Signal compensation method and device based on power carrier OFDM system

Abstract

The invention relates to a signal compensation method and device based on a power carrier OFDM (Orthogonal Frequency Division Multiplexing) system. The method comprises the following steps: acquiring an accumulated sampling phase deviation value of each subcarrier of a symbol to be demodulated in a frame signal according to a sampling phase deviation value of each subcarrier and an initial position of the frame signal; and then judging whether the absolute value of the accumulated sampling phase deviation value of each subcarrier of the symbol to be demodulated is greater than a preset phase deviation threshold, and performing phase compensation on the subcarrier signal of the symbol to be demodulated according to the judgment result. According to the embodiment of the invention, the selective phase compensation is carried out through the judgment of the accumulated sampling phase deviation value of each subcarrier, so that the calculation resources can be greatly saved, the signal processing speed can be increased, and the signal processing efficiency can be improved on the premise of guaranteeing the signal quality no matter for a frame signal with a short frame length or a frame signal with a long frame length. And the overall signal processing efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of power line carrier communication, and in particular to a signal compensation method and device based on a power line carrier OFDM system. Background Art

[0002] Power line carrier communication technology is a power system communication that uses the transmission line as the transmission medium of the carrier signal. Compared with single carrier communication, OFDM modulation and demodulation technology is widely used in the field of power line carrier communication due to its advantages such as high frequency band utilization, high transmission rate and strong anti-interference ability. In OFDM technology, each subcarrier is orthogonal to each other, allowing the subchannel spectrum to overlap for parallel data transmission, which can maximize the spectrum utilization. A key feature of the OFDM system is the orthogonality between subcarriers, which means that in the frequency domain, the signals of different subcarriers are independent of each other and will not interfere with each other. However, in the actual communication process, due to the difference between the sampling frequency of the digital-to-analog converter (DAC) at the transmitter and the sampling frequency of the analog-to-digital converter (ADC) at the receiver, the sampling point at the receiver is always slightly slower or faster than the sampling clock at the transmitter, which causes the amplitude and phase of the signal at the receiver to change, resulting in signal distortion; at the same time, inter-carrier interference is introduced, destroying the orthogonality between subcarriers, thereby affecting the demodulation effect of the signal. In addition, the length of the frame signal will directly affect the demodulation effect. If the frame signal duration is short (that is, the frame signal length is short), the frequency difference will have little effect on the demodulation result; but if the frame signal duration is long (that is, the frame signal length is long), the later the data symbol, the more serious the amplitude phase or carrier interference, the greater the impact on the demodulation result, and it may even lead to the inability to demodulate the accurate signal.

[0003] In the prior art, there are two methods for correcting the frequency difference between the transmitter and the receiver: the fractional frequency division method and the filter interpolation method. The fractional frequency division method uses fractional frequency division to adjust the clock frequency to correct the frequency deviation, and the filter interpolation method uses the Farrow filter to correct the frequency deviation by filtering after interpolation or filtering after extraction. However, the fractional frequency division PLL phase-locked loop method has high requirements for the PLL, which increases the chip IP cost; the Farrow filter method adds additional digital logic area overhead; at the same time, these two methods cannot selectively process signals with long or short frames, which greatly affects the signal processing speed and efficiency.

[0004] Therefore, how to correct the signal distortion caused by the difference between the transmitting and receiving frequencies and improve the signal processing efficiency is an urgent problem to be solved. Summary of the invention

[0005] In view of this, the embodiments of the present application provide a signal compensation method and device based on a power line carrier OFDM system to solve at least one problem existing in the background technology.

[0006] In a first aspect, an embodiment of the present application provides a signal compensation method based on a power carrier OFDM system, the method comprising:

[0007] Performing time domain synchronization on the received signal according to the local synchronization symbol to obtain the starting position of the frame signal in the received signal;

[0008] Convert each synchronization symbol in the frame signal from the time domain to the frequency domain according to the starting position of the frame signal to obtain a subcarrier phase value corresponding to each synchronization symbol in the frame signal;

[0009] Calculate the sampling phase offset value of each subcarrier according to the subcarrier phase value corresponding to each synchronization symbol in the frame signal;

[0010] Obtaining, according to the sampling phase offset value of each subcarrier and the starting position of the frame signal, the accumulated sampling phase offset value of each subcarrier of the symbol to be demodulated in the frame signal;

[0011] Convert the symbol to be demodulated from the time domain to the frequency domain according to the starting position of the frame signal to obtain each subcarrier signal of the symbol to be demodulated;

[0012] It is determined whether the absolute value of the accumulated sampling phase offset value of each subcarrier of the symbol to be demodulated is greater than a preset phase offset threshold, and phase compensation is performed on the subcarrier signal of the symbol to be demodulated according to the determination result.

[0013] Optionally, performing phase compensation on the subcarrier signal of the symbol to be demodulated according to the judgment result includes:

[0014] If the absolute value of the accumulated sampling phase offset value of a certain subcarrier of the symbol to be demodulated is greater than a preset phase offset threshold, phase compensation is performed on the subcarrier signal according to the accumulated sampling phase offset value of the subcarrier;

[0015] If the absolute value of the accumulated sampling phase offset value of a certain subcarrier in the symbol to be demodulated is smaller than a preset phase offset threshold, no phase compensation is performed on the subcarrier signal.

[0016] Optionally, phase compensation is performed on the subcarrier signal according to the accumulated sampling phase offset value of the subcarrier, specifically:

[0017]

[0018] In the formula, x k (t)′ represents the complex form of the compensated subcarrier signal numbered k; ε k represents the cumulative sampling phase offset value of the subcarrier numbered k, ranging from [-π, π]; t represents the data point, d krepresents the amplitude of the subcarrier signal numbered k; j represents the imaginary unit; f k represents the frequency of the subcarrier signal numbered k; e represents a constant.

[0019] Optionally, after converting the to-be-demodulated symbol from the time domain to the frequency domain according to the starting position of the frame signal to obtain each subcarrier signal of the to-be-demodulated symbol, the method further includes:

[0020] Perform channel estimation based on the local synchronization symbol and the frame signal to obtain a phase estimation compensation value of each subcarrier in the synchronization symbol corresponding to the starting position of the frame signal;

[0021] Correspondingly, it is determined whether the cumulative sampling phase offset value of each subcarrier of the symbol to be demodulated is greater than a preset phase offset threshold, and the phase compensation value of each subcarrier in the symbol to be demodulated is obtained according to the judgment result and the phase estimation compensation value of each subcarrier, and phase compensation is performed on the subcarrier signal of the symbol to be demodulated according to the phase compensation value of each subcarrier of the symbol to be demodulated.

[0022] Optionally, obtaining the phase compensation value of each subcarrier in the to-be-demodulated symbol according to the judgment result and the phase estimation compensation value of each subcarrier includes:

[0023] If the cumulative sampling phase offset value of a subcarrier in the to-be-demodulated symbol is greater than a preset phase offset threshold, the phase compensation value of the subcarrier in the to-be-demodulated symbol is equal to the sum of the cumulative sampling phase offset value of the subcarrier and the subcarrier phase estimation compensation value;

[0024] If the accumulated sampling phase offset value of a certain subcarrier in the symbol to be demodulated is less than a preset phase offset threshold, the phase compensation value of the subcarrier in the symbol to be demodulated is equal to the subcarrier phase estimation compensation value.

[0025] Optionally, calculating each subcarrier sampling phase offset value according to a subcarrier phase value corresponding to each synchronization symbol in the frame signal includes:

[0026] The initial phase difference of the subcarriers corresponding to two adjacent synchronization symbols is calculated to obtain the sampling phase offset value of each subcarrier.

[0027] Optionally, calculating each subcarrier sampling phase offset value according to a subcarrier phase value corresponding to each synchronization symbol in the frame signal includes:

[0028] The average value of the subcarrier phase difference values ​​corresponding to two adjacent synchronization symbols is the sampling phase offset value of each subcarrier.

[0029] Optionally, according to the sampling phase offset value of each subcarrier and the starting position of the frame signal, the cumulative sampling phase offset value of each subcarrier of the symbol to be demodulated in the frame signal is obtained, specifically:

[0030]

[0031] Among them, ε k represents the cumulative sampling phase offset value of the subcarrier numbered k, ε k The range of is [-π,π]; represents the sampling phase offset value of the subcarrier numbered k; a represents the number of sampling points between the starting position of the frame signal and the initial sampling point of the symbol to be demodulated.

[0032] In a second aspect, an embodiment of the present application provides a signal compensation device based on a power line carrier OFDM system, the device comprising:

[0033] A synchronization module, used to perform time domain synchronization on a received signal according to a local synchronization symbol to obtain a starting position of a frame signal in the received signal;

[0034] A synchronization symbol conversion module, used to convert each synchronization symbol in the frame signal from the time domain to the frequency domain according to the starting position of the frame signal, and obtain a subcarrier phase value corresponding to each synchronization symbol in the frame signal;

[0035] A sampling phase offset calculation module, used to calculate the sampling phase offset value of each subcarrier according to the subcarrier phase value corresponding to each synchronization symbol in the frame signal;

[0036] The cumulative phase offset calculation module is used to obtain the cumulative sampling phase offset value of each subcarrier of the to-be-demodulated symbol in the frame signal according to the sampling phase offset value of each subcarrier and the starting position of the frame signal;

[0037] A demodulation symbol conversion module, used to convert the to-be-demodulated symbol from the time domain to the frequency domain according to the starting position of the frame signal, to obtain each subcarrier signal of the to-be-demodulated symbol;

[0038] The judgment and compensation module is used to judge whether the absolute value of the accumulated sampling phase offset value of each subcarrier of the symbol to be demodulated is greater than a preset phase offset threshold, and perform phase compensation on the subcarrier signal of the symbol to be demodulated according to the judgment result.

[0039] In a third aspect, an embodiment of the present application provides a computer-readable storage medium, which stores instructions. When the instructions are executed by a processor of an electronic device, the electronic device can execute the signal compensation method based on the power carrier OFDM system provided in any one of the first aspects above.

[0040] In a fourth aspect, an embodiment of the present application provides an electronic device, the electronic device comprising:

[0041] processor;

[0042] memory for storing computer executable instructions;

[0043] The processor is used to execute the computer executable instructions to implement the signal compensation method based on the power carrier OFDM system as described in any one of the first aspects above.

[0044] In the embodiment of the present application, the cumulative sampling phase offset value of each subcarrier of the symbol to be demodulated in the frame signal is obtained according to the sampling phase offset value of each subcarrier and the starting position of the frame signal; then, it is determined whether the absolute value of the cumulative sampling phase offset value of each subcarrier of the symbol to be demodulated is greater than a preset phase offset threshold, and phase compensation is performed on the subcarrier signal of the symbol to be demodulated according to the determination result. In the embodiment of the present application, selective phase compensation is performed by determining the size of the cumulative sampling phase offset value of each subcarrier, so that regardless of the frame signal with a short frame length or a long frame length, it can greatly save computing resources, speed up signal processing, and improve the overall signal processing efficiency while ensuring signal quality.

[0045] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0047] Figure 1 A schematic flow chart of a signal compensation method based on a power line carrier OFDM system provided in one embodiment of the present application;

[0048] Figure 2 A structural diagram of a physical layer data frame in a power communication standard provided in an embodiment of the present application;

[0049] Figure 3 A schematic diagram of a signal compensation device based on a power line carrier OFDM system provided in one embodiment of the present application;

[0050] Figure 4 A schematic diagram of the structure of an electronic device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0051] In order to make the technical solutions and beneficial effects of the present invention more clearly understood, the following is a detailed description by listing specific embodiments. Unless otherwise defined, the technical and scientific terms used herein have the same meanings as those in the technical field to which this application belongs.

[0052] Figure 1 A schematic flow chart of a signal compensation method based on a power line carrier OFDM system provided in one embodiment of the present application. Figure 1 As shown, the method includes:

[0053] S1. Perform time domain synchronization on the received signal according to the local synchronization symbol to obtain the starting position of the frame signal in the received signal.

[0054] The synchronization symbol is a specific symbol used for synchronization in power carrier communication. It has a specific structure and modulation mode. When the synchronization symbol in the received signal matches the local synchronization symbol, a correlation peak is generated. The starting position of the frame signal can be locked through the correlation peak. In power carrier communication, the frame signal has a fixed structure and format to facilitate the identification and parsing of the receiving end. It usually includes a preamble, frame control and payload data. The preamble includes a synchronization symbol, specifically a forward synchronization SYNCP symbol and a reverse synchronization SYNCM symbol. The SYNCP and SYNCM are located by performing correlation operations with the local synchronization symbol and searching for correlation peaks, thereby locking the starting position of the frame signal. The frame control contains important control information required for demodulating the data frame, including the length, data type, modulation mode, etc. of the frame; the payload data is the part of the frame signal used to transmit the actual data information. In addition, the frame signal may also include redundant information such as a cyclic prefix or a guard interval for retrieving channel interference. Figure 2 A structural diagram of a physical layer data frame in a power communication standard provided in an embodiment of the present application. Figure 2As shown, the data frame has a fixed format, wherein the leading part has 13 synchronization symbols, namely, 10.5 SYNCP symbols and 2.5 SYNCM symbols, each SYNCP symbol or SYNCM symbol is 1024 sampling points long, each frame control symbol and each data payload symbol is also 1024 sampling points long, the roll-off interval is 124 sampling points, the frame control protection interval is 458 sampling points, the protection interval of the first and second symbols of the payload data is 458 sampling points, and the protection interval after the third symbol of the payload data is 264 sampling points. It should be noted that in the implementation of the present application, the starting position of the frame signal is the starting point of a synchronization symbol in the leading part, for example, it can be the starting point of the first SYNCP symbol in the frame signal, or it can be the starting point of the first SYNCM symbol, which needs to be set according to the actual communication protocol. In the embodiment of the present application, according to the starting position of the frame signal and the known fixed format of the frame signal, each frame control symbol or payload data symbol can be subjected to subsequent Fourier transform (FFT), demodulation and other processing. It should be noted that FFT converts the time domain into the frequency domain. It does not transform all data, but transforms each synchronization symbol, each frame control symbol, and each payload data symbol.

[0055] S2. Convert each synchronization symbol in the frame signal from the time domain to the frequency domain according to the starting position of the frame signal, and obtain the phase value of each subcarrier corresponding to each synchronization symbol in the frame signal.

[0056] In the embodiment of the present application, the frame signal has a fixed format, and the sampling point corresponding to each synchronization symbol in the received signal can be determined by the starting position of the frame signal, so that each synchronization symbol can be converted from the time domain to the frequency domain. Specifically, each synchronization symbol is converted from the time domain to the frequency domain by FFT to obtain the phase value of the subcarrier corresponding to each synchronization symbol in the frame signal. Where n is the serial number of the synchronization symbol in the frame signal, and k is the number of the subcarrier. It should be noted that the serial numbers of the synchronization symbols in the frame signal are numbered in sequence according to the sampling time. For example, the phase value of the subcarrier in the first synchronization symbol is The initial phase value of the subcarrier in the second synchronization symbol is It should be noted that during the FFT transformation, all sampling points included in each synchronization symbol are transformed in turn. For example, when the number of sampling points in each SYNCP is 1024 points, the time domain data corresponding to the 1024 sampling points contained in the first synchronization symbol is first transformed into frequency domain data, and then the second synchronization symbol is transformed into frequency domain data. The subcarrier phase value in the embodiment of the present application refers to the phase value of the initial point of the subcarrier in the frequency domain data. The subcarrier curve corresponding to each frequency in the transmitted signal is fixed. Therefore, the phase value of the entire subcarrier can be determined based on the initial point phase value. If there is a deviation in the subcarrier phase, the corresponding subcarrier rotates on the carrier phase. The phase of the subcarrier can be compensated by reverse rotation.

[0057] S3. Calculate the sampling phase offset value of each subcarrier according to the subcarrier phase value corresponding to each synchronization symbol in the frame signal.

[0058] The sampling phase offset value of each subcarrier represents the accumulated phase deviation value generated by each subcarrier in the sampling point duration corresponding to a synchronization symbol.

[0059] Specifically, calculating the sampling phase offset value of each subcarrier according to the initial phase of the subcarrier corresponding to each synchronization symbol in the frame signal includes:

[0060] The initial phase difference of the subcarriers corresponding to two adjacent synchronization symbols is calculated to obtain the sampling phase offset value of each subcarrier.

[0061] Specifically, it is calculated by the following formula:

[0062]

[0063] in, Indicates the sampling phase offset value of the subcarrier numbered k. The number of sampling points between the starting points of two adjacent synchronization symbols is equal to the number of sampling points included in a synchronization symbol, so It represents the phase offset of the subcarrier numbered k at the sampling time corresponding to a synchronization symbol length. For example, when each synchronization symbol length is 1024 sampling points, Indicates the phase offset generated by 1024 sampling points. Correspondingly, the phase offset generated by each sampling point is

[0064] As an optional specific implementation manner, an average value of subcarrier phase difference values ​​corresponding to a plurality of adjacent two synchronization symbols is a sampling phase offset value of each subcarrier.

[0065] Specifically, it is calculated by the following formula:

[0066]

[0067] In the embodiment of the present application, the average value of the sampling phase offset values ​​of each subcarrier corresponding to two adjacent synchronization symbols is taken, so that the difference in the starting phase deviation between adjacent synchronization symbols can be reduced, and a more accurate subcarrier sampling phase offset value can be obtained. It should be noted that if the frequency of the DAC at the transmitting end is the same as the ADC frequency at the receiving end, then after each synchronization symbol is FFT transformed, the initial phases of the corresponding subcarriers are the same. However, in reality, since the frequency of the DAC at the transmitting end is inconsistent with the ADC frequency at the receiving end, the phases of the subcarriers corresponding to each synchronization symbol are not the same due to different sampling times. At the same time, due to the influence of other factors such as the transmission channel, the phase difference values ​​of the subcarriers corresponding to two adjacent synchronization symbols are also different (ideally, the phase difference values ​​of the subcarriers calculated for two adjacent synchronization symbols are not the same). are equal); in the time domain, the frequency inconsistency between the transmitting end and the receiving end will cause the sampling point time offset, and in the frequency domain, it will cause the data symbol phase to offset. Therefore, the phase deviation caused by the frequency deviation between the transmitting end and the receiving end can be corrected by phase compensation. In the embodiment of the present application, by calculating the average value, a more accurate It should be noted that frequency deviation includes not only the difference between the DAC frequency at the transmitting end and the ADC frequency at the receiving end, but also the carrier frequency deviation; the difference between the DAC frequency at the transmitting end and the ADC frequency at the receiving end is due to the inconsistency of the sampling clock frequencies of the two, which mainly causes the signal to be distorted during the sampling process, affecting the precision and accuracy of signal restoration; carrier frequency deviation is the deviation between the carrier frequency and the theoretical value, which is mainly caused by factors such as the frequency instability of the transmitter, which mainly causes unstable signal transmission and affects the communication quality; in power carrier communication, power lines are generally used and based on baseband signals for transmission, without the need for up and down frequency conversion of the carrier shift, so the carrier frequency deviation has little impact, and the sampling clock frequency deviation has a greater impact.

[0068] S4. Obtain the accumulated sampling phase offset value of each subcarrier of the symbol to be demodulated in the frame signal according to the sampling phase offset value of each subcarrier and the starting position of the frame signal.

[0069] Specifically, the cumulative sampling phase offset value of each subcarrier of the symbol to be demodulated is calculated according to the following formula:

[0070]

[0071] Among them, ε k represents the accumulated sampling phase offset value of the subcarrier numbered k; represents the sampling phase offset value of the subcarrier numbered k; a represents the number of sampling points between the starting position of the frame signal and the initial sampling point of the symbol to be demodulated. It should be noted that ε k The range is [-π, π], if εk If ε exceeds the range, normalization is required. k Out of range, ε k The absolute value of is greater than π, then Where b represents The integer part of .

[0072] S5. Convert the symbol to be demodulated from the time domain to the frequency domain according to the starting position of the frame signal to obtain each subcarrier signal of the symbol to be demodulated.

[0073] In the embodiment of the present application, the symbol to be demodulated includes a frame control symbol and a payload data symbol. According to the starting position of the frame signal and the format of the frame signal, the initial sampling point position of the symbol to be demodulated can be obtained, and the symbol to be demodulated is subjected to FFT transformation to obtain each subcarrier signal in the symbol to be demodulated. Specifically, each subcarrier signal in the symbol to be demodulated is:

[0074]

[0075] Among them, x k (t) represents the complex form of the subcarrier signal numbered k in the symbol to be demodulated, t represents the data point, d k represents the amplitude of the subcarrier signal numbered k, j represents the imaginary unit, and f k represents the frequency of the subcarrier signal numbered k, and e represents a constant.

[0076] S6. Determine whether the absolute value of the accumulated sampling phase offset value of each subcarrier of the symbol to be demodulated is greater than a preset phase offset threshold, and perform phase compensation on the subcarrier signal of the symbol to be demodulated according to the determination result.

[0077] Specifically: if the absolute value of the cumulative sampling phase offset value of a certain subcarrier in the symbol to be demodulated is greater than the preset phase offset threshold, the subcarrier signal is phase compensated according to the cumulative sampling phase offset value of the subcarrier; if the absolute value of the cumulative sampling phase offset value of a certain subcarrier in the symbol to be demodulated is less than the preset phase offset threshold, the subcarrier signal is not phase compensated. It should be noted that the setting of the preset phase offset threshold needs to be comprehensively considered according to factors such as the signal transmission rate and noise level.

[0078] In an embodiment of the present application, if the absolute value of the cumulative sampling phase offset value of a certain subcarrier is greater than the preset phase offset threshold, it indicates that the initial point of the corresponding symbol to be demodulated is far away from the starting position of the frame signal, indicating that the frame signal has a long frame length, and the phase offset has a more significant impact on signal analysis, which is easy to cause signal analysis errors. At this time, phase compensation can be used to correct the phase deviation caused by the different frequencies of the transmitting end and the receiving end; when the absolute value of the cumulative sampling phase offset value of a certain subcarrier is less than the preset phase offset threshold, it indicates that the initial point of the corresponding symbol to be demodulated is close to the starting position of the frame signal. At this time, the phase of the symbol to be demodulated is slightly offset, which will not cause signal analysis errors, so phase compensation can be omitted, thereby saving computing resources and speeding up signal analysis efficiency. In the embodiment of the present application, by comparing with the preset phase offset threshold, for the to-be-demodulated symbols in the frame signal with a shorter frame length, since the slight phase offset has little effect on the signal analysis, no phase compensation is required, thereby improving the signal processing speed and effectively saving computing resources; for the to-be-demodulated symbols in the frame signal with a longer frame length, compensation is also performed selectively (the absolute value of the cumulative sampling phase offset value of each subcarrier in a part is small and does not require compensation; the absolute value of the cumulative sampling phase offset value of each subcarrier in another part is large and requires compensation). This selective compensation strategy ensures the accuracy of signal analysis, avoids unnecessary calculations, and improves the overall processing efficiency. It should be noted that the cumulative sampling phase offset value ε of each subcarrier is k The range is [-π,π]. Therefore, for frame signals with longer frame lengths, the cumulative sampling phase offset value of the subcarrier will be normalized. Therefore, in addition to the symbols to be demodulated that are closer to the starting point of the frame signal, some symbols to be demodulated that are farther from the starting point of the frame signal do not need to be compensated. For example, if the cumulative sampling phase offset value of a subcarrier of a symbol to be demodulated is 3.1π, it will be 0.1π after normalization. At this time, although the symbol to be demodulated is farther from the starting position of the frame signal, it does not need phase compensation.

[0079] It should be noted that the sampling frequencies of the receiving end and the transmitting end are different, which is manifested as an offset of the sampling point time in the time domain and a rotation of the received signal in the frequency domain. This phase rotation will cause signal distortion, thereby affecting the communication quality and signal demodulation results. Phase compensation is to use the phase offset to perform an anti-phase rotation on the subcarrier to eliminate the signal distortion caused by the phase rotation. In the embodiment of the present application, the subcarrier signal is phase compensated according to the cumulative sampling phase offset value of the subcarrier, specifically, the subcarrier signal is reversely phase rotated according to the cumulative sampling phase offset value of the subcarrier, that is, by the following formula:

[0080]

[0081] In the formula, xk (t)′ represents the complex form of the compensated subcarrier signal numbered k, ε k represents the cumulative sampling phase offset value of the subcarrier numbered k, t represents the data point, d k represents the amplitude of the subcarrier signal numbered k, j represents the imaginary unit, and f k represents the frequency of the subcarrier signal numbered k, and e represents a constant.

[0082] In an embodiment of the present application, the cumulative sampling phase offset value of each subcarrier in the symbol to be demodulated is first calculated by the relative position of the initial sampling point of the symbol to be demodulated and the starting position of the frame signal, and then selective phase compensation is performed based on the comparison between the cumulative sampling phase offset value of each subcarrier and the preset phase offset value. Therefore, regardless of whether the frame length is short or long, computing resources can be greatly saved, the signal processing speed can be accelerated, and the overall signal processing efficiency can be improved while ensuring signal quality.

[0083] As an optional specific implementation manner, after S5, the method further includes:

[0084] Channel estimation is performed according to the local synchronization symbol and the frame signal to obtain the phase estimation compensation value of each subcarrier in the synchronization symbol corresponding to the starting position of the frame signal.

[0085] In an embodiment of the present application, the phase estimation compensation value of each subcarrier corresponding to the synchronization symbol at the starting position includes the phase deviation value accumulated by the receiving end from the start of receiving the signal to the sampling point corresponding to the starting position of the frame signal and the phase deviation value generated by the transmission channel. It should be noted that since the signal transmission is carried out in the same environment, the phase deviation value of each symbol in the frame signal (including the leading symbol, the frame control symbol or the payload data symbol) caused by the transmission channel is theoretically equal. In an embodiment of the present application, the actual phase deviation value of each subcarrier in the synchronization symbol corresponding to the starting position of the frame signal can be obtained through channel estimation. It should be noted that the subcarrier phase estimation compensation value range is also [-π,π]. If it exceeds the range, normalization processing is required.

[0086] Correspondingly, S6 is:

[0087] Determine whether the cumulative sampling phase offset value of each subcarrier in the symbol to be demodulated is greater than a preset phase offset threshold, obtain the phase compensation value of each subcarrier in the symbol to be demodulated according to the judgment result and the phase estimation compensation value of each subcarrier, and perform phase compensation on the subcarrier signal of the symbol to be demodulated according to the phase compensation value of each subcarrier in the symbol to be demodulated.

[0088] Specifically, obtaining the phase compensation value of each subcarrier in the symbol to be demodulated according to the judgment result and the estimated compensation value of each subcarrier phase includes:

[0089] If the accumulated sampling phase offset value of a subcarrier in the symbol to be demodulated is greater than a preset phase offset threshold, the phase compensation value of the subcarrier in the symbol to be demodulated is equal to the sum of the accumulated sampling phase offset value of the subcarrier and the phase estimation compensation value of the subcarrier;

[0090] If the accumulated sampling phase offset value of a subcarrier in the demodulation symbol is less than the preset phase offset threshold, the phase compensation value of the subcarrier in the to-be-demodulated symbol is equal to the subcarrier phase estimation compensation value.

[0091] In the embodiment of the present application, the accumulated sampling phase offset value of each subcarrier is essentially the phase deviation value of each subcarrier of the symbol to be demodulated relative to the synchronization symbol corresponding to the starting position of the frame signal. Through the phase estimation compensation value of each subcarrier and the number of sampling points between the demodulated symbol and the starting position symbol, the final phase offset value of each subcarrier in the symbol to be demodulated can be obtained. The final phase offset value is used to perform phase compensation on the symbol to be demodulated, thereby eliminating the phase distortion caused by frequency differences and various factors during the transmission process, so that the demodulated symbol is closer to the original transmitted signal. In the embodiment of the present application, phase compensation is performed by calculating the final phase offset value, so that the corrected symbol to be demodulated can be obtained after only one phase compensation process, thereby reducing multiple iterations or complex calculations, and ensuring the accuracy and efficiency of phase correction.

[0092] The phase compensation is performed on the subcarrier signal of the symbol to be demodulated according to the phase compensation value of each subcarrier in the symbol to be demodulated, specifically:

[0093]

[0094] In the formula, x k (t)′ represents the complex form of the compensated subcarrier signal numbered k, ε k ' represents the phase compensation value of the subcarrier numbered k, t represents the data point, d k represents the amplitude of the subcarrier signal numbered k, j represents the imaginary unit, and f k represents the frequency of the subcarrier signal numbered k, and e represents a constant. It should be noted that the subcarrier phase compensation value range is also [-π, π]. If it exceeds the range, normalization processing is required.

[0095] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0096] Figure 3 Schematic diagram of a signal compensation device based on a power line carrier OFDM system provided in one embodiment of the present application. Figure 3 As shown, the signal device based on the power line carrier OFDM system of the embodiment of the present application includes:

[0097] The synchronization module 201 is used to perform time domain synchronization on the received signal according to the local synchronization symbol to obtain the starting position of the frame signal in the received signal.

[0098] The synchronization symbol conversion module 202 is used to convert each synchronization symbol in the frame signal from the time domain to the frequency domain according to the starting position of the frame signal, and obtain the subcarrier phase value corresponding to each synchronization symbol in the frame signal.

[0099] The sampling phase offset calculation module 203 is used to calculate the sampling phase offset value of each subcarrier according to the subcarrier phase value corresponding to each synchronization symbol in the frame signal.

[0100] The cumulative phase offset calculation module 204 is used to obtain the cumulative sampling phase offset value of each subcarrier of the to-be-demodulated symbol in the frame signal according to the sampling phase offset value of each subcarrier and the starting position of the frame signal.

[0101] The demodulation symbol conversion module 205 is used to convert the to-be-demodulated symbol from the time domain to the frequency domain according to the starting position of the frame signal, so as to obtain each subcarrier signal of the to-be-demodulated symbol.

[0102] The judgment and compensation module 206 is used to judge whether the absolute value of the accumulated sampling phase offset value of each subcarrier of the symbol to be demodulated is greater than a preset phase offset threshold, and perform phase compensation on the subcarrier signal of the symbol to be demodulated according to the judgment result.

[0103] The embodiment of the present application further provides a computer-readable storage medium. The computer-readable storage medium stores instructions, which, when executed by a processor of an electronic device, enable the electronic device to execute the steps of the signal compensation method based on a power carrier OFDM system in any of the above embodiments.

[0104] Embodiments of the present application may be systems, methods and / or computer program products. The computer program product may include a computer-readable storage medium on which a computer-readable program instruction is loaded for enabling a processor to implement various aspects of the present application. In certain embodiments, by utilizing the state information of the computer-readable program instruction to personalize an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA) or a programmable logic array (PLA), the electronic circuit may execute the computer-readable program instruction, thereby implementing various aspects of the present application.

[0105] Computer readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. Computer readable storage medium is a tangible device that can keep and store instructions used by an instruction execution device. The readable storage medium can include, for example, but is not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage medium include: portable computer disk, hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disk read-only memory (CD-ROM), digital versatile disk (DVD), memory stick, floppy disk, mechanical encoding device, such as a punch card or a protruding structure in a groove on which instructions are stored, and any suitable combination of the above.

[0106] Various aspects of the present application are described herein with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of the present application. It should be understood that each box in the flowchart and / or block diagram and the combination of each box in the flowchart and / or block diagram can be implemented by computer-readable program instructions.

[0107] An embodiment of the present application also provides an electronic device. Figure 4 This is a schematic diagram of the structure of an electronic device provided by an embodiment of the present application. Figure 4 As shown, the electronic device 300 includes: one or more processors 301 and a memory 302; the memory 302 stores computer executable instructions; the processor 301 is used to execute the computer executable instructions to implement the steps in the signal compensation method based on the power carrier OFDM system as in any of the above embodiments.

[0108] The processor 301 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0109] The memory 302 may include one or more computer program products, and the computer program products may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory (cache), etc. Non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 301 may execute the program instructions to implement the steps in the text recognition method of each embodiment of the present application described above and / or other desired functions.

[0110] In one example, the electronic device 300 may further include: an input device and an output device, and these components are interconnected via a bus system and / or other forms of connection mechanisms (not shown in the figure).

[0111] In addition, the input device may also include, for example, a keyboard, a mouse, a microphone, etc. The output device may output various information to the outside, and may include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto, and the like.

[0112] Of course, to simplify, Figure 4 Only a part of the components related to the present application in the electronic device 300 is shown, and components such as a bus, an input device / output interface, etc. are omitted. In addition, according to specific application conditions, the electronic device 300 may also include any other appropriate components.

[0113] It should be noted that the signal compensation method embodiment based on the power carrier OFDM system, the signal compensation device embodiment based on the power carrier OFDM system, the computer-readable storage medium embodiment and the electronic device embodiment provided in the embodiments of the present application belong to the same concept; the technical features in the technical solutions recorded in each embodiment can be arbitrarily combined without conflict.

[0114] It should be understood that the above embodiments are exemplary and are not intended to include all possible implementations included in the claims. Various modifications and changes may be made on the basis of the above embodiments without departing from the scope of the present disclosure. Similarly, the various technical features of the above embodiments may be arbitrarily combined to form other embodiments of the present invention that may not be explicitly described. Therefore, the above embodiments only express several implementations of the present invention and do not limit the scope of protection of the patent of the present invention.

Claims

1. A signal compensation method based on a power line carrier OFDM system, characterized in that: The method comprises: Performing time domain synchronization on the received signal according to the local synchronization symbol to obtain the starting position of the frame signal in the received signal; Convert each synchronization symbol in the frame signal from the time domain to the frequency domain according to the starting position of the frame signal to obtain a subcarrier phase value corresponding to each synchronization symbol in the frame signal; Calculate the sampling phase offset value of each subcarrier according to the subcarrier phase value corresponding to each synchronization symbol in the frame signal; Obtaining, according to the sampling phase offset value of each subcarrier and the starting position of the frame signal, the accumulated sampling phase offset value of each subcarrier of the symbol to be demodulated in the frame signal; Convert the symbol to be demodulated from the time domain to the frequency domain according to the starting position of the frame signal to obtain each subcarrier signal of the symbol to be demodulated; It is determined whether the absolute value of the accumulated sampling phase offset value of each subcarrier of the symbol to be demodulated is greater than a preset phase offset threshold, and phase compensation is performed on the subcarrier signal of the symbol to be demodulated according to the determination result.

2. The signal compensation method based on the power carrier OFDM system according to claim 1, characterized in that: Performing phase compensation on the subcarrier signal of the to-be-demodulated symbol according to the judgment result, including: If the absolute value of the accumulated sampling phase offset value of a certain subcarrier of the symbol to be demodulated is greater than a preset phase offset threshold, phase compensation is performed on the subcarrier signal according to the accumulated sampling phase offset value of the subcarrier; If the absolute value of the accumulated sampling phase offset value of a certain subcarrier in the symbol to be demodulated is smaller than a preset phase offset threshold, no phase compensation is performed on the subcarrier signal.

3. The signal compensation method based on the power carrier OFDM system according to claim 2, characterized in that: The phase compensation of the subcarrier signal is performed according to the accumulated sampling phase offset value of the subcarrier, specifically: In the formula, x k (t)′ represents the complex form of the compensated subcarrier signal numbered k; ε k Indicates the cumulative sampling phase offset value of the subcarrier numbered k, ranging from [-π,π]; t represents the data point, d k represents the amplitude of the subcarrier signal numbered k; j represents the imaginary unit; f k represents the frequency of the subcarrier signal numbered k; e represents a constant.

4. The signal compensation method based on the power carrier OFDM system according to claim 1, characterized in that: After converting the to-be-demodulated symbol from the time domain to the frequency domain according to the starting position of the frame signal to obtain each subcarrier signal of the to-be-demodulated symbol, the method further includes: Perform channel estimation based on the local synchronization symbol and the frame signal to obtain a phase estimation compensation value of each subcarrier in the synchronization symbol corresponding to the starting position of the frame signal; Correspondingly, it is determined whether the cumulative sampling phase offset value of each subcarrier of the symbol to be demodulated is greater than a preset phase offset threshold, and the phase compensation value of each subcarrier in the symbol to be demodulated is obtained according to the judgment result and the phase estimation compensation value of each subcarrier, and phase compensation is performed on the subcarrier signal of the symbol to be demodulated according to the phase compensation value of each subcarrier of the symbol to be demodulated.

5. The signal compensation method based on the power line carrier OFDM system according to claim 4, characterized in that: The obtaining, according to the judgment result and the phase estimation compensation value of each subcarrier in the to-be-demodulated symbol, a phase compensation value of each subcarrier includes: If the cumulative sampling phase offset value of a subcarrier in the to-be-demodulated symbol is greater than a preset phase offset threshold, the phase compensation value of the subcarrier in the to-be-demodulated symbol is equal to the sum of the cumulative sampling phase offset value of the subcarrier and the subcarrier phase estimation compensation value; If the accumulated sampling phase offset value of a certain subcarrier in the symbol to be demodulated is less than a preset phase offset threshold, the phase compensation value of the subcarrier in the symbol to be demodulated is equal to the subcarrier phase estimation compensation value.

6. The signal compensation method based on the power carrier OFDM system according to claim 1, characterized in that: Calculating each subcarrier sampling phase offset value according to the subcarrier phase value corresponding to each synchronization symbol in the frame signal, including: The initial phase difference of the subcarriers corresponding to two adjacent synchronization symbols is calculated to obtain the sampling phase offset value of each subcarrier.

7. The signal compensation method based on the power carrier OFDM system according to claim 1, characterized in that: Calculating each subcarrier sampling phase offset value according to the subcarrier phase value corresponding to each synchronization symbol in the frame signal, including: The average value of the subcarrier phase difference values ​​corresponding to two adjacent synchronization symbols is the sampling phase offset value of each subcarrier.

8. The signal compensation method based on the power line carrier OFDM system according to claim 1, characterized in that: According to the sampling phase offset value of each subcarrier and the starting position of the frame signal, the cumulative sampling phase offset value of each subcarrier of the symbol to be demodulated in the frame signal is obtained, specifically: Among them, ε k represents the cumulative sampling phase offset value of the subcarrier numbered k, ε k The range of is [-π,π]; represents the sampling phase offset value of the subcarrier numbered k; a represents the number of sampling points between the starting position of the frame signal and the initial sampling point of the symbol to be demodulated.

9. A signal compensation device based on a power line carrier OFDM system, characterized in that: The device comprises: A synchronization module, used to perform time domain synchronization on a received signal according to a local synchronization symbol to obtain a starting position of a frame signal in the received signal; A synchronization symbol conversion module, used to convert each synchronization symbol in the frame signal from the time domain to the frequency domain according to the starting position of the frame signal, and obtain a subcarrier phase value corresponding to each synchronization symbol in the frame signal; A sampling phase offset calculation module, used to calculate the sampling phase offset value of each subcarrier according to the subcarrier phase value corresponding to each synchronization symbol in the frame signal; The cumulative phase offset calculation module is used to obtain the cumulative sampling phase offset value of each subcarrier of the to-be-demodulated symbol in the frame signal according to the sampling phase offset value of each subcarrier and the starting position of the frame signal; A demodulation symbol conversion module, used to convert the to-be-demodulated symbol from the time domain to the frequency domain according to the starting position of the frame signal, to obtain each subcarrier signal of the to-be-demodulated symbol; The judgment and compensation module is used to judge whether the absolute value of the accumulated sampling phase offset value of each subcarrier of the symbol to be demodulated is greater than a preset phase offset threshold, and perform phase compensation on the subcarrier signal of the symbol to be demodulated according to the judgment result.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores instructions, and when the instructions are executed by a processor of an electronic device, the electronic device is enabled to execute the signal compensation method based on a power carrier OFDM system as described in any one of claims 1 to 8.

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