Power line communication anti-noise method and device based on MMSE (Minimum Mean Square Error) equalization and adaptive notch

Abstract

The invention discloses a power line communication anti-noise method and device based on MMSE equalization and adaptive notch, and belongs to the technical field of power line communication, the method comprises the following steps: dynamically selecting a polar code rate at a sending end according to the SNR of a current channel, and carrying out polar code coding on information bits; qPSK / OFDM modulation is carried out on code words after polar code coding to form sending signals, dense pilots are inserted during QPSK modulation, and a cyclic prefix CP is added during OFDM modulation; carrying out time domain processing on the sending signal to suppress impulse noise, and carrying out frequency domain processing to suppress periodic noise; and introducing a noise sensing MMSE iterative equalizer at a receiving end, and carrying out iterative equalization decoding by using the soft information decoded by the polarization code to obtain an output signal. The interference influence of communication noise can be reduced, and the power line communication performance is improved.

Description

Technical Field

[0001] This invention relates to the field of power line communication technology, and in particular to a power line communication noise reduction method and apparatus based on MMSE equalization and adaptive notch filtering. Background Technology

[0002] Power line communication (PLC) is a technology that uses existing power line networks as the communication medium for information transmission. The data to be transmitted is modulated into a signal suitable for power line transmission, output, and coupled into the power line for transmission. The receiving end uses decoupling and demodulation techniques to extract the useful signal from the power line and then transmits it to the user terminal, completing the information transmission. PLC technology uses power lines as the communication medium and is a wired communication technology. Compared with other wired communication technologies, it has advantages such as wide coverage, low cost, convenient access, stable operation, and high transmission rate, and is widely used in many fields, such as industrial automation, energy management systems, and smart grids. These advantages have made power line communication a current research hotspot in the field of communications.

[0003] However, power line transmission was originally designed for power transmission, not information transmission. Therefore, unlike other systems dedicated to communication, its transmission environment is not ideal. First, power line channels exhibit significant attenuation, which can be very large at the communication frequencies of interest. Second, during signal transmission, the loads connected to the network are constantly being disconnected and connected, causing dynamic changes in load impedance, which can lead to signal reflection when the load impedance is mismatched. Finally, due to the harsh electromagnetic environment, power line channels are subject to various types of noise interference. These include background noise caused by environmental factors, narrowband interference from other radio and wireless communication systems, and high-power impulse noise interference, which is a prominent type of noise in PLC noise scenarios, characterized by a wide spectral range, high suddenness, and large amplitude.

[0004] Complex and variable noise interference in power line communication channels is a major factor affecting communication quality, and reducing the harmful effects of noise interference is a key issue in power line communication technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a power line communication noise reduction method and device based on MMSE equalization and adaptive notch filtering, thereby solving the technical problem that the existing technical solutions cannot effectively suppress noise interference, resulting in poor power line communication signal transmission quality.

[0006] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0007] In a first aspect, the present invention provides a power line communication noise reduction method based on MMSE equalization and adaptive notch filtering, comprising:

[0008] At the transmitting end, the polar code rate is dynamically selected based on the current channel SNR, and the information bits are polar code encoded.

[0009] The codeword encoded with polar code is QPSK / OFDM modulated to form the transmission signal. Dense pilots are inserted during QPSK modulation, and a cyclic prefix (CP) is added during OFDM modulation.

[0010] The transmitted signal is processed in the time domain to suppress impulse noise and in the frequency domain to suppress periodic noise.

[0011] A noise-aware MMSE iterative equalizer is introduced at the receiver, and the output signal is obtained by iterative equalization decoding using the soft information of polar code decoding.

[0012] Secondly, the present invention provides a power line communication noise reduction device based on MMSE equalization and adaptive notch filtering, comprising:

[0013] The transmitting end processing module is configured to dynamically select the polar code rate based on the current channel SNR at the transmitting end, and encode the information bits using polar codes; to perform QPSK / OFDM modulation on the polar code-encoded codewords to form a transmission signal, inserting dense pilots during QPSK modulation and adding a cyclic prefix CP during OFDM modulation; and to suppress impulse noise through time-domain processing and suppress periodic noise through frequency-domain processing of the transmission signal.

[0014] The receiver processing module is configured to introduce a noise-aware MMSE iterative equalizer at the receiver end, and use the soft information of polar code decoding to perform iterative equalization decoding to obtain the output signal.

[0015] Thirdly, the present invention provides an electronic device, including a processor and a storage medium;

[0016] The storage medium is used to store instructions;

[0017] The processor is configured to operate according to the instructions to perform the steps according to the method described above.

[0018] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0020] This invention provides a power line communication noise reduction method and apparatus based on MMSE equalization and adaptive notch filtering, which has the following characteristics: 1. It adopts polar code encoding and includes CRC check and SCL decoding to improve the error correction capability of the system, especially in low signal-to-noise ratio and impulse noise environments, solving the problem of high bit error rate in traditional uncoded systems. The code rate of the polar code is dynamically adjusted according to the current SNR. The code rate is adaptively selected under different channel conditions; a low code rate is used to improve reliability at low SNR, and a high code rate is used to improve transmission efficiency at high SNR. 2. It adopts time-frequency domain duplex adaptive notch filtering to effectively suppress impulse noise and periodic noise in power line communication. 3. It introduces a noise-aware MMSE iterative equalizer, using the soft information from polar code decoding for iterative equalization. Iterative equalization improves the accuracy of channel estimation and equalization. 4. It adds pilot signals for channel estimation and equalization, reducing the impact of inaccurate channel estimation on carrier communication performance. 5. It introduces cyclic prefix (CP) processing to effectively eliminate inter-symbol interference (ISI) caused by multipath effects. In summary, the present invention can effectively suppress noise interference and improve signal transmission quality. Attached Figure Description

[0021] Figure 1 This is a flowchart of the power line communication noise reduction method based on MMSE equalization and adaptive notch filtering provided in the embodiments of the present invention;

[0022] Figure 2 This is a flowchart of the power line communication noise reduction method after adding CRC check and SCL decoding provided in the embodiments of the present invention;

[0023] Figure 3 This is a schematic diagram of the simulation results of the power line communication model provided in the embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the power line communication noise reduction optimization method provided in an embodiment of the present invention;

[0025] Figure 5 This is a flowchart of the implementation steps of the noise suppression scheme provided in the embodiments of the present invention;

[0026] Figure 6 This is a schematic diagram of the simulation results optimized according to this embodiment of the invention. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0028] Example 1:

[0029] like Figure 1 As shown, this invention provides a power line communication noise reduction method based on MMSE equalization and adaptive notch filtering, comprising the following steps:

[0030] Step S1: At the transmitting end, the polar code rate is dynamically selected according to the current channel SNR, and the information bits are polar code encoded.

[0031] Specifically, in this embodiment, dynamically selecting the polar code rate based on the current channel SNR includes:

[0032] The current channel SNR is matched with a preset SNR threshold range, and the polar code rate corresponding to the matched SNR threshold range is selected as the selection result; satisfying the following: a low polar code rate is used when the SNR is low, and a high polar code rate is used when the SNR is high; the code rate is adaptive by adjusting the number of information bits K.

[0033] After determining the polar code rate, the information bits are polar-coded: 1. Generate a frozen bit sequence (the first K bits are information bits); 2. Construct an input vector, filling the frozen bits with 0s and the information bits with the original bits; 3. Calculate the codeword using the generator matrix. The specific process is as follows:

[0034] (1) By using the channel polarization phenomenon, the physical channel is decomposed into a reliable channel and an unreliable channel;

[0035] (2) Construct the input vector based on the reliable channel and the unreliable channel. :

[0036]

[0037]

[0038] In the formula, This refers to the set of information bit indices and the set of frozen bit indices corresponding to reliable and unreliable channels. For bit index, Number of bits;

[0039] (3) Based on input vector Based on the generator matrix Calculate codewords :

[0040]

[0041]

[0042] In the formula, The encoded codeword, polarization kernel matrix of Kronecker product, This is a bit-reversed permutation matrix. .

[0043] Step S2: QPSK / OFDM modulation is applied to the codeword after polar code encoding to form the transmission signal. Dense pilots are inserted during QPSK modulation, and a cyclic prefix CP is added during OFDM modulation.

[0044] Step S3: Suppress impulse noise by processing the transmitted signal in the time domain and suppress periodic noise by processing it in the frequency domain.

[0045] Specifically, in this embodiment, suppressing impulse noise by time-domain processing of the transmitted signal includes:

[0046] Pulse detection, identifying pulse position based on a dynamic threshold of the 99th percentile;

[0047] Pulse replacement, using local median filtering to eliminate impulse noise;

[0048] Adaptive limiting, the dynamic threshold is dynamically adjusted according to the signal standard deviation, the dynamic threshold = 0.9 × 3σ, where σ is the instantaneous signal standard deviation;

[0049] Suppressing periodic noise through frequency domain processing includes:

[0050] Harmonic detection: Harmonic frequencies (0~550Hz odd harmonics) are identified by Welch power spectrum estimation.

[0051] Adaptive notch filter: The adaptive notch filter is dynamically designed based on the harmonic bandwidth.

[0052] Specifically, in this embodiment, the transfer function of the adaptive notch filter... for:

[0053]

[0054] In the formula, It is a zero-point polynomial, containing conjugate zeros, used to eliminate frequencies. , It is a pole polynomial containing conjugate poles, used to control bandwidth.

[0055]

[0056]

[0057] This is the gain compensation factor, ensuring that the adaptive notch filter has a gain of 1 at DC (zero frequency). , Let be the radius of the pole. , Bandwidth adjustment factor ; Notch frequency The normalized angular frequency, The sampling frequency; Delay operator for units;

[0058] Among them, notch frequency The acquisition process includes:

[0059] Signal power spectrum calculated using the Welch method Find the harmonic frequency of maximum signal power within a specific window. As The estimated value;

[0060]

[0061] In the formula, As the center for harmonic frequency search, This is the width of the harmonic frequency search window.

[0062] Among them, bandwidth adjustment factor The acquisition process includes:

[0063] Dynamically adjust the bandwidth adjustment factor using the -3dB bandwidth. :

[0064]

[0065] In the formula, This represents the -3dB bandwidth of the adaptive notch filter.

[0066] Step S4: Introduce a noise-aware MMSE iterative equalizer at the receiving end, and use the soft information of polar code decoding to perform iterative equalization decoding to obtain the output signal.

[0067] Specifically, in this embodiment, the output signal is obtained by iterative equalization decoding using the soft information of polar code decoding, including:

[0068] Symbol estimation for initializing the MMSE iterative equalizer :

[0069]

[0070] In the formula, This is the estimated channel frequency response. For channel conjugate, In order to receive signals, For noise variance, The average power of the transmitted signal;

[0071] Initialize the number of iterations Repeat the following steps until the preset maximum number of iterations is reached, and then output the final output signal:

[0072] Symbol estimation and received signals Input polar code decoder, generate output signal and logarithmic natural ratio According to the natural logarithm Calculate the expectation of soft symbols :

[0073]

[0074] In the formula, for function;

[0075] Based on soft symbol expectation Computational symbol estimation :

[0076]

[0077] In the formula, For weight parameters, , The prior sign variance;

[0078] make .

[0079] Specifically, in this embodiment, polar code decoding includes:

[0080] initialization Path, Path Metrics , ;

[0081] Initialize bit index Repeat the following steps until , For the number of bits, from the reserved Select the path with the smallest metric from the path options:

[0082] like Then forced No split path;

[0083] like The path will then be split into and ; For information bit index set and frozen bit index set;

[0084] Update path metrics:

[0085]

[0086] In the formula, For the first The path in the first A path metric of bits. For the first The path in the first The log-likelihood ratio of each bit, For the first The path to the first The decision value of 1 bit, For the judgment function, ;

[0087] Keep the path with the smallest metric A path.

[0088] Furthermore, during polar code encoding, the information bits are first CRC encoded; during polar code decoding, the candidate information bits of each path are checked against a CRC check, and those that pass are marked as valid paths. After adding CRC check and SCL decoding, the flow of the power line communication noise immunity method is as follows: Figure 2 As shown.

[0089] To verify the performance of the power line communication noise reduction method provided in the embodiments of the present invention, a power line communication model is constructed:

[0090]

[0091] In the formula: , These are the source and sink signals, respectively. For the channel's transmission function, , , These are the background noise function, impulse noise function, and periodic noise function, respectively. This represents the convolution operation.

[0092] Based on the selected model, a signal-to-noise ratio range (0 to 20 dB, step size 2 dB), a subcarrier count of 64, an OFDM symbol count of 100, and a power frequency of 50 Hz were chosen. MATLAB was used to conduct a communication performance simulation study. The simulation results are as follows: Figure 3 As shown.

[0093] Figure 3 The horizontal axis represents the signal-to-noise ratio (SNR, in dB), and the vertical axis represents the bit error rate (BER), illustrating the performance of power line carrier communication under different SNR conditions. The distribution of BER under different SNR conditions is shown in Table 1.

[0094] Table 1: Bit Error Rate Distribution at Different Signal-to-Noise Ratios

[0095]

[0096] The data in Table 1 show that the bit error rate under different signal-to-noise ratios is always close to 50% (49%~50%), which is almost consistent with the bit error rate of random guessing (the theoretical limit of 50% in binary transmission without coding).

[0097] Based on the above simulation results, such as Figure 4 As shown, embodiments of the present invention achieve noise suppression and improved transmission signal quality by introducing the following optimization methods:

[0098] 1. It employs Polar Code encoding, incorporating CRC checksum and SCL decoding. This enhances the system's error correction capability, particularly in low signal-to-noise ratio and impulse noise environments, addressing the high bit error rate issue of traditional uncoded systems.

[0099] 2. A time-frequency domain duplex adaptive notch filter is employed to effectively suppress impulse noise and periodic noise in power line communication. Pulse noise suppression is achieved by detecting the pulse at the 99th percentile and using median filtering. This effectively eliminates large-amplitude pulses, preventing them from causing transient interference to the signal. Periodic noise is suppressed by automatically detecting harmonic frequencies and designing a notch filter, realizing an adaptive notch filter. This filter can specifically suppress power frequency harmonics (50Hz, 150Hz, 250Hz, etc.) and reduce periodic noise. Dynamic limiting is achieved by adaptively adjusting the limiting threshold (based on signal statistical characteristics). Dynamic limiting prevents excessive signal amplitude and reduces signal distortion.

[0100] 3. Introduce a noise-aware MMSE iterative equalizer, utilizing the soft information from polar code decoding for iterative equalization. Iterative equalization improves the accuracy of channel estimation and equalization.

[0101] 4. Add pilot signals for channel estimation and equalization to reduce the impact of inaccurate channel estimation on carrier communication performance.

[0102] 5. Dynamically adjust the polar code rate based on the current SNR. Adaptively select the code rate under different channel conditions: use a low code rate to improve reliability when the SNR is low, and use a high code rate to improve transmission efficiency when the SNR is high.

[0103] 6. Introduce cyclic prefix (CP) processing to effectively eliminate inter-symbol interference (ISI) caused by multipath effects.

[0104] like Figure 5 As shown, the specific implementation steps include:

[0105] I. Dynamic coding modulation

[0106] 1. Dynamically select the polar code rate based on the current SNR.

[0107] 2. After the information bits are checked by CRC, they are encoded in polar code and random interleaving is added.

[0108] 2. Signal generation

[0109] 1. The encoded bits are QPSK modulated and dense pilots are inserted (spaced 4 subcarriers).

[0110] 2. OFDM modulation (IFFT+CP) is used to form the transmitted signal.

[0111] III. Channel Transmission

[0112] 1. Simulate signal attenuation and delay through multipath channels.

[0113] IV. Noise Injection

[0114] 1. Synthesize three types of noise: AR background noise, Middleton impulse noise, and power frequency harmonic noise (50 / 150 / 250Hz).

[0115] 2. Distribute noise power proportionally (background 40%, impulse 40%, harmonics 20%).

[0116] V. Time-Frequency Full-Duplex Noise Suppression

[0117] 1. Time Domain Processing

[0118] Step 1: Pulse detection, i.e., identifying the pulse position based on the dynamic threshold of the 99th percentile.

[0119] Step 2: Pulse replacement, i.e., using local median filtering to eliminate pulses.

[0120] Step 3: Adaptive limiting, i.e., the threshold is dynamically adjusted according to the standard deviation of the signal.

[0121] 2. Frequency Domain Processing

[0122] Step 1: Harmonic detection, which involves automatically identifying harmonic frequencies (odd harmonics of 50~550Hz) through Welch power spectrum estimation.

[0123] Step 2: Adaptive notch filtering, i.e., dynamically designing IIR notch filter parameters based on harmonic bandwidth.

[0124] VI. Receiver Processing

[0125] 1. Frequency domain noise suppression: Soft masking of subcarriers based on a threshold of noise power estimation.

[0126] 2. Two-dimensional channel estimation: The channel response is estimated in the time-frequency two-dimensional plane using spline interpolation.

[0127] 3. Iterative Equalization Decoding

[0128] Step 1: Initialization. Without prior information (first iteration), an initial estimate of the received signal is performed using a conventional MMSE equalizer. This estimate is based on channel state and noise power, outputting an initial symbol estimate. .

[0129] Step 2: Soft symbol feedback. The initial estimate (or the estimate from the previous iteration) is fed into the polar code decoder, and the decoder outputs... Value. Then, using The function will Convert to soft symbolic expectation (prior information) This step feeds the decoder's soft output back to the equalizer to improve the equalization in the next iteration.

[0130] Step 3: Iterative Update. Utilizing prior information. and received signals The current symbol estimate is updated through interference cancellation and weighted estimation.

[0131] 4. CRC-assisted path selection: Select the optimal SCL path that passes the CRC check.

[0132] The simulation results of the method in the embodiments of the present invention are as follows: Figure 6 As shown, compared to Figure 3 After introducing techniques such as CRC-assisted polar code, SCL decoding, time-frequency domain duplex adaptive notch filtering, and noise-aware MMSE iterative equalization, the simulation results show a significant improvement. The bit error rate decreases continuously with increasing signal-to-noise ratio. Table 2 shows the bit error rate values ​​at different signal-to-noise ratios during simulation. Compared to Table 1, the noise suppression effect is significant, and the overall bit error rate is greatly reduced.

[0133] Table 2: Bit Error Rate Distribution at Different Signal-to-Noise Ratios

[0134]

[0135] Compared to Table 1, the bit error rate (BER) at each signal-to-noise ratio (SNR) in Table 2 decreased to varying degrees. At low SNR (0dB), the BER decreased by 24.2 percentage points (49.2422% → 24.9792%). At medium SNR (10dB), the BER decreased by 49.7 percentage points (50.8359% → 1.1667%). At high SNR (20dB), the BER was further optimized to near its limit, decreasing by 48.9 percentage points (48.9688% → 0). These data effectively demonstrate that the noise suppression algorithm exhibits stronger robustness under different noise environments. Further analysis of the data shows that the noise suppression algorithm reduces the BER by 24-40 percentage points at low SNR, enhancing reliability in harsh environments; and at high SNR, the BER approaches zero, meeting the requirements of high-precision communication.

[0136] In summary, this invention addresses the problems of high bit error rate, difficulty in noise suppression, channel distortion, and insufficient system robustness in power line communication. It introduces techniques such as dynamic polar code encoding, CRC-SCL decoding, time-frequency domain duplex adaptive notch filtering, and noise-aware MMSE iterative equalization. A noise-aware MMSE iterative equalization and adaptive notch filter jointly optimized for power line communication is proposed. This method effectively suppresses noise interference and improves signal transmission quality. It is of great significance for reducing the impact of communication noise and improving the performance of power line communication.

[0137] Example 2:

[0138] This invention provides a power line communication noise reduction device based on MMSE equalization and adaptive notch filtering, comprising:

[0139] The transmitting end processing module is configured to dynamically select the polar code rate based on the current channel SNR at the transmitting end, and encode the information bits using polar codes; to perform QPSK / OFDM modulation on the polar code encoded codewords to form the transmitted signal, inserting dense pilots during QPSK modulation and adding a cyclic prefix CP during OFDM modulation; and to suppress impulse noise through time-domain processing and suppress periodic noise through frequency-domain processing of the transmitted signal.

[0140] The receiver processing module is configured to introduce a noise-aware MMSE iterative equalizer at the receiver end, and use the soft information of polar code decoding to perform iterative equalization decoding to obtain the output signal.

[0141] Example 3:

[0142] Based on the power line communication noise reduction method provided in Embodiment 1, this embodiment of the invention provides an electronic device, including a processor and a storage medium;

[0143] Storage media are used to store instructions;

[0144] The processor is used to perform operations according to instructions to execute the steps according to the method described above.

[0145] Example 4:

[0146] Based on the power line communication noise reduction method provided in Embodiment 1, this embodiment of the invention provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the above method.

[0147] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0148] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0149] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0150] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0151] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A power line communication noise reduction method based on MMSE equalization and adaptive notch filtering, characterized in that, include: At the transmitting end, the polar code rate is dynamically selected based on the current channel SNR, and the information bits are polar code encoded. The codeword encoded with polar code is QPSK / OFDM modulated to form the transmission signal. Dense pilots are inserted during QPSK modulation, and a cyclic prefix (CP) is added during OFDM modulation. The transmitted signal is processed in the time domain to suppress impulse noise and in the frequency domain to suppress periodic noise. A noise-aware MMSE iterative equalizer is introduced at the receiver, and the output signal is obtained by iterative equalization decoding using the soft information of polar code decoding.

2. The power line communication noise reduction method based on MMSE equalization and adaptive notch filtering according to claim 1, characterized in that, The dynamic selection of polar code rate based on the current channel SNR includes: The current channel SNR is matched with a preset SNR threshold range, and the polar code rate corresponding to the matched SNR threshold range is selected as the selection result; satisfying the following: low polar code rate is used when SNR is low, and high polar code rate is used when SNR is high. The polar code encoding of the information bits includes: The physical channel is decomposed into reliable and unreliable channels by the phenomenon of channel polarization. Construct the input vector based on reliable and unreliable channels. : In the formula, This refers to the set of information bit indices and the set of frozen bit indices corresponding to reliable and unreliable channels. For bit index, Number of bits; Based on input vector Based on the generator matrix Calculate codewords : In the formula, The encoded codeword, polarization kernel matrix of Kronecker product, This is a bit-reversed permutation matrix. .

3. The power line communication noise reduction method based on MMSE equalization and adaptive notch filtering according to claim 1, characterized in that, The step of suppressing impulse noise by time-domain processing of the transmitted signal includes: Pulse detection, identifying pulse position based on a dynamic threshold of the 99th percentile; Pulse replacement, using local median filtering to eliminate impulse noise; Adaptive limiting, the dynamic threshold is dynamically adjusted according to the signal standard deviation, the dynamic threshold = 0.9 × 3σ, where σ is the instantaneous signal standard deviation; The suppression of periodic noise through frequency domain processing includes: Harmonic detection: Harmonic frequencies are identified through Welch power spectrum estimation. Adaptive notch filter: The adaptive notch filter is dynamically designed based on the harmonic bandwidth.

4. The power line communication noise reduction method based on MMSE equalization and adaptive notch filtering according to claim 3, characterized in that, The transfer function of the adaptive notch filter for: In the formula, It is a zero-point polynomial. It is a pole polynomial. This is the gain compensation coefficient. , Let be the radius of the pole. , This is the bandwidth adjustment factor; Notch frequency The normalized angular frequency, The sampling frequency; Delay operator for units; Wherein, the notch frequency The acquisition process includes: Signal power spectrum calculated using the Welch method Find the harmonic frequency of maximum signal power within a specific window. As The estimated value; In the formula, As the center for harmonic frequency search, This is the width of the harmonic frequency search window. Wherein, the bandwidth adjustment factor The acquisition process includes: Dynamically adjust the bandwidth adjustment factor using the -3dB bandwidth. : In the formula, This represents the -3dB bandwidth of the adaptive notch filter.

5. The power line communication noise reduction method based on MMSE equalization and adaptive notch filtering according to claim 1, characterized in that, The iterative equalization decoding using soft information from polar code decoding to obtain the output signal includes: Symbol estimation for initializing the MMSE iterative equalizer : In the formula, This is the estimated channel frequency response. For channel conjugate, In order to receive signals, For noise variance, The average power of the transmitted signal; Initialize the number of iterations Repeat the following steps until the preset maximum number of iterations is reached, and then output the final output signal: Symbol estimation and received signals Input polar code decoder, generate output signal and logarithmic natural ratio According to the natural logarithm Calculate the expectation of soft symbols : In the formula, for function; Based on soft symbol expectation Computational symbol estimation : In the formula, For weight parameters, , The prior sign variance; make .

6. The power line communication noise reduction method based on MMSE equalization and adaptive notch filtering according to claim 1, characterized in that, During polar code encoding, the information bits are first CRC encoded; during polar code decoding, the candidate information bits of each path are checked against the CRC, and if they pass the check, they are marked as valid paths.

7. The power line communication noise reduction method based on MMSE equalization and adaptive notch filtering according to claim 1, characterized in that, The polar code decoding includes: initialization Path, Path Metrics , ; Initialize bit index Repeat the following steps until , For the number of bits, from the reserved Select the path with the smallest metric from the path options: like Then forced No split path; like The path will then be split into and ; For information bit index set and frozen bit index set; Update path metrics: In the formula, For the first The path in the first A path metric of bits. For the first The path in the first The log-likelihood ratio of each bit, For the first The path to the first The decision value of 1 bit, For the judgment function, ; Keep the path with the smallest metric A path.

8. A power line communication noise reduction device based on MMSE equalization and adaptive notch filtering, characterized in that, include: The transmitting end processing module is configured to dynamically select the polar code rate based on the current channel SNR at the transmitting end and encode the information bits using polar codes. The codeword encoded with polar code is QPSK / OFDM modulated to form the transmission signal. Dense pilots are inserted during QPSK modulation, and a cyclic prefix CP is added during OFDM modulation. The transmission signal is processed in the time domain to suppress impulse noise and in the frequency domain to suppress periodic noise. The receiver processing module is configured to introduce a noise-aware MMSE iterative equalizer at the receiver end, and use the soft information of polar code decoding to perform iterative equalization decoding to obtain the output signal.

9. An electronic device, characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1-6.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1-6.

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