Method, device and equipment for tracking frequency deviation of wireless signal in dual-mode power line carrier communication

Abstract

The application relates to the technical field of dual-mode power carrier communication, and discloses a wireless signal frequency offset tracking method, device and equipment in dual-mode power carrier communication, which comprises the following steps: acquiring load data signals corrected through coarse frequency offset tracking results, the load data signals are composed of multiple orthogonal frequency division multiplexing symbols, and the orthogonal frequency division multiplexing symbols comprise multiple pilot subcarriers; determining the number of symbols in a current frequency offset tracking group based on a preset number, the preset number is used for reflecting the frequency of frequency offset tracking; determining the i-th channel estimation result according to the i-th pilot subcarrier in the current frequency offset tracking group, i is an integer, 1<=i<=the preset number; when i is the preset number, determining the current channel estimation result according to the channel estimation result of the preset number; and determining the current frequency offset tracking result according to the current channel estimation result and the last channel estimation result. The application improves the accuracy of frequency offset estimation and reduces the calculation amount of frequency offset estimation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dual-mode power carrier communication, and particularly relates to a wireless signal frequency offset tracking method, device and equipment in dual-mode power carrier communication. BACKGROUND

[0002] In the process of wireless signal transmission in power dual-mode communication based on Orthogonal Frequency Division Multiplexing (OFDM), there is a frequency offset, which will destroy the orthogonality between subcarriers in the OFDM system, cause Inter-Carrier Interference (ICI) between subcarriers, and seriously affect the performance of the system, reduce the accuracy and reliability of data transmission. Therefore, accurately and effectively tracking and compensating the frequency offset is a key link to ensure the normal operation of the power dual-mode communication system based on OFDM.

[0003] In order to realize frequency offset tracking, in the related art, pilots are usually inserted in the OFDM symbol of the wireless signal, and then the frequency offset is tracked and compensated based on the pilots in each OFDM symbol. The frequency band of the wireless signal in dual-mode communication is relatively narrow compared with the power line signal, and the number of subcarriers in the OFDM symbol is small, which results in poor accuracy of the frequency offset tracking result. At the same time, the number of subcarriers of the OFDM symbol is different in different communication modes (frequency bands), and the number of pilot subcarriers is also different, which results in large difference in frequency offset tracking in different frequency bands, thereby affecting the subsequent signal demodulation process and the like. SUMMARY

[0004] The present application provides a wireless signal frequency offset tracking method, device and equipment in dual-mode power carrier communication, to solve the problem of large difference in frequency offset tracking in different frequency bands, which affects the subsequent signal demodulation process and the like.

[0005] In a first aspect, the present application provides a wireless signal frequency offset tracking method in dual-mode power carrier communication, the method comprising: obtaining a load data signal corrected by a coarse frequency offset tracking result, wherein the load data signal is composed of a plurality of orthogonal frequency division multiplexing (OFDM) symbols, and each OFDM symbol comprises a plurality of pilot subcarriers; determining a symbol number in a current frequency offset tracking group based on a preset number, wherein the preset number is used to reflect the frequency of frequency offset tracking, the current frequency offset tracking group is one of a plurality of frequency offset tracking groups, and each frequency offset tracking group comprises OFDM symbols of the symbol number; determining an i-th channel estimation result according to an i-th pilot subcarrier in the current frequency offset tracking group, i is an integer, 1≤i≤the preset number, and the preset number of pilot subcarriers are from OFDM symbols of the symbol number; determining a current channel estimation result according to the preset number of channel estimation results when i is the preset number; and determining a current frequency offset tracking result according to the current channel estimation result and a previous channel estimation result.

[0006] The wireless signal frequency offset tracking method in dual-mode power carrier communication provided by the embodiment determines the symbol number in the current frequency offset tracking group based on the determination of the preset number after obtaining the load data signal corrected by the coarse frequency offset tracking result, then determines the i-th channel estimation result according to the i-th pilot subcarrier in the current frequency offset tracking group, and when i is the preset number, determines the current channel estimation result according to the preset number of channel estimation results, and finally determines the current frequency offset tracking result according to the current channel estimation result and the previous channel estimation result.

[0007] The embodiment determines the frequency offset through the preset number of pilot subcarriers, increases the number of pilot subcarriers corresponding to the frequency offset estimation, and the number of pilot subcarriers corresponding to the frequency offset estimation can be several times the number of pilot subcarriers contained in a single OFMD symbol, thereby improving the accuracy of frequency offset estimation. Meanwhile, the present application does not perform frequency offset compensation on each OFMD symbol, compared with performing frequency offset estimation on each OFMD symbol, the symbol number is determined based on the preset number, the OFMD symbols are grouped according to the symbol number, and the frequency offset compensation is performed according to the group, thereby reducing the calculation amount of frequency offset estimation and improving the calculation efficiency of frequency offset estimation. Since the number of pilot subcarriers used for calculating the frequency offset each time is the preset number, the same number of pilot subcarriers can be used to calculate the frequency offset for all communication modes, so that the frequency offset tracking effects obtained by different communication modes are the same.

[0008] In an optional implementation, determining the symbol number in the current frequency offset tracking group based on the preset number comprises: determining the symbol number in the current frequency offset tracking group according to the number of pilot subcarriers contained in the OFDM symbol in a plurality of communication modes.

[0009] In the embodiment, the number of symbols is determined based on the number of pilot subcarriers of OFDM symbols in different communication modes, the number of pilot subcarriers used for calculating frequency offset is the same in each communication mode, consistency of frequency offset tracking in different frequency bands can be ensured, and accuracy of subsequent signal demodulation process is improved.

[0010] In an optional implementation, the preset number is the least common multiple of the number of pilot subcarriers contained in the OFDM symbols in the plurality of communication modes.

[0011] In the embodiment, the preset number is determined based on the least common multiple, requirements of the plurality of communication modes on the number of pilot subcarriers can be met at the same time, and unified processing of the plurality of communication modes is implemented.

[0012] In an optional implementation, the current channel estimation result is determined according to the channel estimation result of the preset number, including: taking the last OFDM symbol in the current frequency offset tracking group as a reference, frequency offset compensation is performed on the channel estimation result of the preset number according to the last frequency offset tracking result; and the average value of the channel estimation result of the preset number after the frequency offset compensation is determined as the current channel estimation result.

[0013] In an optional implementation, when the current frequency offset tracking group is the first frequency offset tracking group, the coarse frequency offset tracking result is determined as the last frequency offset tracking result.

[0014] In an optional implementation, the current frequency offset tracking result is determined according to the current channel estimation result and the last channel estimation result, including: the current channel estimation result and the last channel estimation result are conjugate multiplied to obtain an initial frequency offset tracking result; and the initial frequency offset tracking result is smoothed by a second-order phase-locked loop to obtain the current frequency offset tracking result.

[0015] In the embodiment, after the current channel estimation result is obtained, the current channel estimation result and the last channel estimation result are conjugate multiplied to obtain an initial frequency offset tracking result, and then the initial frequency offset tracking result is smoothed by a second-order phase-locked loop to obtain the current frequency offset tracking result, which can more thoroughly eliminate frequency offset residues and obtain a smoother and more accurate current frequency offset tracking result.

[0016] In an alternative embodiment, before the payload data signal corrected by the coarse frequency offset tracking result is acquired, the method further comprises: receiving a wireless signal from a transmitter, wherein the wireless signal comprises a short training field, a long training field and the payload data signal; performing time domain synchronization on the wireless signal according to the short training field to obtain a synchronized wireless signal; performing Fourier transform processing on the synchronized long training field to obtain a first frequency domain signal and a second frequency domain signal; determining a first channel estimation result according to the first frequency domain signal and a second channel estimation result according to the second frequency domain signal; performing conjugate multiplication on the first channel estimation result and the second channel estimation result to determine the coarse frequency offset tracking result; and correcting the frequency offset of the payload data signal according to the coarse frequency offset tracking result.

[0017] In an alternative embodiment, after the current frequency offset tracking result is determined, the method further comprises: correcting the frequency offset of the orthogonal frequency division multiplexing symbol after the current frequency offset tracking group according to the current channel estimation result and the current frequency offset tracking result.

[0018] In a second aspect, the present application provides a wireless signal frequency offset tracking device in dual-mode power line carrier communication, the device comprising: an acquisition module configured to acquire a payload data signal corrected by a coarse frequency offset tracking result, wherein the payload data signal is composed of a plurality of orthogonal frequency division multiplexing symbols, and the orthogonal frequency division multiplexing symbol comprises a plurality of pilot subcarriers; a quantity determination module configured to determine the number of symbols in a current frequency offset tracking group based on a preset number, wherein the preset number is used to reflect the frequency of frequency offset tracking, the current frequency offset tracking group is one of a plurality of frequency offset tracking groups, and each frequency offset tracking group comprises a number of orthogonal frequency division multiplexing symbols; a first channel estimation module configured to determine an i-th channel estimation result according to an i-th pilot subcarrier in the current frequency offset tracking group, i being an integer, 1≤i≤the preset number, and the preset number of pilot subcarriers being from the number of orthogonal frequency division multiplexing symbols; a second channel estimation module configured to determine a current channel estimation result according to the preset number of channel estimation results when i is the preset number; and a frequency offset tracking module configured to determine a current frequency offset tracking result according to the current channel estimation result and a previous channel estimation result.

[0019] In a third aspect, the present application provides a communication device, comprising: a memory and a processor, which are communicatively connected to each other, and the memory stores computer instructions, and the processor executes the computer instructions to perform the wireless signal frequency offset tracking method in dual-mode power line carrier communication of the first aspect or any of the corresponding embodiments thereof. BRIEF DESCRIPTION OF DRAWINGS

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of a physical data unit frame according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of a physical layer service data unit according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of OFDM symbols according to an embodiment of the present invention;

[0024] Figure 4 This is a flowchart illustrating a wireless signal frequency offset tracking method in dual-mode power line carrier communication according to an embodiment of the present invention.

[0025] Figure 5 This is a flowchart illustrating another method for tracking the frequency offset of a wireless signal in dual-mode power line carrier communication according to an embodiment of the present invention.

[0026] Figure 6 This is a schematic diagram of a second-order phase-locked loop according to an embodiment of the present invention;

[0027] Figure 7 This is a structural block diagram of a wireless signal frequency offset tracking device in dual-mode power line carrier communication according to an embodiment of the present invention;

[0028] Figure 8 This is a schematic diagram of the hardware structure of a communication device according to an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] In the field of power communication, dual-mode power communication (also known as dual-mode power line carrier communication) is an important communication method that integrates wired and wireless transmission modes. It aims to fully leverage the advantages of stable and reliable wired communication and flexible and convenient wireless communication to meet the complex and diverse communication needs of power systems.

[0032] Orthogonal Frequency Division Multiplexing (OFDM) technology has been widely used in the wireless transmission portion of power line dual-mode communication due to its significant advantages such as high spectral efficiency and strong resistance to multipath interference. OFDM technology effectively improves data transmission efficiency and reliability by decomposing a high-speed data stream into multiple low-speed sub-data streams and modulating them onto mutually orthogonal subcarriers for parallel transmission.

[0033] In OFDM-based power line dual-mode wireless signal transmission, frequency offset is a critical factor that cannot be ignored. Frequency offset arises from two main causes: firstly, the frequency difference between the transmitter and receiver's local oscillators. Due to factors such as manufacturing processes and environmental temperature variations, it is difficult to guarantee that the local oscillators of the transmitter and receiver oscillate at exactly the same frequency, leading to a frequency shift between the received and transmitted signals. Secondly, the power communication environment is complex and variable, with channel characteristics changing rapidly over time. For example, electromagnetic interference from power equipment operation and weather changes (such as rain and fog) can alter channel parameters, resulting in phase and frequency variations in the received signal.

[0034] To achieve frequency offset tracking, as described in the background section, in OFDM-based power line dual-mode communication systems, pilot signals are inserted into the data symbols of the radio signal. A specific number of subcarriers serve as pilot signals within an OFDM symbol. For example, in communication mode option 1, each OFDM symbol includes 128 subcarriers, of which 8 are pilot signals. Frequency offset tracking is then performed based on the pilot signals within each OFDM symbol.

[0035] However, the number of subcarriers in OFDM symbols differs across communication modes, as does the number of pilot subcarriers. This results in varying frequency offset tracking accuracy across different frequency bands, leading to significant differences and impacting subsequent signal demodulation processes.

[0036] In view of this, the present invention provides a method, apparatus and device for frequency offset tracking of wireless signals in dual-mode power line carrier communication. Frequency offset tracking is performed only after the number of pilot subcarriers reaches a preset number, which increases the number of pilot subcarriers corresponding to frequency offset estimation, thereby improving the accuracy of frequency offset estimation and reducing the computational load of frequency offset estimation.

[0037] To facilitate a better understanding of this invention, the relevant terminology involved in this invention will first be explained.

[0038] (1) Physical Protocol Data Unit (PPDU) frame of wireless signal

[0039] like Figure 1 As shown, the Physical Data Unit (PPDU) structure typically consists of a Short Training Field (STF), a Long Training Field (LTF), a PHR Control Signal (SIG), a Physical Header (PHR), and a Physical Service Data Unit (PSDU).

[0040] STF is used for time-domain synchronization. After receiving a signal, the communication device at the receiving end performs time-domain synchronization based on STF. Once synchronization is successful, a Fast Fourier Transform (FFT) is performed on the received signal, starting from LTF. LTF is mainly used for channel estimation and frequency offset correction. SIG is the control word for PHR, used to indicate the modulation and coding scheme of the PHR. The PHR contains detailed information about the PSDU, such as the PSDU length, modulation scheme, and coding rate, carrying information for correct reception and demodulation of the PSDU.

[0041] PSDU is the actual data unit transmitted, and it includes different numbers of OFDM symbols depending on the data size. For example, Figure 2 As shown, PSDU includes n One OFDM symbol, n An integer greater than 1. Each OFDM symbol consists of a corresponding number of subcarriers, for example, such as... Figure 3 As shown, each OFDM symbol includes m Subcarriers, m It is an integer greater than 1.

[0042] (2) Communication modes of wireless signals

[0043] The number of subcarriers and pilot subcarriers in an OFDM symbol varies depending on the communication mode (frequency band). For example, as shown in Table 1, in communication mode Option 1, an OFDM symbol consists of 128 subcarriers, of which 104 are active subcarriers, 8 are pilot subcarriers, and 96 are data subcarriers. In communication mode Option 2, an OFDM symbol consists of 64 subcarriers, with 52 active subcarriers, 4 pilot subcarriers, and 48 data subcarriers. In communication mode Option 3, an OFDM symbol consists of 32 subcarriers, with 20 active subcarriers, 2 pilot subcarriers, and 18 data subcarriers.

[0044] Table 1 Communication Modes and Bandwidth

[0045]

[0046] Available subcarriers, also known as active subcarriers, refer to the number of subcarriers actually involved in communication. Pilot subcarriers are used for auxiliary functions such as channel estimation and frequency offset tracking, while data subcarriers are used to transmit actual service data. Parameters refer to the various indicators in the table used to describe the communication mode and bandwidth; nominal bandwidth refers to the nominal frequency bandwidth under the communication mode, reflecting the frequency range of transmittable signals; channel spacing refers to the frequency interval between adjacent channels, used to avoid inter-channel interference; Fast Fourier Transform Size (FFT Size) is the number of points in the FFT operation, determining characteristics such as the number of subcarriers in an OFDM symbol.

[0047] The following is a detailed description of the wireless signal frequency offset tracking method in dual-mode power line carrier communication provided by the present invention, with reference to the accompanying drawings. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a communication device such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than that shown here.

[0048] This embodiment provides a method for tracking the frequency offset of wireless signals in dual-mode power line carrier communication, which can be used as a communication device as a receiver. Figure 4 This is a flowchart of a wireless signal frequency offset tracking method in dual-mode power line carrier communication according to an embodiment of the present invention, as follows: Figure 4 As shown, the process includes the following steps:

[0049] Step S401: Obtain the load data signal corrected by the coarse frequency offset tracking result.

[0050] The payload data signal consists of multiple orthogonal frequency division multiplexing (OFDM) symbols, and each OFDM symbol includes multiple pilot subcarriers.

[0051] Specifically, after receiving the wireless signal, the communication device, as the receiving end, first performs frequency offset tracking (referred to as coarse frequency offset tracking) based on the LTF in the wireless signal to obtain the coarse frequency offset tracking result; then, it corrects (compensates) the payload data signal in the wireless signal based on the coarse frequency offset tracking result; and then performs frequency offset tracking (referred to as fine frequency offset tracking or residual frequency offset tracking) on ​​the payload data signal corrected by the coarse frequency offset tracking result. The subsequent steps S402 to S405 of this invention are the fine frequency offset tracking process.

[0052] The process of obtaining coarse frequency offset tracking results by performing frequency offset tracking based on the LTF in the wireless signal, and correcting the payload data signal in the wireless signal based on the coarse frequency offset tracking results, can adopt conventional methods in the field, and this invention does not impose specific limitations.

[0053] Step S402: Determine the number of symbols in the current frequency offset tracking group based on a preset quantity.

[0054] The preset quantity is the number of pilot subcarriers, used to reflect the frequency of frequency offset tracking. The preset quantity is set according to the actual communication situation.

[0055] For example, the communication modes involved in the communication equipment include Option 1, Option 2 and Option 3. In Option 1, the number of pilot subcarriers corresponding to each OFDM symbol is 8, in Option 2, the number of pilot subcarriers corresponding to each OFDM symbol is 4, and in Option 3, the number of pilot subcarriers corresponding to each OFDM symbol is 2. The preset number can be a multiple of 8, for example, the preset number can be 8 or 16, etc.

[0056] For example, the preset quantity can be set or changed according to the actual communication situation. For instance, it can be adjusted according to the bit error rate (BER); if the BER is high, the preset quantity should be increased, and if the BER is low, the preset quantity should be decreased. It can also be adjusted according to the signal-to-noise ratio (SNR); when the SNR is high, it indicates that the channel conditions are good, and the impact on frequency offset tracking reliability is relatively small, so the preset quantity can be decreased, and vice versa.

[0057] Specifically, the number of pilot subcarriers is crucial to the accuracy of frequency offset tracking. The more pilot subcarriers there are, the higher the accuracy of the final frequency offset tracking result. If all subcarriers are pilots, the accuracy of the frequency offset tracking result will be the highest.

[0058] The current frequency offset tracking group is one of multiple frequency offset tracking groups, and each frequency offset tracking group includes a number of orthogonal frequency division multiplexing (OFDM) symbols. In other words, the number of symbols is determined based on a preset number, and then multiple OFDM symbols are divided into multiple frequency offset tracking groups according to the number of symbols. The subsequent current channel estimation result is determined on a unit basis using the frequency offset tracking group.

[0059] After determining the preset number, the number of symbols is determined based on the number of pilot subcarriers contained in each OFDM symbol and the preset number. The number of symbols is equal to the preset number divided by the number of pilot subcarriers contained in each OFDM symbol.

[0060] In one example, the communication mode is Option 3, and each OFDM symbol includes 2 pilot subcarriers. If the preset number is 8, then the number of symbols is 4 = 8 ÷ 2. Each group consists of 4 OFDM symbols and the multiple OFDM symbols included in the payload data signal are divided into multiple frequency offset tracking groups. If the preset number is 16, then the number of symbols is 8 = 16 ÷ 2, and each group consists of 8 OFDM symbols.

[0061] Step S403: Determine the i-th channel estimation result based on the i-th pilot subcarrier in the current frequency offset tracking group.

[0062] Where i is an integer, 1≤i≤preset number, and the preset number of pilot subcarriers comes from the OFDM symbols of the symbol number.

[0063] For example, after obtaining the i-th pilot subcarrier, the i-th channel estimation result can be determined by the following formula (1).

[0064]

[0065] In the formula, This represents the i-th channel estimation result within the current frequency offset tracking group. This represents the i-th pilot subcarrier within the current frequency offset tracking group. This refers to the pilot subcarrier stored locally by the communication device acting as the receiving end.

[0066] Step S404: When i is a preset number, determine the current channel estimation result based on the preset number of channel estimation results.

[0067] The current channel estimation result is the channel estimation result corresponding to the current frequency offset tracking group.

[0068] Specifically, based on the preset number of pilot subcarriers in the current frequency offset tracking group, after determining the preset number of channel estimation results corresponding to them one by one in sequence or simultaneously, frequency offset compensation is performed on the preset number of channel estimation results, and then the average value of the compensated preset number of channel estimation results can be used as the current channel estimation result.

[0069] Currently, after acquiring the payload data signal corrected by coarse frequency offset tracking, frequency offset tracking is usually performed on each OFMD symbol among the multiple OFMD symbols contained in the payload data signal. Specifically, channel estimation is performed using the pilot subcarriers of each OFMD symbol, and then the frequency offset is determined and corrected based on the channel estimation results of each OFMD symbol.

[0070] For example, if the communication mode is Option 3, the channel estimation result is determined based on the two pilot subcarriers contained in each OFMD symbol, and then the frequency offset of each OFMD symbol is determined. If the communication mode is Option 2, the channel estimation result is determined based on the four pilot subcarriers contained in each OFMD symbol, and then the frequency offset of each OFMD symbol is determined. In the above process, because the number of pilot subcarriers used in different communication modes is different, the frequency offset tracking effect varies greatly. At the same time, the smaller number of pilot subcarriers used to determine the frequency offset will lead to lower frequency offset tracking accuracy, affecting the subsequent demodulation process.

[0071] This application does not perform frequency offset correction based on the number of pilot subcarriers in each OFDM symbol. Instead, it determines the number of symbols based on a preset number, then groups the multiple OFDM symbols contained in the payload data signal according to the number of symbols, and determines the channel estimation result for spectral correction by group. Taking the communication mode as Option 3 as an example, if the preset number is 8, the current channel estimation result is calculated and frequency offset compensation is performed every four OFDM symbols.

[0072] The group contains multiple OFMD symbols. The number of pilot subcarriers used for each frequency offset calculation is a preset number, which may be several times the number of pilot subcarriers contained in a single OFMD symbol. Using a larger number of pilot subcarriers for frequency offset calculation improves the accuracy of frequency offset tracking results. Furthermore, since the number of pilot subcarriers used for each frequency offset calculation is preset, all communication modes can use the same number of pilot subcarriers to calculate the frequency offset, thus ensuring consistent frequency offset tracking performance across different communication modes.

[0073] Step S405: Determine the current frequency offset tracking result based on the current channel estimation result and the previous channel estimation result.

[0074] Specifically, after obtaining the current channel estimation result and the previous channel estimation result, the current channel estimation result and the previous channel estimation result are multiplied by their conjugate to obtain the current frequency offset tracking result. Frequency offset tracking requires a phase-locked loop (PLL) to smooth the frequency offset tracking result. A first-order PLL or a second-order PLL can be used. A first-order PLL is easier to stabilize, but its tracking accuracy is not high. A second-order PLL has a slower tracking speed, but its tracking accuracy is high and it is less prone to losing lock.

[0075] It should be noted that if the current frequency offset tracking group is the first frequency offset tracking group, the channel estimation result determined based on LTF will be used as the previous channel estimation result.

[0076] The wireless signal frequency offset tracking method in dual-mode power line carrier communication provided in this embodiment, after acquiring the payload data signal corrected by coarse frequency offset tracking results, determines the number of symbols in the current frequency offset tracking group based on a preset number, then determines the i-th channel estimation result based on the i-th pilot subcarrier in the current frequency offset tracking group, and when i is a preset number, determines the current channel estimation result based on the preset number of channel estimation results, and finally determines the current frequency offset tracking result based on the current channel estimation result and the previous channel estimation result.

[0077] This embodiment determines the frequency offset by using a preset number of pilot subcarriers, increasing the number of pilot subcarriers corresponding to the frequency offset estimation. This number of pilot subcarriers for frequency offset estimation may be several times the number of pilot subcarriers contained in a single OFMD symbol, thereby improving the accuracy of frequency offset estimation. Furthermore, this invention does not perform frequency offset compensation for every OFMD symbol. Compared to frequency offset estimation per OFMD symbol, determining the number of symbols based on a preset number, grouping OFMD symbols by symbol number, and performing frequency offset compensation by group reduces the computational load of frequency offset estimation and improves computational efficiency. Since the number of pilot subcarriers used for each frequency offset calculation is a preset number, all communication modes can use the same number of pilot subcarriers to calculate the frequency offset, thus ensuring the same frequency offset tracking effect across different communication modes.

[0078] In some embodiments, prior to step S401 above, the wireless signal frequency offset tracking method in dual-mode power line carrier communication further includes:

[0079] Step a1: Receive wireless signals from the transmitter.

[0080] Among them, such as Figure 1 As shown, the wireless signal includes the Short Training Domain (STF), the Long Training Domain (LTF), and the payload data signal.

[0081] Step a2: Synchronize the wireless signal in the time domain according to the short training domain to obtain the synchronized wireless signal.

[0082] The method of synchronizing wireless signals in the time domain based on the short training domain can be a conventional method in the field, and will not be described in detail in this invention.

[0083] Specifically, assume that the wireless signal sequence transmitted by the communication device acting as the transmitter is as follows: The time-domain estimated frequency offset is 1. Ignoring noise, the sequence of wireless signals received by the communication device acting as the receiver. It can be shown in formula (2):

[0084]

[0085] In the formula, Indicates the sampling point index. The imaginary unit, Indicates the sampling period. Indicates the sampling frequency.

[0086] Since STF is a periodically repeating sequence, let the period be... ,Right now .

[0087] The following formula (3) is used to... Perform autocorrelation:

[0088]

[0089] In the formula, Indicates complex conjugation. Represents a constant.

[0090] By taking the phase of the above autocorrelation results and averaging them, we can obtain... The estimated value of 1 is used to locate the LTF.

[0091] Step a3: Perform Fourier transform processing on the synchronized long training domain to obtain the first frequency domain signal and the second frequency domain signal.

[0092] Specifically, the communication protocol includes two OFDM symbols in the LTF. Fourier transform (FFT) processing is performed on the synchronized LTF 1 and LTF 2 to obtain the first frequency domain signal (Y). LTF1 ) and second frequency domain signal (Y) LTF2 ).

[0093] Step a4: Determine the first channel estimation result based on the first frequency domain signal and the second channel estimation result based on the second frequency domain signal.

[0094] Specifically, after obtaining the first frequency domain signal and the second frequency domain signal, the first channel estimation result and the second channel estimation result can be determined respectively by the following formula (4):

[0095]

[0096] In the formula, Represents frequency domain signals, Y can be LTF1 Or Y LTF2 ; The channel estimation result is represented in hour, The first channel estimation result H LTF1 ,exist hour, The second channel estimation result H LTF2 ; Represents the local LTF symbol.

[0097] Step a5: Perform conjugate multiplication on the first channel estimation result and the second channel estimation result to determine the coarse frequency offset tracking result.

[0098] Specifically, H LTF1 and H LTF2 The coarse frequency offset tracking result (i.e., the phase estimate) can be determined by performing conjugate multiplication.

[0099] For OFDM signals, the expression can be shown in formula (5):

[0100]

[0101] In the formula, Let N represent the time-domain signal of the l-th OFDM symbol, and let N represent the number of subcarriers in the OFDM symbol. This represents the frequency domain subcarrier data of the l-th OFDM symbol, where k represents the subcarrier index. This represents the complex exponential carrier (orthogonal subcarrier) of OFDM modulation, used to achieve orthogonality between subcarriers.

[0102] Assume there exists a normalized frequency offset as shown in formula (6). :

[0103]

[0104] In the formula, This indicates frequency offset estimation in the frequency domain. Indicates the subcarrier spacing. .

[0105] Received time-domain signal with frequency offset ε It can be shown in formula (7):

[0106]

[0107] right The FFT process can be performed as shown in formula (8):

[0108]

[0109] In the formula, Indicates to The frequency domain received signal obtained after FFT processing This represents the frequency domain subcarrier data of the l-th OFDM symbol, where m is the subcarrier index.

[0110] when Then, the above formula (8) can be simplified to formula (9):

[0111]

[0112] The remaining terms represent the interference from all other subcarriers to the current subcarrier, i.e., inter-carrier interference (ICI), assuming... It is very small and can be ignored, therefore the above formula (9) can be transformed into formula (10):

[0113]

[0114] Since OFDM symbols include two identical LTFs, therefore, It can be as shown in formula (11), It can be as shown in formula (12), It can be shown in formula (13).

[0115]

[0116] The two LTFs are periodically repeating and satisfy the conditions shown in the following formula (14):

[0117]

[0118] In the formula, This indicates the FFT length, which is the number of subcarriers in an OFDM symbol.

[0119] therefore It can be shown in formula (15):

[0120]

[0121] From the frequency domain perspective, all subcarriers of the entire OFDM symbol have shifted to a common phase. As the symbol number increases, the corresponding phase rotation angle increases linearly, and the result of the conjugate multiplication can be shown in formula (16):

[0122]

[0123] Taking the phase of formula (15) and averaging it, we get The estimated value is then obtained. The estimated value of 2.

[0124] Step a6: Correct the frequency offset of the load data signal based on the coarse frequency offset tracking results.

[0125] Specifically, after obtaining the coarse frequency offset tracking result, the frequency offset of the first channel estimation result and the second channel estimation result can be corrected using the following formula (17), and then the corrected wireless signal can be obtained using formula (18). .

[0126]

[0127] In the formula, This represents the corrected channel estimation result. The corrected first channel estimation result H LTF1 'or the corrected second channel estimation result H LTF2 '; This indicates the results of coarse frequency offset tracking; This refers to the complex form of the received wireless signal, specifically the signal following LTF.

[0128] In some embodiments, after step S405, the wireless signal frequency offset tracking method in dual-mode power line carrier communication further includes: performing frequency offset compensation on the payload data after the OFDM symbol corresponding to the current frequency offset tracking group based on the current frequency offset tracking result.

[0129] The current frequency offset tracking result is used to compensate the load data signal, that is, to use the phase rotation amount corresponding to the frequency offset to reverse the phase shift of the load data signal. Specifically, after determining the current frequency offset tracking result, frequency offset compensation can be performed on the load data after the OFDM symbol corresponding to the current frequency offset tracking group using formulas similar to those in formulas (17) and (18) above. At this time, in formula (17) Replace with the current frequency offset tracking result.

[0130] This embodiment also provides another method for tracking the frequency offset of wireless signals in dual-mode power line carrier communication, which can be used as a communication device as a receiver. Figure 5 This is a flowchart of another method for tracking the frequency offset of a wireless signal in dual-mode power line carrier communication according to an embodiment of the present invention, as follows:Figure 5 As shown, the process includes the following steps:

[0131] Step S501: Obtain the load data signal corrected by the coarse frequency offset tracking result.

[0132] Please see details Figure 4 Step S401 of the illustrated embodiment will not be described again here.

[0133] Step S502: Determine the number of symbols in the current frequency offset tracking group based on the number of pilot subcarriers contained in the orthogonal frequency division multiplexing symbols under various communication modes.

[0134] In some embodiments, the least common multiple of the number of pilot subcarriers contained in an OFDM symbol under various communication modes can be determined as a preset number. Then, the ratio of the preset number to the number of pilot subcarriers contained in an OFDM symbol is determined as the number of symbols.

[0135] For example, if the communication mode involved by the communication device as the receiving end includes Option 1 and Option 2, and the number of pilot subcarriers contained in the OFDM symbol in Option 1 is 8, and the number of pilot subcarriers contained in the OFDM symbol in Option 2 is 4, then the least common multiple of 8 is determined as the preset number; if the communication mode involved by the communication device as the receiving end includes Option 2 and Option 3, and the number of pilot subcarriers contained in the OFDM symbol in Option 3 is 2, then the least common multiple of 4 is determined as the preset number.

[0136] If the preset number is 8, then when the communication mode is Option 1, the number of symbols is 1 = 8 / 8; when the communication mode is Option 2, the number of symbols is 2 = 8 / 4.

[0137] In other embodiments, the maximum number of pilot subcarriers contained in the orthogonal frequency division multiplexing symbol under various communication modes can be determined as a preset number.

[0138] Step S503: Determine the i-th channel estimation result based on the i-th pilot subcarrier in the current frequency offset tracking group.

[0139] Please see details Figure 4 Step S403 of the illustrated embodiment will not be described again here.

[0140] Step S504: When i is a preset number, determine the current channel estimation result based on the preset number of channel estimation results.

[0141] Specifically, step S504 above may include:

[0142] Step S5041: Using the last orthogonal frequency division multiplexing symbol in the current frequency offset tracking group as a reference, frequency offset compensation is performed on a preset number of channel estimation results based on the previous frequency offset tracking result.

[0143] Among them, the previous frequency offset tracking result is the frequency offset tracking result of the previous frequency offset tracking group.

[0144] Specifically, frequency offset accumulates with different signal reception times, and the channel response calculated based on the current frequency offset tracking group is also inconsistent due to the frequency offset. Therefore, to calculate the current channel estimation result, frequency offset compensation is needed to bring them to the same reference. This application uses the last OFDM symbol in the current frequency offset tracking group as the reference, and performs frequency offset compensation on the channel estimation result based on the interval between the OFDM symbol containing the pilot subcarrier corresponding to the channel estimation result and the last OFDM symbol, as well as the previous frequency offset tracking result.

[0145] Taking Option 3 as the communication mode and the preset number of 8 as an example, the current channel estimation result is calculated once every four OFDM symbols. The four OFDM symbols included in the current frequency offset tracking group are denoted as OFDM 1, OFDM 2, OFDM 3 and OFDM 4. OFDM 4 is the last OFDM symbol in the current frequency offset tracking group. Then, the two channel estimation results corresponding to OFDM 3 are compensated for frequency offset by one symbol interval, the two channel estimation results corresponding to OFDM 2 are compensated for frequency offset by two symbol intervals, and the two channel estimation results corresponding to OFDM 1 are compensated for frequency offset by three symbol intervals. That is, the frequency offset of the 8 (preset number) channel estimation results can be compensated for using formula (19):

[0146]

[0147] In the formula, H11 represents the channel estimation result corresponding to the first pilot subcarrier in OFDM 1, H11' represents H11 after frequency offset compensation, b represents the previous frequency offset tracking result, H12 represents the channel estimation result corresponding to the second pilot subcarrier in OFDM 1, H12' represents H12 after frequency offset compensation, H21 represents the channel estimation result corresponding to the first pilot subcarrier in OFDM 2, H21' represents H21 after frequency offset compensation, H22 represents the channel estimation result corresponding to the second pilot subcarrier in OFDM 2, H22' represents H22 after frequency offset compensation, H31 represents the channel estimation result corresponding to the first pilot subcarrier in OFDM 3, H31' represents H31 after frequency offset compensation, H32 represents the channel estimation result corresponding to the second pilot subcarrier in OFDM 3, H32' represents H32 after frequency offset compensation, and H41 represents OFDM 1. In OFDM 4, the channel estimation result corresponding to the first pilot subcarrier is H41', which represents H41 after frequency offset compensation. In OFDM 4, the channel estimation result corresponding to the second pilot subcarrier is H42', which represents H42 after frequency offset compensation.

[0148] When the current frequency offset tracking group is the first frequency offset tracking group, the coarse frequency offset tracking result is determined as the previous frequency offset tracking result, i.e., b= a .

[0149] Step S5042: The average value of the preset number of channel estimation results after frequency offset compensation is determined as the current channel estimation result.

[0150] Specifically, if the communication mode is Option 3 and the preset quantity is 8, the current channel estimation result is: , .

[0151] Step S505: Determine the current frequency offset tracking result based on the current channel estimation result and the previous channel estimation result.

[0152] Specifically, step S505 above may include:

[0153] Step S5051: Perform conjugate multiplication on the current channel estimation result and the previous channel estimation result to obtain the initial frequency offset tracking result.

[0154] Step S5052: Use a second-order phase-locked loop to smooth and filter the initial frequency offset tracking result to obtain the current frequency offset tracking result.

[0155] The second-order phase-locked loop achieves smooth tracking of frequency deviation through a closed-loop mechanism of phase error detection, proportional-integral (PI) control, and phase / frequency accumulation.

[0156] Specifically, such as Figure 6As shown, the phase error err = x - reg is first determined to provide a basis for subsequent adjustments. The phase error is also... Figure 6 In x represents the initial frequency offset tracking result, and reg represents the previous frequency offset tracking result; then the ratio ( Branch adjustment, determining the proportional term This allows for rapid response to current errors, making immediate adjustments to instantaneous frequency offset changes and improving tracking timeliness; simultaneously, integration is performed ( Branch adjustment to determine the integral term , This represents the historical value of the integrator accumulator (initially 0). Each iteration will integrate the current error component. The values ​​are accumulated to historical values ​​to eliminate long-term frequency offset residues (such as deviations from incomplete compensation of the proportional branch), improving tracking accuracy and stability; then, the proportional and integral terms are accumulated to determine the smoothed output result. Then, reg3 is assigned to reg as the historical smoothing value for the next moment, and the loop continues until the number of iterations reaches the preset number or reg3 meets the convergence condition.

[0157] Figure 6 The frequency accumulator (freq. acc.) is the accumulation module for the integration branch, storing the historical values ​​of the integration term. The phase acc. is the final smoothing output module, which, through a delay unit (z... -1 Iterative updates are achieved.

[0158] In short, the smoothing filtering of a second-order phase-locked loop (PLL) uses a proportional-integral closed-loop iteration to refine the initial frequency offset tracking result that fluctuates in real time into a continuous, stable, and accurate tracking result, providing a reliable basis for frequency offset compensation for subsequent signal demodulation.

[0159] Compared to a first-order phase-locked loop, a second-order phase-locked loop, by introducing an integral term, can more thoroughly eliminate frequency offset residue, avoid loss of lock, and obtain smoother and more accurate frequency offset tracking results.

[0160] Step S506: Based on the current channel estimation result and the current frequency offset tracking result, perform frequency offset correction on the orthogonal frequency division multiplexing symbols following the current frequency offset tracking group.

[0161] Specifically, after obtaining the current frequency offset tracking result, the current channel estimation result can be frequency offset corrected using the following formula (20), and then the frequency offset correction result of the OFDM symbols after the current frequency offset tracking group can be obtained using formula (21). .

[0162]

[0163] In the formula, This represents the corrected current channel estimation result; This indicates the current bias tracking result, i.e., the filtered frequency bias tracking result; The complex form of the received wireless signal refers specifically to the OFDM symbol following the current frequency offset tracking group.

[0164] Specifically, after correcting the frequency offset of the orthogonal frequency division multiplexing symbols following the current frequency offset tracking group, the next frequency offset tracking group is taken as the current frequency offset tracking group, and the above steps S503 to S506 are repeated until the current frequency offset tracking group is the last of multiple frequency offset tracking groups.

[0165] In this embodiment, after obtaining the current channel estimation result, the current channel estimation result and the previous channel estimation result are multiplied by conjugate to obtain the initial frequency offset tracking result. Then, a second-order phase-locked loop is used to smooth and filter the initial frequency offset tracking result to obtain the current frequency offset tracking result. This can more thoroughly eliminate frequency offset residue and obtain a smoother and more accurate current frequency offset tracking result.

[0166] This embodiment also provides a wireless signal frequency offset tracking device for dual-mode power line carrier communication. This device is used to implement the above embodiments and preferred embodiments, and details already described will not be repeated. As used below, the term "module" can refer to 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 implementation, or a combination of software and hardware, is also possible and contemplated.

[0167] This embodiment provides a wireless signal frequency offset tracking device for dual-mode power line carrier communication, such as... Figure 7 As shown, it includes:

[0168] The acquisition module 701 is used to acquire the load data signal corrected by the coarse frequency offset tracking result. The load data signal consists of multiple orthogonal frequency division multiplexing symbols, and the orthogonal frequency division multiplexing symbols include multiple pilot subcarriers.

[0169] The quantity determination module 702 is used to determine the number of symbols in the current frequency offset tracking group based on a preset quantity, wherein the preset quantity is used to reflect the frequency of frequency offset tracking, the current frequency offset tracking group is one of multiple frequency offset tracking groups, and each frequency offset tracking group includes orthogonal frequency division multiplexing symbols of the number of symbols.

[0170] The first channel estimation module 703 is used to determine the i-th channel estimation result based on the i-th pilot subcarrier in the current frequency offset tracking group, where i is an integer, 1≤i≤preset number, and the preset number of pilot subcarriers comes from the orthogonal frequency division multiplexing symbols of the symbol number;

[0171] The second channel estimation module 704 is used to determine the current channel estimation result based on the channel estimation results of the preset number when i is a preset number;

[0172] The frequency offset tracking module 705 is used to determine the current frequency offset tracking result based on the current channel estimation result and the previous channel estimation result.

[0173] In some alternative implementations, the quantity determination module 702 includes:

[0174] The first determining unit is used to determine the number of symbols in the current frequency offset tracking group based on the number of pilot subcarriers contained in the orthogonal frequency division multiplexing symbols under various communication modes.

[0175] In some optional implementations, the preset number is the least common multiple of the number of pilot subcarriers contained in the orthogonal frequency division multiplexing symbols under various communication modes.

[0176] In some alternative implementations, the second channel estimation module 704 includes:

[0177] The frequency offset compensation unit is used to compensate for the frequency offset of a preset number of channel estimation results based on the last orthogonal frequency division multiplexing symbol in the current frequency offset tracking group and the previous frequency offset tracking result.

[0178] The second determining unit is used to determine the average value of a preset number of channel estimation results after frequency offset compensation as the current channel estimation result.

[0179] In some alternative implementations, when the current frequency offset tracking group is the first frequency offset tracking group, the coarse frequency offset tracking result is determined as the previous frequency offset tracking result.

[0180] In some alternative implementations, the frequency offset tracking module 705 includes:

[0181] The conjugate multiplication unit is used to perform conjugate multiplication on the current channel estimation result and the previous channel estimation result to obtain the initial frequency offset tracking result;

[0182] The smoothing filter unit is used to smooth the initial frequency offset tracking result using a second-order phase-locked loop to obtain the current frequency offset tracking result.

[0183] In some alternative embodiments, the apparatus further includes:

[0184] The receiving module is used to receive wireless signals from the transmitter, wherein the wireless signals include short training domain, long training domain and payload data signals;

[0185] The time-domain synchronization module is used to synchronize the wireless signal in the time domain according to the short training domain to obtain the synchronized wireless signal.

[0186] The processing module is used to perform Fourier transform processing on the synchronized long training domain to obtain the first frequency domain signal and the second frequency domain signal.

[0187] The third channel estimation module is used to determine the first channel estimation result based on the first frequency domain signal and to determine the second channel estimation result based on the second frequency domain signal.

[0188] The coarse frequency offset tracking module is used to perform conjugate multiplication on the first channel estimation result and the second channel estimation result to determine the coarse frequency offset tracking result.

[0189] The first frequency offset correction module is used to correct the frequency offset of the load data signal based on the coarse frequency offset tracking results.

[0190] In some alternative embodiments, the apparatus further includes:

[0191] The second frequency offset correction module is used to correct the frequency offset of the orthogonal frequency division multiplexing symbols following the current frequency offset tracking group based on the current channel estimation result and the current frequency offset tracking result.

[0192] The wireless signal frequency offset tracking device in dual-mode power line carrier communication provided in this embodiment of the invention can execute the wireless signal frequency offset tracking method in dual-mode power line carrier communication provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the method. Further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0193] Figure 8 This is a schematic diagram of the structure of a communication device provided in an embodiment of the present invention.

[0194] The following is a detailed reference. Figure 8 The diagram illustrates a structural schematic suitable for implementing a communication device according to an embodiment of the present invention. The communication device may include a processor (e.g., a central processing unit, graphics processing unit, etc.) 801, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 802 or a program loaded from memory 808 into random access memory (RAM) 803. The RAM 803 also stores various programs and data required for the operation of the communication device. The processor 801, ROM 802, and RAM 803 are interconnected via a bus 804. An input / output (I / O) interface 805 is also connected to the bus 804.

[0195] Typically, the following devices can be connected to I / O interface 805: input devices 806 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 807 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; memory devices 808 including, for example, magnetic tapes, hard disks, etc.; and communication devices 809. Communication device 809 allows communication devices to exchange data wirelessly or via wired communication with other devices. Although Figure 8 Communication devices with various means are shown, but it should be understood that it is not required to implement or have all the means shown, and more or fewer means may be implemented or have instead.

[0196] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device 809, or installed from a memory 808, or installed from a ROM 802. When the computer program is executed by a processor 801, it performs the functions defined in the wireless signal frequency offset tracking method in dual-mode power line carrier communication according to embodiments of the present invention.

[0197] Figure 8 The communication device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0198] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the wireless signal frequency offset tracking method in dual-mode power line carrier communication shown in the above embodiments is implemented.

[0199] A portion of this invention can be applied to computer program products, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installation program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0200] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A method for tracking the frequency offset of wireless signals in dual-mode power line carrier communication, characterized in that, The method includes: Acquire a payload data signal corrected by coarse frequency offset tracking results, wherein the payload data signal is composed of multiple orthogonal frequency division multiplexing symbols, and the orthogonal frequency division multiplexing symbols include multiple pilot subcarriers; Based on a preset quantity, the number of symbols in the current frequency offset tracking group is determined, wherein the preset quantity reflects the frequency of frequency offset tracking, and the current frequency offset tracking group is one of multiple frequency offset tracking groups, each frequency offset tracking group including orthogonal frequency division multiplexing symbols of the specified number of symbols; determining the number of symbols in the current frequency offset tracking group based on the preset quantity includes: determining the number of symbols in the current frequency offset tracking group according to the number of pilot subcarriers contained in the orthogonal frequency division multiplexing symbols under various communication modes, wherein the preset quantity is the least common multiple of the number of pilot subcarriers contained in the orthogonal frequency division multiplexing symbols under the various communication modes; Based on the i-th pilot subcarrier in the current frequency offset tracking group, the i-th channel estimation result is determined, where i is an integer, 1≤i≤the preset number, and the preset number of pilot subcarriers comes from the orthogonal frequency division multiplexing symbols of the symbol number; When i is the preset number, the current channel estimation result is determined based on the channel estimation results of the preset number; Based on the current channel estimation result and the previous channel estimation result, the current frequency offset tracking result is determined.

2. The method according to claim 1, characterized in that, Determining the current channel estimation result based on the preset number of channel estimation results includes: Based on the last orthogonal frequency division multiplexing symbol in the current frequency offset tracking group, frequency offset compensation is performed on the preset number of channel estimation results according to the previous frequency offset tracking result; The average value of a preset number of channel estimation results after frequency offset compensation is determined as the current channel estimation result.

3. The method according to claim 2, characterized in that, When the current frequency offset tracking group is the first frequency offset tracking group, the coarse frequency offset tracking result is determined as the previous frequency offset tracking result.

4. The method according to any one of claims 1 to 3, characterized in that, The step of determining the current frequency offset tracking result based on the current channel estimation result and the previous channel estimation result includes: The current channel estimation result and the previous channel estimation result are multiplied by conjugate to obtain the initial frequency offset tracking result; The initial frequency offset tracking result is smoothed and filtered using a second-order phase-locked loop to obtain the current frequency offset tracking result.

5. The method according to any one of claims 1 to 3, characterized in that, Before acquiring the load data signal corrected by coarse frequency offset tracking results, the method further includes: Receive wireless signals from a transmitter, wherein the wireless signals include a short training domain, a long training domain, and payload data signals; The wireless signal is time-domain synchronized according to the short training domain to obtain the synchronized wireless signal. The synchronized long training domain is subjected to Fourier transform processing to obtain the first frequency domain signal and the second frequency domain signal; A first channel estimation result is determined based on the first frequency domain signal, and a second channel estimation result is determined based on the second frequency domain signal; The first channel estimation result and the second channel estimation result are multiplied by conjugate to determine the coarse frequency offset tracking result; The load data signal is frequency offset corrected based on the coarse frequency offset tracking results.

6. The method according to any one of claims 1 to 3, characterized in that, After determining the current frequency offset tracking result, the method further includes: Based on the current channel estimation result and the current frequency offset tracking result, frequency offset correction is performed on the orthogonal frequency division multiplexing symbols following the current frequency offset tracking group.

7. A wireless signal frequency offset tracking device for dual-mode power line carrier communication, characterized in that, The device includes: The acquisition module is used to acquire the payload data signal corrected by the coarse frequency offset tracking result, wherein the payload data signal is composed of multiple orthogonal frequency division multiplexing symbols, and the orthogonal frequency division multiplexing symbols include multiple pilot subcarriers; The quantity determination module is used to determine the number of symbols in the current frequency offset tracking group based on a preset quantity, wherein the preset quantity reflects the frequency of frequency offset tracking, the current frequency offset tracking group is one of multiple frequency offset tracking groups, and each frequency offset tracking group includes orthogonal frequency division multiplexing symbols of the specified number of symbols; determining the number of symbols in the current frequency offset tracking group based on the preset quantity includes: determining the number of symbols in the current frequency offset tracking group according to the number of pilot subcarriers contained in the orthogonal frequency division multiplexing symbols under various communication modes, wherein the preset quantity is the least common multiple of the number of pilot subcarriers contained in the orthogonal frequency division multiplexing symbols under the various communication modes; The first channel estimation module is used to determine the i-th channel estimation result based on the i-th pilot subcarrier in the current frequency offset tracking group, where i is an integer, 1≤i≤the preset number, and the preset number of pilot subcarriers comes from the orthogonal frequency division multiplexing symbols of the symbol number; The second channel estimation module is used to determine the current channel estimation result based on the channel estimation results of the preset number when i is the preset number; The frequency offset tracking module is used to determine the current frequency offset tracking result based on the current channel estimation result and the previous channel estimation result.

8. A communication device, characterized in that, include: A memory and a processor are communicatively connected, the memory stores computer instructions, and the processor executes the computer instructions to perform the wireless signal frequency offset tracking method in dual-mode power line carrier communication as described in any one of claims 1 to 6.

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