CN117879653B - Power line carrier communication method, communication system and storage medium - Google Patents
Power line carrier communication method, communication system and storage medium Download PDFInfo
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- H—ELECTRICITY
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- H04B—TRANSMISSION
- H04B3/00—Line transmission systems
- H04B3/54—Systems for transmission via power distribution lines
- H04B3/56—Circuits for coupling, blocking, or by-passing of signals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/7136—Arrangements for generation of hop frequencies, e.g. using a bank of frequency sources, using continuous tuning or using a transform
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- H—ELECTRICITY
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- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/715—Interference-related aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
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- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
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Abstract
The invention discloses a power line carrier communication method, a communication system and a storage medium, and relates to the field of power line carrier communication, wherein the method comprises the following steps: acquiring service data generated by an electric power user, wherein the service data is a serial data stream composed of N a bit symbols; transforming the serial data stream to N a sub-channels in parallel, and performing QAM keying modulation on the service data in each sub-channel to obtain a data signal of each sub-channel; performing frequency hopping modulation on the data signal of each sub-channel to obtain a plurality of paths of frequency hopping modulation signals, wherein the frequency hopping modulation is as follows: presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, and controlling the frequency of the data signal of each sub-channel to randomly choose and change by combining a frequency hopping multiple access technology on the basis of the frequency hopping sequence set; summing the multipath frequency hopping modulation signals to obtain a symbol signal processed by mixing an orthogonal frequency division multiplexing technology and a frequency hopping multiple access technology; the symbol signal is coupled to a power line carrier communication channel.
Description
Technical Field
The present invention relates to the field of power line carrier communication, and more particularly, to a power line carrier communication method, a communication system, and a storage medium.
Background
The Power line carrier communication (Power LINE CARRIER, PLC) uses a Power wire as a transmission medium, has huge coverage scale, and does not need to additionally lay a communication line and a communication network, so that the Power line carrier communication (PLC) has wide application scenes in future Power Internet of things such as Power service acquisition, source-network-load-storage cooperation, intelligent transformer stations, intelligent electric equipment control and the like. But the power line carrier communication technology also has obvious shortcomings and challenges: firstly, in a power network (particularly a power distribution network), background noise interference and frequency selective fading of a power line carrier communication channel are bad due to various power loads, flexible and changeable network topology, frequent start and stop of high-power electric equipment and the like; in addition, the random access of the large-scale wide-area power Internet of things equipment, the multiplexing of multi-service data in a limited frequency spectrum resource (the physical characteristics of the power line determine that the available frequency band is [0.3MHz,20MHz ], the transmission rate and the transmission quality of multi-service power line carrier communication can be greatly limited, so that how to improve the transmission performance, the anti-interference capability and the system capacity of the power line carrier communication under the limited PLC frequency spectrum resource and the multi-service access becomes a key bottleneck for the future development and the application of the technology.
The conventional power line carrier communication generally adopts a multi-carrier orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) modulation mode, so that the high transmission rate of the power line carrier communication is ensured, and meanwhile, the influence of frequency selective fading is reduced. The multi-carrier orthogonal frequency division multiplexing technology converts high-speed serial data into low-speed parallel data, reduces the bandwidth of an original transmission signal, and can enable the bandwidth of the original transmission signal to be smaller than the relevant bandwidth of a power line carrier communication channel, thereby reducing the influence of frequency selective fading of the power line carrier communication channel. In recent years, in order to further improve performance. It is also proposed to apply spread spectrum techniques to power line carrier communication systems. The spreading technology mainly comprises a frequency hopping technology (Frequency hopping, FH) and a direct sequence spreading technology, and the interference signal resistance and channel attenuation principles of the two spreading technologies are basically the same: the method comprises the steps of performing 'spread spectrum' on a useful signal at a transmitting end of a power line carrier communication system and performing 'de-spread' on a receiving end; since the pseudo-random spread spectrum code signal and the channel noise (interference) signal are not related to each other, various interferences can be effectively restrained through the spread spectrum-despread operation, and the transmission performance of the power line carrier communication can be improved.
The physical channels available for power line carrier communication are typically [0.3mhz,20mhz ], and there are many deep fades within this band, as shown in fig. 1, as can be seen from fig. 1: in the operating frequency band of the power line carrier communication, the average fading degree (decibel) increases as the frequency increases, and some frequency bands have deep fading. If wideband orthogonal frequency division multiplexing modulation is directly used on the power line carrier communication channel, the signal may fall into a large fading (or deep fading) frequency band (such as around 0.3MHz, around 1MHz, around 1.6MHz, etc.), besides, the PLC channel has a large amount of background noise and impulse noise, which tend to increase the error rate of the communication system.
If the power line carrier communication system adopts the orthogonal frequency division multiplexing technology of direct sequence spread spectrum, the bandwidth of the transmitted signal occupies most of the available frequency band more easily, and these deep fades cannot be avoided. There have been studies on PLC signal transmission schemes (OFDM overall frequency hopping) in which OFDM symbols are directly connected in series with frequency hopping. However, the PLC frequency band resources are very short, the overall frequency hopping of the OFDM symbols does not substantially reduce the possibility that a single OFDM symbol is subjected to deep fading, and the waste of PLC frequency spectrum resources is also aggravated. In addition, conventional pseudo-random frequency hopping strategies generally have uniform characteristics. The existing OFDM integral frequency hopping also adopts the frequency hopping strategy. For the power line carrier communication channel of the fixed node power grid topology, a specific transfer function (shown in fig. 1) is provided, the quality difference of the power line carrier communication channel cannot be finely distinguished by the traditional frequency hopping, the quality difference of the subcarrier channel of the OFDM PLC cannot be flexibly utilized, the transmission quality and the system capacity of the power line carrier communication are limited, and the further improvement cannot be realized.
Disclosure of Invention
The invention aims to provide a power line carrier communication method, a communication system and a storage medium, which are used for solving the problems of insufficient transmission quality and transmission capacity caused by deep fading and channel interference of a frequency band existing in a limited PLC frequency band in power line carrier communication.
The technical aim of the invention is realized by the following technical scheme:
in a first aspect of the present invention, there is provided a power line carrier communication method, performed by a transmitting end, the method including:
Acquiring service data generated by a power user under a time scale, wherein the service data is a serial data stream composed of N a bit symbols, and N a represents the number of sub-channels of an orthogonal frequency division multiplexing technology;
Transforming the serial data stream to N a sub-channels in parallel, and performing QAM keying modulation on the service data in each sub-channel to obtain a data signal of each sub-channel;
The data signal of each sub-channel is subjected to frequency hopping modulation to obtain a plurality of paths of frequency hopping modulation signals, wherein the frequency hopping modulation comprises the following specific steps: presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, and controlling the frequency of the data signal of each sub-channel to randomly hop by combining a frequency hopping multiple access technology on the basis of the frequency hopping sequence set;
summing the multipath frequency hopping modulation signals to obtain a symbol signal processed by mixing an orthogonal frequency division multiplexing technology and a frequency hopping multiple access technology;
The symbol signal is coupled to a power line carrier communication channel.
In one implementation, a set of hopping sequences for controlling frequency point hopping of power users is preset on each sub-channel, including:
Removing deep fading frequency points in a transfer function of a power line carrier communication channel to obtain a power line carrier communication frequency band formed by non-deep fading frequency points;
equally dividing a power line carrier communication frequency band into N a sub-frequency bands, wherein each sub-frequency band contains q sub-frequency points, and N a and q are positive integers;
Generating prime frequency hopping sequence groups matched with a center frequency point set formed by q sub-frequency points, and performing m-time cascade expansion on the prime frequency hopping sequence groups to obtain a frequency hopping sequence set formed by k frequency hopping sequences and m prime frequency hopping sequence groups; wherein the frequency hopping point usage rate of the frequency hopping sequence set is related to the attenuation characteristic of the transfer function of the power line carrier communication channel, and k and m are positive integers.
In one implementation, a set of hopping sequences for controlling frequency point hopping of power users is preset on each sub-channel, and the method further includes:
Setting the corresponding use times condition of each frequency point of the center frequency point set, wherein the use times of q sub-frequency points of the center frequency point set are sequentially decreased;
And in each frequency hopping sequence of the k frequency hopping sequences, replacing the sub-frequency point with the least use frequency with the sub-frequency point with the most use frequency according to the descending order of the central frequency point set, repeating the replacement until the given use frequency condition is met, and obtaining the k frequency hopping sequences matched with the transfer function of the power line carrier communication channel.
In one implementation, the symbol signal has the expression:
nT is less than or equal to T is less than or equal to (n+1) T, wherein N a represents the number of parallel sub-channels of an orthogonal frequency division multiplexing technology, N represents a time scale, Bit data representing the ith sub-channel, P representing the kth power-user transmit power, T representing the time width of the first symbol signal, f d representing the bandwidth of the orthogonal frequency division multiplexing sub-channel,The value is determined by a preset frequency hopping sequence set for the frequency hopping frequency point used on the first sub-channel of the node k; t represents a time scale and k represents a power consumer.
In a second aspect of the present invention, there is provided a power line carrier communication method, performed by a receiving end, the method comprising:
Receiving symbol signals transmitted from a plurality of power line carrier communication channels, wherein the generation process of the symbol signals is specifically as follows: acquiring service data generated by a power user under a time scale, wherein the service data is a serial data stream composed of N a bit symbols, and N a represents the number of sub-channels of an orthogonal frequency division multiplexing technology; transforming the serial data stream to N a parallel sub-channels in a serial-parallel transformation mode, and performing phase keying modulation on the service data in each sub-channel to obtain a data signal of each sub-channel; carrying out subcarrier modulation on the data signal of each subchannel to obtain a multipath subcarrier modulation signal; summing the multi-path subcarrier modulation signals to obtain a first symbol signal, wherein the first symbol signal is formed by frequency points of each subchannel; presetting a frequency hopping sequence set of frequency point hopping, controlling a frequency hopping mode of the central frequency of a first symbol signal based on a frequency hopping multiple access technology by combining the frequency hopping sequence set so as to realize frequency hopping processing of the first symbol and obtain a symbol signal;
in each branch of the orthogonal frequency division multiplexing technology, utilizing a frequency hopping sequence set of the expected user to perform frequency hopping so as to obtain a frequency hopping signal of each branch of the expected user;
performing coherent demodulation on the debounced signals of each branch to obtain multipath debounced QAM signals;
converting the multipath de-hopped QAM signals into serial data groups in a parallel-serial conversion mode;
And extracting orthogonal vectors of the real part and the imaginary part of each serial data in the serial data group, and judging the orthogonal vectors by utilizing a maximum likelihood judgment criterion to obtain service data generated by each power user under the time scale.
In one implementation, the maximum likelihood decision criterion is specifically: and solving the Euclidean distance between the quadrature vector of the real part and the imaginary part of each serial data and the QAM signal, and taking the minimum Euclidean distance as a maximum likelihood judgment criterion.
In a third aspect of the present invention, there is provided a transmitting end, including:
The data acquisition module is used for acquiring service data generated by an electric power user under a time scale, wherein the service data is a serial data stream composed of N a bit symbols, and N a represents the number of sub-channels of an orthogonal frequency division multiplexing technology;
The keying modulation module is used for converting the serial data stream to N a sub-channels in parallel, and performing QAM keying modulation on the service data in each sub-channel to obtain a data signal of each sub-channel;
The frequency hopping modulation module is used for carrying out frequency hopping modulation on the data signal of each sub-channel to obtain a plurality of paths of frequency hopping modulation signals, wherein the frequency hopping modulation specifically comprises the following steps: presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, and controlling the frequency of the data signal of each sub-channel to randomly hop by combining a frequency hopping multiple access technology on the basis of the frequency hopping sequence set;
The signal summation module is used for summing the multipath frequency hopping modulation signals to obtain a symbol signal which is processed by mixing an orthogonal frequency division multiplexing technology and a frequency hopping multiple access technology;
And a transmitting module for coupling the symbol signal to the power line carrier communication channel.
In a fourth aspect of the present invention, there is provided a receiving terminal, including:
The receiving module is used for receiving the symbol signals sent by the power line carrier communication channels, wherein the generation process of the symbol signals is specifically as follows: acquiring service data generated by a power user under a time scale, wherein the service data is a serial data stream composed of N a bit symbols, and N a represents the number of sub-channels of an orthogonal frequency division multiplexing technology; transforming the serial data stream to N a sub-channels in parallel, and performing QAM keying modulation on the service data in each sub-channel to obtain a data signal of each sub-channel; the data signal of each sub-channel is subjected to frequency hopping modulation to obtain a plurality of paths of frequency hopping modulation signals, wherein the frequency hopping modulation comprises the following specific steps: presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, and controlling the frequency of the data signal of each sub-channel to randomly hop by combining a frequency hopping multiple access technology on the basis of the frequency hopping sequence set; summing the multipath frequency hopping modulation signals to obtain a symbol signal processed by mixing an orthogonal frequency division multiplexing technology and a frequency hopping multiple access technology;
The system comprises a de-hopping module, a receiving module and a receiving module, wherein the de-hopping module is used for de-hopping by utilizing a frequency hopping sequence set of an expected user in each branch of an orthogonal frequency division multiplexing technology to obtain a de-hopping signal of each branch of the expected user;
The demodulation module is used for carrying out coherent demodulation on the debounced signals of each branch to obtain multipath debounced QAM signals;
the conversion module is used for converting the multipath de-hopped QAM signals into serial data groups in a parallel-serial conversion mode;
And the judging module is used for extracting orthogonal vectors of the real part and the imaginary part of each serial data in the serial data group, judging the orthogonal vectors by utilizing the maximum likelihood judging criterion and obtaining service data generated by each power user under the time scale.
A fifth aspect of the present invention provides a power line carrier communication system, comprising:
a transmitting end configured to implement the power line carrier communication method as provided in the first aspect of the present invention;
a receiving end configured to implement the power line carrier communication method as provided in the second aspect of the present invention.
In a sixth aspect of the present invention, there is provided a storage medium having instructions stored therein; the instructions, when executed on a processor, perform a power line carrier communication method as provided in the first aspect of the invention and in the second aspect of the invention.
Compared with the prior art, the invention has the following beneficial effects:
1. Aiming at the problems of limited bandwidth resources, frequency selective fading, background noise and impulse noise of a power line carrier communication channel, the invention provides a signal processing mode based on mixed connection of subcarrier frequency hopping and orthogonal frequency division multiplexing, and realizes a multi-service access power line carrier communication transmission scheme by a frequency hopping multiple access technology. Compared with the prior art, the sub-channel frequency points of the orthogonal frequency division multiplexing technology of the transmission scheme provided by the invention can more flexibly select the power line carrier communication frequency band which is not physically adjacent, effectively avoid the influence of the frequency selective fading and various noise interferences of the power line carrier communication channel, and further save the frequency band resources of the power line carrier communication.
2. In order to further improve the transmission performance of the power line carrier communication system, the invention constructs a frequency hopping sequence set matched with the quality of the power line carrier communication channel. The frequency hopping sequence set utilizes the difference of the power line carrier communication channel gains in different frequency bands, so that the use probabilities of the different frequency bands are different, and the frequency band multiple message with good quality and the frequency band fewer message with poor quality are realized. Meanwhile, the frequency hopping sequence set can effectively reduce the mutual interference of multiplexing of multiple service types. The frequency hopping mode fully utilizes the limited frequency point bandwidth of the power line carrier communication, improves the frequency spectrum efficiency and the transmission quality of the power line carrier communication, and is suitable for the high-speed reliable transmission requirement under the fusion of the control business of the power system.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:
Fig. 1 shows a schematic diagram of multipath fading characteristics (4-path and 6-path conditions) of a power line carrier communication channel in a fixed grid topology;
fig. 2 shows a signal processing flow chart of a multi-service PLC communication system for frequency hopping modulation of data signals of subchannels according to an embodiment of the present invention;
fig. 3 is a schematic flow chart of a power line carrier communication method performed by a transmitting end according to an embodiment of the present invention;
Fig. 4 is a schematic flow chart of a power line carrier communication method performed by a receiving end according to an embodiment of the present invention;
fig. 5 shows a schematic diagram of comparison of error rates of a single-service PLC communication system with frequency hopping modulation of data signals of subchannels according to an embodiment of the present invention;
Fig. 6 shows a schematic diagram of comparing error rates of an asynchronous multi-service access PLC communication system with frequency hopping modulation of data signals of subchannels according to an embodiment of the present invention;
Fig. 7 is a schematic diagram illustrating comparison of spectral efficiency of a PLC communication system for frequency hopping modulation of data signals of subchannels according to an embodiment of the present invention.
Detailed Description
For the purpose of making apparent the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present invention and the descriptions thereof are for illustrating the present invention only and are not to be construed as limiting the present invention.
It is noted that the terms "comprises" or "comprising" when utilized in various embodiments of the present application are indicative of the existence of the claimed function, operation or element and do not limit the addition of one or more functions, operations or elements. Furthermore, as used in various embodiments of the application, the terms "comprises," "comprising," and their cognate terms are intended to refer to a particular feature, number, step, operation, element, component, or combination of the foregoing, and should not be interpreted as first excluding the existence of or increasing likelihood of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing.
Furthermore, terms such as "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
Currently, the available physical channels for power line carrier communication are typically [0.3mhz,20mhz ], and there are many deep fades in this frequency band, as shown in fig. 1, as can be seen from fig. 1: in the operating frequency band of the power line carrier communication, the average fading degree (decibel) increases as the frequency increases, and some frequency bands have deep fading. If wideband orthogonal frequency division multiplexing modulation is directly used on the power line carrier communication channel, the signal may fall into a large fading (or deep fading) frequency band (such as around 0.3MHz, around 1MHz, around 1.6MHz, etc.), besides, the PLC channel has a large amount of background noise and impulse noise, which tend to increase the error rate of the communication system.
If the power line carrier communication system adopts the orthogonal frequency division multiplexing technology of direct sequence spread spectrum, the bandwidth of the transmitted signal occupies most of the available frequency band more easily, and these deep fades cannot be avoided. There have been studies on PLC signal transmission schemes (OFDM overall frequency hopping) in which OFDM symbols are directly connected in series with frequency hopping. However, the PLC frequency band resources are very short, the overall frequency hopping of the OFDM symbols does not substantially reduce the possibility that a single OFDM symbol is subjected to deep fading, and the waste of PLC frequency spectrum resources is also aggravated. In addition, conventional pseudo-random frequency hopping strategies generally have uniform characteristics. The existing OFDM integral frequency hopping also adopts the frequency hopping strategy. For the power line carrier communication channel of the fixed node power grid topology, a specific transfer function (shown in fig. 1) is provided, the quality difference of the power line carrier communication channel cannot be finely distinguished by the traditional frequency hopping, the quality difference of the subcarrier channel of the OFDM PLC cannot be flexibly utilized, the transmission quality and the system capacity of the power line carrier communication are limited, and the further improvement cannot be realized.
Firstly, describing the transmitting end and the receiving end of the power line carrier communication system provided by the embodiment of the invention, the PLC communication system generally adopts an OFDM modulation mode to improve the PLC data transmission rate and reduce the PLC channel frequency selective fading, but the OFDM modulation technology generally occupies a continuous subcarrier frequency band, so that deep fading is difficult to avoid. Therefore, in order to improve the transmission performance of the PLC system, the embodiment of the present invention designs a signal processing manner based on mixed connection of subcarrier frequency hopping and orthogonal frequency division multiplexing, as shown in fig. 2, in a transmitting end, serial data streams generated by power users are transformed to OFDM parallel sub-channels through a serial/parallel converter, and each sub-channel adopts QAM keying (QAM) modulation; then, frequency hopping modulation is carried out on the data signal of each sub-channel to obtain a plurality of frequency hopping modulation signals, namely, a frequency hopping sequence set for controlling the frequency point hopping of the power user is preset on each sub-channel, and the frequency of the data signal of each sub-channel is controlled to randomly hop by combining a frequency hopping multiple access technology based on the frequency hopping sequence set; finally, combining the frequency hopping modulation signals to obtain a symbol signal which is processed by mixing an orthogonal frequency division multiplexing technology and a frequency hopping multiple access technology; the symbol signal is coupled to a power line carrier communication channel for transmission onto the power conductor.
Secondly, after receiving multiplexing data sent by a plurality of service data at a receiving end, on a parallel sub-channel, utilizing a frequency hopping sequence set of an expected user to perform frequency hopping so as to obtain a frequency hopping signal of each branch of the expected user; and then carrying out coherent demodulation on the debounced signals of each branch to obtain multipath debounced QAM signals. The multipath de-hopped QAM signal is converted into serial data sets by means of parallel-to-serial conversion. Finally, the sending data is obtained after the parallel/serial conversion and QAM detection judgment module.
The application scenarios of the transmitting end and the receiving end of the power line carrier communication system may be, for example, scenarios in which the smart electric meters installed on the plurality of power users transmit back the power consumption data of the users to the corresponding power substation, the smart electric meters are used as the transmitting end, the power substation is used as the receiving end, and then the power consumption data of the plurality of received smart electric meters are summarized at the power substation, so that the power consumption data of the power supply area corresponding to the power substation is obtained. And then, the power consumption data of the power supply areas corresponding to the plurality of the power transformation electronic stations are summarized at the power transformation master station, so that the total power consumption data of the total power supply areas of the plurality of the power transformation electronic stations corresponding to the power transformation master station is obtained.
It is understood that power line communication is commonly referred to as power line carrier (Power Line Communication-PLC) communication, and refers to a special communication mode for voice or data transmission using a high voltage power line (generally referred to as a voltage class of 35kV and above in the power line carrier field), a medium voltage power line (referred to as a voltage class of 10 kV) or a low voltage distribution line (380/220V subscriber line) as an information transmission medium. Existing power lines and sockets are used to build a network to connect PCs, ADSL modems, set-top boxes, audio devices, monitoring devices, and other intelligent electrical devices (e.g., refrigerators, air conditioners, washing machines, etc.) to transmit data, voice, and video.
Referring to fig. 3, fig. 3 shows a flowchart of a power line carrier communication method according to an embodiment of the present invention, where, as shown in fig. 3, the method is performed by a transmitting end, and includes:
S310, service data generated by a power user under a time scale is acquired, wherein the service data is a serial data stream composed of N a bit symbols, and N a represents the number of sub-channels of an orthogonal frequency division multiplexing technology.
In this embodiment, at the transmitting end, it is assumed that a serial data stream composed of N a bit symbols is represented asWherein N a is the number of sub-channels of OFDM, and N represents the time scale.
S320, the serial data stream is transformed to N a sub-channels in parallel, and QAM keying modulation is carried out on the service data in each sub-channel to obtain the data signal of each sub-channel.
In this embodiment, the serial data stream is converted by serial/parallel conversion to bit dataThe data are sent to the corresponding sub-channels, which are shown in the transmitting end of fig. 2, and each sub-channel is respectively subjected to QAM keying modulation. QAM keying modulation is a type of multilevel modulation scheme. For M-ary QAM modulation, the M-ary data can be represented as two-way quadrature vectors: Where E g represents the energy of the transmitted signal pulse, and a m,c and a m,s represent the amplitude of the modulated orthogonal two-way signal, respectively.
S330, performing frequency hopping modulation on the data signal of each sub-channel to obtain a plurality of paths of frequency hopping modulation signals, wherein the frequency hopping modulation specifically comprises: and presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, and controlling the frequency of the data signal of each sub-channel to randomly hop by combining a frequency hopping multiple access technology based on the frequency hopping sequence set.
In this embodiment, the power line carrier communication frequency band is equally divided into N a sub-bands, each sub-band contains q sub-frequency points, and the sub-carriers of the parallel sub-channels are deselected on the corresponding sub-bands. The selection is based on a predetermined frequency hopping strategy.
Specifically, because there are a plurality of power users on the power conductor, the invention combines the frequency hopping sequence set to control the frequency of the data signal of each sub-channel to carry out random hopping on the basis of the frequency hopping multiple access technology, thereby realizing the frequency hopping processing of the data signal of the sub-channel of the orthogonal multiplexing multiple access technology, and further obtaining one path of frequency hopping modulation signal, but because the number of the sub-channels is more than one, the data signal is more than one, and thus the multipath frequency hopping modulation signal is obtained.
S340, summing the multipath frequency hopping modulation signals to obtain the symbol signals processed by the mixed processing of the orthogonal frequency division multiplexing technology and the frequency hopping multiple access technology.
In this embodiment, the multipath frequency hopping modulation signals are summed to obtain a symbol signal which is processed by a mixture of an orthogonal frequency division multiplexing technique and a frequency hopping multiple access technique, that is, an OFDM symbol signal S (k) (t). After the signal processing of the transmitting end, the second symbol signal generated by the power consumer k at the time n is expressed as: nT is less than or equal to T is less than or equal to (n+1) T, wherein N a represents the number of parallel sub-channels of an orthogonal frequency division multiplexing technology, N represents a time scale, Bit data representing the ith sub-channel, P representing the kth power-user transmit power, T representing the time width of the first symbol signal, f d representing the bandwidth of the orthogonal frequency division multiplexing sub-channel,The value of the frequency hopping frequency point used by the kth power user at the nth symbol time of the l sub-channels is determined by a preset frequency hopping sequence, t represents a time scale, and k represents the power user.
Specifically, a set of hopping sequences for controlling the hopping of the power consumer frequency points is preset on each sub-channel, and the method comprises the following steps: removing deep fading frequency points in a transfer function of a power line carrier communication channel to obtain a power line carrier communication frequency band formed by non-deep fading frequency points; equally dividing a power line carrier communication frequency band into N a sub-frequency bands, wherein each sub-frequency band contains q sub-frequency points, and N a and q are positive integers; generating prime frequency hopping sequence groups matched with a center frequency point set formed by q sub-frequency points, and performing m-time cascade expansion on the prime frequency hopping sequence groups to obtain a frequency hopping sequence set formed by k frequency hopping sequences and m prime frequency hopping sequence groups; wherein the frequency hopping point usage rate of the frequency hopping sequence set is related to the attenuation characteristic of the transfer function of the power line carrier communication channel, and k and m are positive integers.
In this embodiment, from the perspective of a frequency hopping technique in a subcarrier frequency hopping OFDMA PLC system, each frequency hopping point in the conventional pseudo-random frequency hopping has a uniform distribution characteristic; the traditional pseudo-random frequency hopping regards the available frequency bands as the same channel quality, and the communication user randomly and uniformly selects one frequency point from the frequency points to use. However, for a fixed topology power grid architecture, the PLC channel fading characteristics are determined and each frequency band fades differently (as shown in fig. 1, the PLC multipath fading model generated by the 4 paths). The conventional pseudo-random frequency hopping strategy cannot finely distinguish the attenuation difference of the PLC frequency band. According to the method, a novel frequency hopping strategy (frequency hopping sequence set) matched with the PLC signal quality is constructed by adopting methods such as an optimal base sequence, cascade expansion and the like according to a PLC channel transfer function |H (f) |, and the use probability of frequency hopping points in the strategy is closely related to the attenuation characteristic of the PLC channel quality |H (f) |.
The steps of constructing the set of hopping sequences are as follows:
Step 1, (PLC channel quality detection): it is first assumed that the PLC channel transfer function |h (f) | has been obtained by the channel detection method. After eliminating deep fading frequency points in the I H (f), dividing the rest PLC frequency band into Na sub-frequency bands (discontinuous frequency bands) which contain q sub-frequency points, wherein Na and q are positive integers. The center frequency points of these sub-frequency points are assumed to be: f= { F h |h=0, 1..q-1 }. In the subsequent steps, for convenience of description, the subband f h is denoted by h, and q is to be a prime power.
Step 2, (optimal base sequence construction): at the set of frequency points f= { F 0,f1,f2,…fq-1 }, a prime hopping sequence family P (q, L p,Kp,Hm) is generated using the following algorithm.
Wherein Lp is the length of prime number hopping sequence, the number of Kp prime number hopping sequence, and the Hamming correlation value of Hm prime number hopping sequence. Assume that the length of the PLC channel matching hopping sequence to be generated is l=ml p, where m is a positive integer. Therefore, the prime number sequence set P is cascade-extended m times:
kth hopping sequence:
The average occurrence number of each frequency point is And twice.
Step 3, (frequency point replacement strategy): presetting a hopping sequence set for controlling the hopping of the power user frequency points on each sub-channel, and further comprising: setting the corresponding use times condition of each frequency point of the center frequency point set, wherein the use times of q sub-frequency points of the center frequency point set are sequentially decreased; and in each frequency hopping sequence of the k frequency hopping sequences, replacing the sub-frequency point with the least use frequency with the sub-frequency point with the most use frequency according to the descending order of the central frequency point set, repeating the replacement until the given use frequency condition is met, and obtaining the k frequency hopping sequences matched with the transfer function of the power line carrier communication channel.
Specifically, according to the detected PLC channel quality |h (f) |, the number of occurrences of each frequency point is sequentially decreased according to the attenuation degree of |h (f) |. Assume that the number of uses of the q frequency points of f 0,f1,f2,…fq-1 decreases in order (i.e., the number of uses corresponding to each frequency point is given as [ m 0,m1,...,mq-1],ml-ml+1 =Δ > 0 "). Assume that the number of uses of f 0 isAnd is also provided withIn each sequence in the set of hopping sequences Q, the most used frequency points are replaced with the least used frequency points in the order of f 0,f1,f2,…fq-1 (i.eEtc.), the substitution is repeated until a given number of times condition [ m 0,m1,...,mq-1],ml-ml+1 =Δ > 0 is satisfied.
And (3) integrating the steps 1-3, and constructing a frequency hopping sequence set S which is obtained by replacing each frequency point of the Q, namely the constructed frequency hopping pattern. The frequency hopping pattern satisfies that all sub-bands { f h |h=0, 1, & gt, q-1} are used, and has a good frequency diversity function. The frequency of the sub-bands in each sequence is different, the sub-bands with small attenuation mapped to the PLC channels are frequently used, the frequency of the sub-bands with large attenuation is less, and the frequency hopping pattern is matched with the PLC channel quality. The probability of collision of frequency points between any two frequency hopping sequences in the frequency hopping sequence set S is minimum, so that the mutual interference of multi-service data access to the power line carrier communication system is effectively reduced.
The following describes in detail the mixed design of subcarrier hopping and OFDM:
1) And pre-eliminating the frequency points of deep fading in the whole PLC frequency band W= [0.3MHz and 20MHz ] and equally dividing the frequency points into N a sub-bands. The N a subbands may be discontinuous in physical frequency band, i.e The starting point of this Na sub-band is denoted as f l,l＝0,1,2,…,Na -1.
2) Assuming that the data symbol bandwidth on the OFDM subchannel is f d and that OFDM has N a subchannels, one OFDM symbol occupies a bandwidth of W OFDM＝fdNa.
3) Within each sub-band { W 0,W1,..,WNa-1 } is equally divided into q sub-frequency bins, i.e., { f h |h=1, 2. In order to ensure the frequency orthogonality on each sub-channel of the OFDM signal, the physical frequency points of the OFDM sub-channel l are hopped over q sub-frequency points in the corresponding sub-frequency band W l.
The q value is consistent with the frequency point set of the frequency hopping strategy to be constructed in the next section. The center frequency of the first symbol signal is based on the designed frequency hopping strategy (frequency hopping sequence set)And selecting one frequency point of the sub-frequency point set { f h |h=1, 2, & gt, q } in the sub-frequency band to carry out frequency hopping so as to send service data of the power user. Different power users k use different frequency hopping strategies to realize the OFDM/FHMA PLC communication system based on frequency hopping multiple access.
S350, coupling the symbol signal to a power line carrier communication channel.
In the subcarrier frequency hopping OFDMA PLC system designed in the embodiment of the present invention, a frequency hopping strategy (a set of frequency modulation sequences) for controlling frequency point hopping determines in which frequency band the subcarriers of the first symbol signal are transmitted. By designing a flexible frequency hopping strategy, signals can be effectively prevented from falling into a frequency band with poor channel quality (deep fading), and limited PLC channel quality difference is fully utilized. Therefore, the data of multi-service transmission can be effectively accessed into the PLC communication system. Although the traditional pseudo-random frequency hopping can achieve the partial targets, the frequency hopping strategies are not completely matched with a PLC channel with specific fading characteristics, so that a frequency hopping sequence set which can be adapted to the fading characteristics of the PLC channel is constructed by adopting methods such as optimal base sequence, cascade expansion and the like, and the transmission performance of power line communication can be further improved.
In this embodiment, the coupling of the symbol signal to the power line carrier communication channel is a well known technique for those skilled in the art, and the specific description of this embodiment is omitted.
In summary, in a power line carrier communication method executed at a transmitting end, first, the present invention proposes a signal processing manner based on mixed connection of subcarrier frequency hopping and orthogonal frequency division multiplexing, and implements a multi-service access power line carrier communication transmission scheme by using a frequency hopping multiple access technology, where signal frequencies of data signals of subchannels are in corresponding subbands, and random hopping modulation is performed according to a set of frequency hopping sequences, so as to obtain frequency hopping modulation signals, thereby implementing multi-power user multiplexing of a power line carrier communication system based on orthogonal frequency division multiplexing by using the frequency hopping multiple access technology. Compared with the prior art, the sub-channel frequency points of the orthogonal frequency division multiplexing technology of the transmission scheme provided by the invention can more flexibly select the power line carrier communication frequency band which is not physically adjacent, effectively avoid the influence of the frequency selective fading and various noise interferences of the power line carrier communication channel, and further save the frequency band resources of the power line carrier communication.
Secondly, in order to further improve the transmission performance of the power line carrier communication system, the invention constructs a frequency hopping sequence set matched with the quality of the power line carrier communication channel, and the frequency hopping sequence set is constructed by using methods of optimal base sequence, cascade extension, channel quality attenuation quantization and the like. The frequency hopping sequence set utilizes the difference of the power line carrier communication channel gains in different frequency bands, so that the use probabilities of the different frequency bands are different, and the frequency band multiple message with good quality and the frequency band fewer message with poor quality are realized. Meanwhile, the frequency hopping sequence set can effectively reduce the mutual interference of multiplexing of multiple service types. The frequency hopping mode fully utilizes the limited frequency point bandwidth of the power line carrier communication, improves the frequency spectrum efficiency and the transmission quality of the power line carrier communication, and is suitable for the high-speed reliable transmission requirement under the fusion of the control business of the power system.
Referring to fig. 4, fig. 4 shows a flowchart of a power line carrier communication method according to an embodiment of the present invention, and as shown in fig. 4, the method is performed by a receiving end, and includes:
S410, receiving symbol signals sent by a plurality of power line carrier communication channels, wherein the generation process of the symbol signals is specifically as follows: acquiring service data generated by a power user under a time scale, wherein the service data is a serial data stream composed of N a bit symbols, and N a represents the number of sub-channels of an orthogonal frequency division multiplexing technology; transforming the serial data stream to N a sub-channels in parallel, and performing QAM keying modulation on the service data in each sub-channel to obtain a data signal of each sub-channel; the data signal of each sub-channel is subjected to frequency hopping modulation to obtain a plurality of paths of frequency hopping modulation signals, wherein the frequency hopping modulation comprises the following specific steps: presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, and controlling the frequency of the data signal of each sub-channel to randomly hop by combining a frequency hopping multiple access technology on the basis of the frequency hopping sequence set; and summing the multipath frequency hopping modulation signals to obtain the symbol signals processed by the mixed processing of the orthogonal frequency division multiplexing technology and the frequency hopping multiple access technology.
Specifically, assuming that K control services in the power grid are accessed through a PLC channel, and a transmission signal is affected by PLC multipath frequency selective fading (as shown in fig. 1) and additive background/impulse noise, a multi-service access sub-channel frequency hopping OFDM PLC system reception signal is expressed as: Where τ k represents the relative delay of the access system for service k. n I(t)+nB (t) represents the sum of background noise and impulse noise, Representing PLC channel frequency pointsThe upper channel meets the frequency attenuation characteristic H (f) in the time domain impulse response and the frequency domain.
S420, in each branch of the orthogonal frequency division multiplexing technology, utilizing a frequency hopping sequence set of the expected user to perform the frequency hopping so as to obtain a frequency hopping signal of each branch of the expected user; s430, carrying out coherent demodulation on the debounced signals of each branch to obtain multipath debounced QAM signals; s440, converting the multipath de-hopped QAM signal into a serial data group by a parallel-serial conversion mode; s450, extracting orthogonal vectors of the real part and the imaginary part of each serial data in the serial data group, and judging the orthogonal vectors by utilizing a maximum likelihood judgment criterion to obtain service data generated by each power user under the time scale.
For the four steps of steps S420-S450 in this embodiment, the processes of frequency hopping signal demodulation, OFDM demodulation and QAM demodulation are all known in the art, and since the inventive concept of the present invention does not reside in demodulation of the signal receiving end, the demodulation process of the receiving end will not be described in detail. Only the signal processing procedure in the sub-channel hopping OFDM PLC receiver side block diagram shown in fig. 2 will be briefly described. The method comprises the following steps:
As can be seen from the system block diagram of the receiving end shown in fig. 2, first, the received signal r (t) is sent to an OFDM correlator bank having N a branches, and each branch is debounced with r (t); without loss of generality, the first user is sent as the desired user, and the local hopping sequence of the receiving end is completely synchronized with the sending end of the user 1 (i.e. the hopping sequence of the receiving end and the hopping sequence of the first user Completely consistent) and the relative access delay for that user is 0. After the signal processing of the receiving end, the signal on the mth receiving end branch at the ith moment can be expressed as:
The signal processing is carried out on each receiving branch, parallel/serial change is carried out, a serial data group Z i＝[Z0,m,Z1,m,…,ZNa-1,m at the ith moment can be obtained, the real part and the imaginary part of each data are taken, the real part and the imaginary part of the orthogonal vector are judged by utilizing the maximum likelihood judgment criterion, and thus, the signal data sent by a sending end can be recovered at a receiving end
In some embodiments, the maximum likelihood decision criteria are specifically: and solving the Euclidean distance between the quadrature vector of the real part and the imaginary part of each serial data and the QAM signal, and taking the minimum Euclidean distance as a maximum likelihood judgment criterion.
Specifically, solving two-way orthogonal vectors of real part and imaginary part of serial dataThe Euclidean distance of the reference signal vector s m modulated by QAM is s m corresponding to the minimum Euclidean distance as the detection result of the receiver detector, namelyWherein, Representing all sets of vectors of the QAM modulated reference signal.
The two formulas describe the signal processing flow of the receiving end of the sub-channel hopping OFDMAPLC in this embodiment. From the above analysis, it can be seen that the frequency hopping strategy of the user determines how the first symbol signal uses the frequency band resource of the PLC channel, which plays a vital role in the performance of the PLC system. And then combining the frequency hopping strategy (frequency hopping sequence set) which is constructed based on the optimal base sequence, the cascade extension and the channel quality attenuation quantization and is matched with the PLC channel attenuation, thereby fully utilizing the limited PLC bandwidth and achieving the optimal error rate performance and the frequency efficiency.
Aiming at the power line carrier communication method executed at the transmitting end and the receiving end provided by the embodiment, the embodiment of the invention also analyzes the communication performance of the power line carrier communication method, and specifically comprises the following steps: the Matlab simulation method is adopted to study the transmission performance of the novel sub-channel frequency hopping OFDM PLC system. The multipath PLC fading channel adopts a 4-path attenuation model shown in fig. 1, and is assumed to be equally divided into Na=8 physical sub-frequency bands for Na OFDM sub-channels after the whole PLC frequency band [0.3MHz,20MHz ] is removed, each sub-channel also contains q=7 mutually-misaligned sub-frequency points, and the frequency interval between the sub-frequency points is f d. For comparison, the present embodiment performs simulation comparison on the conventional OFDM PLC system, the existing OFDM overall frequency hopping PLC system, and the subcarrier frequency hopping OFDMA PLC system proposed in the present patent. The parameters of these frequency hopping strategies are consistent with those proposed in this embodiment.
Fig. 5 shows the error rate curve of a single service PLC communication system based on subcarrier frequency hopping OFDM. From the simulation graph, the new frequency hopping strategy subcarrier frequency hopping OFDM scheme provided by the embodiment has the lowest error rate performance, and the error rate of the traditional OFDM PLC system is the highest. This means that the signal processing and transmission scheme performed by applying FH to OFDM subcarriers in the PLC system is an effective scheme. Compared with the OFDM/FHMA technology adopting the traditional pseudo-random frequency hopping strategy, the subcarrier frequency hopping OFDM PLC system provided by the embodiment has 7dB signal-to-noise ratio gain. The embodiment provides that the flexibility of subcarrier frequency hopping is higher, the PLC deep interference frequency band can be effectively avoided, in addition, the new frequency hopping strategy is matched with the PLC channel fading quality, information is transmitted by fully utilizing the differentiation of the PLC channel quality, and the influence of a poor channel on the system performance can be further reduced.
Fig. 6 shows a comparison of error rates (m=10) of a multi-service asynchronous access OFDM/FHMAPLC communication system. The bit error rate curve law is basically similar to the conclusion of fig. 6: the novel frequency hopping strategy OFDM/FHMA scheme provided by the embodiment has optimal performance (compared with the whole frequency hopping PLC of OFDM, the novel frequency hopping strategy OFDM/FHMA scheme has 12dB signal-to-noise ratio gain). The signal-to-noise ratio gain obtained by the embodiment is from subcarrier frequency hopping to avoid deep fading on one hand; on the other hand, the designed frequency hopping strategy is matched with the quality of the PLC channel, has smaller mutual collision (i.e. less multi-user interference), and the traditional frequency hopping strategy does not have the two advantages. When the channel ratio SNR increases sufficiently (SNR >40 dB), the bit error rate curve exhibits a BER plateau, and the BER plateau of the PLC system of the present embodiment is lower.
Fig. 7 analyzes the spectral efficiency of the subcarrier frequency hopping OFDMA PLC system. The frequency hopping strategy provided by the embodiment can fully utilize all frequency bands of the PLC channel, and each frequency band is used according to the quality of the PLC channel, so that the frequency band use strategy is more flexible, and the frequency spectrum efficiency is higher than that of other PLC transmission schemes. Simulation researches of fig. 5 to 7 prove that the subcarrier frequency hopping OFDMA PLC transmission scheme and the PLC channel quality matching frequency hopping strategy thereof provided by the embodiment can provide multi-service multiplexing access for a PLC communication system, and simultaneously ensure better transmission quality and spectrum efficiency.
Simulation verification of the performance analysis is mainly performed by analyzing and explaining the performance of the subcarrier frequency hopping OFDMA PLC system under the 4-path PLC fading channel. For other multipath PLC channel conditions under the fixed power grid topological structure, channel gains can be known in advance through channel monitoring and estimation, and the subcarrier frequency hopping OFDMA PLC transmission scheme and the PLC channel quality matching frequency hopping pattern design method designed in the embodiment are still effective and are not described in detail herein.
The embodiment of the invention also provides a transmitting end, which comprises the following steps:
The data acquisition module is used for acquiring service data generated by an electric power user under a time scale, wherein the service data is a serial data stream composed of N a bit symbols, and N a represents the number of sub-channels of an orthogonal frequency division multiplexing technology;
The keying modulation module is used for converting the serial data stream to N a sub-channels in parallel, and performing QAM keying modulation on the service data in each sub-channel to obtain a data signal of each sub-channel;
The frequency hopping modulation module is used for carrying out frequency hopping modulation on the data signal of each sub-channel to obtain a plurality of paths of frequency hopping modulation signals, wherein the frequency hopping modulation specifically comprises the following steps: presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, and controlling the frequency of the data signal of each sub-channel to randomly hop by combining a frequency hopping multiple access technology on the basis of the frequency hopping sequence set;
The signal summation module is used for summing the multipath frequency hopping modulation signals to obtain a symbol signal which is processed by mixing an orthogonal frequency division multiplexing technology and a frequency hopping multiple access technology;
And a transmitting module for coupling the symbol signal to the power line carrier communication channel.
It can be appreciated that, for a power line carrier communication method performed by the transmitting end provided in this embodiment, reference may be made to the embodiments and the relevant portions of S310 to S350 shown in fig. 3 provided above, which are not described herein.
The embodiment of the invention also provides a receiving end, which comprises:
The receiving module is used for receiving the symbol signals sent by the power line carrier communication channels, wherein the generation process of the symbol signals is specifically as follows: acquiring service data generated by a power user under a time scale, wherein the service data is a serial data stream composed of N a bit symbols, and N a represents the number of sub-channels of an orthogonal frequency division multiplexing technology; transforming the serial data stream to N a sub-channels in parallel, and performing QAM keying modulation on the service data in each sub-channel to obtain a data signal of each sub-channel; the data signal of each sub-channel is subjected to frequency hopping modulation to obtain a plurality of paths of frequency hopping modulation signals, wherein the frequency hopping modulation comprises the following specific steps: presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, and controlling the frequency of the data signal of each sub-channel to randomly hop by combining a frequency hopping multiple access technology on the basis of the frequency hopping sequence set; summing the multipath frequency hopping modulation signals to obtain a symbol signal processed by mixing an orthogonal frequency division multiplexing technology and a frequency hopping multiple access technology;
The system comprises a de-hopping module, a receiving module and a receiving module, wherein the de-hopping module is used for de-hopping by utilizing a frequency hopping sequence set of an expected user in each branch of an orthogonal frequency division multiplexing technology to obtain a de-hopping signal of each branch of the expected user;
The demodulation module is used for carrying out coherent demodulation on the debounced signals of each branch to obtain multipath debounced QAM signals;
the conversion module is used for converting the multipath de-hopped QAM signals into serial data groups in a parallel-serial conversion mode;
And the judging module is used for extracting orthogonal vectors of the real part and the imaginary part of each serial data in the serial data group, judging the orthogonal vectors by utilizing the maximum likelihood judging criterion and obtaining service data generated by each power user under the time scale.
It can be appreciated that, for the power line carrier communication method performed by the receiving end provided in this embodiment, reference may be made to the embodiments S410 to S450 and the related parts provided in fig. 4, which are not described herein.
The embodiment of the invention also provides a power line carrier communication system, which is characterized by comprising:
a transmitting end configured to implement a power line carrier communication method shown in fig. 3;
A receiving end configured to implement a power line carrier communication method shown in fig. 4.
It can be appreciated that, in the power line carrier communication system provided in this embodiment, reference may be made to the embodiments and the associated parts provided above and illustrated in S310 to S350 in fig. 3, and the embodiments and the associated parts illustrated in S410 to S450 in fig. 4, which are not described herein.
The embodiment of the invention also provides a storage medium, wherein the storage medium is stored with instructions, and when the instructions run on a processor, the processor is caused to execute any one of the power line carrier communication methods. Optionally, the storage medium is an electronic storage medium. The storage medium described above is optionally a computer-readable storage medium, but may be a storage medium readable by other apparatuses. Alternatively, the storage medium may be a non-transitory (non-transitory) storage medium, but may also be a transitory storage medium. Such as a storage medium disposed at the transmitting end, for storing program instructions of a power line carrier communication method performed by the transmitting end. Also for example, a storage medium disposed at the receiving end for storing program instructions of the power line carrier communication method performed by the receiving end.
The embodiment of the invention also provides a program product, which when being executed by a processor, causes the processor to execute any one of the power line carrier communication methods. Optionally, the above-described program product is a computer program product.
The embodiments of the present invention also provide a computer program which, when run on a processor, causes the processor to perform any of the above power line carrier communication methods.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (8)
1. A power line carrier communication method, performed by a transmitting end, the method comprising:
Acquiring service data generated by a power user under a time scale, wherein the service data is a serial data stream composed of N a bit symbols, and N a represents the number of sub-channels of an orthogonal frequency division multiplexing technology;
Transforming the serial data stream to N a sub-channels in parallel, and performing QAM keying modulation on the service data in each sub-channel to obtain a data signal of each sub-channel;
The data signal of each sub-channel is subjected to frequency hopping modulation to obtain a plurality of paths of frequency hopping modulation signals, wherein the frequency hopping modulation comprises the following specific steps: presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, and controlling the frequency of the data signal of each sub-channel to randomly hop by combining a frequency hopping multiple access technology on the basis of the frequency hopping sequence set; the method comprises the steps of presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, wherein the frequency hopping sequence set comprises the following steps: removing deep fading frequency points in a transfer function of a power line carrier communication channel to obtain a power line carrier communication frequency band formed by non-deep fading frequency points; equally dividing a power line carrier communication frequency band into N a sub-frequency bands, wherein each sub-frequency band contains q sub-frequency points, and N a and q are positive integers; generating prime frequency hopping sequence groups matched with a center frequency point set formed by q sub-frequency points, and performing m-time cascade expansion on the prime frequency hopping sequence groups to obtain a frequency hopping sequence set formed by k frequency hopping sequences and m prime frequency hopping sequence groups; wherein the utilization rate of the frequency hopping points of the frequency hopping sequence set is related to the attenuation characteristic of the transfer function of the power line carrier communication channel, and k and m are positive integers;
The cascade extension is carried out on the prime frequency hopping sequence family for m times to obtain k frequency hopping sequences, wherein the k frequency hopping sequences are specifically as follows:
kth hopping sequence: wherein P represents prime frequency hopping sequence family, Q represents frequency hopping sequence set; l represents the length of the hopping sequence;
Further comprises: setting the corresponding use times condition of each frequency point of the center frequency point set, wherein the use times of q sub-frequency points of the center frequency point set are sequentially decreased; in each frequency hopping sequence of the k frequency hopping sequences, replacing the sub-frequency point with the least use frequency with the sub-frequency point with the most use frequency according to the descending order of the central frequency point set, repeating the replacement until the given use frequency condition is met, and obtaining k frequency hopping sequences matched with the transfer function of the power line carrier communication channel;
summing the multipath frequency hopping modulation signals to obtain a symbol signal processed by mixing an orthogonal frequency division multiplexing technology and a frequency hopping multiple access technology;
The symbol signal is coupled to a power line carrier communication channel.
2. The power line carrier communication method according to claim 1, wherein the symbol signal has an expression of: nT is less than or equal to T is less than or equal to (n+1) T, wherein N a represents the number of parallel sub-channels of an orthogonal frequency division multiplexing technology, N represents a time scale, Bit data representing the ith sub-channel, P representing the kth power-user transmit power, T representing the time width of the first symbol signal, f d representing the bandwidth of the orthogonal frequency division multiplexing sub-channel,The value is determined by a preset frequency hopping sequence set for the frequency hopping frequency point used on the first sub-channel of the node k; t represents a time scale, k represents a power consumer, and f l represents a starting frequency point of the first sub-channel.
3. A power line carrier communication method, performed by a receiving end, the method comprising:
Receiving symbol signals transmitted from a plurality of power line carrier communication channels, wherein the generation process of the symbol signals is specifically as follows: acquiring service data generated by a power user under a time scale, wherein the service data is a serial data stream composed of N a bit symbols, and N a represents the number of sub-channels of an orthogonal frequency division multiplexing technology; transforming the serial data stream to N a sub-channels in parallel, and performing QAM keying modulation on the service data in each sub-channel to obtain a data signal of each sub-channel; the data signal of each sub-channel is subjected to frequency hopping modulation to obtain a plurality of paths of frequency hopping modulation signals, wherein the frequency hopping modulation comprises the following specific steps: presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, and controlling the frequency of the data signal of each sub-channel to randomly hop by combining a frequency hopping multiple access technology on the basis of the frequency hopping sequence set; summing the multipath frequency hopping modulation signals to obtain a symbol signal processed by mixing an orthogonal frequency division multiplexing technology and a frequency hopping multiple access technology; the method comprises the steps of presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, wherein the frequency hopping sequence set comprises the following steps: removing deep fading frequency points in a transfer function of a power line carrier communication channel to obtain a power line carrier communication frequency band formed by non-deep fading frequency points; equally dividing a power line carrier communication frequency band into N a sub-frequency bands, wherein each sub-frequency band contains q sub-frequency points, and N a and q are positive integers; generating prime frequency hopping sequence groups matched with a center frequency point set formed by q sub-frequency points, and performing m-time cascade expansion on the prime frequency hopping sequence groups to obtain a frequency hopping sequence set formed by k frequency hopping sequences and m prime frequency hopping sequence groups; wherein the utilization rate of the frequency hopping points of the frequency hopping sequence set is related to the attenuation characteristic of the transfer function of the power line carrier communication channel, and k and m are positive integers;
The cascade extension is carried out on the prime frequency hopping sequence family for m times to obtain k frequency hopping sequences, wherein the k frequency hopping sequences are specifically as follows:
kth hopping sequence: wherein P represents prime frequency hopping sequence family, Q represents frequency hopping sequence set; l represents the length of the hopping sequence;
Further comprises: setting the corresponding use times condition of each frequency point of the center frequency point set, wherein the use times of q sub-frequency points of the center frequency point set are sequentially decreased; in each frequency hopping sequence of the k frequency hopping sequences, replacing the sub-frequency point with the least use frequency with the sub-frequency point with the most use frequency according to the descending order of the central frequency point set, repeating the replacement until the given use frequency condition is met, and obtaining k frequency hopping sequences matched with the transfer function of the power line carrier communication channel;
in each branch of the orthogonal frequency division multiplexing technology, utilizing a frequency hopping sequence set of the expected user to perform frequency hopping so as to obtain a frequency hopping signal of each branch of the expected user;
performing coherent demodulation on the debounced signals of each branch to obtain multipath debounced QAM signals;
converting the multipath de-hopped QAM signals into serial data groups in a parallel-serial conversion mode;
And extracting orthogonal vectors of the real part and the imaginary part of each serial data in the serial data group, and judging the orthogonal vectors by utilizing a maximum likelihood judgment criterion to obtain service data generated by each power user under the time scale.
4. The power line carrier communication method according to claim 3, wherein the maximum likelihood decision criterion is specifically: and solving the Euclidean distance between the quadrature vector of the real part and the imaginary part of each serial data and the QAM signal, and taking the minimum Euclidean distance as a maximum likelihood judgment criterion.
5. A transmitting terminal, comprising:
The data acquisition module is used for acquiring service data generated by an electric power user under a time scale, wherein the service data is a serial data stream composed of N a bit symbols, and N a represents the number of sub-channels of an orthogonal frequency division multiplexing technology;
The keying modulation module is used for converting the serial data stream to N a sub-channels in parallel, and performing QAM keying modulation on the service data in each sub-channel to obtain a data signal of each sub-channel;
The frequency hopping modulation module is used for carrying out frequency hopping modulation on the data signal of each sub-channel to obtain a plurality of paths of frequency hopping modulation signals, wherein the frequency hopping modulation specifically comprises the following steps: presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, and controlling the frequency of the data signal of each sub-channel to randomly hop by combining a frequency hopping multiple access technology on the basis of the frequency hopping sequence set; the method comprises the steps of presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, wherein the frequency hopping sequence set comprises the following steps: removing deep fading frequency points in a transfer function of a power line carrier communication channel to obtain a power line carrier communication frequency band formed by non-deep fading frequency points; equally dividing a power line carrier communication frequency band into N a sub-frequency bands, wherein each sub-frequency band contains q sub-frequency points, and N a and q are positive integers; generating prime frequency hopping sequence groups matched with a center frequency point set formed by q sub-frequency points, and performing m-time cascade expansion on the prime frequency hopping sequence groups to obtain a frequency hopping sequence set formed by k frequency hopping sequences and m prime frequency hopping sequence groups; wherein the utilization rate of the frequency hopping points of the frequency hopping sequence set is related to the attenuation characteristic of the transfer function of the power line carrier communication channel, and k and m are positive integers;
The cascade extension is carried out on the prime frequency hopping sequence family for m times to obtain k frequency hopping sequences, wherein the k frequency hopping sequences are specifically as follows:
kth hopping sequence: wherein P represents prime frequency hopping sequence family, Q represents frequency hopping sequence set; l represents the length of the hopping sequence;
Further comprises: setting the corresponding use times condition of each frequency point of the center frequency point set, wherein the use times of q sub-frequency points of the center frequency point set are sequentially decreased; in each frequency hopping sequence of the k frequency hopping sequences, replacing the sub-frequency point with the least use frequency with the sub-frequency point with the most use frequency according to the descending order of the central frequency point set, repeating the replacement until the given use frequency condition is met, and obtaining k frequency hopping sequences matched with the transfer function of the power line carrier communication channel;
The signal summation module is used for summing the multipath frequency hopping modulation signals to obtain a symbol signal which is processed by mixing an orthogonal frequency division multiplexing technology and a frequency hopping multiple access technology;
And a transmitting module for coupling the symbol signal to the power line carrier communication channel.
6. A receiving terminal, comprising:
The receiving module is used for receiving the symbol signals sent by the power line carrier communication channels, wherein the generation process of the symbol signals is specifically as follows: acquiring service data generated by a power user under a time scale, wherein the service data is a serial data stream composed of N a bit symbols, and N a represents the number of sub-channels of an orthogonal frequency division multiplexing technology; transforming the serial data stream to N a sub-channels in parallel, and performing QAM keying modulation on the service data in each sub-channel to obtain a data signal of each sub-channel; the data signal of each sub-channel is subjected to frequency hopping modulation to obtain a plurality of paths of frequency hopping modulation signals, wherein the frequency hopping modulation comprises the following specific steps: presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, and controlling the frequency of the data signal of each sub-channel to randomly hop by combining a frequency hopping multiple access technology on the basis of the frequency hopping sequence set; summing the multipath frequency hopping modulation signals to obtain a symbol signal processed by mixing an orthogonal frequency division multiplexing technology and a frequency hopping multiple access technology; the method comprises the steps of presetting a frequency hopping sequence set for controlling the frequency point hopping of the power user on each sub-channel, wherein the frequency hopping sequence set comprises the following steps: removing deep fading frequency points in a transfer function of a power line carrier communication channel to obtain a power line carrier communication frequency band formed by non-deep fading frequency points; equally dividing a power line carrier communication frequency band into N a sub-frequency bands, wherein each sub-frequency band contains q sub-frequency points, and N a and q are positive integers; generating prime frequency hopping sequence groups matched with a center frequency point set formed by q sub-frequency points, and performing m-time cascade expansion on the prime frequency hopping sequence groups to obtain a frequency hopping sequence set formed by k frequency hopping sequences and m prime frequency hopping sequence groups; wherein the utilization rate of the frequency hopping points of the frequency hopping sequence set is related to the attenuation characteristic of the transfer function of the power line carrier communication channel, and k and m are positive integers;
The cascade extension is carried out on the prime frequency hopping sequence family for m times to obtain k frequency hopping sequences, wherein the k frequency hopping sequences are specifically as follows:
kth hopping sequence: wherein P represents prime frequency hopping sequence family, Q represents frequency hopping sequence set; l represents the length of the hopping sequence;
Further comprises: setting the corresponding use times condition of each frequency point of the center frequency point set, wherein the use times of q sub-frequency points of the center frequency point set are sequentially decreased; in each frequency hopping sequence of the k frequency hopping sequences, replacing the sub-frequency point with the least use frequency with the sub-frequency point with the most use frequency according to the descending order of the central frequency point set, repeating the replacement until the given use frequency condition is met, and obtaining k frequency hopping sequences matched with the transfer function of the power line carrier communication channel;
The system comprises a de-hopping module, a receiving module and a receiving module, wherein the de-hopping module is used for de-hopping by utilizing a frequency hopping sequence set of an expected user in each branch of an orthogonal frequency division multiplexing technology to obtain a de-hopping signal of each branch of the expected user;
The demodulation module is used for carrying out coherent demodulation on the debounced signals of each branch to obtain multipath debounced QAM signals;
the conversion module is used for converting the multipath de-hopped QAM signals into serial data groups in a parallel-serial conversion mode;
And the judging module is used for extracting orthogonal vectors of the real part and the imaginary part of each serial data in the serial data group, judging the orthogonal vectors by utilizing the maximum likelihood judging criterion and obtaining service data generated by each power user under the time scale.
7. A power line carrier communication system, comprising:
A transmitting end configured to implement the power line carrier communication method according to any one of claims 1 to 2;
a receiving end configured to implement the power line carrier communication method as claimed in any one of claims 3 to 4.
8. A storage medium, characterized in that, the storage medium stores instructions; the power line carrier communication method of any one of claims 1 to 2 and 3 to 4, when the instructions are run on a processor.
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