Frequency offset compensation method

Abstract

The embodiment of the invention provides a frequency offset compensation method, and the method comprises the steps: carrying out the time-domain frequency offset estimation and compensation of a PPDU (Physical Protocol Data Unit), and determining a first frequency offset compensation value of the time domain of the PPDU; and converting the frequency domain residual frequency offset compensation value of the signaling field of the PPDU into a second frequency offset compensation value of the time domain, and updating the first frequency offset compensation value according to the second frequency offset compensation value. According to the embodiment of the invention, the problem that the accuracy of the generated PPDU frequency offset compensation value is low in the related technology is solved, and the effect of generating the accurate frequency offset compensation value through the feedback mechanism of the frequency domain residual frequency offset is achieved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of communications, and in particular, to a frequency offset compensation method. Background Art

[0002] Frequency offset estimation and compensation are unavoidable methods and devices on the receiving side of wireless local area network (Wireless Fidelity, Wi-Fi) systems. Current frequency offset estimation methods and devices primarily use the short and long training sequences defined in 802.11 for coarse and fine frequency offset estimation and compensation, respectively, and then use pilot subcarriers in the frequency domain to estimate and compensate for residual frequency offset. However, this method can only address frequency offset correction for non-HT PPDUs (non-high-throughput PPDUs). With the introduction of other Physical Layer Protocol Data Units (PPDUs) specified in the 802.11 protocol suite, the residual frequency offset estimation method using a Kalman filter has significantly reduced its effectiveness for estimating residual frequency offset for the first few data symbols. Furthermore, as PPDU length increases, frequency offset accumulates with data symbols. Once the frequency offset accumulates to a certain level, the accuracy of traditional methods gradually deteriorates. Summary of the Invention

[0003] The embodiments of the present application provide a frequency offset compensation method to at least solve the problem of low accuracy of the PPDU frequency offset compensation value generated in the related art.

[0004] According to one embodiment of the present application, a frequency offset compensation method is provided, comprising: performing time domain frequency offset estimation and compensation on a physical layer protocol data unit (PPDU), determining a first time domain frequency offset compensation value of the PPDU; converting a frequency domain residual frequency offset compensation value of a signaling field of the PPDU into a second time domain frequency offset compensation value, and updating the first frequency offset compensation value according to the second frequency offset compensation value.

[0005] According to another embodiment of the present application, a computer program product is provided, including a computer program and instructions, wherein the computer program and instructions implement the steps in the above method embodiment when executed by a processor.

[0006] According to another embodiment of the present application, a computer-readable storage medium is provided, in which a computer program is stored. The computer program is configured to execute the steps in the above method embodiment when running.

[0007] According to another embodiment of the present application, an electronic device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor is configured to run the computer program to execute the steps in the above method embodiment.

[0008] According to the embodiment of the present application, since determining the frequency offset compensation value includes determining the frequency offset compensation values ​​in the time domain and the frequency domain, the frequency offset is first estimated and compensated in the time domain to determine the first frequency offset compensation value in the time domain, and then the residual frequency offset compensation value in the frequency domain is determined. In order to be able to feed back the residual frequency offset compensation value in the frequency domain to the frequency offset compensation value in the time domain, the residual frequency offset compensation value in the frequency domain is converted into a second frequency offset compensation value in the time domain, and finally the first frequency offset compensation value is updated with the second frequency offset compensation value. Therefore, the problem of low accuracy of the PPDU frequency offset compensation value generated in the related art can be solved, and the effect of generating a more accurate frequency offset compensation value through the feedback mechanism of the residual frequency offset in the frequency domain is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a hardware structure block diagram of a Wi-Fi system receiving-side device according to the frequency offset compensation method of an embodiment of the present application;

[0010] Figure 2 is a flow chart of a frequency offset compensation method according to an embodiment of the present application;

[0011] Figure 3 is a structural block diagram of a frequency offset compensation device according to an embodiment of the present application;

[0012] Figure 4 is a structural block diagram of a frequency offset compensation device according to yet another embodiment of the present application;

[0013] Figure 5 is a flow chart of a frequency offset compensation method according to yet another embodiment of the present application. DETAILED DESCRIPTION

[0014] The embodiments of the present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0015] It should be noted that the terms "first", "second", etc. in the description and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0016] The method embodiments provided in the embodiments of the present application can be executed in a Wi-Fi system receiving side device or a similar computing device. The Wi-Fi system receiving side device can be a router, a mobile terminal (for example, a mobile phone terminal) or a computer terminal. Figure 1 FIG. 1 is a hardware structure block diagram of a Wi-Fi system receiving side device of a frequency offset compensation method according to an embodiment of the present application. Figure 1 As shown, the receiving side device may include one or more ( Figure 1Only one is shown in the figure) a processor 102 (the processor 102 may include but is not limited to a microprocessor MCU or a programmable logic device FPGA and other processing devices) and a memory 104 for storing data. The above-mentioned Wi-Fi system receiving side device may also include a transmission device 106 and an input and output device 108 for communication functions. It will be understood by those skilled in the art that Figure 1 The structure shown is for illustration only and does not limit the structure of the above-mentioned Wi-Fi system receiving side device. For example, the Wi-Fi system receiving side device may also include Figure 1 More or fewer components than shown, or with Figure 1 Different configurations shown.

[0017] The memory 104 can be used to store computer programs, for example, software programs and modules of application software, such as the computer program corresponding to the frequency offset compensation method in the embodiment of the present application. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, that is, implementing the above-mentioned method. The memory 104 may include a high-speed random access memory and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 104 may further include a memory remotely located relative to the processor 102, and these remote memories can be connected to the receiving side device of the Wi-Fi system via 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 combinations thereof.

[0018] The transmission device 106 is used to receive or send data via a network. Specific examples of the aforementioned network may include a wireless network provided by a communications provider of a Wi-Fi system receiving-side device. In one embodiment, the transmission device 106 includes a network interface controller (NIC), which can be connected to other network devices via a base station to communicate with the Internet. In one embodiment, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0019] In this embodiment, a frequency offset compensation method running on the receiving-side device of the above-mentioned Wi-Fi system is provided. Figure 2 Flowchart of the frequency offset compensation method according to an embodiment of the present application. The embodiment of the present application can be applied to a receiving side device in a Wi-Fi system, such as a router, a mobile terminal (such as a mobile phone terminal) or a computer terminal. Figure 2 As shown, the process includes the following steps:

[0020] Step S202: performing time domain frequency offset estimation and compensation on a physical layer protocol data unit PPDU to determine a first time domain frequency offset compensation value of the PPDU.

[0021] Step S202 of the embodiment of the present application includes: performing a coarse frequency offset estimation of the PPDU in the time domain based on the short training sequence of the PPDU, and performing a fine frequency offset estimation of the PPDU in the time domain based on the long training sequence of the PPDU; adding the coarse frequency offset estimation result and the fine frequency offset estimation result of the PPDU to determine a first frequency offset compensation value; wherein the PPDU is a high-throughput PPDU.

[0022] It should be noted that in the 802.11 standard, the PPDU includes a specific signal sequence, a short training sequence, which is used for frequency offset estimation. Coarse frequency offset estimation in the time domain is performed by observing the signal characteristics of the short training sequence. The short training sequence typically contains known frequency characteristics, such as a fixed frequency interval or a specific frequency sequence. By performing time domain analysis on the short training sequence in the received PPDU, the frequency offset of the signal can be observed. By analyzing the signal characteristics in the short training sequence, the frequency offset of the signal can be estimated, thereby correcting or adjusting the signal. This coarse frequency offset estimation can help the receiving end perform preliminary processing of the signal before receiving the data, thereby improving the reliability and performance of data transmission.

[0023] The 802.11 standard includes a specific signal sequence, a long training sequence, in the PPDU. This sequence is used by the receiver to estimate the signal in the time and frequency domains for channel estimation and data demodulation. Time-domain processing of the long training sequence in the PPDU enables estimation of the signal's frequency deviation. Frequency deviation refers to the difference between the actual signal frequency and the local clock frequency of the receiver, typically caused by clock drift between the transmitter and receiver. Time-domain processing of the long training sequence detects phase changes in the signal in the time domain, thereby estimating the signal's frequency deviation. Time-domain processing of the long training sequence allows for frequency calibration of the signal, improving demodulation performance and accuracy at the receiver. This precise frequency deviation estimation helps reduce errors in signal demodulation and improves the overall performance and reliability of the communication system.

[0024] In an exemplary embodiment of the present application, the frequency domain residual frequency offset compensation value of the signaling field of the PPDU is converted into a second frequency offset compensation value in the time domain, including: demodulating each symbol of the signaling field of the PPDU in turn, and generating a frequency domain residual frequency offset estimation value of the next symbol of the current symbol based on the demodulation results of all data subcarriers of the signaling field; determining the frequency domain residual frequency offset compensation value of the next symbol based on the frequency domain residual frequency offset estimation value of the next symbol and the time difference between the current symbol and the long training sequence; and converting the frequency domain residual frequency offset compensation value into the second frequency offset compensation value in the time domain when the signaling field ends or the Lth symbol of the signaling field ends, where L is a positive integer.

[0025] In one embodiment, the data subcarriers of the signaling field are specific frequency subcarriers used to transmit control signaling information. These data subcarriers are typically used to transmit synchronization, modulation, coding, and other control information to ensure normal communication and accurate data transmission. In an Orthogonal Frequency Division Multiplexing (OFDM) system, the data subcarriers of the signaling field are specific frequency ranges in the spectrum allocated for signaling transmission. Through these data subcarriers, the communication system can achieve reliable transmission and decoding of signaling information.

[0026] In an exemplary embodiment of the present application, each symbol of the signaling field of the PPDU is sequentially demodulated, including: performing multiple-input and output antenna system MIMO demodulation on each symbol of the signaling field of the PPDU in sequence.

[0027] It's important to note that Multiple Input Multiple Output (MIMO) is a wireless communication technology that uses multiple transmit and receive antennas on the same frequency to improve data transmission rates and signal quality. Demodulation is the process by which the receiver processes the received signal to recover the original transmitted signal.

[0028] In one embodiment, MIMO demodulation of each symbol in the signaling field of the PPDU involves: sampling and quantizing the received signal to obtain a baseband signal; inputting the received baseband signal into each receiver, one for each antenna; and performing MIMO demodulation on the signal in each receiver. This typically involves channel estimation and signal demodulation algorithms. Channel estimation is used to estimate channel characteristics, such as attenuation and phase, to compensate for them during the demodulation process; each symbol is demodulated using a MIMO demodulation algorithm to convert the symbol into the original data; and bit error rate assessment and error correction are performed on the demodulated data to ensure data accuracy and integrity.

[0029] In an exemplary embodiment of the present application, a frequency domain residual frequency offset estimate value of the next symbol of the current symbol is generated based on the demodulation results of all data subcarriers of the signaling field, including: accumulating the demodulation results of all data subcarriers and obtaining the accumulated value, calculating the phase of the real part and the imaginary part of the accumulated value, and generating the frequency domain residual frequency offset estimate value of the next symbol.

[0030] In an exemplary embodiment of the present application, the frequency domain residual frequency offset compensation value of the next symbol is determined based on the frequency domain residual frequency offset estimation value of the next symbol and the time difference between the current symbol and the long training sequence, including: multiplying the frequency domain residual frequency offset estimation value of the next symbol by the time difference between the current symbol and the long training sequence to determine the frequency domain residual frequency offset compensation of the next symbol.

[0031] Step S204: Convert the frequency-domain residual frequency offset compensation value of the signaling field of the PPDU into a second frequency offset compensation value in the time domain, and update the first frequency offset compensation value according to the second frequency offset compensation value.

[0032] In step S204 of an embodiment of the present application, the frequency domain residual frequency offset compensation value of the signaling field of the PPDU is converted into a second frequency offset compensation value in the time domain, including: performing an inverse Fourier transform on the frequency domain residual frequency offset compensation value of the signaling field through an inverse Fourier transform algorithm to generate a second frequency offset compensation value.

[0033] In one embodiment, the updated time-domain frequency offset compensation value is the sum of the first frequency offset compensation value and the second frequency offset compensation value.

[0034] Through the description of the above implementation methods, those skilled in the art can clearly understand that the method according to the above embodiment can be implemented by means of software plus the necessary general hardware platform, and of course it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, 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 number of instructions for enabling a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in each embodiment of the present application.

[0035] This embodiment also provides a frequency offset compensation device for implementing the above-mentioned embodiments and preferred embodiments. Details already described are omitted for clarity. As used below, the term "module" may refer to a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented using software, implementation using hardware, or a combination of software and hardware, is also possible and contemplated.

[0036] Figure 3is a structural block diagram of a frequency offset compensation device according to an embodiment of the present application, such as Figure 3 As shown, the device includes a determination module 10 and an update module 20.

[0037] Determining module 10: configured to perform frequency offset estimation and compensation in the time domain on a physical layer protocol data unit PPDU, and determine a first frequency offset compensation value in the time domain of the PPDU;

[0038] The updating module 20 is configured to convert the frequency domain residual frequency offset compensation value of the signaling field of the PPDU into a second frequency offset compensation value in the time domain, and update the first frequency offset compensation value according to the second frequency offset compensation value.

[0039] Figure 4 FIG. 1 is a structural block diagram of a frequency offset compensation device according to another embodiment of the present application. Figure 4 As shown, the device includes Figure 3 In addition to all the modules shown, the determination module 10 further includes an estimation unit 11 and a summation unit 12 .

[0040] Estimation unit 11: used to perform coarse frequency offset estimation of the PPDU in the time domain according to the short training sequence of the PPDU, and perform fine frequency offset estimation of the PPDU in the time domain according to the long training sequence of the PPDU;

[0041] The summing unit 12 is configured to add a coarse frequency offset estimation result and a fine frequency offset estimation result of the PPDU to determine a first frequency offset compensation value; wherein the PPDU is a high-throughput PPDU.

[0042] It should be noted that the above modules can be implemented through software or hardware. For the latter, it can be implemented in the following ways, but not limited to: the above modules are all located in the same processor; or the above modules are located in different processors in any combination.

[0043] To facilitate understanding of the technical solutions provided in this application, the following will be described in detail with reference to specific embodiments of the present invention.

[0044] Figure 5 FIG. 1 is a flow chart of a frequency offset compensation method according to another embodiment of the present application. Figure 5 As shown, the process includes the following steps:

[0045] Step S501 : performing a coarse frequency offset estimation in the time domain using a short training sequence, and performing a fine frequency offset estimation in the time domain using a long training sequence.

[0046] Step S502: Perform frequency offset compensation in the time domain.

[0047] Specifically, the frequency offset compensation value T=T0+T1+T2, where T0 is the coarse frequency offset estimation result, T1 is the fine frequency offset estimation result, and T2 is the result of converting the frequency domain residual frequency offset estimation value F to the time domain.

[0048] Step S503: Generate a frequency domain residual frequency offset compensation value.

[0049] Specifically, the residual frequency offset estimate F0 is multiplied by the time difference between the current symbol and the long training sequence to obtain the frequency domain residual frequency offset compensation value F. The first symbol initializes the residual frequency offset compensation value to 0;

[0050] Step S504: Generate a frequency domain residual frequency offset estimation value.

[0051] Specifically, MIMO demodulation is performed on the signaling field, the demodulation results of all data subcarriers are accumulated, and the arc tangent of the accumulated value is calculated as the frequency domain residual frequency offset estimate F0 of the next symbol;

[0052] Step S505 , determining whether the signaling field ends or the Lth data symbol ends.

[0053] Specifically, if the judgment result is yes, proceed to step S506, and if the judgment result is no, proceed to step S503.

[0054] Step S506: Update the frequency offset compensation value.

[0055] Specifically, the frequency domain residual frequency offset estimation value F is converted to T2, and T in step S502 is updated, while F in step S503 is cleared.

[0056] An embodiment of the present application further provides a computer-readable storage medium, in which a computer program is stored. The computer program is configured to execute the steps of any of the above method embodiments when run.

[0057] In an exemplary embodiment, the computer-readable storage medium may include, but is not limited to, various media that can store computer programs, such as a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk, or an optical disk.

[0058] An embodiment of the present application further provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor is configured to run the computer program to execute the steps in any one of the above method embodiments.

[0059] In an exemplary embodiment, the electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor, and the input / output device is connected to the processor.

[0060] For specific examples in this embodiment, reference may be made to the examples described in the above embodiments and exemplary implementation modes, and this embodiment will not be described in detail here.

[0061] Through the embodiments of the present application, the residual frequency offset estimation method for the high-throughput PPDU signaling field is optimized. By utilizing data subcarriers with a larger number of subcarriers, the estimated variance can be effectively reduced compared to the method using pilot subcarriers. The embodiments of the present application can reduce the residual frequency offset of the first few data symbols to compensate for the performance loss of the Kalman filter in the early stages. A frequency domain residual frequency offset feedback mechanism is added to periodically feedback the residual frequency offset in the signaling field and data symbols, updating the compensation value in the time domain and reducing the residual frequency offset carried by subsequent PPDU symbols.

[0062] Obviously, those skilled in the art should understand that the modules or steps of the present application described above can be implemented using a general-purpose computing device, they can be concentrated on a single computing device, or distributed across a network composed of multiple computing devices, they can be implemented using program code executable by the computing device, and thus, they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be performed in a different order than herein, or they can be fabricated into separate integrated circuit modules, or multiple modules or steps can be fabricated into a single integrated circuit module for implementation. Thus, the present application is not limited to any specific combination of hardware and software.

[0063] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A frequency offset compensation method, characterized in that: include: Performing time-domain frequency offset estimation and compensation on a physical layer protocol data unit (PPDU), and determining a first time-domain frequency offset compensation value for the PPDU; The frequency domain residual frequency offset compensation value of the signaling field of the PPDU is converted into a second frequency offset compensation value in the time domain, and the first frequency offset compensation value is updated according to the second frequency offset compensation value.

2. The method according to claim 1, characterized in that The performing time-domain frequency offset estimation and compensation on a physical layer protocol data unit PPDU, and determining a first time-domain frequency offset compensation value of the PPDU, includes: Performing a coarse frequency offset estimation on the PPDU in the time domain according to the short training sequence of the PPDU, and performing a fine frequency offset estimation on the PPDU in the time domain according to the long training sequence of the PPDU; Adding a coarse frequency offset estimation result and a fine frequency offset estimation result of the PPDU to determine the first frequency offset compensation value; The PPDU is a high-throughput PPDU.

3. The method according to claim 2, characterized in that The converting the frequency domain residual frequency offset compensation value of the signaling field of the PPDU into a second frequency offset compensation value in the time domain includes: Demodulate each symbol of the signaling field of the PPDU in sequence, and generate a frequency-domain residual frequency offset estimate of a symbol next to the current symbol based on the demodulation results of all data subcarriers of the signaling field; Determining a frequency domain residual frequency offset compensation value of the next symbol according to a frequency domain residual frequency offset estimation value of the next symbol and a time difference between the current symbol and the long training sequence; When the signaling field ends or the Lth symbol of the signaling field ends, the frequency domain residual frequency offset compensation value is converted into a second frequency offset compensation value in the time domain, wherein L is a positive integer.

4. The method according to claim 3, characterized in that The demodulating each symbol of the signaling field of the PPDU in sequence includes: Multiple-input-output antenna system MIMO demodulation is performed on each symbol of the signaling field of the PPDU in sequence.

5. The method according to claim 3, characterized in that Generating a frequency domain residual frequency offset estimation value of a symbol next to a current symbol according to demodulation results of all data subcarriers of the signaling field, comprising: The demodulation results of all the data subcarriers are accumulated to obtain an accumulated value, the phases of the real part and the imaginary part of the accumulated value are calculated, and a frequency domain residual frequency offset estimation value of the next symbol is generated.

6. The method according to claim 3, characterized in that Determining a frequency domain residual frequency offset compensation value of the next symbol according to a frequency domain residual frequency offset estimation value of the next symbol and a time difference between the current symbol and the long training sequence, comprising: The frequency domain residual frequency offset compensation of the next symbol is determined by multiplying the frequency domain residual frequency offset estimation value of the next symbol by the time difference between the current symbol and the long training sequence.

7. The method according to claim 1, characterized in that Converting the frequency domain residual frequency offset compensation value of the signaling field of the PPDU into a second frequency offset compensation value in the time domain includes: Performing an inverse Fourier transform on the frequency domain residual frequency offset compensation value of the signaling field through an inverse Fourier transform algorithm to generate the second frequency offset compensation value.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, wherein when the computer program is executed by a processor, the steps of the method described in any one of claims 1 to 7 are implemented.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the steps of the method described in any one of claims 1 to 7 are implemented.

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