Frame synchronization method and apparatus based on WIFI system

Abstract

Provided in the embodiments of the present disclosure are a frame synchronization method and apparatus based on a WiFi system. The method comprises: performing delayed autocorrelation on short training sequences of a primary channel and a secondary channel; performing bandwidth detection on the current WiFi frame on the basis of a delayed autocorrelation result of the primary channel and the secondary channel; when a bandwidth detection result of the current WiFi frame is greater than a specified bandwidth, performing coarse synchronization on the basis of the delayed autocorrelation result of the primary channel and the secondary channel, so as to obtain long training sequences of the primary channel and the secondary channel; and searching for correlation peaks on the basis of a cross-correlation result of the long training sequences of the primary channel and the secondary channel and long training sequences of local sequences to perform fine synchronization, so as to determine a symbol boundary of the current WiFi frame. By means of the present disclosure, the problems of only using a primary 20M channel without using other channels and a timing error deteriorating due to a PPDU length are solved.

Description

Frame synchronization method and device based on WIFI system

[0001] Cross-reference to Related Applications

[0002] The present disclosure is based on Chinese Patent Application No.CN202410849872.9 entitled "Frame synchronization method and device based on WIFI system" filed on June 27, 2024, and claims priority to the patent application, the disclosure of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] Embodiments of the present disclosure relate to the field of communication, in particular, to a frame synchronization method and device based on WIFI system. BACKGROUND

[0004] In the receiving process of WIFI frame, frame synchronization is a practical problem to be solved. Without an accurate synchronization method, the symbol boundary of WIFI frame cannot be determined, and thus the transmitted data cannot be reliably received. The short training symbol field and the long training symbol field are the contents of the physical layer (PHY) preamble in the PHY Protocol Data Unit (PPDU) format defined by the 802.11 protocol, wherein the short training symbol field is composed of ten identical short training sequences, each with a length of 0.8us, and the total length is 8us; the long training symbol field is composed of a guard interval and two repeated long training sequences, the guard interval has a length of 1.6us, and the long training sequence has a length of 3.2us, wherein the guard interval is obtained by copying the second half of the long training sequence.

[0005] The current mainstream frame synchronization method only uses the main 20M channel. In the case where the channel bandwidth of the 802.11 protocol cluster has been expanded to 160M and above, the data of other channels is not fully utilized, and in addition, the increase in PPDU length leads to the continuous deterioration of timing error with the accumulation of symbol length. SUMMARY

[0006] Embodiments of the present disclosure provide a frame synchronization method and device based on WIFI system to at least solve the problem that in the related art, only the main 20M channel is used, in the case where the channel bandwidth has been expanded to 160M and above, the data of other channels is not fully utilized, and in addition, the increase in PPDU length leads to the continuous deterioration of timing error with the accumulation of symbol length.

[0007] According to one embodiment of the present disclosure, a frame synchronization method based on a WIFI system is provided, comprising: performing time-delay autocorrelation on short training sequences of a primary channel and a secondary channel; performing bandwidth detection on a current WIFI frame according to a result of the time-delay autocorrelation of the primary channel and the secondary channel; in a case where a bandwidth detection result of the current WIFI frame is greater than a specified bandwidth, performing coarse synchronization according to the result of the time-delay autocorrelation of the primary channel and the secondary channel to obtain long training sequences of the primary channel and the secondary channel; and performing fine synchronization by searching for a correlation peak of a result of cross-correlation between the long training sequences of the primary channel and the secondary channel and a long training sequence of a local sequence to determine a symbol boundary of the current WIFI frame.

[0008] According to another embodiment of the present disclosure, a frame synchronization device based on a WIFI system is provided, comprising: an autocorrelation module configured to perform time-delay autocorrelation on short training sequences of a primary channel and a secondary channel; a detection module configured to perform bandwidth detection on a current WIFI frame according to a result of the time-delay autocorrelation of the primary channel and the secondary channel; a coarse synchronization module configured to, in a case where a bandwidth detection result of the current WIFI frame is greater than a specified bandwidth, perform coarse synchronization according to the result of the time-delay autocorrelation of the primary channel and the secondary channel to obtain long training sequences of the primary channel and the secondary channel; and a fine synchronization module configured to perform fine synchronization by searching for a correlation peak of a result of cross-correlation between the long training sequences of the primary channel and the secondary channel and a long training sequence of a local sequence to determine a symbol boundary of the current WIFI frame.

[0009] According to still another embodiment of the present disclosure, a computer readable storage medium is also provided, and the computer readable storage medium stores a computer program, wherein the computer program is configured to execute the steps in any of the method embodiments described above when running.

[0010] According to still another embodiment of the present disclosure, an electronic device is also provided, comprising a memory and a processor, the memory stores a computer program, and the processor is configured to execute the computer program to perform the steps in any of the method embodiments described above.

[0011] According to still another embodiment of the present disclosure, a computer program product is also provided, comprising a computer program, and the computer program is executed by a processor to implement the steps in any of the method embodiments described above. BRIEF DESCRIPTION OF DRAWINGS

[0012] FIG. 1 is a hardware structure block diagram of a mobile terminal of a frame synchronization method based on a WIFI system according to an embodiment of the present disclosure;

[0013] FIG. 2 is a flowchart of a frame synchronization method based on a WIFI system according to an embodiment of the present disclosure;

[0014] FIG. 3 is another flowchart of a frame synchronization method based on a WIFI system according to an embodiment of the present disclosure;

[0015] FIG. 4 is a structural block diagram of a frame synchronization apparatus based on a WIFI system according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0016] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings and in conjunction with embodiments.

[0017] It should be noted that the terms "first", "second" and the like in the description and claims of the present disclosure and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence.

[0018] The method embodiments provided in the embodiments of the present disclosure can be executed in a mobile terminal, a computer terminal or a similar computing device. Taking an example of running on a mobile terminal, FIG. 1 is a hardware structural block diagram of a mobile terminal for a frame synchronization method based on a WIFI system according to an embodiment of the present disclosure. As shown in FIG. 1, the mobile terminal can include one or more (only one is shown in FIG. 1) processors 102 (the processor 102 can include but not limited to a processing device such as a microprocessor MCU or a programmable logic device FPGA) and a memory 104 configured to store data, wherein the above-mentioned mobile terminal can further include a transmission device 106 configured to have a communication function and an input and output device 108. Those skilled in the art can understand that the structure shown in FIG. 1 is only schematic, which does not limit the structure of the above-mentioned mobile terminal. For example, the mobile terminal can further include more or less components than those shown in FIG. 1, or have a different configuration from that shown in FIG. 1.

[0019] The memory 104 can be configured to store computer programs, for example, software programs of application software and modules, such as a computer program corresponding to the frame synchronization method based on a WIFI system in the embodiments of the present disclosure. The processor 102 executes various function applications and data processing by running the computer programs stored in the memory 104, that is, implements the above-mentioned method. The memory 104 can include a high-speed random access memory, and can further include a non-volatile memory, such as one or more magnetic storage devices, flash memories, or other non-volatile solid-state memories. In some examples, the memory 104 can further include a memory remotely arranged with respect to the processor 102, which can be connected to the mobile terminal through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network and a combination thereof.

[0020] The transmission device 106 is configured to receive or send data via a network. The network can include a wireless network provided by a communication provider of the mobile terminal. In one embodiment, the transmission device 106 includes a network interface controller (NIC) that can be connected to other network devices through a base station to communicate with the Internet. In one embodiment, the transmission device 106 can be a radio frequency (RF) module configured to communicate with the Internet wirelessly.

[0021] In the embodiment, a frame synchronization method based on a WIFI system running on the mobile terminal is provided. FIG. 2 is a flowchart of the frame synchronization method based on the WIFI system according to the embodiment of the disclosure. As shown in FIG. 2, the flow includes the following steps:

[0022] In step S202, the short training sequences of the primary channel and the secondary channel are subjected to delay autocorrelation.

[0023] In the embodiment, the short training sequences of the primary channel and the secondary channel can be subjected to delay autocorrelation on the primary channel and the secondary channel respectively according to the periodicity of the short training sequences of the primary channel and the secondary channel. Then, the accumulated window smoothing values of the primary channel and the secondary channel are obtained by performing accumulated window smoothing respectively. Finally, the accumulated window smoothing average value sequence is obtained by adding the accumulated window smoothing values of the primary channel and the secondary channel.

[0024] In step S204, the bandwidth of the current WIFI frame is detected according to the results of the delay autocorrelation of the primary channel and the secondary channel.

[0025] In the embodiment, the reference value of the primary channel, the reference value of the secondary channel and the reference average value need to be obtained first, and then the bandwidth of the current WIFI frame is detected according to the reference value of the primary channel and the reference average value. The reference value of the primary channel can be obtained by adding the first accumulated window smoothing value and the second accumulated window smoothing value of the primary channel and averaging them. Similarly, the reference value of the secondary channel can be obtained by adding the first accumulated window smoothing value and the second accumulated window smoothing value of the secondary channel and averaging them. After obtaining the reference value of the primary channel and the reference value of the secondary channel, the reference average value is obtained by adding the reference value of the primary channel and the reference value of the secondary channel and averaging them. Finally, whether the modulus of the reference value of the primary channel is less than the product of the modulus of the reference average value and the bandwidth detection factor is detected to determine the bandwidth of the current WIFI frame.

[0026] In step S206, if the bandwidth detection result of the current WIFI frame is greater than a specified bandwidth, coarse synchronization is performed according to the results of the delay autocorrelation of the primary channel and the secondary channel to obtain the long training sequences of the primary channel and the secondary channel.

[0027] In the embodiment, if it is determined that the current WIFI frame is greater than the specified bandwidth, coarse synchronization needs to be performed according to the accumulated window smoothed mean sequence and the reference mean. Specifically, it is detected whether the real part of the product of the conjugate of the reference mean and the current accumulated window smoothed mean is less than the product of the square of the modulus of the reference mean and the coarse synchronization detection factor. If the real part of the product of the conjugate of the reference mean and the current accumulated window smoothed mean is less than the product of the square of the modulus of the reference mean and the coarse synchronization detection factor, it is determined that the coarse synchronization is successful, otherwise the detection is continued.

[0028] If it is determined that the current WIFI frame is not greater than the specified bandwidth, coarse synchronization needs to be performed according to the accumulated window smoothed value sequence of the main channel and the reference value of the main channel. Specifically, it is detected whether the real part of the product of the conjugate of the reference value of the main channel and the current accumulated window smoothed value of the main channel is less than the product of the square of the modulus of the reference value of the main channel and the coarse synchronization detection factor. If the real part of the product of the conjugate of the reference value of the main channel and the current accumulated window smoothed value of the main channel is less than the product of the square of the modulus of the reference value of the main channel and the coarse synchronization detection factor, it is determined that the coarse synchronization is successful, otherwise the detection is continued.

[0029] In the embodiment, after the long training sequences of the main channel and the secondary channel are obtained, coarse frequency offset compensation can also be performed on the long training sequences of the main channel and the secondary channel according to the results of the delay autocorrelation of the main channel and the secondary channel.

[0030] In step S208, fine synchronization is performed on the results of the cross-correlation of the long training sequences of the main channel and the secondary channel and the long training sequence of the local sequence to find the correlation peak to determine the symbol boundary of the current WIFI frame.

[0031] In the embodiment, if the current WIFI frame is greater than the specified bandwidth, the long training sequences of the main channel and the secondary channel are cross-correlated with the long training sequence of the local sequence respectively to obtain the cross-correlation results of the main channel and the secondary channel respectively. Then the cross-correlation results of the main channel and the secondary channel are added and averaged, and then accumulated one by one to obtain the cross-correlation accumulated mean. The accumulated window smoothing is performed on the cross-correlation accumulated mean to obtain the cross-correlation accumulated smoothed mean sequence. If the current cross-correlation accumulated smoothed mean is greater than the comparison value, the comparison value is updated to the current cross-correlation accumulated smoothed mean. If the next cross-correlation accumulated smoothed mean is less than the updated comparison value, the starting position of the SIG field of the current WIFI frame is determined according to the updated comparison value.

[0032] If the current WIFI frame is not greater than the specified bandwidth, the long training sequence of the primary channel and the long training sequence of the local sequence are cross-correlated to obtain a cross-correlation result of the primary channel. The cross-correlation result of the primary channel is then accumulated one by one to obtain a cross-correlation accumulation value of the primary channel, and the cross-correlation accumulation value of the primary channel is accumulated and smoothed by a window to obtain a cross-correlation accumulation smoothing value sequence of the primary channel. If the current cross-correlation accumulation smoothing value of the primary channel is greater than the comparison value, the comparison value is updated to the current cross-correlation accumulation smoothing value of the primary channel, and if the cross-correlation accumulation smoothing value of the next primary channel is less than the updated comparison value, the starting position of the SIG field of the current WIFI frame is determined according to the updated comparison value.

[0033] In the embodiment, the frame synchronization point of the next symbol can also be dynamically adjusted according to whether the sampling frequency offset of each symbol frequency domain feedback of the current WIFI frame changes compared with the sampling frequency offset of the last symbol. For example, in the case that the sampling frequency offset of the current symbol is greater than the sampling frequency offset of the last symbol, the frame synchronization point of the next symbol is moved forward by one sampling point, and in the case that the sampling frequency offset of the current symbol is less than the sampling frequency offset of the last symbol, the frame synchronization point of the next symbol is moved backward by one sampling point.

[0034] In an embodiment, the specified bandwidth can be set to 20M. For example, when performing the step S204, the bandwidth of the current WIFI frame is determined by detecting whether the modulus of the reference value of the primary channel is less than the product of the modulus of the reference average value and the bandwidth detection factor. If it is detected that the modulus of the reference value of the primary channel is less than the product of the modulus of the reference average value and the bandwidth detection factor, it is determined that the current WIFI frame is greater than or equal to 40M, otherwise it is determined that the current WIFI frame is 20M. Furthermore, in the subsequent step S206, when the current WIFI frame is greater than or equal to 40M, coarse synchronization can be performed according to the accumulation window smoothing average sequence and the reference average value, or when the current WIFI frame is 20M, coarse synchronization can be performed according to the accumulation window smoothing value sequence of the primary channel and the reference value of the primary channel. Similarly, in the subsequent step S208, when the current WIFI frame is greater than or equal to 40M, the results of cross-correlation between the long training sequences of the primary channel and the secondary channel and the long training sequence of the local sequence are used to find the correlation peak for fine synchronization to determine the symbol boundary of the current WIFI frame, otherwise, when the current WIFI frame is 20M, the results of cross-correlation between the long training sequence of the primary channel and the long training sequence of the local sequence are used to find the correlation peak for fine synchronization to determine the symbol boundary of the current WIFI frame.

[0035] By the above steps, the bandwidth detection is performed by using the autocorrelation result of the short training sequence, when the bandwidth detection is higher than the specified bandwidth, the frame synchronization is performed by using the primary channel and the secondary channel together, the synchronization point of the next symbol is dynamically adjusted according to the sampling frequency offset of each symbol in the frequency domain, the synchronization point is selected to be moved forward or backward by one sampling point according to the change of the sampling frequency offset of the current symbol and the sampling frequency offset of the last symbol, the problem that only the primary 20M channel is used in the related art, and the data of other channels is not perfectly used when the channel bandwidth has been expanded to 160M or above, and in addition, the increase of the PPDU length causes the timing error to be continuously deteriorated with the accumulation of the symbol length is solved, the frame synchronization precision and the anti-interference ability of the WIFI system frame synchronization device are improved, the probability of the error code caused by the too long PPDU length and the frame synchronization error accumulation is reduced, and since the coarse frame synchronization needs to perform the autocorrelation of the short training sequence, the performance of the frame synchronization device can be enhanced with very small calculation cost.

[0036] FIG. 3 is another flowchart of a WIFI system-based frame synchronization method according to an embodiment of the present disclosure, as shown in FIG. 3, the flowchart includes the following steps:

[0037] Step S301: performing delay autocorrelation on the short training sequences of the primary channel and the secondary channel, for example, performing delay autocorrelation on the short training sequences of the primary 20M channel and the secondary 20M channel - according to the periodicity of the short training sequence 0.8us, performing 0.8us and 1.6us delay autocorrelation operations on the primary 20M channel and the secondary 20M channel (channel bandwidth is more than 20M) respectively, the operation results of the primary 20M channel are recorded as R 20 and Q 20 respectively, and the two are smoothed by a 0.8us accumulation window, and the smoothed results are recorded as P 20 ; the above operation results of the secondary 20M channel are added to the corresponding operation results of the primary 20M channel to obtain R 40 , Q 40 and P 40 .

[0038] Step S302: performing bandwidth detection on the current WIFI frame according to the result of the delay autocorrelation - the first smoothed result P 201 of the primary 20M channel in step S301 and the 0.8us smoothed result P 202 are averaged to obtain the reference value P top20 of the primary 20M channel; similarly, the above operation results of the secondary 20M channel are added to the corresponding operation results of the primary 20M channel to obtain the reference value P top40 ; the bandwidth detection factor is T bwd (T bwd(where P is a constant, defaulting to 1.5, which can be changed according to specific circumstances). The bandwidth detection inequality is |P|. top20 | <T bwd ·|P top40 |, where |*| is the modulo operation. If the modulo operation is satisfied, the current frame is determined to be greater than or equal to 40M; otherwise, the current frame is 20M.

[0039] Step S303: Based on the bandwidth detection results, select the autocorrelation results of the primary 20M or primary 40M channel (the primary 40M channel is the sum of the primary 20M and the secondary 20M channels) for coarse synchronization—if step S302 determines that the current frame is greater than or equal to 40M, select P. 40 P top40 For P, P top Perform coarse synchronization detection; otherwise, select P. 20 P top20 For P, P top ; T sso For coarse synchronization detection factor (T) sso (This is a constant, defaulting to 0.25, which can be changed according to specific circumstances). The coarse synchronization inequality is: Where P[n] represents the P value at index n, For P top Take the conjugate, Re{*} is the real part. If it is satisfied, then coarse synchronization is considered successful; otherwise, continue to compare the inequality.

[0040] Step S304: Perform coarse frequency offset compensation on the long training sequence - Apply the coarse frequency offset angle calculated by the delay autocorrelation result in step S301 to the long training sequence of the main 20M channel and the secondary 20M channel (the data after step S303 is considered as the long training sequence) to complete the coarse frequency offset compensation.

[0041] Step S305: Based on the bandwidth detection results, select the long training sequence of the primary 20M or primary 40M channel (the primary 40M channel is the sum of the primary 20M and secondary 20M channels) and perform cross-correlation with the local sequence to find the correlation peak for fine synchronization—perform cross-correlation calculation on the locally stored original long training sequence and the long training sequence completed in step S304. If step S302 determines that the current frame is greater than or equal to 40M, then add the cross-correlation calculation results of the primary 20M channel and the secondary 20M channel respectively, calculate the average, and then accumulate them one by one; otherwise, select the cross-correlation calculation result of the primary 20M channel and accumulate them one by one, and record the cross-correlation calculation result to be accumulated as X[n] (n=1,2,3...64). Smooth the accumulated result by 0.4us, and record it as X. avg [n](n=8,9,10...64), the precision synchronization determination expression is X avg [n]>X avg_max Xavg_max Initial value is 0, if satisfied, then use X avg [n] update X avg_max , X avg The index corresponding to the maximum value of [n] is the fine synchronization point, and the starting position of the SIG field is determined subsequently.

[0042] Step S306: dynamically adjust the frame synchronization point of the next symbol to move forward or backward by one sample point according to whether the sampling frequency offset of each symbol frequency domain feedback changes compared with the sampling frequency offset of the last symbol—if the sampling frequency offset of the current symbol is greater than the sampling frequency offset of the last symbol, the synchronization point is moved forward by one sample point; otherwise, the synchronization point is moved backward by one sample point.

[0043] Through the description of the above implementation, those skilled in the art can clearly understand that the method according to the above embodiment can be realized by means of software and the necessary general hardware platform, of course, it can also be realized by hardware, but in many cases the former is a better implementation. Based on such understanding, the technical solutions of the disclosure can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a plurality of instructions for making a terminal device (which can be a mobile phone, computer, server, or network device, etc.) execute the method of each embodiment of the disclosure.

[0044] In the embodiment, a frame synchronization device based on a WIFI system is also provided, which is configured to implement the above embodiments and preferred embodiments, and will not be described again. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware, or a combination of software and hardware is also possible and contemplated.

[0045] FIG. 4 is a structural block diagram of a frame synchronization device based on a WIFI system according to an embodiment of the disclosure, as shown in FIG. 4, the device 400 includes:

[0046] The autocorrelation module 402 is configured to perform delay autocorrelation on the short training sequences of the primary channel and the secondary channel;

[0047] The detection module 404 is configured to perform bandwidth detection on the current WIFI frame according to the results of the delay autocorrelation of the primary channel and the secondary channel;

[0048] The coarse synchronization module 406 is configured to perform coarse synchronization according to the results of the delay autocorrelation of the primary channel and the secondary channel to obtain the long training sequences of the primary channel and the secondary channel in the case that the bandwidth detection result of the current WIFI frame is greater than a specified bandwidth;

[0049] The fine synchronization module 408 is configured to find a correlation peak of a result of cross-correlation of the long training sequences of the primary channel and the secondary channel and the long training sequence of the local sequence to perform fine synchronization, so as to determine a symbol boundary of the current WIFI frame.

[0050] In the embodiment, the apparatus 400 further comprises:

[0051] The adjustment module is configured to dynamically adjust the frame synchronization point of the next symbol according to whether the sampling frequency offset of each symbol of the current WIFI frame is changed compared with the sampling frequency offset of the last symbol.

[0052] In the embodiment, the adjustment module is further configured to move the frame synchronization point of the next symbol forward by one sampling point if the sampling frequency offset of the current symbol is greater than the sampling frequency offset of the last symbol, and move the frame synchronization point of the next symbol backward by one sampling point if the sampling frequency offset of the current symbol is less than the sampling frequency offset of the last symbol.

[0053] In the embodiment, the apparatus 400 further comprises:

[0054] The coarse frequency offset compensation module is configured to perform coarse frequency offset compensation on the long training sequences of the primary channel and the secondary channel according to a result of delay self-correlation of the primary channel and the secondary channel.

[0055] In the embodiment, the self-correlation module 402 comprises:

[0056] The first self-correlation submodule is configured to first perform delay self-correlation on the primary channel and the secondary channel respectively according to the periodicity of the short training sequences of the primary channel and the secondary channel, and then perform accumulation window smoothing, so as to obtain an accumulation window smoothing value sequence of the primary channel and the secondary channel respectively.

[0057] The second self-correlation submodule is configured to add and average the accumulation window smoothing value sequences of the primary channel and the secondary channel to obtain an accumulation window smoothing average value sequence.

[0058] In the embodiment, the detection module 404 comprises:

[0059] The first average value obtaining submodule is configured to add and average the first accumulation window smoothing value and the second accumulation window smoothing value of the primary channel to obtain a reference value of the primary channel.

[0060] The second average value obtaining submodule is configured to add and average the first accumulation window smoothing value and the second accumulation window smoothing value of the secondary channel to obtain a reference value of the secondary channel.

[0061] The third average value obtaining submodule is configured to add and average the reference value of the primary channel and the reference value of the secondary channel to obtain a reference average value.

[0062] The detection submodule is configured to determine that the current WIFI frame is greater than or equal to 40M or 20M according to the reference value of the main channel and the reference average value.

[0063] In the embodiment, the detection submodule includes:

[0064] The first detection submodule is configured to detect whether the modulus of the reference value of the main channel is less than the product of the modulus of the reference average value and the bandwidth detection factor, and if so, determine that the current WIFI frame is greater than or equal to 40M, otherwise, determine that the current WIFI frame is 20M.

[0065] In the embodiment, the coarse synchronization module 406 includes:

[0066] The coarse synchronization submodule is configured to perform coarse synchronization according to the accumulated window smoothing average value sequence and the reference average value in the case of determining that the current WIFI frame is greater than or equal to 40M.

[0067] In the embodiment, the coarse synchronization submodule is further configured to perform coarse synchronization according to the accumulated window smoothing value sequence of the main channel and the reference value of the main channel in the case of determining that the current WIFI frame is 20M.

[0068] In the embodiment, the coarse synchronization submodule includes:

[0069] The second detection submodule is configured to detect whether the real part of the product of the conjugate of the reference average value and the current accumulated window smoothing average value is less than the product of the square of the modulus of the reference average value and the coarse synchronization detection factor in the case of the current WIFI frame being greater than or equal to 40M, and if so, determine that the coarse synchronization is successful, otherwise, continue to detect.

[0070] The second detection submodule is further configured to detect whether the real part of the product of the conjugate of the reference value of the main channel and the current accumulated window smoothing value of the main channel is less than the product of the square of the modulus of the reference value of the main channel and the coarse synchronization detection factor in the case of the current WIFI frame being 20M, and if so, determine that the coarse synchronization is successful, otherwise, continue to detect.

[0071] In the embodiment, the fine synchronization module 408 includes:

[0072] The cross-correlation submodule is configured to perform cross-correlation between the long training sequence of the main channel and the long training sequence of the local sequence to obtain a cross-correlation result of the main channel, and perform cross-correlation between the long training sequence of the secondary channel and the long training sequence of the local sequence to obtain a cross-correlation result of the secondary channel.

[0073] The accumulation submodule is configured to add and average the cross-correlation results of the main channel and the secondary channel, and then accumulate them one by one to obtain cross-correlation accumulated average values.

[0074] The smoothing submodule is configured to perform accumulated window smoothing on the cross-correlation accumulated average values to obtain a cross-correlation accumulated smoothing average value sequence.

[0075] The updating sub-module is configured to update the comparison value to the current cross-correlation accumulated smoothed mean value in a case that the current cross-correlation accumulated smoothed mean value is greater than the comparison value.

[0076] The determining sub-module is configured to determine the start position of the SIG field of the current WIFI frame according to the updated comparison value in a case that the next cross-correlation accumulated smoothed mean value is less than the updated comparison value.

[0077] In the embodiment, the cross-correlation sub-module is further configured to perform cross-correlation between the long training sequence of the main channel and the long training sequence of the local sequence to obtain a cross-correlation result of the main channel.

[0078] The accumulating sub-module is further configured to accumulate the cross-correlation results of the main channel one by one to obtain a cross-correlation accumulated value of the main channel.

[0079] The smoothing sub-module is further configured to perform accumulation window smoothing on the cross-correlation accumulated value of the main channel to obtain a cross-correlation accumulated smoothed value sequence of the main channel.

[0080] The updating sub-module is further configured to update the comparison value to the current cross-correlation accumulated smoothed value of the main channel in a case that the current cross-correlation accumulated smoothed value of the main channel is greater than the comparison value.

[0081] The determining sub-module is further configured to determine the start position of the SIG field of the current WIFI frame according to the updated comparison value in a case that the next cross-correlation accumulated smoothed value of the main channel is less than the updated comparison value.

[0082] It should be noted that the above various modules can be implemented by software or hardware, and for the latter, the following implementation manners can be used, but are not limited thereto: the above modules are located in the same processor; or the above various modules are located in different processors in any combination.

[0083] Embodiments of the present disclosure further provide a computer readable storage medium, which stores a computer program, and the computer program is configured to execute the steps in any of the above method embodiments when running.

[0084] In an example embodiment, the above computer readable storage medium can include, but is not limited to, a U disk, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk, and various media that can store computer programs.

[0085] The embodiment of the present disclosure further provides an electronic device, comprising a memory and a processor, the memory stores a computer program, and the processor is configured to run the computer program to perform the steps in any of the above method embodiments.

[0086] In an exemplary embodiment, the electronic device described above can further comprise a transmission device connected to the processor and an input and output device connected to the processor.

[0087] The specific examples in the embodiment can refer to the examples described in the above embodiments and exemplary embodiments, and the embodiment will not be repeated here.

[0088] The embodiment of the present disclosure further provides a computer program product, comprising computer instructions, which, when executed by a processor, implement the steps in any of the above method embodiments.

[0089] The embodiment of the present disclosure further provides a computer program product, comprising a non-volatile computer readable storage medium, which stores a computer program, and the computer program, when executed by a processor, implements the steps in the method described in various embodiments of the present disclosure.

[0090] Obviously, those skilled in the art should understand that the above-mentioned modules or steps of the present disclosure can be realized by general computing devices, which can be concentrated on a single computing device or distributed on a network composed of multiple computing devices, and they can be realized by program codes executable by computing devices, so that they can be stored in storage devices and executed by computing devices, and in some cases, the steps shown or described can be executed in different order, or they can be manufactured into individual integrated circuit modules, or multiple modules or steps can be manufactured into a single integrated circuit module. Thus, the present disclosure is not limited to any specific combination of hardware and software.

[0091] The above only describes the preferred embodiments of the present disclosure and is not intended to limit the present disclosure. Those skilled in the art can make various modifications and changes to the present disclosure. Any modification, equivalent replacement, improvement, etc. within the principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A frame synchronization method based on a WIFI system, comprising: Delayed autocorrelation is performed on short training sequences of the main channel and secondary channel; The bandwidth of the current WIFI frame is detected based on the delay autocorrelation results of the primary and secondary channels. If the bandwidth detection result of the current WIFI frame is greater than the specified bandwidth, coarse synchronization is performed based on the delay autocorrelation results of the main channel and the secondary channel to obtain the long training sequence of the main channel and the secondary channel. The correlation peaks are found by cross-correlation of the long training sequences of the main channel and the secondary channel with the long training sequence of the local sequence, and fine synchronization is performed to determine the symbol boundaries of the current WIFI frame.

2. The method according to claim 1, wherein, Also includes: The frame synchronization point of the next symbol is dynamically adjusted based on whether the sampling frequency offset of each symbol of the current WIFI frame changes compared to the sampling frequency offset of the previous symbol.

3. The method according to claim 2, wherein, The frame synchronization point of the next symbol is dynamically adjusted based on whether the sampling frequency offset of each symbol of the current WIFI frame changes compared to the sampling frequency offset of the previous symbol, including: If the sampling frequency offset of the current symbol is greater than the sampling frequency offset of the previous symbol, then the frame synchronization point of the next symbol is shifted forward by one sampling point. If the sampling frequency offset of the current symbol is less than that of the previous symbol, then the frame synchronization point of the next symbol will be shifted to the next sampling point.

4. The method according to claim 1, wherein, After obtaining the long training sequences of the primary and secondary channels, the process includes: Coarse frequency offset compensation is performed on the long training sequences of the main channel and the secondary channel based on the delay autocorrelation results of the main channel and the secondary channel.

5. The method according to claim 1, wherein, Delayed autocorrelation of short training sequences for the primary and secondary channels includes: Based on the periodicity of the short training sequences of the main channel and the secondary channel, delayed autocorrelation is first performed on the main channel and the secondary channel respectively, and then cumulative window smoothing is performed to obtain the cumulative window smoothing value sequences of the main channel and the secondary channel respectively. The accumulated window smoothed value sequences of the main channel and the secondary channel are added together and averaged to obtain the accumulated window smoothed mean sequence.

6. The method according to claim 5, wherein, Bandwidth detection of the current WIFI frame based on the delay autocorrelation results of the primary and secondary channels includes: The first and second accumulated window smoothing values ​​of the main channel are added together and averaged to obtain the reference value of the main channel. The first and second accumulated window smoothing values ​​of the secondary channel are added together and averaged to obtain the reference value of the secondary channel. The reference value of the main channel and the reference value of the secondary channel are added together and averaged to obtain the reference mean value; Based on the reference value of the main channel and the average reference value, the current WIFI frame is determined to be greater than or equal to 40M, or the current WIFI frame is determined to be 20M.

7. The method according to claim 6, wherein, The determination of the current WIFI frame based on the reference value of the main channel and the reference average value includes: Detect whether the modulus of the reference value of the main channel is less than the product of the modulus of the reference mean and the bandwidth detection factor; If the current WIFI frame rate is less than 40M, then the current WIFI frame rate is determined to be greater than or equal to 40M; otherwise, the current WIFI frame rate is determined to be 20M.

8. The method according to claim 6, wherein, If the bandwidth detection result of the current WIFI frame is greater than the specified bandwidth, coarse synchronization is performed based on the delay autocorrelation results of the primary channel and the secondary channel, including: If the current WIFI frame is determined to be greater than or equal to 40M, coarse synchronization is performed based on the accumulated window smoothed mean sequence and the benchmark mean.

9. The method according to claim 6, wherein, When the bandwidth detection result of the current WIFI frame is greater than the specified bandwidth, the coarse synchronization based on the delay autocorrelation results of the primary channel and the secondary channel further includes: If the current WIFI frame is determined to be 20M, coarse synchronization is performed based on the cumulative window smoothing value sequence of the main channel and the reference value of the main channel.

10. The method according to claim 8, wherein, Coarse synchronization includes: The real part of the product of the conjugate of the baseline mean and the current accumulated window smoothed mean is less than the product of the square of the modulus of the baseline mean and the coarse synchronization detection factor. If the value is less than the specified value, then coarse synchronization is considered successful; otherwise, continue the detection process.

11. The method according to claim 9, wherein, Coarse synchronization includes: The real part of the product of the conjugate of the reference value of the main channel and the accumulated window smoothing value of the current main channel is less than the product of the square of the modulus of the reference value of the main channel and the coarse synchronization detection factor. If the value is less than the specified value, then coarse synchronization is considered successful; otherwise, continue the detection process.

12. The method according to claim 8, wherein, The results of cross-correlation between the long training sequences of the primary and secondary channels and the long training sequence of the local sequence are used to find correlation peaks for fine synchronization, in order to determine the symbol boundaries of the current WIFI frame, including: The long training sequences of the main channel and the secondary channel are cross-correlated with the long training sequence of the local sequence to obtain the cross-correlation results of the main channel and the secondary channel, respectively. The cross-correlation results of the main channel and the secondary channel are added together and averaged, and then accumulated one by one to obtain the cumulative average cross-correlation value; The cumulative mean of cross-correlation is smoothed by a cumulative window to obtain a sequence of cross-correlation cumulative smoothed mean; If the current cross-correlation cumulative smoothed mean is greater than the comparison value, the comparison value is updated to the current cross-correlation cumulative smoothed mean; If the next cross-correlation cumulative smoothed mean is less than the updated comparison value, the starting position of the SIG field of the current WIFI frame is determined based on the updated comparison value.

13. The method according to claim 9, wherein, The process of cross-correlation between the long training sequences of the primary and secondary channels and the long training sequence of the local sequence to find correlation peaks for fine synchronization, in order to determine the symbol boundaries of the current WIFI frame, also includes: The long training sequence of the main channel is cross-correlated with the long training sequence of the local sequence to obtain the cross-correlation result of the main channel; The cross-correlation results of the main channel are accumulated one by one to obtain the accumulated cross-correlation value of the main channel; The cross-correlation accumulation value of the main channel is smoothed by an accumulation window to obtain the cross-correlation accumulation smoothed value sequence of the main channel; If the current cross-correlation cumulative smoothing value of the main channel is greater than the comparison value, the comparison value is updated to the current cross-correlation cumulative smoothing value of the main channel. If the cross-correlation cumulative smoothing value of the next main channel is less than the updated comparison value, the starting position of the SIG field of the current WIFI frame is determined according to the updated comparison value.

14. A frame synchronization device based on a WIFI system, comprising: The autocorrelation module is configured to perform delayed autocorrelation on short training sequences of the main channel and the secondary channel; The detection module is configured to perform bandwidth detection on the current WIFI frame based on the delay autocorrelation results of the primary channel and the secondary channel. The coarse synchronization module is configured to perform coarse synchronization based on the delay autocorrelation results of the primary channel and the secondary channel when the bandwidth detection result of the current WIFI frame is greater than a specified bandwidth, so as to obtain the long training sequence of the primary channel and the secondary channel. The fine synchronization module is configured to perform fine synchronization by finding correlation peaks in the cross-correlation results of the long training sequences of the main channel and the secondary channel with the long training sequence of the local sequence, so as to determine the symbol boundary of the current WIFI frame.

15. The apparatus according to claim 14, wherein, include: The adjustment module is configured to dynamically adjust the frame synchronization point of the next symbol based on whether the sampling frequency offset of each symbol of the current WIFI frame changes compared to the sampling frequency offset of the previous symbol.

16. A computer-readable storage medium storing a computer program, wherein, When the computer program is executed by a processor, it implements the steps of the method described in any one of claims 1 to 13.

17. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, performs the steps of the method of any one of claims 1 to 13.

18. A computer program product comprising a computer program that, when executed by a processor, implements the steps of the method described in any one of claims 1-13.

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