Self-adaptive modulation method and device for power line carrier communication system

Abstract

The invention discloses a self-adaptive modulation method and device for a power line carrier communication system, which belongs to the technical field of power line carrier communication, and comprises the following steps of: acquiring channel information of the power line carrier communication system, including a transmission characteristic value of each sub-channel and the total transmitting power of the system, and calculating the signal-to-noise ratio of each sub-channel; according to the signal-to-noise ratio of each sub-channel and the total transmission power of the system, calculating the power value allocated to each sub-channel, adjusting the original power peak-to-average ratio of the sub-channel, determining the adjusted power peak-to-average ratio, and calculating the adjusted coding gain through an optimization coefficient related to the system characteristics in combination with the adjusted power peak-to-average ratio and the original coding gain; according to the method, the performance and the reliability of the power line carrier communication system are improved by reasonably distributing the sub-channel power, controlling the peak-to-average power ratio, optimizing the error control coding gain and intelligently switching the working mode.

Description

Technical Field

[0001] The present invention relates to the technical field of power line carrier communication, and in particular to an adaptive modulation method and device for a power line carrier communication system. Background Art

[0002] Power line carrier communication refers to a special communication method that uses power lines as an information transmission medium for voice or data transmission. In the power line carrier communication system, since the power lines themselves are not specially designed for communication, their channel environment is complex and changeable, and there are problems such as large noise interference, severe signal attenuation, and multipath effects, resulting in unstable communication quality and high bit error rate.

[0003] To improve the performance of power line carrier communication systems, adaptive modulation techniques are necessary. However, in existing power line carrier communication systems, subchannel power allocation often adopts a fixed approach, failing to fully consider the differences in transmission characteristics of different subchannels. This results in some subchannels having excessively high power and others having too low power, making it difficult to fully utilize channel resources and reducing overall system transmission efficiency. High peak-to-average power ratios (PAPRs) can also cause signal distortion during transmission, increasing the bit error rate (BER) and reducing system reliability. Existing methods do not effectively control the PAPRs of subchannels and fail to consider the impact of subchannel power on PAPR, resulting in system performance degradation under high PAPR conditions. Furthermore, existing error control coding methods do not fully consider variations in channel conditions and PAPRs, making it difficult to dynamically adjust the coding gain based on actual conditions. This results in insufficient error correction capabilities under varying channel conditions, hindering effective bit error rate reduction. More importantly, existing technologies struggle to intelligently switch between error detection and retransmission and forward error correction (FEC) modes based on channel conditions, resulting in suboptimal system performance under varying channel conditions. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the existing technology has the shortcomings of unreasonable sub-channel power allocation, too high power peak-to-average ratio, insufficient optimization of error control coding gain and lack of adaptive switching mechanism. To this end, we propose an adaptive modulation method and device for power line carrier communication system.

[0005] The technical solution is mainly: an adaptive modulation method for a power line carrier communication system, which specifically includes the following steps:

[0006] Step 1: Obtain the channel information of the power line carrier communication system, including the transmission characteristic value of each sub-channel and the total transmission power of the system, and calculate the signal-to-noise ratio of each sub-channel;

[0007] Step 2: Calculating the power value allocated to each subchannel based on the signal-to-noise ratio of each subchannel and the total system transmit power;

[0008] Step 3: Based on the power value allocated to each subchannel, adjust the original peak-to-average power ratio of the subchannel, and determine the adjusted peak-to-average power ratio;

[0009] Step 4: Calculate the adjusted coding gain by combining the adjusted peak-to-average power ratio and the original coding gain with an optimization coefficient related to system characteristics;

[0010] Step 5: Based on the adjusted coding gain, determine whether the gain is high or low, dynamically select the modulation mode, and adjust the ratio of forward error correction and error detection retransmission.

[0011] Preferably, the specific method of allocating the power value to each sub-channel in step 2 is:

[0012] By comparing the signal-to-noise ratios of the sub-channels, the calculation formula for allocating the total system transmit power to the sub-channels in proportion is as follows:

[0013]

[0014] in:

[0015] W i is the power value of the i-th subchannel;

[0016] SNR i is the signal-to-noise ratio of the ith subchannel, M is the total number of channels, W total is the total system transmit power;

[0017] This subchannel is the i-th subchannel;

[0018] Sub-channels with higher signal-to-noise ratios are allocated a higher power percentage, while sub-channels with lower signal-to-noise ratios are allocated a lower power percentage, thereby ensuring that the power allocation matches the actual transmission capacity of the sub-channels.

[0019] Preferably, the sub-steps of step 3 include:

[0020] The peak-to-average power ratio is determined by analyzing the signal waveform in the time domain to obtain the ratio of the peak power to the average power.

[0021] The original peak-to-average power ratio is combined with the power value of the i-th sub-channel W i The adjusted peak-to-average power ratio is calculated based on the system preset adjustment coefficient to reduce the risk of signal distortion caused by high power fluctuations.

[0022] Preferably, the specific method of adjusting the original peak-to-average power ratio of the sub-channel in step 3 is as follows:

[0023] PAPR adj,i =PAPR 0,i -t×Wi ;

[0024] in:

[0025] PAPR adj,i is the adjusted peak-to-average power ratio of the i-th subchannel;

[0026] PAPR 0,i is the original peak-to-average power ratio of the i-th subchannel, and t is the adjustment coefficient;

[0027] The adjusted peak-to-average power ratio (PAPR) of the i-th sub-channel is calculated. adj,i After that, the received signal automatically converts the original power peak-to-average ratio PAPR of the i-th sub-channel into the power peak-to-average ratio PAPR of the i-th sub-channel in the next step 3. 0,i Replaced by the adjusted peak-to-average power ratio PAPR of the i-th subchannel adj,i .

[0028] Preferably, the sub-step of step 4 includes determining the original coding gain by comparing the signal-to-noise ratio difference between the coding and non-coding systems;

[0029] The original coding gain is combined with the adjusted peak-to-average power ratio (PAPR) of the i-th sub-channel adj,i and the optimization coefficient preset by the system, calculate the adjusted coding gain, and enhance the error correction capability of the system under different channel conditions.

[0030] Preferably, the specific method of calculating the adjusted coding gain in step 4 is as follows:

[0031] CG adj,i =CG 0,i -b×PAPR adj,i ;

[0032] in:

[0033] CG adj,i is the adjusted coding gain of the i-th subchannel, CG 0,i is the original coding gain of the i-th subchannel, b is the optimization coefficient;

[0034] The adjusted coding gain CG of the i-th sub-channel is calculated adj,i After that, the received signal automatically converts the original coding gain CG of the i-th subchannel into the original coding gain CG of the i-th subchannel in the next step 3. 0,i Replaced by the adjusted coding gain CG of the i-th subchannel adj,i .

[0035] Preferably, the specific method of dynamically selecting the modulation mode and adjusting the ratio of forward error correction and error detection retransmission in step 5 is as follows:

[0036] The adjusted coding gain CG of the i-th sub-channel of all sub-channels in the system adj,i Sort by

[0037] The adjusted coding gain CG of the i-th subchannel ranked higher than the median adj,i Determining that the high-gain interference is small, selecting a BCH code or an RS code, and reducing the number of error detection and retransmissions;

[0038] The adjusted coding gain CG of the i-th subchannel ranked lower than the median adj,i Determining that the low-gain interference is large, selecting a Hamming code, and increasing the number of error detection and retransmissions;

[0039] Wherein, if the adjusted coding gain CG of the i-th subchannel is adj,i If the burst is high, select RS code;

[0040] If the adjusted coding gain CG of the i-th subchannel adj,i If it remains high, select the BCH code.

[0041] Also disclosed is an adaptive modulation device for a power line carrier communication system, comprising a channel information acquisition module, a communication processing and adjustment module, and an adaptive modulation execution module;

[0042] The channel information acquisition module is used to acquire channel information of the power line carrier communication system;

[0043] The communication processing and adjustment module is configured to receive the channel information acquired by the channel information acquisition module and calculate the signal-to-noise ratio, power value, original peak-to-average power ratio, adjusted peak-to-average power ratio, original coding gain, and adjusted coding gain of each subchannel;

[0044] The adaptive modulation execution module is used to receive the adjusted coding gain calculated by the communication processing and adjustment module, and dynamically select a modulation mode and adjust the ratio of forward error correction and error detection retransmission based on the adjusted coding gain.

[0045] Technical effects and advantages of the present invention:

[0046] In the present invention, the power value allocated to each subchannel is first calculated based on the signal-to-noise ratio of the subchannel, thereby realizing a reasonable distribution of power among different subchannels. This method fully considers the differences in transmission characteristics of the subchannels, can allocate more power to subchannels with better transmission characteristics, improves the utilization rate of channel resources, and thus optimizes the overall transmission efficiency of the system. Then, the influence of the power value allocated to each subchannel on the power peak-to-average ratio is considered. This method can effectively reduce the negative impact of high power peak-to-average ratio on system performance, thereby reducing signal distortion, improving system reliability and reducing bit error rate. Finally, the adjusted power peak-to-average ratio is combined to optimize the error control coding gain to obtain the adjusted error control coding gain. This method fully considers the changes in channel conditions and power peak-to-average ratio, and can dynamically adjust the coding gain according to actual conditions, thereby improving the error correction capability of the system under different channel conditions and effectively reducing the bit error rate.

[0047] In the present invention, based on the calculated adjusted coding gain, error detection and retransmission are used when the noise is large and there are many errors, while forward error correction is used when the noise is small and there are few errors. This intelligent switching mechanism can fully utilize the higher adjusted coding gain and adaptively switch between the two working modes according to the channel conditions, thereby optimizing the error correction strategy, improving the signal-to-noise ratio of the sub-channel, and further improving the communication quality of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A method flow chart of an adaptive modulation method for a power line carrier communication system;

[0049] Figure 2 This is a schematic diagram of the overall module of the adaptive modulation device for power line carrier communication system. DETAILED DESCRIPTION

[0050] The present invention will now be described in further detail with reference to the accompanying drawings and preferred embodiments.

[0051] Reference Figure 1 As shown, the present invention provides an adaptive modulation method for a power line carrier communication system, which specifically includes the following steps:

[0052] Step 1: Obtain the channel information of the power line carrier communication system, including the transmission characteristic value of each sub-channel and the total transmission power of the system, and calculate the signal-to-noise ratio of each sub-channel;

[0053] Step 2: Calculate the power value allocated to each subchannel based on the signal-to-noise ratio of each subchannel and the total system transmit power;

[0054] Step 3: Based on the power value allocated to each subchannel, adjust the original peak-to-average power ratio of the subchannel and determine the adjusted peak-to-average power ratio;

[0055] Step 4: Calculate the adjusted coding gain by combining the adjusted peak-to-average power ratio and the original coding gain with an optimization coefficient related to system characteristics.

[0056] Step 5: Based on the adjusted coding gain, determine whether the gain is high or low, dynamically select the modulation mode, and adjust the ratio of forward error correction and error detection retransmission.

[0057] In this embodiment, step 1 obtains subchannel characteristics and calculates subchannel power with the help of a channel information acquisition module. Step 2, after processing by a communication processing and adjustment module, provides a power allocation basis for system modulation. Then, step 3 adjusts the peak-to-average power ratio based on the obtained subchannel power to reduce signal distortion. Step 4 then optimizes the error control coding gain based on the adjusted peak-to-average power ratio. Finally, step 5 combines the working mode switching module and the modulation mode allocation module, as well as equipment such as a spectrum analyzer and an oscilloscope, to achieve reasonable subchannel power allocation, effective control of the peak-to-average power ratio, and optimization of the error control coding gain in the power line carrier communication system. The system adaptively switches working modes, improves system transmission efficiency and reliability, and reduces bit error rate.

[0058] The method and device of this embodiment realize adaptive modulation of the power line carrier communication system through a closed-loop process of sub-channel power allocation, peak-to-average ratio adjustment, and coding gain optimization, thereby effectively improving channel resource utilization, reducing signal distortion, enhancing error correction capabilities, and ultimately improving the reliability and transmission efficiency of the communication system.

[0059] Reference Figure 1 and Figure 2 As shown, in this embodiment: the specific method of allocating power values ​​to each sub-channel in step 2 is:

[0060] By comparing the signal-to-noise ratio of each sub-channel, the calculation formula for allocating the total system transmit power to each sub-channel in proportion is as follows:

[0061]

[0062] in:

[0063] W i is the power value of the i-th subchannel;

[0064] SNR i is the signal-to-noise ratio of the ith subchannel, M is the total number of channels, W total is the total system transmit power;

[0065] This subchannel is the i-th subchannel.

[0066] In this embodiment, SNR i = ith subchannel signal / ith subchannel noise, SNRi and SNR j These two parameters represent certain characteristic values ​​of the subchannel, including the gain of the subchannel, which can be obtained through channel estimation. Channel estimation can use pilot signals or training sequences to estimate the channel. Specifically, the transmitter periodically sends pilot signals, and the receiver receives these pilot signals and compares them with the known pilot sequence to obtain information such as the frequency response of the channel, and then determine the SNR. i and SNR j ,They reflect the transmission characteristics of the sub-channels and embody the ability of different sub-channels to influence signal transmission;

[0067] and Yes The summation operation is performed from j=1 to j=M, where i represents the subchannel currently being focused on, j is the index of all subchannels traversed, and M is the total number of subchannels. The calculation result reflects the comprehensive proportional relationship between all sub-channel characteristics and the current sub-channel characteristics, and reflects the relative transmission capacity between sub-channels;

[0068] System total transmit power W total Combined with the comprehensive proportional relationship of the sub-channel characteristics, the i-th sub-channel power value W of each sub-channel is calculated i , to achieve reasonable distribution of power among different sub-channels.

[0069] Reference Figure 1 and Figure 2 As shown, in this embodiment: the sub-steps of step 3 include:

[0070] The ratio of peak power to average power is obtained by analyzing the signal time domain waveform to determine the original power peak-to-average ratio;

[0071] The original peak-to-average power ratio combined with the power value of the i-th subchannel W i and the system preset adjustment coefficient to calculate the adjusted peak-to-average power ratio.

[0072] The specific method of step 3 adjusting the original peak-to-average power ratio of the subchannel is as follows:

[0073] PAPR adj,i =PAPR 0,i -t×W i ;

[0074] in:

[0075] PAPR adj,i is the adjusted peak-to-average power ratio of the i-th subchannel;

[0076] PAPR 0,i is the original peak-to-average power ratio of the i-th subchannel, and t is the adjustment coefficient;

[0077] The peak-to-average power ratio (PAPR) of the adjusted i-th sub-channel is calculated. adj,i After that, the received signal automatically converts the original power peak-to-average ratio PAPR of the i-th subchannel into the next step 3. 0,i Replaced by the adjusted peak-to-average power ratio PAPR of the i-th subchannel adj,i .

[0078] In this embodiment, the original peak-to-average power ratio (PAPR) of the i-th sub-channel is 0,i The specific calculation formula is as follows:

[0079]

[0080] x[n] is a discrete-time signal, n=0, 1, ..., N-1, and N is the signal length;

[0081] max0≤n≤N-1|x i [n]| 2 is the i-th subchannel signal x i The peak power of [n], E[||x i [n]| 2 ] is the i-th subchannel signal x i The average power of [n], It reflects the degree of fluctuation of signal power;

[0082] In the power line carrier communication system, high peak-to-average power ratio will cause signal distortion during transmission and increase the bit error rate. In step 3, by introducing the i-th subchannel power value W i and the adjustment coefficient t to adjust the original peak-to-average power ratio PAPR of the i-th subchannel 0,i , the adjusted peak-to-average power ratio PAPR of the i-th subchannel is obtained adj,i , which can effectively reduce the power fluctuation of the signal, reduce signal distortion, improve system reliability, and reduce the bit error rate. It also takes into account the impact of sub-channel power on signal characteristics. Different sub-channels have different powers, and their impact on the peak-to-average power ratio is also different. In this way, the peak-to-average power ratio of each sub-channel can be controlled more accurately, further optimizing the communication quality of the system.

[0083] Reference Figure 1 and Figure 2 As shown, in this embodiment: the sub-step of step 4 includes determining the original coding gain by comparing the signal-to-noise ratio difference between the coding system and the non-coding system;

[0084] The original coding gain combined with the adjusted peak-to-average power ratio (PAPR) of the i-th subchannel adj,i and the system preset optimization coefficient to calculate the adjusted coding gain.

[0085] The specific method for calculating the adjusted coding gain in step 4 is as follows:

[0086] CG adj,i =CG 0,i -b×PAPR adj,i ;

[0087] in:

[0088] CG adj,i is the adjusted coding gain of the i-th subchannel, CG 0,i is the original coding gain of the i-th subchannel, b is the optimization coefficient;

[0089] After calculating the adjusted coding gain CG of the i-th subchannel adj,i After that, the received signal automatically converts the original coding gain CG of the i-th subchannel into the original coding gain CG of the i-th subchannel in the next step 3. 0,i Replaced by the adjusted coding gain CG of the i-th subchannel adj,i .

[0090] In this embodiment, the coding gain is defined as the difference between the input signal-to-noise ratio required by the non-coding system and the input signal-to-noise ratio required by the system using error correction coding under a certain bit error rate. The specific calculation formula is: CG 0,i =E b / N0{non-encoding}-E b / N0{coding} reflects the original error control coding gain of the i-th subchannel and reflects the improvement of the transmission performance of the subchannel by the error correction coding;

[0091] Under different channel conditions, the signal power peak-to-average ratio will change, and this change will affect the effect of error control coding. Step 4 combines the original coding gain CG of the i-th subchannel 0,i and the adjusted peak-to-average power ratio (PAPR) of the i-th subchannel adj,i , introduce the optimization coefficient b to calculate the adjusted coding gain CG of the i-th subchannel adj,i ,Through this formula, the coding gain can be dynamically adjusted according to the adjusted peak-to-average power ratio,,which improves the error correction capability of the system under different channel conditions and effectively reduces the bit error rate.

[0092] In addition, the adjustment coefficient t and the optimization coefficient b can use machine learning algorithms, including neural networks and genetic algorithms, to learn and train a large amount of historical data to automatically find the optimal adjustment coefficient t and optimization coefficient b. They can also use optimization algorithms to use system performance indicators as objective functions to continuously iteratively adjust the values ​​of the adjustment coefficient t and the optimization coefficient b to achieve the optimal value.

[0093] Reference Figure 1As shown, in this embodiment, the specific method of step 5 dynamically selecting the modulation mode and adjusting the ratio of forward error correction and error detection retransmission is as follows:

[0094] The adjusted coding gain CG of the i-th subchannel of all subchannels in the system adj,i Sort by

[0095] The adjusted coding gain CG of the i-th subchannel ranked higher than the median adj,i It is determined that the high gain interference is small, and the BCH code or RS code is selected to reduce the number of error detection and retransmission;

[0096] The adjusted coding gain CG of the i-th subchannel ranked lower than the median adj,i It is determined that the low-gain interference is large, and Hamming code is selected and the number of error detection and retransmission is increased;

[0097] Among them, if the adjusted coding gain CG of the i-th subchannel is adj,i If the burst is high, select RS code;

[0098] If the adjusted coding gain CG of the i-th subchannel adj,i If it remains high, select BCH code.

[0099] In this embodiment, when the adjusted coding gain CG of the i-th sub-channel is adj,i When it is high in the whole channel, it means that the channel can use the coding gain with higher efficiency to enhance the transmission quality of the signal. In physical terms, the high i-th sub-channel adjusted coding gain CG adj,i This usually corresponds to better channel conditions, that is, relatively small interference. In this case, the signal is less affected by noise and interference during transmission. Error correction coding can fully play its role, effectively improving signal reliability and recoverability, thereby achieving high gain. In this case, a coding method with higher complexity and stronger error correction capability can be selected, such as the BCH code or RS code mentioned above, to further improve system performance.

[0100] On the contrary, when the coding gain CG of the i-th subchannel is adjusted adj,i When it is low in the whole channel, it means that the channel is facing greater interference and noise, which makes it difficult for the coding gain to fully play its role. The low i-th sub-channel adjusted coding gain CG adj,i This means that the signal has been severely interfered with during transmission, and the effectiveness of error correction coding is limited, making it unable to effectively improve the signal quality. In this case, a more conservative strategy is needed, such as selecting a simple Hamming code and increasing the frequency of error detection and retransmission to ensure reliable data transmission.

[0101] Among them, BCH code performs well in correcting random errors and is suitable for situations where random noise interference is dominant in the channel. RS code has a strong error correction capability for burst errors and is more suitable for channels with burst interference. Therefore, when the interference in the channel is dominated by random noise and the coding gain CG of the i-th sub-channel is adjusted, adj,i When the signal level is continuously high, the BCH code can be selected first. If there is a lot of sudden interference, including the instantaneous strong interference that may occur in power line communication, the RS code is more suitable.

[0102] By adjusting the coding gain CG of the i-th subchannel adj,i Through monitoring and analysis, the system can understand the channel status in real time and adaptively adjust the coding method, power allocation and error correction strategy according to its size, thereby improving the overall performance and reliability of the power line carrier communication system. The above steps are repeated continuously, and the coding gain CG after adjustment is obtained based on the real-time monitored channel parameters and the calculated i-th sub-channel. adj,i The forward error correction coding strategy and error detection and retransmission mechanism are continuously adjusted. Through this cyclic adjustment and optimization, the system can adapt to changes in channel conditions, always maintain a high signal-to-noise ratio, and ensure the improvement of the performance and reliability of the power line carrier communication system.

[0103] It should be noted that any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present invention should also be within the scope of protection of the present invention.

Claims

1. An adaptive modulation method for a power line carrier communication system, characterized in that: The specific steps include: Step 1: Obtain the channel information of the power line carrier communication system, including the transmission characteristic value of each sub-channel and the total transmission power of the system, and calculate the signal-to-noise ratio of each sub-channel; Step 2: Calculating the power value allocated to each subchannel based on the signal-to-noise ratio of each subchannel and the total system transmit power; Step 3: Based on the power value allocated to each subchannel, adjust the original peak-to-average power ratio of the subchannel, and determine the adjusted peak-to-average power ratio; Step 4: Calculate the adjusted coding gain by combining the adjusted peak-to-average power ratio and the original coding gain with an optimization coefficient related to system characteristics; Step 5: Based on the adjusted coding gain, determine whether the gain is high or low, dynamically select the modulation mode, and adjust the ratio of forward error correction and error detection retransmission.

2. The adaptive modulation method for a power line carrier communication system according to claim 1, characterized in that: The specific method of allocating the power value to each sub-channel in step 2 is: By comparing the signal-to-noise ratios of the sub-channels, the calculation formula for allocating the total system transmit power to the sub-channels in proportion is as follows: in: W i is the power value of the i-th subchannel; SNR i is the signal-to-noise ratio of the ith subchannel, M is the total number of channels, W total is the total transmission power of the system; This subchannel is the i-th subchannel.

3. The adaptive modulation method for a power line carrier communication system according to claim 2, characterized in that: The sub-steps of step 3 include: The peak-to-average power ratio is determined by analyzing the signal waveform in the time domain to obtain the ratio of the peak power to the average power. The original peak-to-average power ratio is combined with the power value of the i-th sub-channel W i and the system preset adjustment coefficient, and calculate the adjusted peak-to-average power ratio.

4. The adaptive modulation method for a power line carrier communication system according to claim 3, characterized in that: The specific method of adjusting the original peak-to-average power ratio of the sub-channel in step 3 is as follows: translations paperback adj,i =PAPR 0,i -t×W i , in: PAPR adj,i is the adjusted peak-to-average power ratio of the i-th subchannel; PAPR 0,i is the original peak-to-average power ratio of the i-th subchannel, and t is the adjustment coefficient; The adjusted peak-to-average power ratio (PAPR) of the i-th sub-channel is calculated. adj,i After that, the received signal automatically converts the original power peak-to-average ratio PAPR of the i-th sub-channel into the power peak-to-average ratio PAPR of the i-th sub-channel in the next step 3. 0,i Replaced by the adjusted peak-to-average power ratio PAPR of the i-th subchannel adj,i .

5. The adaptive modulation method for a power line carrier communication system according to claim 4, characterized in that: The sub-steps of step 4 include determining the original coding gain by comparing the signal-to-noise ratio difference between the coding and non-coding systems; The original coding gain is combined with the adjusted peak-to-average power ratio (PAPR) of the i-th sub-channel adj,i and the optimization coefficient preset by the system to calculate the adjusted coding gain.

6. The adaptive modulation method for a power line carrier communication system according to claim 5, characterized in that: The specific method of calculating the adjusted coding gain in step 4 is as follows: CG adj,i =CG 0,i -b×PAPR adj,i ; in: CG adj,i is the adjusted coding gain of the i-th subchannel, CG 0,i is the original coding gain of the i-th subchannel, b is the optimization coefficient; The adjusted coding gain CG of the i-th sub-channel is calculated adj,i After that, the received signal automatically converts the original coding gain CG of the i-th subchannel into the original coding gain CG of the i-th subchannel in the next step 3. 0,i Replaced by the adjusted coding gain CG of the i-th subchannel adj,i .

7. The adaptive modulation method for a power line carrier communication system according to claim 6, characterized in that: The specific method of dynamically selecting the modulation mode and adjusting the ratio of forward error correction and error detection retransmission in step 5 is as follows: The adjusted coding gain CG of the i-th sub-channel of all sub-channels in the system adj,i Sort by The adjusted coding gain CG of the i-th subchannel ranked higher than the median adj,i Determining that the high-gain interference is small, selecting a BCH code or an RS code, and reducing the number of error detection and retransmissions; The adjusted coding gain CG of the i-th subchannel ranked lower than the median adj,i Determining that the low-gain interference is large, selecting a Hamming code, and increasing the number of error detection and retransmissions; Wherein, if the adjusted coding gain CG of the i-th subchannel is adj,i If the burst is high, select RS code; If the adjusted coding gain CG of the i-th subchannel adj,i If it remains high, select BCH code.

8. An adaptive modulation device for executing the adaptive modulation method for a power line carrier communication system according to any one of claims 1 to 7, characterized in that: It includes a channel information acquisition module, a communication processing and adjustment module, and an adaptive modulation execution module; The channel information acquisition module is used to acquire channel information of the power line carrier communication system; The communication processing and adjustment module is configured to receive the channel information acquired by the channel information acquisition module and calculate the signal-to-noise ratio, power value, original peak-to-average power ratio, adjusted peak-to-average power ratio, original coding gain, and adjusted coding gain of each subchannel; The adaptive modulation execution module is used to receive the adjusted coding gain calculated by the communication processing and adjustment module, and dynamically select a modulation mode and adjust the ratio of forward error correction and error detection retransmission based on the adjusted coding gain.

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