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, and the method comprises the following steps: S1, obtaining the channel information of the power line carrier communication system, and calculating the signal-to-noise ratio of each data subcarrier; and S2, based on a preset mapping relationship between different data subcarrier signal-to-noise ratios and corresponding modulation modes, according to the signal-to-noise ratio of each data subcarrier calculated in the step S1, adaptively allocating a corresponding modulation mode to each data subcarrier for modulation. According to the channel information of the power line carrier communication system, under the condition that the constraint of the target bit error rate is met, a proper modulation mode can be adaptively selected for each data subcarrier, and the system throughput is improved while the communication reliability is ensured.

Description

Technical Field

[0001] The present invention relates to the 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 Communication (PLC) is data transmission based on power lines, with the advantages of convenient connection, wide connection range, and no need for repeated wiring. Multi-Input Multi-Output (MIMO) technology can be extended to PLC systems. Orthogonal Frequency Division Multiplexing (OFDM) technology has advantages in combating frequency selective fading, multipath delay, improving frequency band utilization and transmission efficiency, and is suitable for power line communication.

[0003] Adaptive technology is a key technology for optimizing data rate and improving system performance. Adaptive technology is to adaptively change the modulation mode, coding rate, transmission power and other parameters according to the changes in the channel to improve the spectrum efficiency. It is known that the power line carrier communication channel has serious multipath effects and frequency selective fading, and the channel quality of different subcarriers varies greatly. In power line communication, adaptive modulation of data according to the channel quality of each subcarrier can effectively improve the spectrum efficiency under the constraint of the target bit error rate.

[0004] The disclosure of the above background technology content is only used to assist in understanding the concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the invention

[0005] The purpose of the present invention is to improve the throughput of a power line carrier communication system under the constraint of a target bit error rate. To achieve the above purpose, the present invention proposes an adaptive modulation method and device for a power line carrier communication system, which specifically includes the following steps.

[0006] S1: Obtain channel information of the power line carrier communication system and calculate the signal-to-noise ratio of each data subcarrier;

[0007] S2: Based on the preset mapping relationship between different data subcarrier signal-to-noise ratios and corresponding modulation modes, adaptively assign a corresponding modulation mode to each data subcarrier for modulation according to the signal-to-noise ratio of each data subcarrier calculated in step S1.

[0008] In step S1, when the power line carrier communication system is a SISO communication system, the specific method of obtaining the channel information of the power line carrier communication system and calculating the signal-to-noise ratio of each data subcarrier in step S1 is:

[0009]

[0010] Among them, SNR k is the signal-to-noise ratio of the kth data subcarrier in the SISO communication system, is the average signal-to-noise ratio of the data subcarrier in the SISO communication system, H k is the channel information of the kth data subcarrier in the SISO communication system, k=1, 2, ..., N, N is the number of data subcarriers, and ||·||2 is the 2-norm operation.

[0011] In step S2, when the power line carrier communication system is a MIMO communication system, the specific method of obtaining the channel information of the power line carrier communication system and calculating the data subcarrier signal-to-noise ratio in step S1 is:

[0012] The power line carrier MIMO communication system adopts the MMSE signal detection algorithm. After signal detection, the signal-to-noise ratio of the kth data subcarrier of the i-th stream of the MIMO communication system is:

[0013]

[0014] in, is the average signal-to-noise ratio of the data subcarrier in the MIMO communication system, N ss is the maximum number of streams in the MIMO communication system, H k,i is the channel information matrix H of the kth data subcarrier in the MIMO communication system k The i-th column vector of k The size is N RX ×N TX . N tX , N RX are the number of transmitters and receivers in the MIMO communication system, is the channel information matrix H k The i-th row of the obtained MMSE signal detection matrix, |·| is a modular operation.

[0015] After the kth data subcarrier signal of the i-th stream is detected, the interference generated by the kth data subcarrier detection signal of the i+1-th stream has been deleted from the received signal in the process of selecting the kth data subcarrier detection signal of the i-th stream. Then update the channel information matrix H k , and then according to the updated channel information matrix H kRecalculate the MMSE signal detection matrix, and finally substitute it into the above formula to calculate the signal-to-noise ratio of the i+1-th stream and the k-th data subcarrier.

[0016] Then, in step S2, look up the corresponding modulation method in the table according to the signal-to-noise ratio of the data subcarrier.

[0017] In step S2, when the power line carrier communication system is a SISO communication system, based on the preset mapping relationship between the signal-to-noise ratio of each data subcarrier and the corresponding modulation method, adaptively allocate the corresponding modulation method for each data subcarrier. The specific method for obtaining the modulation method corresponding to the signal-to-noise ratio of each data subcarrier by looking up the table is as follows:

[0018] The SISO communication system looks up the modulation method of the corresponding data subcarrier according to the obtained signal-to-noise ratio SNR of the data subcarrier. k The signal-to-noise ratio threshold rule for looking up the table is: when SNR k < STh2, select the BPSK modulation method; when STh2 ≤ SNR k < STh3, select the QPSK modulation method; STh3 ≤ SNR k < STh4, select 2 3 QAM modulation method,..., Select Modulation, Is The minimum signal-to-noise ratio when the modulation satisfies the target bit error rate. There are a total of B SISO Modulation methods in the signal-to-noise ratio threshold of the power line carrier SISO communication system.

[0019] In step S2, when the power line carrier communication system is a MIMO communication system, based on the preset mapping relationship between the signal-to-noise ratio of each data subcarrier and the corresponding modulation method, adaptively allocate the corresponding modulation method for each data subcarrier. The specific method for obtaining the modulation method corresponding to the signal-to-noise ratio of each data subcarrier by looking up the table is as follows:

[0020] The MIMO communication system looks up the modulation method of the corresponding data subcarrier according to the obtained signal-to-noise ratio of the data subcarrier The signal-to-noise ratio threshold rule for looking up the table is: when Select the BPSK modulation method; when Select the QPSK modulation method; Select 2 3 QAM modulation method, Select Modulation. Is The minimum signal-to-noise ratio when the data of the i-th stream in the MIMO communication system meets the target bit error rate. There are B signal-to-noise ratio thresholds in the power line carrier MIMO communication system. MIMO A modulation method.

[0021] In step S2, when the power line carrier communication system is adaptively modulated, the modulation mode of the corresponding data subcarrier can be obtained by looking up the table according to the signal-to-noise ratio of each data subcarrier in turn, or the modulation mode of the corresponding subcarrier group can be obtained by looking up the table according to the minimum signal-to-noise ratio of each data subcarrier group. The modulation mode of the corresponding data subcarrier group is obtained by looking up the table according to the minimum signal-to-noise ratio of each data subcarrier group. Specifically, the data subcarriers are grouped, each group contains n consecutive data subcarriers, and the N data subcarriers are divided into G = NNN / n groups. When the power line carrier communication system is a SISO communication system, the minimum SNR in each group of data subcarriers is k As the basis for selecting the modulation method, it is recorded as snr g . Look up the table to get snr g The corresponding modulation mode m g , g = 1, 2, ... G. When the power line carrier communication system is a MIMO communication system, each stream data subcarrier is grouped, and then the minimum number of subcarriers in each group of data subcarriers is As the basis for selecting the modulation method, it is recorded as Look up the table to get Corresponding modulation method

[0022] The present invention also provides an adaptive modulation device for a power line carrier communication system, comprising: a data subcarrier signal-to-noise ratio acquisition module, used to obtain the signal-to-noise ratio information of each data subcarrier; an adaptive modulation module, used to adaptively assign a corresponding modulation mode to each data subcarrier for modulation based on a preset mapping relationship between different data subcarrier signal-to-noise ratios and corresponding modulation modes according to the signal-to-noise ratios of each data subcarrier.

[0023] The present invention also provides a computer program product, comprising a computer program, wherein when the computer program is executed by a processor, the adaptive modulation method for a power line carrier communication system is implemented.

[0024] The beneficial effects of the present invention include:

[0025] The present invention can selectively perform adaptive modulation on data subcarriers one by one or in the form of data subcarrier groups. Performing adaptive modulation in the form of data subcarrier groups can reduce the number of table lookups, reduce complexity, and is more suitable for multi-antenna multi-carrier systems.

[0026] The present invention adaptively allocates modulation modes to data subcarriers with large channel quality differences in a power line carrier communication system. Under the constraint of a target bit error rate, a higher-order modulation mode is allocated to data subcarriers with good channel quality, thereby improving the throughput and spectrum efficiency of the power line carrier communication system, and a low-order modulation mode is allocated to data subcarriers with poor channel quality, thereby ensuring the communication reliability of the power line carrier communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a flowchart of an adaptive modulation method for a power line carrier communication system according to an embodiment of the present invention.

[0028] Figure 2 This is a throughput performance comparison diagram of the power line carrier SISO communication system according to an embodiment of the present invention.

[0029] Figure 3 This is a throughput performance comparison diagram of a power line carrier MIMO communication system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] The embodiment of the present invention provides an adaptive modulation method for a power line carrier communication system, comprising the following steps:

[0032] Embodiment 1:

[0033] In this embodiment, a power line carrier SISO communication system with one transmitting end and one receiving end is first established. Figure 1 The adaptive modulation method flow chart of the power line carrier communication system is used for adaptive modulation. Specifically, it comprises the following steps:

[0034] Step 1: The data subcarrier signal-to-noise ratio acquisition module acquires the channel information H of the power line carrier SISO communication system k , and calculate the signal-to-noise ratio (SNR) of each data subcarrier k .

[0035]

[0036] in, is the average signal-to-noise ratio of the data subcarrier in the SISO communication system, H k is the channel information of the kth data subcarrier in the SISO communication system, k=1, 2, ..., N, N is the number of data subcarriers, and ||·||2 is the 2-norm operation.

[0037] Step 2: The adaptive modulation module looks up the table to obtain the signal-to-noise ratio (SNR) of each data subcarrier k Corresponding to the modulation mode, each data subcarrier is adaptively modulated.

[0038] SISO communication system is based on the data subcarrier signal-to-noise ratio (SNR). k The modulation mode is obtained by looking up the table. This embodiment takes BPSK, QPSK, 16QAM, and 64QAM as examples. The above four modulation modes meet 10 -3 The signal-to-noise ratio thresholds for bit error rate are shown in Table 1.

[0039] Table 1

[0040] Signal-to-noise ratio threshold (dB) <![CDATA[SNR k <10]]> <![CDATA[10≤SNR k <17]]> <![CDATA[17≤SNR k <23]]> <![CDATA[SNR k ≥23]]> Modulation BPSK QPSK 16QAM 64QPSK

[0041] In step 2, the embodiment of the present invention adopts two methods: continuous data subcarrier table lookup and data subcarrier group table lookup, specifically:

[0042] (1) The SISO communication system adaptively modulates the signal-to-noise ratio (SNR) of each data subcarrier in turn. k A table lookup is performed to obtain the modulation mode of the corresponding data subcarrier.

[0043] (2) When the SISO communication system is adaptively modulated, the modulation mode of the corresponding data subcarrier group is obtained by looking up the table according to the minimum signal-to-noise ratio of each data subcarrier group. Specifically, the data subcarriers are grouped, each group contains n consecutive data subcarriers, and the N data subcarriers are divided into G = NNN / n groups. The minimum SNR in each group of data subcarriers is k As the basis for selecting the modulation method, it is recorded as snr g . Look up the table to get snr g The corresponding modulation mode m g , g=1,2,…G. In this embodiment, N is 60 and n is 10.

[0044] The throughput performance comparison diagram of an adaptive modulation method for a power line carrier SISO communication system according to an embodiment of the present invention is shown in FIG. Figure 2As shown, the vertical axis in the figure is the effective bit amount loaded per data subcarrier. Under the constraint of meeting the target bit error rate, the figure shows that the effective bit amount loaded per data subcarrier by the method of the present invention is greater than the effective bit amount of the adaptive modulation method without data subcarriers. The greater the effective bit amount loaded per data subcarrier, the greater the throughput of the power line carrier SISO communication system. Under the constraint of meeting the bit error rate, the method of the present invention allocates a higher modulation order to the signal-to-noise ratio large data subcarrier. Therefore, the throughput of the power line carrier SISO communication system is the largest when the method of the present invention is grouped without data subcarriers, and the method of the present invention is the second largest when the adaptive modulation method of grouping data subcarriers. Although the effective bit amount loaded per data subcarrier decreases after the data subcarriers are grouped, the number of table lookups in this method is greatly reduced, reducing the complexity of the algorithm.

[0045] Embodiment 2:

[0046] In this embodiment, a power line carrier MIMO communication system with two transmitting ends and two receiving ends is first established. Figure 1 The adaptive modulation method flow chart of the power line carrier communication system is used for adaptive modulation. Specifically, it comprises the following steps:

[0047] Step 1: The data subcarrier signal-to-noise ratio acquisition module obtains the channel information matrix H of the power line carrier MIMO communication system k , and calculate the data subcarrier signal-to-noise ratio The power line carrier MIMO communication system of this embodiment adopts the MMSE-SIC signal detection algorithm. After signal detection, the signal-to-noise ratio of the kth data subcarrier in the first stream is:

[0048]

[0049] Among them, H k is the channel information matrix of the kth data subcarrier in the MIMO communication system, k = 1, 2, ..., N, N is the number of data subcarriers, H k,1 is the channel information matrix H k The first column vector of is the channel information matrix H k The first row of the obtained MMSE signal detection matrix, is the average signal-to-noise ratio of data subcarriers in the MIMO communication system.

[0050] After detecting the k-th subcarrier data of the 11th stream, the channel detection matrix of the k-th data subcarrier is updated to adopt H k,2 The channel detection matrix obtained Then, according to the formula, the signal-to-noise ratio of the kth data subcarrier in the second stream is obtained as:

[0051]

[0052] Step 2: The adaptive modulation module looks up the table to obtain the signal-to-noise ratio of each data subcarrier Corresponding to the modulation mode, each data subcarrier is adaptively modulated.

[0053] MIMO communication system is based on the data subcarrier signal-to-noise ratio The modulation mode is obtained by looking up the table. This embodiment takes BPSK, QPSK, 16QAM, and 64QAM as examples. The above four modulation modes meet 10 -3 The signal-to-noise ratio thresholds for bit error rate are shown in Table 2.

[0054] Table 2:

[0055]

[0056] In step 2, the embodiment of the present invention adopts two methods: continuous data subcarrier table lookup and data subcarrier group table lookup, specifically:

[0057] (1) The MIMO communication system adaptively modulates the signal-to-noise ratio of each data subcarrier in turn. Look up the table to obtain the modulation mode of the corresponding data subcarrier. and Refer to Query Table 2.

[0058] (2) When the MIMO communication system is adaptively modulated, the modulation mode of the corresponding data subcarrier group is obtained by looking up the table according to the minimum signal-to-noise ratio of each data subcarrier group. Specifically, the data subcarriers of each stream are grouped, each group contains n consecutive data subcarriers, and the N data subcarriers are divided into G = NNN / n groups. The minimum signal-to-noise ratio of each data subcarrier group is As the basis for selecting the modulation method, it is recorded as Look up the table to get Corresponding modulation method g=1,2,…G. In this embodiment, N is 60 and n is 10. and Refer to Query Table 2.

[0059] The throughput performance comparison diagram of an adaptive modulation method for a power line carrier MIMO communication system according to an embodiment of the present invention is shown in FIG. Figure 3As shown. In the MIMO communication system, the effective bit amount loaded on each data subcarrier by the method of the present invention under the constraint of meeting the target bit error rate is still greater than that of the non-data subcarrier adaptive modulation method. The greater the effective bit amount loaded on each data subcarrier, the greater the throughput of the power line carrier MIMO communication system. The throughput performance of the non-data subcarrier grouping of the method of the present invention under the constraint of the target bit error rate is the best, and the throughput performance of the data subcarrier grouping of the method of the present invention is second.

[0060] In summary, through the analysis of the throughput performance under the power line carrier SISO and MIMO communication systems, the results show that the method of the present invention, an adaptive modulation method for a power line carrier communication system, can adaptively allocate modulation modes to data subcarriers according to channel information, and allocate higher-order modulation modes to data subcarriers with good channel quality and lower-order modulation modes to subcarriers with poor channel quality under the constraint of meeting the target bit error rate, thereby improving the system throughput, ensuring the communication reliability, and reducing the algorithm complexity by grouping data subcarriers.

[0061] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art of the present invention, several equivalent substitutions or obvious variations can be made without departing from the concept of the present invention, and the performance or use is the same, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. An adaptive modulation method for a power line carrier communication system, characterized in that: The following steps are involved: S1: Obtain channel information of the power line carrier communication system and calculate the signal-to-noise ratio of each data subcarrier; S2: Based on the preset mapping relationship between different data subcarrier signal-to-noise ratios and corresponding modulation modes, adaptively assign a corresponding modulation mode to each data subcarrier for modulation according to the signal-to-noise ratio of each data subcarrier calculated in step S1.

2. The adaptive modulation method for a power line carrier communication system according to claim 1, characterized in that: When the power line carrier communication system is a SISO communication system, the specific method of obtaining the channel information of the power line carrier communication system and calculating the signal-to-noise ratio of each data subcarrier in step S1 is: Among them, SNR k is the signal-to-noise ratio of the kth data subcarrier in the SISO communication system, is the average signal-to-noise ratio of the data subcarrier in the SISO communication system, H k is the channel information of the kth data subcarrier in the SISO communication system, k = 1, 2, …, N, N is the number of data subcarriers, and ‖·‖2 is the 2-norm operation.

3. The adaptive modulation method for a power line carrier communication system according to claim 1, characterized in that: When the power line carrier communication system is a MIMO communication system, the specific method of obtaining the channel information of the power line carrier communication system and calculating the data subcarrier signal-to-noise ratio in step S1 is: The power line carrier MIMO communication system adopts the MMSE signal detection algorithm. After signal detection, the signal-to-noise ratio of the kth data subcarrier of the i-th stream of the MIMO communication system is: in, is the average signal-to-noise ratio of the data subcarrier in the MIMO communication system, N ss is the maximum number of streams in the MIMO communication system, H k,i is the channel information matrix H of the kth data subcarrier in the MIMO communication system k The i-th column vector of k The size is N RX ×N TX ; N tX , N RX are the number of transmitters and receivers in the MIMO communication system, is the channel information matrix H k The i-th row of the obtained MMSE signal detection matrix, |·| is a modular operation; After the kth data subcarrier signal of the i-th stream is detected, in the process of selecting the kth data subcarrier detection signal of the i+1-th stream, the interference generated by the kth data subcarrier detection signal of the i-th stream has been deleted from the received signal; then the channel information matrix H is updated. k , and then according to the updated channel information matrix H k Recalculate the MMSE signal detection matrix and finally substitute it into the above formula to calculate the signal-to-noise ratio of the kth data subcarrier of the i+1th stream.

4. The adaptive modulation method for a power line carrier communication system according to claim 2, characterized in that: When the power line carrier communication system is a SISO communication system, step S2 adaptively allocates a corresponding modulation mode to each data subcarrier based on a preset mapping relationship between the signal-to-noise ratio of each data subcarrier and the corresponding modulation mode, and obtains the modulation mode corresponding to the signal-to-noise ratio of each data subcarrier by looking up a table. The specific method is: The SISO communication system determines the modulation method for the corresponding data subcarrier based on the obtained data subcarrier signal-to-noise ratio (SNR). k By referring to a look-up table, the modulation method for the corresponding data subcarrier is obtained. The SNR threshold rules for referring to the look-up table are as follows: when SNR k < STh2, the BPSK modulation method is selected; when STh2 ≤ SNR k < STh3, the QPSK modulation method is selected; when STh3 ≤ SNR k < STh4, the 2 3 QAM modulation method is selected. Select modulation, is the minimum SNR value when the modulation meets the target bit error rate. There are a total of B SISO modulation methods in the SNR threshold of the power line carrier SISO communication system.

5. The adaptive modulation method for a power line carrier communication system according to claim 3, characterized in that: When the power line carrier communication system is a MIMO communication system, step S2 adaptively allocates a corresponding modulation mode to each data subcarrier based on a preset mapping relationship between different data subcarrier signal-to-noise ratios and corresponding modulation modes, and obtains the modulation mode corresponding to each data subcarrier signal-to-noise ratio by looking up a table. The specific method is: MIMO communication system obtains data based on the subcarrier signal-to-noise ratio The modulation mode of the corresponding data subcarrier is obtained by looking up the table. The signal-to-noise ratio threshold rule based on the table lookup is: Select BPSK modulation mode; when Select QPSK modulation mode; Option 2 3 QAM modulation method, choose modulation, for BPSK,QPSK,…,2 BMIMO The minimum signal-to-noise ratio when the data of the i-th stream in the QAM modulation MIMO communication system meets the target bit error rate. There are B in the signal-to-noise ratio threshold of the power line carrier MIMO communication system. MIMO A modulation method.

6. The adaptive modulation method for a power line carrier communication system according to any one of claims 4 and 5, characterized in that: When the power line carrier communication system is adaptively modulated, the modulation mode of the corresponding data subcarrier can be obtained by looking up the table according to the signal-to-noise ratio of each data subcarrier in turn.

7. The adaptive modulation method for a power line carrier communication system according to claim 4, characterized in that: When the power line carrier communication system is a SISO communication system, the power line carrier communication system can obtain the modulation mode of the corresponding data subcarrier group according to the minimum signal-to-noise ratio of each data subcarrier group when adaptively modulating, specifically: grouping the data subcarriers, each group contains n consecutive data subcarriers, and the N data subcarriers are divided into G = N / n groups, and the minimum SNR in each group of data subcarriers is k As the basis for looking up the table to select the modulation method, it is recorded as snr g . Look up the table to get snr g The corresponding modulation mode m g , g=1,2,…G.

8. The adaptive modulation method for a power line carrier communication system according to claim 5, characterized in that: When the power line carrier communication system is a MIMO communication system, the power line carrier communication system can obtain the modulation mode of the corresponding data subcarrier group according to the minimum signal-to-noise ratio of the data subcarrier group when adaptively modulating, specifically: group each stream data subcarrier, each group contains n consecutive data subcarriers, N data subcarriers are divided into G = N / n groups, and the minimum signal-to-noise ratio of each group of data subcarriers is divided into As the basis for selecting the modulation method by looking up the table, it is recorded as Look up the table to get Corresponding modulation method 9. An adaptive modulation device for a power line carrier communication system, characterized in that: include: A data subcarrier signal-to-noise ratio acquisition module, used to acquire signal-to-noise ratio information of each data subcarrier; The adaptive modulation module is used to adaptively allocate a corresponding modulation mode to each data subcarrier for modulation based on the preset mapping relationship between different data subcarrier signal-to-noise ratios and corresponding modulation modes and according to the signal-to-noise ratio of each data subcarrier.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the adaptive modulation method for a power line carrier communication system according to any one of claims 1 to 8 is implemented.

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