Power line carrier signal modulation method and device based on OFDM system

Abstract

The application relates to a power line carrier signal modulation method and device based on an OFDM system. The method comprises the following steps: obtaining a sub-carrier signal-to-noise ratio according to a channel quality measurement result, combining a preset diversity number, a preset modulation mode and a target code rate to determine available sub-carriers; determining the bit number of each to-be-sent symbol transmission based on the preset modulation mode and the available sub-carriers, and then calculating the to-be-sent symbol number; and finally comparing the to-be-sent symbol numbers under different preset modulation modes and different preset diversity numbers, and modulating target data based on the available sub-carriers, the preset modulation mode and the preset diversity number corresponding to the minimum to-be-sent symbol number. The application is based on actual channel quality and a target code rate, and through accurate matching of a modulation mode, available sub-carriers and a preset diversity number, the transmission efficiency is maximized, and the reliability and stability of power line carrier communication are effectively enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power line carrier communication, in particular to a power line carrier signal modulation method and device based on an OFDM system. BACKGROUND

[0002] With the development of smart grid, minute-level collection of power data is crucial. Minute-level collection means that power-related data is collected at a minute level (1 minute, 5 minutes or 10 minutes), which can timely and accurately reflect the real-time operation state of the power system, providing key basis for power operation analysis, fault prediction, load regulation, etc., and strongly supporting the efficient and stable operation of the smart grid. However, current power line carrier communication faces many challenges in achieving stable and reliable minute-level data collection, for example, the power line environment is changeable and is easily disturbed by various random noises, resulting in various errors in the signal transmission process, and the existing transmission rate is difficult to meet the needs of minute-level collection.

[0003] In the existing power line carrier communication protocol, the modulation mode and diversity times of the payload data are configured in advance. Specifically, the diversity copies of the payload data support 14 basic modes and 14 extended modes, and each mode is pre-configured with key information such as modulation mode, diversity times, physical block, etc. In the actual communication process, different modes need to be configured by software according to specific needs. However, this pre-configuration method has obvious shortcomings. The pre-configured mode lacks flexibility and cannot be adjusted according to the real-time changing channel quality, resulting in waste of subcarrier resources with good channel quality and inability to normally analyze subcarriers with poor channel quality, which limits the improvement of transmission rate and transmission reliability.

[0004] The existing power line carrier communication technology is difficult to meet the requirements of smart grid for minute-level collection of power data in terms of transmission rate, and therefore, how to improve the transmission rate and transmission reliability of power line carrier communication has become a problem to be solved. SUMMARY

[0005] Therefore, the embodiments of the present application provide a power line carrier signal modulation method and device based on an OFDM system to solve at least one problem in the background art.

[0006] In a first aspect, the power line carrier signal modulation method based on the OFDM system comprises:

[0007] obtaining the signal-to-noise ratio of the subcarrier based on the channel quality measurement result;

[0008] determining the available subcarriers according to the preset diversity times, the preset modulation mode and the target code rate based on the signal-to-noise ratio of the subcarrier;

[0009] determine the number of bits of each to-be-sent symbol transmission based on the preset modulation mode and the available subcarriers;

[0010] calculate the number of to-be-sent symbols based on the number of bits of each to-be-sent symbol transmission, the preset diversity number and the number of bits of the target data;

[0011] compare the number of to-be-sent symbols under different preset modulation modes and different preset diversity numbers, and modulate the target data based on the available subcarriers, the preset modulation mode and the preset diversity number corresponding to the minimum number of to-be-sent symbols.

[0012] In a second aspect, an OFDM system-based power line carrier signal modulation device is provided, and the device comprises:

[0013] an acquisition unit configured to obtain the signal-to-noise ratio of the subcarriers based on the channel quality measurement result;

[0014] an available subcarrier determination unit configured to determine the available subcarriers based on the signal-to-noise ratio of the subcarriers, the preset diversity number, the preset modulation mode and the target code rate;

[0015] a symbol bit number calculation unit configured to determine the number of bits of each to-be-sent symbol transmission based on the preset modulation mode and the available subcarriers;

[0016] a symbol number calculation unit configured to calculate the number of to-be-sent symbols based on the number of bits of each to-be-sent symbol transmission, the preset diversity number and the number of bits of the to-be-sent data;

[0017] a comparison modulation unit configured to compare the number of to-be-sent symbols under different preset modulation modes and different preset diversity numbers, and modulate the target data based on the available subcarriers, the preset modulation mode and the preset diversity number corresponding to the minimum number of to-be-sent symbols.

[0018] In a third aspect, an embodiment of the present application provides a computer readable storage medium, which stores instructions, and when the instructions are executed by a processor of a power line carrier chip, the power line carrier chip can perform the OFDM system-based power line carrier signal modulation method provided in any one of the first aspect.

[0019] In a fourth aspect, an embodiment of the present application provides a power line carrier chip, which comprises:

[0020] a processor;

[0021] a memory configured to store computer executable instructions;

[0022] The processor is configured to execute the computer executable instructions to implement the power line carrier signal modulation method based on the OFDM system according to any one of the first aspect.

[0023] According to the channel quality measurement result, the subcarrier signal-to-noise ratio is obtained, and then the available subcarriers are determined in combination with the preset diversity number, the preset modulation mode and the target code rate; then the bit number of each to-be-sent symbol transmission is determined based on the preset modulation mode and the available subcarriers, and then the to-be-sent symbol number is calculated; finally, the target data is modulated based on the available subcarriers, the preset modulation mode and the preset diversity number corresponding to the minimum to-be-sent symbol number by comparing the to-be-sent symbol numbers under different preset modulation modes and different preset diversity numbers. According to the actual channel quality and the target code rate, the modulation mode, the available subcarriers and the preset diversity number are accurately matched, the transmission efficiency is maximized, and the reliability and stability of the power line carrier communication are effectively enhanced.

[0024] Additional aspects and advantages of the application will be made apparent by the following description. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0026] Figure 1 A power line carrier communication physical layer architecture schematic diagram provided by the embodiment of the application;

[0027] Figure 2 A power line carrier signal modulation method based on the OFDM system applied to a sending end and provided by the embodiment of the application;

[0028] Figure 3 A power line carrier signal modulation device based on the OFDM system and provided by the embodiment of the application;

[0029] Figure 4 A structure schematic diagram of a power line carrier chip provided by the embodiment of the application. DETAILED DESCRIPTION

[0030] In order to make the technical scheme and beneficial effects of the application more apparent and understandable, the following will be described in detail by means of specific embodiments. Unless otherwise defined, the technical and scientific terms used herein have the same meanings as those of the technical and scientific terms in the technical field to which the application belongs.

[0031] The core of Orthogonal Frequency Division Multiplexing (OFDM) modulation technology is to divide a high-speed data stream into multiple orthogonal parallel low-speed subcarrier signals for transmission. Among them, the subcarrier modulation mode, as a key factor affecting the performance of communication transmission, directly determines the anti-noise ability and transmission rate of signal transmission. The modulation mode in power line carrier communication includes Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 16-Quadrature Amplitude Modulation (16QAM), 64QAM, etc. Among them, BPSK has the strongest anti-noise, but the data transmission capacity is weak, and each subcarrier transmits 1 bit; QPSK is second in anti-noise, and each subcarrier transmits 2 bits, and the transmission capacity is improved; 64QAM has the weakest anti-noise, but each subcarrier transmits 6 bits, and has the strongest data transmission capacity in a good channel. However, in the existing wideband power line communication technology, the subcarrier usually adopts fixed parameter configuration, that is, the subcarrier is modulated according to the pre-set modulation mode and diversity number. The fixed parameter configuration cannot dynamically adjust the modulation mode and diversity number of the subcarrier according to the change of the power line channel environment, which limits the further improvement of the communication rate. It should be noted that the modulation mode in the embodiments of the present application includes BPSK, QPSK, 16QAM and 64QAM, the corresponding modulation order is 2, 4, 16 and 64, and the corresponding theoretical transmission bit number is log2(modulation order), that is, the theoretical transmission bit number of each subcarrier is 1, 2, 4 and 6. Among them, for the sending end, the bit number is mapped according to the theoretical value (such as 64QAM mapping 6 bits of data to 1 subcarrier), to ensure that the bit number carried by each subcarrier matches the modulation order. For the receiving end, the theoretical transmission bit number represents the maximum amount of information that can be transmitted without error in a noise-free environment. However, due to noise, interference and channel fading, the constellation points of the received symbols will be offset, causing errors, and the actual reliable transmission bit number will be less than or equal to the theoretical transmission bit number.

[0032] Therefore, the application provides a power line carrier signal modulation method based on an OFDM system.

[0033] The power line carrier target data modulation method provided by the embodiments of the application is described in detail below in combination with the accompanying drawings, specific embodiments and application scenarios.

[0034] For the HPLC system, the physical layer, the data link layer, the application layer protocol and the related inspection specification of the wideband carrier communication standard are specified in detail in the industry technical specification. In the technical specification, the finally transmitted signal is usually transmitted by means of a plurality of PPDU frames (Physical Protocol Data Unit) in sequence. The PPDU frame usually comprises a frame preamble signal (Preamble), a frame control signal (Frame Control, FC) and a data payload (Payload, PL). The frame preamble signal is composed of a plurality of synchronization symbols, and is used for frame synchronization and channel estimation; the frame control signal is used for describing the basic information of the frame, such as the modulation mode of the data payload, the subcarrier distribution, the data payload length and the like, so as to facilitate the subsequent analysis of the data payload signal by the receiving end; the data payload is used for describing the actual data part to be transmitted. It should be noted that the frame preamble signal and the frame control signal generally have a fixed length, and at the same time, since the frame control signal needs to carry the length, the modulation mode and the like of the payload data control information, the modulation mode of the frame control signal is usually limited to a low-order modulation to guarantee the reliability and stability of the transmission.

[0035] Figure 1 The power line carrier communication physical layer architecture schematic diagram provided by the embodiments of the application is shown in FIG. 1. Figure 1As shown, the frame control data and the payload data are respectively processed by encoding, interleaving, etc. to form one OFDM symbol after another, and then converted into time domain data by IFFT, and finally sent out through the analog front end after cyclic windowing, adding a preamble, etc. It should be noted that in the frequency domain, each OFDM symbol is composed of a specific number of subcarriers, each subcarrier carries different bit information, and after IFFT transformation, each OFDM symbol is converted from frequency domain to time domain. Based on the different information carried by each OFDM, the amplitude and phase of the specific number of sampling points corresponding to each OFDM symbol in the time domain are also different. In the existing power line carrier communication technology, the modulation mode and diversity number of the frame control data are fixedly configured, and the payload data is selectively fixedly configured based on the diversity copy mode in the communication protocol. For example, in basic mode 0, the physical block size is 520, the diversity number is 4, and the modulation mode is QPSK; in basic mode 2, the physical block size is 136, the diversity number is 5, and the modulation mode is QPSK; in extended mode 1, the physical block size is 520, the diversity number is 1, and the modulation mode is 16QAM. Among them, the physical block is the basic transmission unit carrying the payload data, which is composed of different number of OFDM symbols according to the physical block size, so as to realize the transmission of data payload. The target data in the embodiment of the present application refers to the payload data which has not been processed, i.e. Figure 1 the payload data which has not been processed by scrambling, encoding, etc.

[0036] Figure 2 The flow chart of the power line carrier signal modulation method based on the OFDM system applied to the sending end provided by the embodiment of the present application is shown in Figure 2 As shown, the method of the embodiment of the present application comprises:

[0037] S1, obtaining the signal-to-noise ratio of the subcarrier based on the channel quality measurement result.

[0038] Specifically, the channel quality measurement result in the embodiment of the present application refers to the channel quality measurement result from the sending end to the receiving end. Specifically, the sending end sends a channel measurement signal to the receiving end, the receiving end calculates the signal-to-noise ratio of the subcarrier after receiving the channel measurement signal, and then reports the signal-to-noise ratio of the subcarrier to the sending end, so that the sending end obtains the channel quality measurement result, i.e. the signal-to-noise ratio of the subcarrier.

[0039] As an optional implementation, the embodiment of the present application divides the subcarriers in the frequency spectrum range into a plurality of subcarrier groups, each of which includes a plurality of subcarriers, and the channel quality measurement result specifically refers to the signal-to-noise ratio of each subcarrier group, and correspondingly, the signal-to-noise ratio of the subcarriers in the subcarrier group is equal to the signal-to-noise ratio of the subcarrier group, so that the signal-to-noise ratio data reported by the receiving end can be greatly reduced, and the channel measurement rate is improved. For example, if the signal-to-noise ratio of the subcarrier group REG1 received by the sending end is 20 dB, the signal-to-noise ratio of the subcarriers included in the subcarrier group is also 20 dB.

[0040] In the embodiment of the present application, the frequency spectrum range can be a certain frequency band range in the power line carrier communication protocol, or can be the maximum frequency band range that can be supported by the power line carrier communication protocol, which is not limited by the present application. For example, in the dual-mode communication interconnection and interworking technical specification (Q / GDW 12087.41), the number of subcarriers in the frequency spectrum range is 512, and the subcarriers are numbered as 0-511 according to the frequency size. According to different communication frequency bands, the number of subcarriers is also different. The frequency band range of frequency band 0 is 1.953-11.96, and the corresponding subcarrier number is 80-490; the frequency band range of frequency band 1 is 2.441-5.615, and the corresponding subcarrier number is 100-230. As an optional implementation, the frequency spectrum range in the embodiment of the present application is the maximum frequency spectrum range that can be supported by the power line carrier communication protocol, and the subcarriers in the corresponding frequency spectrum range are all the subcarriers specified by the protocol, so that the frequency spectrum resources can be fully utilized, and more data can be transmitted. Optionally, each subcarrier group contains a plurality of continuous subcarriers. Here, the continuous subcarriers refer to arranging all the subcarriers in the frequency spectrum range according to the frequency size, and sequentially dividing them to each subcarrier group, each of which includes a part of continuous subcarriers. Further, the number of subcarriers in each subcarrier group is the same. It should be noted that in the prior art, the power line is easily disturbed by various noises, in order to ensure the effective transmission of signals, the communication protocol generally divides the maximum frequency spectrum range into a plurality of frequency bands, and then selects a certain frequency band based on the distance of signal transmission, channel conditions, data size, etc. Although this method ensures the effective transmission of signals, it also reduces the effective utilization of subcarriers and limits the signal transmission rate. In the embodiment of the present application, the channel quality information is determined based on the signal-to-noise ratio of each subcarrier group, so that the available subcarriers can be dynamically selected based on the modulation mode in the subsequent process, thereby improving the transmission rate and the transmission success rate.

[0041] As an optional implementation, before S1, it further includes:

[0042] The channel quality from the sending end to the receiving end is measured in real time to obtain the channel quality measurement result.

[0043] Optionally, the real-time measurement of the channel quality from the sending end to the receiving end comprises:

[0044] sending a full-band signal to the power line channel, so that the receiving end receives the full-band signal transmitted through the power line and calculates the signal-to-noise ratio of each subcarrier group; wherein the full-band signal is composed of all subcarriers in the frequency spectrum range;

[0045] receiving the signal-to-noise ratio data of each subcarrier group sent by the receiving end;

[0046] obtaining the signal-to-noise ratio of the subcarriers based on the signal-to-noise ratio data of each subcarrier group.

[0047] Optionally, the full-band data is composed of multiple synchronization symbols, so as to reduce the complexity (payload signal and frame control signal need to be encoded, interleaved, etc.) of signal generation and processing, and reduce the occupation of hardware resources. It should be noted that the synchronization symbol is a special symbol with a fixed structure in the power line carrier signal, and the receiving end detects the synchronization symbol through autocorrelation or cross-correlation after receiving the signal, so as to determine the starting position of the signal. The receiving end calculates the signal-to-noise ratio based on the synchronization symbol, which is prior art and will not be described here.

[0048] S2, determining the available subcarriers according to the preset diversity number, the preset modulation mode and the target code rate based on the signal-to-noise ratio of the subcarriers.

[0049] In the embodiment of the application, the available subcarriers are determined based on the signal-to-noise ratio, the diversity number, the modulation mode and the target code rate, so that the most matched available subcarriers under different modulation parameters can be accurately determined. It can be understood that the available subcarriers and the modulation mode determine the number of bits that can be transmitted by a single symbol, which directly affects the transmission efficiency; the target code rate and the preset diversity number directly affect the total number of bits transmitted, which also affects the transmission efficiency.

[0050] Specifically, S2 comprises:

[0051] S210, calculating the bit mutual information of each subcarrier according to the preset modulation mode in the order from large to small according to the signal-to-noise ratio and accumulating.

[0052] Specifically, the signal-to-noise ratios of the subcarriers are sorted from large to small, and each subcarrier is processed in turn. For each subcarrier, the bit mutual information of the subcarrier is calculated based on its modulation mode and signal-to-noise ratio. After calculating the bit mutual information of each subcarrier, the bit mutual information is accumulated, that is, the bit mutual information accumulation result is updated, so that the available subcarriers based on the bit mutual information accumulation result can be used in the subsequent process.

[0053] In the embodiments of the present application, the bit mutual information of each subcarrier is related to the signal-to-noise ratio and the modulation mode of the subcarrier; the bit mutual information of the subcarrier represents the ratio of the actual reliable transmission bits of the subcarrier to the theoretical transmission bits under the corresponding signal-to-noise ratio and modulation mode, and reflects the actual transmission bit number capability of the channel. It can be understood that the sender can send the theoretical bit number, and then part of the bits are affected after transmission through the channel to the receiver, so that the receiver can only analyze part of the accurate bit number, and the bit mutual information represents the ratio of the part of the accurate bit number to the bit number transmitted by the sender. It should be noted that the calculation of the bit mutual information of the subcarrier is performed in order according to the signal-to-noise ratio, and therefore the calculation results of the bit mutual information of the corresponding subcarriers are in descending order, that is, the bit mutual information of the current subcarrier is greater than or equal to the bit mutual information of the subsequent subcarriers.

[0054] As an optional implementation, the bit mutual information of each subcarrier is calculated by the following formula:

[0055] I i =log2(1+SNR i ) / log2M

[0056] wherein, I i represents the bit mutual information of the i-th subcarrier; the value range is 0≤I i ≤1, I i reflects the effective degree of the subcarrier transmission information; when I i =0, it indicates that the subcarrier does not carry any effective information in the transmission process, which may be due to the extremely low signal-to-noise ratio, and the signal is completely submerged by the noise; when I i =1, it indicates that the subcarrier can completely transmit information without interference of the noise. SNR i represents the signal-to-noise ratio of the i-th subcarrier; M represents the modulation order corresponding to the modulation mode. It should be noted that in actual calculation, the signal-to-noise ratio may be very high, or the selection of the modulation order M makes I i greater than 1, but I i represents the effective degree of information transmission, and the maximum value can only be 1, so when the calculation result is greater than 1, the final value is specified as 1; similarly, when the calculation result is less than 0, the final value is specified as 0.

[0057] S220, calculating the current code rate based on the bit mutual information accumulation result corresponding to the current subcarrier.

[0058] Specifically, S220 includes:

[0059] Divide the bit mutual information accumulation result corresponding to the current subcarrier by the corresponding subcarrier number to obtain the current code rate.

[0060] In power line communication, the payload data needs to be processed by channel coding, interleaving, diversity copy, etc., and then merged with frame control data, and finally sent to the power line channel after adding the preamble signal. Channel coding is a calculation to resist channel noise and interference by adding redundant bit information to the original data. In essence, it is to add a specific error correction code so that the receiving end can recover the original payload data through a specific error correction code. Code rate refers to the ratio of the number of information bits before coding to the number of information bits after coding, which directly affects the transmission efficiency. Under the same bandwidth and modulation mode, if the code rate is high (such as 5 / 6), it means that the redundancy is small and the transmission efficiency is high, but the anti-interference ability is weak; if the code rate is low (such as 1 / 2), it means that the redundancy is large and the error correction ability is strong, but the transmission efficiency is low. It should be noted that the code rate 5 / 6 means that for every 5 bits of information transmitted, an additional 1 bit of redundancy is added, and the total transmission is 6 bits; that is, the code rate can also be understood as the ratio of the actual transmission of effective bit information to the total transmission of bit information.

[0061] In the embodiments of the present application, the bit mutual information accumulation result corresponding to the current subcarrier is divided by the corresponding subcarrier number, so that the average value of the current bit mutual information can be obtained, that is, the current code rate is obtained. The average value of the current bit mutual information reflects the ratio of the actual transmission of effective bits to the theoretical transmission of bits, that is, it reflects the ability of the system to obtain effective bits in the actual channel. The code rate reflects the ratio of the effective bit information of the payload data corresponding to the system at the channel coding level to the total transmission bit information. Although the two are not completely equivalent in concept, by setting the average value of the current bit mutual information as the current code rate, the current code rate can be completely matched with the actual situation of channel transmission, and the efficiency and reliability of data transmission can be guaranteed. For example, if the average value of the subcarrier bit mutual information is 5 / 6, it means that for every 6 bits of transmission, the receiving end can accurately receive 5 bits. The corresponding matching current code rate is also 5 / 6, which means that the effective information of the actual payload data is 5 bits. By adding an additional 1 bit of redundancy, the influence of noise can be offset, that is, the receiving end receives 6 bits of data (including 5 bits of effective information and 1 bit of redundant information). At this time, the bit mutual information is 5 / 6, so 1 bit of error will occur in the actual channel transmission process, and 5 bits are accurate. At this time, since the code rate is 5 / 6, 1 bit of redundancy and a specific error correction algorithm can be used to correct the error bits, and finally the original 6 bits of original information can be accurately recovered, so that the effective 5 bits of payload data information can be obtained. In the embodiments of the present application, the average value of the bit mutual information is set as the current code rate, so that the matching code rate of the current actual channel coding can be reflected.

[0062] S230, correcting the target code rate based on the preset diversity number to obtain an effective code rate.

[0063] In power line carrier communication, the channel environment is complex and changeable, which greatly reduces the reliability of single transmission of signals. Therefore, in power line carrier communication, diversity copy and interleaving technology are usually used to generate multiple independent copies of the load data, and the risk of transmission failure is reduced through redundant transmission in the spatial, temporal or frequency domain. The diversity copy technology can be understood as repeatedly transmitting data on the time line, thereby reducing the risk of single transmission failure. In the embodiments of the present application, the target code rate is the actual code rate for encoding the load data, which reflects the ratio of the number of information bits before encoding to the number of information bits after encoding. The specific value can be configured according to the actual communication conditions such as the data amount of the load data, and in general communication protocols, it is also fixedly configured according to the mode. The diversity copy is equivalent to generating multiple independent copies. When the signals after diversity copy are regarded as a whole, the number of information bits before encoding is unchanged, but the number of bits after encoding and diversity copy is significantly increased. Therefore, the effective code rate is obtained by modifying the target code rate.

[0064] As an optional specific implementation, in the embodiments of the present application, the target code rate is modified to obtain the effective code rate, including:

[0065] The target code rate is divided by the preset diversity number to obtain the effective code rate.

[0066] The effective code rate reflects the ratio of the number of bits before encoding to the total number of bits. For the receiving end, the effective code rate reflects the minimum requirement for the number of bits that need to be reliably transmitted under the premise that the original signal can be correctly parsed, that is, the ratio of the minimum number of bits that need to be reliably transmitted by the receiving end to the total number of bits after diversity copy. For example, the target code rate is 1 / 2, the number of bits before encoding is 5 bits, the number of bits after encoding is 10 bits, then the diversity copy is twice, the total number of bits is 30 bits, and the corresponding effective code rate is 1 / 6. Then, the receiving end needs to reliably receive more than 5 bits, and then the original signal can be correctly parsed after merging, error correction and deinterleaving. Less than 5 bits cannot restore the original signal through error correction. It should be noted that the merging is to merge the repeated data, and finally the 5 bits of information that can be reliably received are used for error correction processing to restore the original 10 bits of encoded information, so that the 5 bits of information before encoding are finally obtained. In the embodiments of the present application, the effective code rate can be used to evaluate the minimum requirement for the number of bits that need to be reliably transmitted, thereby providing data support for subsequent determination of available subcarriers.

[0067] S240, comparing the size of the current code rate and the effective code rate, and determining the available subcarriers according to the comparison result.

[0068] Specifically, S240 includes:

[0069] If the current code rate is less than the effective code rate, the current subcarrier is an unusable subcarrier, and the calculation is stopped.

[0070] If the current code rate is greater than the effective code rate, the current subcarrier is an available subcarrier, and the code rate corresponding to the next subcarrier is continued to be calculated until a code rate is less than the effective code rate.

[0071] In the embodiment of the application, the current code rate is a matching code rate of the actual transmission of effective bits of the channel, and by comparing the current code rate with the effective code rate, it can be determined whether the number of effective bits that can be transmitted by the current subcarrier and the subcarriers before the current subcarrier can meet the requirement of the effective code rate. If the number is less than the requirement, it means that the requirement is not met, and the current subcarrier is an unavailable subcarrier. If the number is greater than the requirement, it means that the requirement is met, and the current subcarrier is an available subcarrier. It should be noted that the calculation of the bit mutual information of the subcarrier is based on the signal-to-noise ratio from large to small, and the corresponding calculated bit mutual information is also from large to small. If the current code rate is less than the effective code rate, the code rate corresponding to the subcarrier after the current subcarrier will also be less than the effective code rate, that is, the subcarrier after the current subcarrier is also an unavailable subcarrier, and at this time, the calculation is stopped, that is, there is no need to continue to calculate the bit mutual information of the remaining subcarriers and the corresponding code rate. If the current code rate is greater than the effective code rate, the code rate corresponding to the next subcarrier needs to be continued to be calculated until a code rate is less than the effective code rate, and at this time, the subcarrier before the code rate is an available subcarrier. It can be understood that if the current code rate is greater than the effective code rate, it reflects that the actual reliable transmission bit number in the channel is greater than the minimum requirement of the reliable transmission bit number required by the receiving end, and at this time, the receiving end can correctly parse the corresponding transmitted signal. If the current code rate is less than the effective code rate, it reflects that the actual reliable transmission bit number in the channel will be less than the minimum requirement of the reliable transmission bit number required by the receiving end, and at this time, the receiving end cannot correctly parse the corresponding transmitted signal.

[0072] In the embodiment of the application, the available subcarriers are determined based on the comparison between the current code rate and the effective code rate, so that the actual channel environment of each subcarrier is considered, that is, the available subcarriers have considered the interference of the noise in the actual channel, and they can accurately and stably transmit effective bits, and the receiving end can accurately receive and parse, thereby improving the reliability and stability of the power line communication and ensuring the accurate and stable transmission of the payload data. It can be understood that the greater the diversity number is, the smaller the effective code rate is, the more available subcarriers are, and the more bits a single symbol can transmit, thereby improving the transmission rate. However, the greater the diversity number is, the more the total transmission bits are, and the transmission rate is also reduced. Therefore, the diversity number needs to be determined according to the actual communication situation.

[0073] S3, determine the number of bits transmitted by each to-be-transmitted symbol based on the preset modulation mode and the available subcarriers.

[0074] Specifically, the number of available subcarriers is multiplied by the number of theoretical transmission bits corresponding to the preset modulation mode, i.e., the number of bits transmitted by each to-be-sent symbol. It should be noted that, for the sending end, the number of theoretical transmission bits is the number of bits carried by each subcarrier. In the embodiments of the present application, the to-be-sent symbol refers to a to-be-sent symbol corresponding to the payload data. As an optional specific implementation, the to-be-sent symbol is composed of available subcarriers and unavailable subcarriers, i.e., the to-be-sent symbol is composed of all subcarriers in the frequency spectrum. Specifically, the available subcarriers carry corresponding bit information, and the unavailable subcarriers are filled with zeros. In the embodiments of the present application, the frequency and number of available subcarriers dynamically change, and by filling the unavailable subcarriers with zeros, the dynamic change of the number of subcarriers in the to-be-transmitted symbol is avoided, and modulation and demodulation are performed based on the same number of subcarriers, thereby reducing the complexity of modulation and demodulation and improving the stability and reliability of the system.

[0075] S4, calculating the number of to-be-sent symbols based on the number of bits transmitted by each to-be-sent symbol, the preset diversity number, and the number of bits of the target data.

[0076] In the embodiments of the present application, the target data is payload data before encoding and other processing. The number of to-be-sent symbols is calculated by the following formula:

[0077] Symb Num =(Bit Num ×N) / (bit symb )

[0078] wherein Symb Num represents the number of to-be-sent symbols, Bit Num represents the number of bits of the target data, N represents the preset diversity number, and bit symb represents the number of bits transmitted by each to-be-sent symbol.

[0079] In the embodiments of the present application, the more the diversity number, the more the total number of bits transmitted; at the same time, the more the diversity number, the smaller the effective code rate, the more the number of available subcarriers, and the more the number of bits transmitted by a single to-be-sent symbol, and the number of bits transmitted by each subcarrier is also related to the modulation mode. Therefore, the number of to-be-sent symbols is actually affected by the diversity number and the modulation mode.

[0080] S5, comparing the number of to-be-sent symbols under different preset modulation modes and different preset diversity numbers, and modulating the target data based on the available subcarriers, the preset modulation mode, and the preset diversity number corresponding to the smallest number of to-be-sent symbols.

[0081] In the embodiments of the present application, the target data is the actual payload data to be transmitted, and the modulation mode and the diversity number will affect the number of symbols in the corresponding final transmission signal. For example, the more the diversity number is, the smaller the effective code rate is, the more the available subcarriers are, and the more the number of bits transmitted for each to-be-transmitted symbol is, thereby the signal transmission efficiency can be improved. However, the more the diversity number is, the more the total transmission bits are, and the signal transmission efficiency is reduced. The higher the modulation order is, the more the number of bits transmitted by a single subcarrier is, but the bit mutual information is smaller, resulting in fewer available subcarriers. Therefore, in the embodiments of the present application, by comparing the number of to-be-transmitted symbols under different preset diversity numbers and different modulation modes, the minimum number of to-be-transmitted symbols can be obtained, and accordingly, the preset diversity number and the modulation mode can be considered, and the transmission rate is maximized. It should be noted that the number of to-be-transmitted symbols refers to the number of symbols corresponding to the data payload part after diversity copying. Since the number of symbols of the frame preamble signal and the frame control signal is fixed in the power line communication protocol, the minimum number of to-be-transmitted symbols corresponds to the shortest transmission time, thereby the actual channel quality information is fully utilized, and the communication rate is maximized. It should be noted that the range of the preset diversity number is set according to the communication protocol, and the present application is not limited. In the prior art, the best modulation mode for bit loading can be determined according to the signal-to-noise ratio of each subcarrier, and then the target data is modulated according to the best modulation mode of each subcarrier. However, since the modulation mode of each subcarrier is inconsistent in this mode, the same bit will be allocated to subcarriers with different modulation modes in the diversity copying process. On the one hand, the modulation process is relatively complex, and the corresponding hardware design is also relatively complex. On the other hand, the bit merging in the demodulation process also needs to consider the demodulation mode of each subcarrier, which brings great difficulty to demodulation. In the embodiments of the present application, the target data is modulated based on the minimum number of to-be-transmitted symbols, the available subcarriers, the preset modulation mode and the preset diversity number. The modulation mode of each available subcarrier is the same, and the available subcarriers are dynamically selected, thereby the bit loading scheme is simplified without affecting the performance. In the embodiments of the present application, the modulation modes of the available subcarriers are the same, the modulation process is unified and simplified, and the hardware design difficulty is reduced. At the same time, there is no need to process different subcarriers differently during demodulation, and the bit merging is more convenient. At the same time of dynamically selecting subcarriers, the system performance is considered, and the overall communication efficiency and stability are improved.

[0082] The embodiment of the present application obtains the subcarrier signal-to-noise ratio according to the channel quality measurement result, and then determines the available subcarriers in combination with the preset diversity number, the preset modulation mode and the target code rate; then the bit number of each to-be-sent symbol transmission is determined based on the preset modulation mode and the available subcarriers, and then the to-be-sent symbol number is calculated; finally, the target data is modulated based on the available subcarriers, the preset modulation mode and the preset diversity number corresponding to the minimum to-be-sent symbol number by comparing the to-be-sent symbol numbers under different preset modulation modes and different preset diversity numbers. The present application is based on the actual channel quality and the target code rate, and the transmission efficiency is maximized while the reliability and stability of the power line carrier communication are effectively enhanced by accurately matching the modulation mode, the available subcarriers and the preset diversity number.

[0083] The power line carrier target data modulation method provided by the embodiment of the present application can be specifically applied to an electronic device, which can be a terminal or a server or the like.

[0084] It should be understood that, although Figure 2 The steps in the flowchart of the present application are displayed in sequence according to the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, the execution of these steps is not strictly limited in sequence, and these steps can be executed in other orders. Moreover, Figure 2 At least part of the steps in the flowchart of the present application can include multiple steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily sequential, but can be executed in rotation or alternation with at least part of other steps or steps or stages in other steps.

[0085] Figure 3 The modulation device 100 of the present application is shown in the schematic diagram of the power line carrier signal modulation device based on the OFDM system provided by the embodiment of the present application. As Figure 3 shown, the modulation device 100 of the present application includes:

[0086] The acquisition unit 101 is configured to obtain the signal-to-noise ratio of the subcarrier based on the channel quality measurement result;

[0087] The available subcarrier determination unit 102 is configured to determine the available subcarriers according to the preset diversity number, the preset modulation mode and the target code rate based on the signal-to-noise ratio of the subcarrier;

[0088] The symbol bit number calculation unit 103 is configured to determine the bit number of each to-be-sent symbol transmission based on the preset modulation mode and the available subcarriers;

[0089] The symbol number calculation unit 104 is configured to calculate the number of symbols to be transmitted according to the number of bits of each symbol to be transmitted, the preset diversity number and the number of bits of the data to be transmitted.

[0090] The comparison modulation unit 105 is configured to compare the number of symbols to be transmitted under different preset modulation modes and different preset diversity numbers, and modulate the target data based on the available subcarriers, the preset modulation mode and the preset diversity number corresponding to the minimum number of symbols to be transmitted.

[0091] As an optional implementation, the available subcarriers are determined according to the preset diversity number, the preset modulation mode and the target code rate based on the signal-to-noise ratio of the subcarriers, and the method comprises the following steps:

[0092] The bit mutual information of each subcarrier is calculated in sequence according to the preset modulation mode in the order from large to small according to the signal-to-noise ratio, and the bit mutual information is accumulated.

[0093] The current code rate is calculated based on the accumulated result of the bit mutual information corresponding to the current subcarrier.

[0094] The effective code rate is obtained by correcting the target code rate based on the preset diversity number.

[0095] The available subcarriers are determined according to the comparison result.

[0096] As an optional implementation, the available subcarriers are determined according to the comparison result, which comprises the following steps:

[0097] If the current code rate is less than the effective code rate, the current subcarrier is an unusable subcarrier.

[0098] If the current code rate is greater than the effective code rate, the current subcarrier is an available subcarrier, and the code rate corresponding to the next subcarrier is continued to be calculated until a code rate is less than the effective code rate.

[0099] As an optional implementation, the current code rate is calculated based on the accumulated result of the bit mutual information corresponding to the current subcarrier, which comprises the following steps:

[0100] The accumulated result of the bit mutual information corresponding to the current subcarrier is divided by the number of corresponding subcarriers to obtain the current code rate.

[0101] As an optional implementation, the effective code rate is obtained by correcting the target code rate based on the preset diversity number, and the method comprises the following steps:

[0102] The target code rate is divided by the preset diversity number to obtain the effective code rate.

[0103] As an optional implementation, the bit mutual information of each subcarrier is calculated, and the method comprises the following formula:

[0104] Ii = log2(1 + SNR i ) / log2M

[0105] wherein, I i represents the bit mutual information of the i-th subcarrier; the value range is 0≤I i ≤1; SNR i represents the signal-to-noise ratio of the i-th subcarrier; and M represents the modulation order corresponding to the modulation mode.

[0106] As an optional implementation, the number of to-be-sent symbols is calculated according to the number of bits of each to-be-sent symbol transmission, the preset diversity number and the number of bits of to-be-sent data, specifically through the following formula:

[0107] Symb Num = (Bit Num × N) / (bit symb )

[0108] wherein, Symb Num represents the number of to-be-sent symbols, Bit Num represents the number of bits of target data, N represents the preset diversity number, and bit symb represents the number of bits of each to-be-sent symbol transmission.

[0109] The embodiment of the application further provides a computer readable storage medium. The computer readable storage medium stores instructions, when the instructions are executed by a processor of a power line carrier chip, the power line carrier chip can execute the steps in the power line carrier signal modulation method based on an OFDM system in any one of the above embodiments.

[0110] The embodiment of the application can be a system, a method and / or a computer program product. The computer program product can include a computer readable storage medium having computer readable program instructions stored thereon, which are used to enable a processor to implement various aspects of the application. In some embodiments, by utilizing state information of computer readable program instructions, an electronic circuit such as a programmable logic circuit, a field programmable gate array (FPGA) or a programmable logic array (PLA) can be customized and personalized, which can execute the computer readable program instructions, thereby implementing various aspects of the application.

[0111] Computer-readable storage media can take the form of any combination of one or more readable media. A readable medium can be a readable signal medium or a readable storage medium. A computer-readable storage medium is a tangible device capable of holding and storing instructions for use by an instruction execution device. A readable storage medium can be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combinations thereof.

[0112] Various aspects of this application are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It should 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-readable program instructions.

[0113] This application also provides a power line carrier chip. Figure 4 This is a schematic diagram of the power line carrier chip provided in an embodiment of this application. Figure 4 As shown, the power line carrier chip 400 includes: one or more processors 401 and a memory 402; the memory 402 stores computer-executable instructions; the processor 401 is used to execute the computer-executable instructions to implement the steps in the power line carrier signal modulation method based on the OFDM system as described in any of the above embodiments.

[0114] The processor 401 may be a central processing unit (CPU) or other form of processing unit with data processing and / or instruction execution capabilities, and may control other components in the power line carrier chip to perform the desired functions.

[0115] The memory 402 can include one or more computer program products that can include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory, for example, can include random access memory (RAM), and / or a cache, etc. The non-volatile memory, for example, can include read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions can be stored on the computer-readable storage media, and the processor 401 can execute the program instructions to implement the steps in the text recognition method of the various embodiments of the present application described above and / or other desired functions.

[0116] In one example, the power line carrier chip 400 can further include an input device and an output device, which are interconnected through a bus system and / or other forms of connection (not shown in the figure).

[0117] Of course, in order to simplify, Figure 4 Only a part of the components in the power line carrier chip 400 related to the present application is shown in the figure, and components such as buses, input / output interfaces, etc. are omitted. In addition, according to specific application conditions, the power line carrier chip 400 can also include any other appropriate components.

[0118] It should be noted that the power line carrier target data modulation method embodiment, the power line carrier target data modulation device embodiment, the computer readable storage medium embodiment and the power line carrier chip embodiment provided by the embodiments of the present application belong to the same concept; the technical features in the technical solutions recorded by each embodiment can be combined arbitrarily without conflict.

[0119] It should be understood that the above embodiments are all exemplary and are not intended to include all possible implementations of the claims. Various modifications and changes can also be made on the basis of the above embodiments without departing from the scope of the present disclosure. Similarly, each technical feature of the above embodiments can also be combined arbitrarily to form another embodiment of the present application which can not be explicitly described. Therefore, the above embodiments only express several implementation manners of the present application, and do not limit the protection scope of the present application.

Claims

1. A method of modulating a power line carrier signal based on an OFDM system, characterized by, The method comprises: obtaining the signal-to-noise ratio of the subcarriers based on the channel quality measurement result; determining the available subcarriers according to the preset diversity number, the preset modulation mode and the target code rate based on the signal-to-noise ratio of the subcarriers; determining the bit number of each to-be-sent symbol transmission based on the preset modulation mode and the available subcarriers; calculating the to-be-sent symbol number according to the bit number of each to-be-sent symbol transmission, the preset diversity number and the bit number of the target data; comparing the to-be-sent symbol numbers under different preset modulation modes and different preset diversity numbers, and modulating the target data based on the available subcarriers, the preset modulation mode and the preset diversity number corresponding to the minimum to-be-sent symbol number. The method comprises: calculating the bit mutual information of each subcarrier in turn according to the preset modulation mode in the order of the signal-to-noise ratio from large to small and accumulating the bit mutual information; calculating the current code rate based on the bit mutual information accumulation result corresponding to the current subcarrier; correcting the target code rate based on the preset diversity number to obtain the effective code rate; comparing the sizes of the current code rate and the effective code rate, and determining the available subcarriers according to the comparison result.

2. The power line carrier signal modulation method based on OFDM system according to claim 1, wherein, The method comprises: if the current code rate is smaller than the effective code rate, the current subcarrier is an unusable subcarrier, and the calculation is stopped; if the current code rate is larger than the effective code rate, the current subcarrier is an available subcarrier, and the code rate corresponding to the next subcarrier is continued to be calculated until a certain code rate is smaller than the effective code rate.

3. The power line carrier signal modulation method based on OFDM system according to claim 1, wherein, The method comprises: dividing the bit mutual information accumulation result corresponding to the current subcarrier by the corresponding subcarrier number to obtain the current code rate.

4. The power line carrier signal modulation method based on OFDM system according to claim 1, wherein, The method comprises: dividing the target code rate by the preset diversity number to obtain the effective code rate.

5. The power line carrier signal modulation method based on OFDM system according to claim 1, wherein, The method comprises: I i = log2(1 + SNR i ) / log2M wherein I i represents the bit mutual information of the i-th subcarrier; the value range is 0≤I i ≤1; SNR i represents the signal-to-noise ratio of the i-th subcarrier; M represents the modulation order corresponding to the modulation mode.

6. The power line carrier signal modulation method of OFDM based system as claimed in claim 1, wherein, The method comprises: Symb Num =(Bit Num ×N) / (bit symb ) Wherein, Symb Num represents the number of symbols to be sent, Bit Num represents the number of bits of the target data, N represents the preset diversity number, bit symb represents the number of bits transmitted per symbol to be sent.

7. A power line carrier signal modulation apparatus based on an OFDM system, characterized by comprising: The method comprises: The device comprises: an acquisition unit configured to obtain the signal-to-noise ratio of the subcarriers based on the channel quality measurement result; an available subcarrier determination unit configured to determine the available subcarriers according to the preset diversity number, the preset modulation mode and the target code rate based on the signal-to-noise ratio of the subcarriers; a symbol bit number calculation unit configured to determine the bit number of each to-be-sent symbol transmission based on the preset modulation mode and the available subcarriers; a symbol number calculation unit configured to calculate the to-be-sent symbol number according to the bit number of each to-be-sent symbol transmission, the preset diversity number and the bit number of the target data; a comparison modulation unit configured to compare the to-be-sent symbol numbers under different preset modulation modes and different preset diversity numbers, and modulate the target data based on the available subcarriers, the preset modulation mode and the preset diversity number corresponding to the minimum to-be-sent symbol number. The available subcarriers are determined according to a preset diversity number, a preset modulation mode and a target code rate based on the signal-to-noise ratio of the subcarriers, and the method comprises the steps of: According to the preset modulation mode, the bit mutual information of each subcarrier is calculated in sequence according to the order of the signal-to-noise ratio from large to small, and is accumulated; The current code rate is calculated based on the bit mutual information accumulation result corresponding to the current subcarrier; The target code rate is corrected to obtain an effective code rate based on the preset diversity number; The size of the current code rate and the effective code rate is compared, and the available subcarriers are determined according to the comparison result.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium stores instructions, when the instructions are executed by the processor of the power line carrier chip, the power line carrier chip can execute the power line carrier signal modulation method based on the OFDM system in any one of the above claims 1 to 6.

9. A power line carrier chip, characterized by The chip comprises: a processor; a memory for storing computer executable instructions; the processor is used to execute the computer executable instructions to realize the power line carrier signal modulation method based on the OFDM system in any one of the above claims 1 to 6.

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