a higher SNR. Here, the frequency domain waveform matching result is essentially a waveform signal in the frequency domain. Therefore, for the frequency domain waveform matching result of each frequency offset channel, multi-symbol coherent waveform matching is performed on the frequency domain waveform matching result along the time dimension to obtain the multi-symbol waveform matching result. The process of multi-symbol coherent waveform matching is the process of performing multi-symbol accumulation processing.

[0059] likeFigure 2 As shown, the multi-symbol waveform matching result is essentially a frequency-domain vector matrix. Before performing threshold decision, the corresponding squared magnitude is calculated, and then combined with the waveform matching result generated by the offset processing section to form the multi-symbol waveform matching result for threshold decision. During threshold decision, the multi-symbol waveform matching result is thresholded by a preset threshold value to obtain the demodulated signal corresponding to the spread spectrum signal, thereby completing the spread spectrum signal reception and processing process.

[0060] This invention implements a signal processing framework for OFDM-DSSS. By converting the original template for waveform matching of the spread spectrum signal into a waveform template corresponding to the orthogonal frequency division multiplexing (OFDM) system, and then directly performing cyclic cross-correlation processing on the spread spectrum signal transmitted after modulation by the OFDM system, the multi-carrier combining process is reduced, solving the problem of severe inter-carrier interference caused by the OFDM system, reducing computational complexity, and also reducing the design complexity of the signal receiving device. Furthermore, performing multi-symbol coherent waveform matching on the waveform correlation matching output further improves the frequency offset search accuracy, which is more conducive to threshold decision and improves communication reliability under low signal-to-noise ratio conditions.

[0061] In some embodiments, the original template for waveform matching of the spread spectrum signal is converted into a waveform template corresponding to the orthogonal frequency division multiplexing (OFDM) system. Specifically, the spreading code corresponding to the original template is modulated using the OFDM method. The following section combines... Figure 3 This describes the specific process of converting the original template into the waveform template corresponding to the orthogonal frequency division multiplexing system.

[0062] First, the spreading code of the original template used for waveform matching of the spread spectrum signal is converted from serial to parallel to obtain multiple spreading sub-sequences. For example... Figure 3 As shown, the spreading code for the original template First, a serial-to-parallel conversion (SIPO / PISO, S / P) is performed to change the signal transmission mode, resulting in N spread spectrum sub-sequences, represented as... , where n represents the frequency domain.

[0063] Then, for each spread spectrum subsequence, channel processing is performed on the subcarriers divided by the orthogonal frequency division multiplexing system. The spread spectrum sequences after signal channel processing of each subcarrier are then summed to obtain the corresponding spread spectrum sequence template.

[0064] like Figure 3 As shown, each spread spectrum subsequence undergoes channel processing via subcarriers allocated by the orthogonal frequency division multiplexing system. The processing parameters for each subcarrier are denoted as follows: During channel processing, the processing parameters are multiplied by the spreading subsequences, and then the results of each multiplication are summed (represented as...). ), to obtain the corresponding spread spectrum sequence template.

[0065] Finally, the over-sampling coefficient corresponding to the spread spectrum signal is determined, and the spread spectrum sequence template is converted by the over-sampling coefficient, to obtain the waveform template corresponding to the OFDM system. The over-sampling coefficient is represented as Q value, which is used to represent the sampling multiple of the spread spectrum signal. Here, the ratio of the up-sampling multiple U before the spread spectrum signal is sent and the down-sampling multiple D when the signal is received is taken as the over-sampling coefficient Q value, that is, Q = U / D, and then the spread spectrum sequence template is converted by the over-sampling coefficient Q value, to obtain the waveform template corresponding to the OFDM system , for processing the spread spectrum signal.

[0066] In the embodiment of the present application, when the signal is received, the spread spectrum code corresponding to the original template is modulated by the OFDM method, to obtain the reference signal template used for the spread spectrum signal to perform the waveform matching processing, so that the existing multi-carrier signal processing mode is changed to the waveform matching processing mode in the time domain, the multi-carrier combining process is reduced, the problem of serious inter-subcarrier interference caused by the OFDM system is solved, the calculation complexity is reduced, and the design complexity of the signal receiving device is also reduced.

[0067] Further, in the waveform matching processing process, the spread spectrum signal is processed by the cyclic cross-correlation processing according to the waveform template, to obtain the corresponding frequency domain waveform matching result, which is described below.

[0068] As shown in Figure 2 , the object of the waveform template processing is the direct processing part of the spread spectrum signal, the DSSS technology is adopted, and the direct processing part of the spread spectrum signal is processed by the cyclic cross-correlation processing according to the waveform template. First, the waveform template is processed by the fast Fourier transform (FFT), and the transformed result is processed by the frequency domain shift processing, to obtain the reference template signal of multiple frequency offset channels, part of the reference template signal is denoted as , , Here, the reference template signal of multiple frequency offset channels is generated by shifting the transformed result in the frequency domain.

[0069] Then, the direct processing part of the spread spectrum signal divided is processed by the fast Fourier transform, to obtain the corresponding frequency domain signal. As shown in Figure 2 , the direct processing part of the spread spectrum signal is processed by the fast Fourier transform (FFT), so that the spread spectrum signal is converted to the frequency domain by the FFT operation, to obtain the frequency domain signal A.

[0070] In the cyclic cross-correlation processing, the frequency domain signal is waveform matched with the reference template signal of each frequency offset channel to obtain a corresponding frequency domain waveform matching result.

[0071] Specifically, in each frequency domain channel, the frequency domain signal A is multiplied with the reference template signal respectively, and then the multiplication result is inverse fast Fourier transformed (IFFT) to obtain the frequency domain waveform matching result of the corresponding frequency domain channel. Part of the frequency domain waveform matching result is denoted as .

[0072] In the embodiment of the application, when the received signal is waveform matched, the modulated spread spectrum signal is directly subjected to the cyclic cross-correlation processing by the waveform template adjusted by the OFDM system, the mode of processing the multicarrier signal according to the subcarrier and then combining in the prior art is changed into the mode of directly performing waveform matching processing on the signal in the time domain, the process of multicarrier combination is reduced, and the problem of serious inter-subcarrier interference caused by the OFDM system is solved.

[0073] In some embodiments, the frequency domain waveform matching result is subjected to multi-symbol coherent waveform matching according to the time dimension to obtain a multi-symbol waveform matching result, including:

[0074] The frequency domain waveform matching result of each frequency offset channel is subjected to multi-symbol accumulation processing according to the time dimension to obtain the multi-symbol waveform matching result corresponding to each frequency offset channel.

[0075] As shown in Figure 2 , after the cyclic cross-correlation processing is completed, the corresponding frequency domain waveform matching result of each frequency domain channel is output and will be subjected to multi-symbol accumulation processing respectively. Here, the multi-symbol accumulation process of each frequency domain channel is performed independently and does not interfere with each other. In the multi-symbol accumulation process, the corresponding Fourier transform is performed according to the time dimension, and finally the part with frequency domain repetition is removed.

[0076] In the embodiment of the application, the multi-symbol accumulation processing of each frequency offset channel is further performed on the frequency domain waveform matching result of each frequency offset channel, so as to further improve the frequency offset search precision, facilitate the threshold decision, obtain a higher signal-to-noise ratio, and solve the problem of insufficient signal-to-noise ratio that may be caused when the wireless local area network waveform signal is subjected to distance communication, and improve the reliability of communication under a low signal-to-noise ratio.

[0077] Further, in some embodiments, the multi-symbol accumulation processing of the frequency domain waveform matching result includes:

[0078] The frequency domain waveform matching result is vectorized according to the template length of the reference template signal to obtain a vector matrix; the vector matrix is subjected to fast Fourier transform processing according to the time dimension, and the part with frequency domain overlap in the transform result is removed to obtain the corresponding multi-symbol waveform matching result.

[0079] As shown in Figure 2 , first, the frequency domain waveform matching result output by each frequency offset channel is subjected to downsampling processing, which can adopt the sparse signal recovery (SSR) mode, and then is converted to Q times the chip rate. Here, Q is the oversampling coefficient described above. For example, the frequency domain waveform matching result output by a certain frequency offset channel is subjected to downsampling processing of . The frequency domain waveform matching result after such downsampling processing is subjected to vectorization processing according to the template length of the reference template signal to obtain a vector matrix, which is stored in a buffer (Buffer), and then is subjected to fast Fourier transform processing (FFT) according to the time dimension, that is, the vector matrix is subjected to fast Fourier transform processing according to the time sequence extraction to obtain the corresponding transform processing result, and finally, the reserve process (Rerserve) is performed to remove the part with frequency domain overlap in the transform processing result output by each frequency offset channel to obtain the corresponding multi-symbol waveform matching result, denoted as .

[0080] In the embodiment of the application, the multi-symbol accumulation processing process of each frequency offset channel is further performed on the frequency domain waveform matching result of each frequency offset channel, so as to improve the signal-to-noise ratio of the waveform signal, which can solve the problem that the signal-to-noise ratio of the wireless local area network waveform signal may not be sufficient when distance communication is performed, and is beneficial to subsequent threshold decision for signal mediation.

[0081] In some embodiments, the multi-symbol waveform matching result obtained in the step 104 includes the multi-symbol waveform matching result obtained by the direct processing part of the spread spectrum signal division and the waveform matching result obtained by the bias processing part. The waveform matching results of the two parts need to be combined and subjected to threshold decision at the same time. The process of performing threshold decision on the multi-symbol waveform matching result to obtain the signal demodulation result corresponding to the spread spectrum signal is introduced below.

[0082] First, the modulus square value is calculated for the multi-symbol waveform matching result obtained by the direct processing part of the division. As shown in Figure 2 , the multi-symbol waveform matching result is output by each frequency offset channel after multi-symbol accumulation processing. Then, considering that it is also a vector matrix, in order to perform threshold decision, the modulus square of each multi-symbol waveform matching result is calculated, denoted as ".

[0083] And, the bias processing part of the spread spectrum signal, before entering the biased frequency offset search channel, carries out matched filtering to the filtered signal of the OFDM , enters the biased frequency offset search channel, first down-samples and transforms to Q times of chip rate and compensates half symbol rate, then transforms into corresponding vectors by vectorization to form a matrix, and finally obtains corresponding waveform matching results by fast Fourier transform processing, which are used for threshold judgment. The processing procedure of the biased frequency offset search channel can refer to the multi-symbol accumulation processing of the frequency domain channel, which is not described here. The waveform matching results obtained by the biased frequency offset search channel can also calculate corresponding modulus squares, which are used for threshold judgment.

[0084] In the threshold judgment process, the modulus square value and the waveform matching results obtained by the bias processing part are screened according to the preset threshold value T, and the signal demodulation results corresponding to the spread spectrum signal are obtained. When the modulus square value corresponding to the waveform matching result is greater than the preset threshold value T, the corresponding signal demodulation is performed, and the corresponding original information is recovered from the wireless local area network physical layer signal, such as obtaining the transmitted data or network signal instruction.

[0085] Of course, the preset threshold value can be determined according to the signal-to-noise ratio of the wireless local area network physical layer signal, or can be determined according to the bit error rate of the wireless local area network physical layer signal, or can be determined according to the change of the signal amplitude, which is not limited in the embodiment of the application.

[0086] In the embodiment of the application, the threshold value is set according to the signal-to-noise ratio to perform threshold judgment on the waveform matching results corresponding to the wireless local area network physical layer signal, which can ensure that the received wireless local area network physical layer signal can complete signal transmission, overcome the defect that the signal-to-noise ratio is lower than the demodulation threshold due to path loss in long-distance transmission, and improve the communication reliability under low signal-to-noise ratio.

[0087] The low signal-to-noise ratio signal processing device based on multi-symbol coherent waveform matching provided by the application is described below, and the low signal-to-noise ratio signal processing device based on multi-symbol coherent waveform matching described below can be correspondingly referred to the low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching described above.

[0088] As Figure 4 ​As shown, the low SNR signal processing device based on multi-symbol coherent waveform matching provided by the present application comprises a signal receiving module 401, a template conversion module 402, a cross-correlation processing module 403 and a coherent waveform matching module 404. The signal receiving module 401 is configured to receive a spread spectrum signal obtained after a wireless local area network signal is modulated by an OFDM system; the template conversion module 402 is configured to convert an original template for waveform matching of the spread spectrum signal into a waveform template corresponding to the OFDM system; the cross-correlation processing module 403 is configured to perform cyclic cross-correlation processing on the spread spectrum signal according to the waveform template to obtain a corresponding frequency domain waveform matching result; and the coherent waveform matching module 404 is configured to perform multi-symbol coherent waveform matching on the frequency domain waveform matching result in the time dimension to obtain a multi-symbol waveform matching result, and perform threshold judgment on the multi-symbol waveform matching result to obtain a signal demodulation result corresponding to the spread spectrum signal.

[0089] It should be noted that the low SNR signal processing device based on multi-symbol coherent waveform matching and the low SNR signal processing method based on multi-symbol coherent waveform matching described above have corresponding beneficial effects, and therefore the beneficial effects of the low SNR signal processing device based on multi-symbol coherent waveform matching will not be described here.

[0090] Figure 5 An example of a schematic diagram of the physical structure of an electronic device is shown in FIG. 5. Figure 5 As shown, the electronic device can comprise a processor 510, a communications interface 520, a memory 530 and a communications bus 540, wherein the processor 510, the communications interface 520 and the memory 530 can communicate with each other through the communications bus 540. The processor 510 can invoke a logical instruction in the memory 530 to execute a low SNR signal processing method based on multi-symbol coherent waveform matching, which comprises the following steps: receiving a spread spectrum signal obtained after a wireless local area network signal is modulated by an OFDM system; converting an original template for waveform matching of the spread spectrum signal into a waveform template corresponding to the OFDM system; performing cyclic cross-correlation processing on the spread spectrum signal according to the waveform template to obtain a corresponding frequency domain waveform matching result; performing multi-symbol coherent waveform matching on the frequency domain waveform matching result in the time dimension to obtain a multi-symbol waveform matching result, and performing threshold judgment on the multi-symbol waveform matching result to obtain a signal demodulation result corresponding to the spread spectrum signal.

[0091] In addition, the logic instructions in the memory 530 described above can be implemented in the form of software functional units and sold or used as independent products, and can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application or the part of the prior art that contributes essentially or the part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0092] In another aspect, the present application also provides a computer program product, which comprises a computer program, the computer program can be stored on a non-transitory computer readable storage medium, and the computer program can be executed by a processor to enable a computer to execute the low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching provided by the above-mentioned methods. The method comprises: receiving a spread spectrum signal obtained by modulating a wireless local area network signal by an orthogonal frequency division multiplexing system; converting an original template for waveform matching of the spread spectrum signal into a waveform template corresponding to the orthogonal frequency division multiplexing system; performing cyclic cross-correlation processing on the spread spectrum signal according to the waveform template to obtain a corresponding frequency domain waveform matching result; performing multi-symbol coherent waveform matching on the frequency domain waveform matching result in the time dimension to obtain a multi-symbol waveform matching result, and performing threshold judgment on the multi-symbol waveform matching result to obtain a signal demodulation result corresponding to the spread spectrum signal.

[0093] In yet another aspect, the present application also provides a non-transitory computer readable storage medium having a computer program stored thereon, and the computer program is executed by a processor to implement the low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching provided by the above-mentioned methods. The method comprises: receiving a spread spectrum signal obtained by modulating a wireless local area network signal by an orthogonal frequency division multiplexing system; converting an original template for waveform matching of the spread spectrum signal into a waveform template corresponding to the orthogonal frequency division multiplexing system; performing cyclic cross-correlation processing on the spread spectrum signal according to the waveform template to obtain a corresponding frequency domain waveform matching result; performing multi-symbol coherent waveform matching on the frequency domain waveform matching result in the time dimension to obtain a multi-symbol waveform matching result, and performing threshold judgment on the multi-symbol waveform matching result to obtain a signal demodulation result corresponding to the spread spectrum signal.

[0094] The device embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed to multiple network units. Part or all of the modules can be selected to achieve the purposes of the embodiments according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0095] Through the description of the above embodiments, those skilled in the art can clearly understand that the embodiments can be realized by means of software and the necessary general hardware platform, and of course can also be realized by hardware. Based on such understanding, the above technical solutions can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiments.

[0096] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching, characterized in that, include: The spread spectrum signal obtained by modulating the received wireless local area network signal through an orthogonal frequency division multiplexing system; The original template for waveform matching of the spread spectrum signal is converted into a waveform template corresponding to the orthogonal frequency division multiplexing system; The spread spectrum signal is subjected to cyclic cross-correlation processing based on the waveform template to obtain the corresponding frequency domain waveform matching result; Perform multi-symbol coherent waveform matching on the frequency domain waveform matching result according to the time dimension to obtain multi-symbol waveform matching result, and perform threshold judgment on the multi-symbol waveform matching result to obtain the signal demodulation result corresponding to the spread spectrum signal; The step of converting the original template for waveform matching of the spread spectrum signal into a waveform template corresponding to the orthogonal frequency division multiplexing system includes: The spreading code of the original template used for waveform matching of the spread spectrum signal is converted from serial to parallel to obtain multiple spread spectrum sub-sequences. For each spread spectrum subsequence, channel processing is performed using subcarriers allocated by the orthogonal frequency division multiplexing system; The spread spectrum sequences of each subcarrier after channel processing are summed to obtain the corresponding spread spectrum sequence template. Determine the oversampling coefficients corresponding to the spread spectrum signal, and perform a sampling multiple conversion on the spread spectrum sequence template using the oversampling coefficients to obtain the waveform template corresponding to the orthogonal frequency division multiplexing system; The step of performing multi-symbol coherent waveform matching on the frequency domain waveform matching result according to the time dimension to obtain multi-symbol waveform matching result includes: For the frequency domain waveform matching results of each frequency offset channel, multi-symbol accumulation processing is performed according to the time dimension to obtain the multi-symbol waveform matching results corresponding to each frequency offset channel; The multi-symbol accumulation processing of the frequency domain waveform matching results includes: For the frequency domain waveform matching results of each frequency offset channel, vectorization is performed according to the template length of the reference template signal to obtain a vector matrix; The vectors are processed into a matrix by performing a Fast Fourier Transform based on the time dimension. From the transformation results output by each frequency offset channel, the parts with frequency domain overlap are removed to obtain the corresponding multi-symbol waveform matching results.

2. The low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching according to claim 1, characterized in that, The step of performing cyclic cross-correlation processing on the spread spectrum signal according to the waveform template to obtain the corresponding frequency domain waveform matching result includes: The waveform template is subjected to a fast Fourier transform, and the transform result is frequency-domain shifted to obtain reference template signals for multiple frequency offset channels. The direct processing portion of the spread spectrum signal is divided into sections and subjected to a fast Fourier transform to obtain the corresponding frequency domain signal. The frequency domain signal is matched with the reference template signal of each frequency offset channel to obtain the corresponding frequency domain waveform matching result.

3. The low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching according to claim 1, characterized in that, The multi-symbol waveform matching result includes the multi-symbol waveform matching result obtained from the direct processing part of the spread spectrum signal division and the waveform matching result obtained from the offset processing part. The step of performing threshold judgment on the multi-symbol waveform matching result to obtain the signal demodulation result corresponding to the spread spectrum signal includes: For the multi-symbol waveform matching results obtained from the direct processing portion of the partition, the modulus square value is calculated; The waveform matching results obtained from the modulus square value and the bias processing part are filtered according to the preset threshold value to obtain the signal demodulation result corresponding to the spread spectrum signal.

4. A low signal-to-noise ratio signal processing device based on multi-symbol coherent waveform matching, characterized in that, include: The signal receiving module is used to receive the spread spectrum signal obtained by modulating the wireless local area network signal through an orthogonal frequency division multiplexing system. The template conversion module is used to convert the original template for waveform matching of the spread spectrum signal into a waveform template corresponding to the orthogonal frequency division multiplexing system. The cross-correlation processing module is used to perform cyclic cross-correlation processing on the spread spectrum signal according to the waveform template to obtain the corresponding frequency domain waveform matching result; The coherent waveform matching module is used to perform multi-symbol coherent waveform matching on the frequency domain waveform matching result according to the time dimension to obtain the multi-symbol waveform matching result, and to perform threshold judgment on the multi-symbol waveform matching result to obtain the signal demodulation result corresponding to the spread spectrum signal; The step of converting the original template for waveform matching of the spread spectrum signal into a waveform template corresponding to the orthogonal frequency division multiplexing system includes: The spreading code of the original template used for waveform matching of the spread spectrum signal is converted from serial to parallel to obtain multiple spread spectrum sub-sequences. For each spread spectrum subsequence, channel processing is performed using subcarriers allocated by the orthogonal frequency division multiplexing system; The spread spectrum sequences of each subcarrier after channel processing are summed to obtain the corresponding spread spectrum sequence template. Determine the oversampling coefficients corresponding to the spread spectrum signal, and perform a sampling multiple conversion on the spread spectrum sequence template using the oversampling coefficients to obtain the waveform template corresponding to the orthogonal frequency division multiplexing system; The step of performing multi-symbol coherent waveform matching on the frequency domain waveform matching result according to the time dimension to obtain multi-symbol waveform matching result includes: For the frequency domain waveform matching results of each frequency offset channel, multi-symbol accumulation processing is performed according to the time dimension to obtain the multi-symbol waveform matching results corresponding to each frequency offset channel; The multi-symbol accumulation processing of the frequency domain waveform matching results includes: For the frequency domain waveform matching results of each frequency offset channel, vectorization is performed according to the template length of the reference template signal to obtain a vector matrix; The vectors are processed into a matrix by performing a Fast Fourier Transform based on the time dimension. From the transformation results output by each frequency offset channel, the parts with frequency domain overlap are removed to obtain the corresponding multi-symbol waveform matching results.

5. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching as described in any one of claims 1 to 3.

6. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching as described in any one of claims 1 to 3.

7. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the low signal-to-noise ratio signal processing method based on multi-symbol coherent waveform matching as described in any one of claims 1 to 3.

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