Power line carrier communication system and method based on extended frequency band

Abstract

The application discloses a power line carrier communication system and method based on an extended frequency band, and relates to the technical field of power line carrier communication; and is used for solving the problems of low spectrum efficiency and insufficient communication rate caused by the fixed frequency band configuration of the existing low-voltage area carrier communication; the application comprises a concentrator, a channel detection module, a frequency band selection module, a path planning module and a dynamic loading unit arranged in a communication node; the channel detection module extracts characteristic parameters such as background noise, interference intensity and link attenuation of the communication node in each frequency band; the frequency band selection module calculates the theoretical maximum rate of each frequency band based on a Shannon formula to obtain prior coefficients of each frequency band; the path planning module selects an optimal frequency band and a transmission path for a data transmission task in combination with real-time load information and the prior coefficients; and the dynamic loading unit dynamically adjusts the modulation order and the transmission power in the selected frequency band according to real-time subcarrier level channel states; and the application realizes adaptive selection of the frequency band and dynamic loading of bits.

Description

Technical Field

[0001] This invention relates to the field of power line carrier communication technology, specifically to a power line carrier communication system and method based on extended frequency bands. Background Technology

[0002] Power line carrier communication (PLC) is a technology that uses existing power cables as the transmission medium to achieve data communication. This technology transmits and receives data by superimposing high-frequency carrier signals onto power lines without affecting normal power transmission. With the rapid development of new power systems, the role of PLC has expanded from early single-function remote meter reading to a wider range of applications. Currently, this technology not only supports marketing and metering businesses such as electricity information collection and fee control management, but is also widely used in distribution network monitoring, automatic topology identification, and rapid power outage fault handling. Especially in emerging business areas such as distributed photovoltaic grid connection, energy storage equipment regulation, and charging pile group management and control, PLC plays a significant role in improving grid operating efficiency, ensuring power supply reliability, and promoting the consumption of new energy sources. Current broadband carrier communication standards stipulate that a fixed communication frequency band must be used uniformly within a low-voltage distribution area, and a single frequency band configuration method must be adopted. This means that all communication nodes in the entire distribution area must use the same frequency band to ensure that even the most peripheral nodes in the network can communicate. However, this comes at the cost of sacrificing spectrum efficiency. As a result, even nodes with good channel quality, which could have used a wider range of high-frequency bands to achieve high-speed transmission, cannot use this method due to the limitation of the uniform frequency band across the entire distribution area. Summary of the Invention

[0003] In view of the problems in the related technologies, the present invention provides a power line carrier communication system based on extended frequency bands to overcome the technical problems existing in the prior art.

[0004] To solve the aforementioned technical problem, the present invention is achieved through the following technical solution: On one hand, the present invention provides a power line carrier communication system based on extended frequency bands, specifically including: The concentrator periodically broadcasts channel probe frames to obtain analog signals from each communication node; The channel detection module is used to perform feature analysis based on the analog signal to obtain the characteristic parameters of the communication node and the communication link in each frequency band. The characteristic parameters include the background noise power and interference intensity of the communication node, as well as the attenuation value of the communication link in each frequency band. The frequency band detection module is used to calculate prior coefficients for each communication link based on the feature parameters. The prior coefficients are the maximum information transmission rates of the communication links on each frequency band, and the prior coefficients are updated periodically. The path planning module is used to select a target transmission path for each data transmission task based on the prior coefficients and the load parameters of the communication link in real time on each frequency band, and to allocate the optimal frequency band for each hop on the path. The dynamic loading unit, deployed inside each communication node, is used to dynamically adjust the modulation order and transmit power of each subcarrier within the optimal frequency band based on the real-time subcarrier and channel status.

[0005] Preferably, the analysis process for the background noise power and interference intensity of the communication node includes: The analog signal is converted into a discrete time-domain sequence using a digital-to-analog converter, and then windowed and subjected to a Fast Fourier Transform to convert it to the frequency domain, obtaining the complex value X(f) for each frequency point, which corresponds to a subcarrier; the power spectral density P(f) = |X(f)| on each subcarrier is calculated. 2 / (R×Δf), where R is the receiver input impedance and Δf is the subcarrier spacing; for ease of subsequent calculation, its unit is converted to decibels per hertz. The measurement is repeated at different times, and the power spectral density of each subcarrier is averaged over time to obtain the average background noise power spectral density; at the same time, the peak noise power on each subcarrier is recorded. For each subcarrier, its long-term average power spectral density is taken as the background noise power of the subcarrier. The background noise power of all subcarriers in the frequency band is averaged to obtain the background noise power of the frequency band. For each subcarrier, the instantaneous power is compared with the background noise power. If the instantaneous power minus the background noise power is greater than the preset noise interference threshold, then the instantaneous power minus the background noise power is taken as the interference power of the affected subcarrier. Then, the interference power of all subcarriers in the frequency band is averaged to obtain the interference intensity of the frequency band.

[0006] Preferably, the analysis process for the attenuation value of the communication link in each frequency band includes: Extract historical communication records, which include the sending and receiving nodes corresponding to the communication link in each communication record, the receiving time, the frequency band identifier used by the signal, the receiving power of each subcarrier of the receiving node in the frequency band, and the transmitting power used by the sending node when transmitting the signal; The interval time is calculated by subtracting the reception time of each record from the current system time. If the interval time is greater than a preset timeliness threshold, the record is discarded; only records with an interval time less than or equal to the preset timeliness threshold are retained. For each retained record, the set of subcarriers included in the frequency band is determined according to the frequency band used. If uniform power allocation is used, the transmission power of each subcarrier is the total transmission power divided by the number of subcarriers; if dynamic power allocation is used, the transmission power of each subcarrier is extracted from the frame header. For each subcarrier, the signal attenuation on the subcarrier is calculated according to the following formula: d = 10 × log10 (Transmit power) -10×log 10 (Received power), the unit of attenuation d is decibel; take the arithmetic mean of the attenuation of all subcarriers in the frequency band to obtain the average attenuation in the frequency band; thus, the average attenuation of each record can be obtained. For the same link in the same frequency band, all average attenuations are sorted in descending order, and the median is selected as the attenuation value of the communication link in that frequency band. Thus, the attenuation value of each communication link in each frequency band can be obtained.

[0007] Preferably, calculating prior coefficients for each communication link based on the feature parameters includes: The noise floor is calculated by summing the background noise power and interference intensity at the receiving node in the communication link. The noise floor is then converted from decibels to watts. Next, the maximum transmit power of the transmitting node in the communication link is calculated, and the maximum receive power of the receiving node after frequency band attenuation is calculated using the formula: P B =P A，max ×10 -D / 10 Where A represents the sending node, B represents the receiving node, and P... A，max The maximum transmit power of the transmitting node is represented by watts; D is the attenuation value of the communication link in the specified frequency band, in decibels; the signal-to-noise ratio (SNR) is obtained by dividing the maximum receive power of the receiving node B by the noise floor. b ; According to Shannon's formula, the maximum information transmission rate r achievable by receiving node B in a certain frequency band is calculated. b =W b ×log2(1+S) b ), where W b Let b be the width of frequency band b on the frequency axis, and b be the frequency band index; the maximum information transmission rate is used as the prior coefficient of the communication link on each frequency band.

[0008] Preferably, the path planning module includes: The load parameters of the communication link on each frequency band are acquired in real time. The load parameters include the amount of data to be transmitted, the proportion of actual occupied time in the most recent fixed time period, and the retransmission rate. The congestion ratio is obtained by normalizing the amount of data to be transmitted, and the congestion ratio, the proportion of actual occupied time, and the retransmission rate are linearly weighted and fused to obtain a load index with a value range of [0,1]. The prior coefficients are reduced by the load index to obtain the posterior coefficients, and the frequency band with the largest posterior coefficient is selected as the optimal frequency band for the communication link. Based on the source node and target node of the data transmission task, a limited breadth-first search or Dijkstra's algorithm is used to generate candidate transmission paths that do not exceed the preset maximum number of hops. The posterior coefficients of each communication link on the candidate path in the optimal frequency band are aggregated to obtain the transmission index that quantifies the transmission capacity of the candidate path, and the target transmission path is selected according to the service type of the data transmission task.

[0009] Preferably, the aggregation of the posterior coefficients is performed using a minimum value model, that is, the transmission index is obtained by taking the minimum value of the posterior coefficients of each communication link in the candidate path in the optimal frequency band.

[0010] Preferably, selecting the target transmission path based on the service type of the data transmission task includes: When the data transmission task is a second-level or minute-level task, the candidate transmission path with the largest transmission index is selected as the target transmission path; when the data transmission task is an emergency reporting task, the ratio of the transmission index to the number of hops of each candidate path is calculated as the energy efficiency index, and the candidate transmission path with the largest energy efficiency index is selected as the target transmission path. After determining the optimal frequency band and target transmission path, transmission is performed sequentially according to the set priority.

[0011] Preferably, the sequential transmission according to the set priority includes: Priority queues are set up on each communication link, with urgent reporting tasks having the highest transmission priority, followed by second-level tasks, and minute-level tasks having the lowest priority. When there is an urgent reporting task, it is directly transmitted at the top; otherwise, it is transmitted in batches according to fixed time periods. Within the same batch, it is transmitted in order of service priority, and within the same service type, it is transmitted in order of time.

[0012] Preferably, the dynamic loading unit includes: Before data transmission, the background noise power, interference power, and subcarrier attenuation of each subcarrier in the current optimal frequency band are obtained, and the signal-to-noise ratio (SNR) of each subcarrier is calculated. With a preset target bit error rate as a constraint, the Chow algorithm is used to assign a modulation order and power adjustment factor to each subcarrier, generating a modulation parameter table. The modulation mode index or predefined configuration mode number of the modulation parameter table is placed in the frame control header of the data frame to be transmitted. After successfully demodulating the data, the receiving node carries the latest subcarrier SNR and bit error rate back to the transmitting node via a feedback frame. The transmitting node re-executes the modulation parameter table generation process based on the feedback information and monitors the bit error rate to dynamically adjust the overall transmit power.

[0013] On the other hand, the present invention provides a power line carrier communication method based on extended frequency bands, specifically including the following steps: Step 1: Periodically broadcast channel probe frames to obtain analog signals from each communication node; Step 2: Perform feature analysis based on the analog signal to obtain the characteristic parameters of the communication node and communication link in each frequency band. The characteristic parameters include the background noise power and interference intensity of the communication node, as well as the attenuation value of the communication link in each frequency band. Step 3: Calculate prior coefficients for each communication link based on the feature parameters. The prior coefficients are the maximum information transmission rates of the communication links in each frequency band, and update the prior coefficients periodically. Step 4: Based on the prior coefficients and the real-time acquired load parameters of the communication link on each frequency band, select a target transmission path for each data transmission task and allocate the optimal frequency band for each hop on the path. Step 5: Within the optimal frequency band, dynamically adjust the modulation order and transmit power of each subcarrier according to the real-time subcarrier-level channel status.

[0014] The present invention has the following beneficial effects: 1. By periodically broadcasting probe frames and passively listening to communication nodes, power spectrum estimation and interference identification are performed on each subcarrier in the frequency band. Historical communication records are used for passive channel estimation. Without increasing the additional probe traffic, characteristic parameters of background noise, interference intensity and link attenuation of communication nodes in each frequency band are obtained. The channel state is comprehensively described from two dimensions: the local environment of the node and the transmission interference of the link, providing a rich data foundation for frequency band selection and path planning.

[0015] 2. Based on Shannon's formula, and taking into account the noise floor, signal attenuation, and bandwidth of the receiving node in the communication link, the maximum achievable information transmission rate on each frequency band is calculated. The prior coefficients of each frequency band are periodically updated, enabling the system to respond promptly to changes in the channel environment. The prior coefficients provide a unified and quantifiable evaluation basis for link quality comparison and path selection in the path planning module.

[0016] 3. By collecting the amount of data to be transmitted, the proportion of time occupied, and the retransmission rate of each link on each frequency band in real time, and performing comprehensive analysis to obtain the load index, the posterior coefficient is obtained by subtracting the prior coefficient from the load index. The frequency band with the largest posterior coefficient is selected as the optimal frequency band, so that the transmission path selection can avoid congested frequency bands and achieve network load balancing. At the same time, different path selection strategies are designed for transmission tasks of different service types. Specific tasks at the second and minute levels pursue the maximum transmission index, while emergency reporting tasks pursue the maximum energy efficiency index, effectively meeting the differentiated requirements of different services for latency, reliability, and throughput. After each data transmission task is assigned, the amount of data to be transmitted on the corresponding link is updated immediately, so that the load information can be quickly fed back into the transmission path selection of subsequent tasks, forming a closed-loop congestion control process.

[0017] 4. By employing the Chow algorithm to assign each subcarrier the modulation scheme with the highest order that satisfies the target bit error rate, the system can adaptively adjust the transmission rate according to the real-time signal-to-noise ratio, carrying more bits on high-quality subcarriers and reducing bits on low-quality subcarriers, thereby approximating the channel capacity.

[0018] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, the drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 A block diagram of a power line carrier communication system based on extended frequency band is provided for this invention; Figure 2 A flowchart is provided for the present invention regarding a power line carrier communication method based on extended frequency bands. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Application Scenario: Current broadband carrier communication standards stipulate that a fixed communication frequency band is used uniformly within a low-voltage distribution area, employing a single-band configuration. This means that all communication nodes within the entire distribution area must use the same frequency band to ensure communication even for nodes at the network's periphery. However, this comes at the cost of sacrificing spectral efficiency. For example, nodes with good channel quality could utilize wider, higher-frequency bands for high-speed transmission, but this limitation prevents such transmission due to the uniform frequency band across the entire distribution area. Furthermore, with the transformation of new power systems, the physical layer communication rate of current broadband carrier communication is insufficient to support high-speed service requirements such as minute-level full data acquisition, second-level control, and batch concurrent control. To address these technical issues, this invention focuses on a low-voltage distribution area, consisting of a concentrator and several communication nodes. The system supports extended communication frequency bands, allocating an optimal operating frequency band for each communication link and dynamically allocating modulation orders for each subcarrier within the selected frequency band. Finally, data is transmitted under optimized frequency bands and modulation parameters, with continuous adaptive adjustments during transmission. This achieves adaptive frequency band selection and dynamic bit loading based on real-time channel quality, thereby fully utilizing extended frequency band resources and improving communication rate and spectral efficiency. To address the problems mentioned in the background section, such as Figure 1 As shown, this embodiment of the invention provides a power line carrier communication system based on extended frequency bands, specifically including: a concentrator, a channel detection module, a frequency band detection module, a path planning module, and a dynamic loading unit deployed in each communication node; The concentrator communicates with the channel detection module, frequency band detection module, path planning module, and each communication node. It is responsible for sending the optimal frequency band and target transmission path to the communication nodes. The concentrator sends a device capability registration request to all communication nodes, receives and records the capability parameters of each communication node, including the supported channel range and maximum transmit power. This capability registration is a one-time login. Once a communication node is determined, its corresponding capability parameters are also determined. When a communication node is changed, it needs to be re-registered. The concentrator periodically broadcasts channel probes to obtain analog signals from each communication node and sends them to the channel detection module. The channel detection module performs feature analysis based on the analog signals of the communication nodes to obtain the characteristic parameters of the communication nodes and communication links in each frequency band; the specific process includes: The analog signal is converted into a discrete time-domain sequence using a digital-to-analog converter (DAC), and then windowed and subjected to a Fast Fourier Transform (FFT) to convert it to the frequency domain, obtaining the complex value X(f) for each frequency point, which corresponds to an OFDM subcarrier. The power spectral density P(f) = |X(f)| on each subcarrier is then calculated. 2 / (R×Δf), where R is the receiver input impedance, typically 50Ω or 75Ω); Δf is the subcarrier spacing; it should be noted that the calculated power spectral density P(f) is in watts per hertz. For ease of subsequent calculations, its unit is converted to decibels per hertz. The conversion formula between decibels per hertz and watts per hertz is: dB=10×log 10 (Subcarrier power density); To eliminate the influence of transient burst interference, measurements are repeated at multiple different times, and the power spectral density of each subcarrier is averaged over time to obtain the average background noise power spectral density; At the same time, the peak noise power on each subcarrier is recorded to assess the interference intensity; For each subcarrier, its long-term average power spectral density is taken as the background noise power of that subcarrier, and the background noise power of all subcarriers in a certain frequency band is averaged to obtain the background noise power of that frequency band; For each subcarrier, the instantaneous power is compared with the background noise power. If the instantaneous power minus the background noise power is greater than the preset noise interference threshold (set to 10 dB in this embodiment), the subcarrier is considered to be interfered with. This interference is usually narrowband burst interference or transient noise from other devices. The instantaneous power minus the background noise power is then used as the interference power of the interfered subcarrier. The interference power of all subcarriers in the frequency band is then averaged to obtain the interference intensity of the frequency band. To reduce network overhead while accurately quantifying the attenuation of communication links formed by communication nodes in each frequency band, passive channel estimation quantization is performed using historical communication records. Specifically, this includes: extracting historical communication records, which contain the sending node ID and receiving node ID corresponding to the communication link in each record, the receiving time, the frequency band identifier used by the signal, the received power of each subcarrier of the receiving node within that frequency band, and the transmitting power used by the sending node when transmitting the signal. The transmitting power can be obtained from the frame control header or determined according to the system's default value. It should be noted that the communication link here refers to two communication nodes directly transmitting signals, with the communication node transmitting the signal acting as the sending node and the communication node receiving the signal acting as the receiving node. The difference between the receiving time of each record and the current system time is calculated to obtain the interval time. If the interval time is greater than the preset time limit (set to 24 hours in this embodiment), the record is considered outdated and cannot reflect the current channel state, and is therefore discarded. Only records with an interval time of less than or equal to 24 hours are retained. For each retained record, the set of subcarriers included in the frequency band used by the record is determined. If uniform power allocation is used, the transmission power of each subcarrier is the total transmission power divided by the number of subcarriers. If dynamic power allocation is used, the transmission power of each subcarrier is extracted from the frame header. For each subcarrier, the attenuation of the signal on that subcarrier is calculated according to the following formula: d = 10 × log 10(Transmit power) -10×log 10 (Received power), the unit of attenuation d is decibels; the arithmetic mean of the attenuation of all subcarriers in the frequency band is taken to obtain the average attenuation of the signal in the frequency band; thus, the average attenuation of each record can be obtained. For the same link in the same frequency band, all average attenuations are sorted in descending order, and the median is selected as the attenuation value of the communication link in the frequency band. Thus, the attenuation value of each communication link in each frequency band can be obtained; it should be noted that if the number of valid historical records of the same communication link in the same frequency band is less than the preset threshold, in this embodiment the preset threshold is set to 5 times, indicating that there are not enough valid communication records in the frequency band, so that the attenuation cannot be determined by the median, then the communication link is actively probed to supplement data, and the above attenuation calculation process is repeated to obtain the attenuation value of the communication link in the frequency band; The background noise power and interference intensity power of each communication node in each frequency band, as well as the attenuation of each communication link in each frequency band, are used as characteristic parameters of the communication node and communication link in each frequency band. At the same time, the background noise power, interference power, and average attenuation of the subcarriers in each frequency band within the communication link are used as channel state parameters and stored in the concentrator. By periodically broadcasting probe frames and passively listening to communication nodes, power spectrum estimation and interference identification are performed on each subcarrier in the frequency band. Historical communication records are used for passive channel estimation. Without increasing additional probe traffic, characteristic parameters of background noise, interference intensity and link attenuation of communication nodes in each frequency band are obtained. The channel state is comprehensively described from two dimensions: the local environment of the node and the transmission interference of the link, providing a rich data foundation for frequency band selection and path planning.

[0023] The frequency band detection module assigns prior coefficients to each communication link based on the characteristic parameters of the communication nodes and links in each frequency band. These prior coefficients are used to quantify the overall communication capability of the link, providing a basis for subsequent decisions such as path selection and frequency band allocation. The assignment process includes: The noise floor is calculated by summing the background noise power and interference intensity at the receiving node in the communication link. The noise floor is then converted from decibels to watts. Next, the maximum transmit power of the transmitting node in the communication link is calculated, and the maximum receive power of the receiving node after frequency band attenuation is calculated using the formula: P B =P A，max ×10 -D / 10 Where A represents the sending node, B represents the receiving node, and P... A，max The maximum transmit power of the transmitting node is represented by watts; D is the attenuation value of the communication link in the specified frequency band, in decibels; the signal-to-noise ratio (SNR) is obtained by dividing the maximum receive power of the receiving node B by the noise floor. bAccording to Shannon's formula, calculate the maximum information transmission rate r achievable by receiving node B in a certain frequency band. b =W b ×log2(1+S) b ), where W b Let b be the width of frequency band b on the frequency axis, and b be the frequency band index. It is the fundamental physical quantity that determines the potential communication rate of the frequency band. As a multiplicative factor of Shannon's formula, it, together with the signal-to-noise ratio, determines the theoretical maximum rate that the communication link can achieve on the frequency band. The maximum information transmission rate is used as the prior coefficient of the communication link on each frequency band, and the prior coefficient of the communication link on each frequency band is periodically updated to the path planning module. Based on Shannon's formula, and taking into account the noise floor, signal attenuation, and bandwidth of the receiving node in the communication link, the maximum achievable information transmission rate on each frequency band is calculated. The prior coefficients of each frequency band are periodically updated, enabling the system to respond promptly to changes in the channel environment. The prior coefficients provide a unified and quantifiable evaluation basis for link quality comparison and path selection in the path planning module.

[0024] The path planning module selects the optimal frequency band and target transmission path for all data transmission tasks based on the prior coefficients of the communication link in each frequency band to complete data transmission; the specific implementation process includes: Step 1: Real-time acquisition of the load parameters of the communication link on each frequency band. Specific load parameters include: the amount of data to be transmitted on frequency band b, the proportion of actual occupied time on frequency band b within the most recent fixed time period, and the retransmission rate. It should be noted that the amount of data to be transmitted refers to the sum of the data volume of data transmission tasks to be transmitted on frequency band b, reflecting the backlog level. The most recent fixed time period can be selected as the last 30 seconds or 1 minute, for example, the proportion of actual occupied time on frequency band b within the most recent 30 seconds, which represents the channel busyness. The remaining bandwidth is calculated based on the link's maximum theoretical rate and the currently used bandwidth. The retransmission rate refers to the proportion of data occupied within the most recent fixed time period. The data retransmission ratio of the communication link on frequency band b reflects the channel quality fluctuation. The amount of data to be transmitted is divided by the maximum amount of data to be transmitted allowed by the system to normalize the amount of data to be transmitted, and the congestion ratio is obtained. Then, a weight factor is assigned to the congestion ratio, the actual occupied time ratio, and the retransmission rate. The congestion ratio, the actual occupied time ratio, and the retransmission rate are linearly weighted and fused according to the assigned weight factors to obtain the load index. In this embodiment, the weight factors of the congestion ratio, the actual occupied time ratio, and the retransmission rate are 0.4, 0.4, and 0.2, respectively. The value range of the load index is [0,1], where 0 represents complete idleness and 1 represents extreme congestion. Step two involves obtaining the data transmission task. The data transmission task includes the source node, target node, data volume, and service type. It should be noted that the source node represents the starting point of data transmission, i.e., the communication node initiating the data transmission; the target node refers to the final recipient of the data, i.e., the destination to which the data is to be delivered. The data transmission task consists of a transmission path composed of at least one communication link. Service requirements include: second-level tasks, minute-level tasks, and emergency reporting tasks. In this embodiment, second-level tasks are typically second-level control tasks, and minute-level tasks are typically data acquisition tasks. Emergency reporting tasks require rapid access and high reliability, with the optimization objective being to minimize the number of hops and prioritizing links with high prior coefficients and low interference. For data transmission tasks, a restricted breadth-first search or Dijkstra's algorithm is used. The algorithm starts from the source node and traverses to the target node, recording all candidate transmission paths that do not exceed the maximum number of hops. In this embodiment, the maximum number of hops is set to 10, and one communication link in the candidate transmission path represents one hop. The maximum number of hops can be manually adjusted according to different application scenarios. For each candidate transmission path, it is decomposed into several communication links according to the data transmission direction. The prior coefficient γ of each communication link in each frequency band is identified, and the prior coefficient β is obtained by subtracting the prior coefficient using the load index. The subtraction formula is: β = γ × (1 - load index). Among the frequency bands in the communication link, the frequency band with the largest posterior coefficient is selected as the optimal frequency band of the communication link. Thus, the posterior coefficient of each communication link in the optimal frequency band of the candidate transmission path is denoted as βi, where i is the index of each communication link in the candidate transmission path. The posterior coefficients β of each communication link on the candidate data transmission path in the optimal frequency band are aggregated to obtain the transmission index, which quantifies the transmission capability of the candidate transmission path. The aggregation method can be adjusted according to the actual needs of the application scenario. For example, it can be calculated by multiplying the posterior coefficients β of each communication link in the candidate transmission path in the optimal frequency band. The arithmetic mean aggregation is calculated by arithmetically averaging the posterior coefficients β of each communication link in the optimal frequency band. In the specific application of this embodiment, in order to simplify and highlight the bottleneck characteristics of the transmission path, the minimum value model is adopted, that is, transmission index = min(βi). The transmission index reflects the worst-performing hop in the transmission path and is the key bottleneck that determines the end-to-end throughput and latency. Thus, the transmission index of the candidate transmission path for each data transmission task can be obtained. Step 3: When the data transmission task is a second-level or minute-level task, the candidate transmission path with the largest transmission index is selected as the target transmission path for the data transmission task. When the data transmission task is an emergency event reporting task, the hop count of each candidate transmission path is obtained, and the transmission index is divided by the hop count to obtain the energy efficiency index. The candidate transmission path with the largest energy efficiency index is selected as the target transmission path for the data transmission task. Whenever a data transmission task is assigned, the number of pending tasks on the corresponding communication link is incremented by one, and the corresponding amount of pending data is updated to Step 1. Step 4: For each communication link, when a data transmission task is to be sent, its optimal frequency band is used for data transmission. If there is an emergency event reporting task, its transmission task is placed at the top with the highest priority. If there is no emergency event reporting task, it is transmitted in batches according to a fixed time period. In this embodiment, the fixed time period is set to 3 minutes. Data transmission tasks to be sent within 3 minutes constitute a batch, and data transmission is performed sequentially according to the time of the batch. Data transmission satisfies the following constraints: different services within the same batch are transmitted sequentially according to service priority. The specific service priority order is: second-level tasks > minute-level tasks, and the same service type is transmitted sequentially according to time. By collecting real-time data on each link across each frequency band, including the amount of data to be transmitted, the proportion of time occupied, and the retransmission rate, and performing comprehensive analysis to obtain the load index, a posterior coefficient is obtained by subtracting the prior coefficient from the load index. The frequency band with the largest posterior coefficient is selected as the optimal frequency band, enabling transmission path selection to avoid congested frequency bands and achieving network load balancing. At the same time, different path selection strategies are designed for transmission tasks of different service types. Specific tasks at the second and minute levels pursue the maximum transmission index, while emergency reporting tasks pursue the maximum energy efficiency index, effectively meeting the differentiated requirements of different services for latency, reliability, and throughput. After each data transmission task is assigned, the amount of data to be transmitted on the corresponding link is immediately updated, so that load information can be quickly fed back into the path selection of subsequent tasks, forming a closed-loop congestion control process.

[0025] The dynamic loading unit is deployed inside the communication node. Within a selected optimal frequency band, it dynamically adjusts the modulation order and transmit power of each subcarrier based on real-time subcarrier-level channel state information to achieve bit loading, thereby approximating the channel capacity. The specific implementation process includes: Step one: Before sending data, the sending node obtains the latest channel state parameters between itself and the receiving node. Specific channel state parameters include: the background noise power, interference power, and average attenuation of each subcarrier within the currently used frequency band (i.e., the optimal frequency band); and for each subcarrier in the currently used frequency band, its transmission power P is determined. A，kWhere k represents the index of the subcarrier in the currently used frequency band; initially, uniform power allocation can be adopted, that is, the transmit power of each subcarrier is the maximum transmit power P of the node. A，k，max Divide by the total number of subcarriers in the current frequency band; if the system supports dynamic power allocation, the transmit power of each subcarrier can be adjusted according to channel quality; the receive power of the receiving node on subcarrier k is: P B，k =P A，k ×10 -d（k） / 10 , where d(k) is the attenuation of subcarrier k; the background noise power and interference power of each subcarrier in the current frequency band of the receiving node are summed and converted to watts to obtain the noise floor of subcarrier k; then the received power of the receiving node on subcarrier k is divided by the noise floor of subcarrier k to obtain the signal-to-noise ratio s(k) of subcarrier k in the optimal frequency band, which is used for subsequent modulation order allocation; Step two: With the target bit error rate as a constraint, the Chow algorithm is used to assign a modulation order m(k) and a corresponding power adjustment factor to each subcarrier, where m(k) is the number of bits carried by each symbol. The specific algorithm is as follows: Based on the signal-to-noise ratio (SNR) s(k) of the subcarrier, calculate the achievable bit error rate (BER) under a given modulation scheme. Select the modulation scheme with the highest BER that satisfies the target BER and determine the corresponding modulation order m(k). If variable power allocation is adopted, adjust the transmit power of the subcarriers according to their SNR s(k) to maximize the total transmission rate while ensuring that the total power does not exceed the maximum transmit power of the transmitting and receiving nodes. The adjustment principle is as follows: appropriately reduce the power of subcarriers with higher SNR, i.e., set the power adjustment factor to less than one; appropriately increase the power of subcarriers with lower SNR but not exceed the maximum power limit, i.e., set the power adjustment factor to greater than one, so as to maximize the total transmission rate while satisfying the total power constraint. If uniform power allocation is adopted, the power adjustment factor of all subcarriers is set to 1. Step 3: Summarize the modulation order m(k) and power adjustment factor of each subcarrier into a modulation parameter table. This table is used for subsequent symbol mapping and power amplification control. When transmitting data frames, put the modulation mode index or predefined configuration mode number of each subcarrier in the modulation parameter table into the frame control header so that the receiving node can demodulate correctly. Step four: After the receiving node successfully demodulates the data, it carries the latest subcarrier signal-to-noise ratio and the statistical bit error rate back to the transmitting node through an acknowledgment frame or a dedicated feedback frame. The transmitting node then re-executes steps one through three based on the feedback information to update the modulation parameter table and achieve adaptive tracking of channel changes. At the same time, the transmitting node monitors the bit error rate in the feedback: if it receives feedback with a bit error rate higher than the preset target value multiple times in a row, it increases the overall transmit power, but still keeps it below the node's maximum transmit power.

[0026] By employing the Chow algorithm to assign each subcarrier the modulation scheme with the highest order that satisfies the target bit error rate, the system can adaptively adjust the transmission rate based on the real-time signal-to-noise ratio, carrying more bits on high-quality subcarriers and reducing bits on low-quality subcarriers, thereby approaching the Shannon channel capacity.

[0027] like Figure 2 As shown, this embodiment of the invention provides a power line carrier communication method based on extended frequency bands, specifically including the following steps: Step 1: Periodically broadcast channel probe frames to obtain analog signals from each communication node; Step 2: Perform feature analysis based on the analog signal to obtain the characteristic parameters of the communication node and communication link in each frequency band. The characteristic parameters include the background noise power and interference intensity of the communication node, as well as the attenuation value of the communication link in each frequency band. Step 3: Calculate prior coefficients for each communication link based on the feature parameters. The prior coefficients are the maximum information transmission rates of the communication links in each frequency band, and update the prior coefficients periodically. Step 4: Based on the prior coefficients and the real-time acquired load parameters of the communication link on each frequency band, select a target transmission path for each data transmission task and allocate the optimal frequency band for each hop on the path; specifically: The load parameters of the communication link on each frequency band are acquired in real time. The load parameters include the amount of data to be transmitted, the proportion of actual occupied time in the most recent fixed time period, and the retransmission rate. The congestion ratio is obtained by normalizing the amount of data to be transmitted, and the congestion ratio, the proportion of actual occupied time, and the retransmission rate are linearly weighted and fused to obtain a load index with a value range of [0,1]. The prior coefficients are reduced by the load index to obtain the posterior coefficients, and the frequency band with the largest posterior coefficient is selected as the optimal frequency band for the communication link. Based on the source node and target node of the data transmission task, a limited breadth-first search or Dijkstra's algorithm is used to generate candidate transmission paths that do not exceed the preset maximum number of hops. The posterior coefficients of each communication link on the candidate path in the optimal frequency band are aggregated to obtain the transmission index that quantifies the transmission capacity of the candidate path, and the target transmission path is selected according to the service type of the data transmission task. Step 5: Within the optimal frequency band, dynamically adjust the modulation order and transmit power of each subcarrier based on the real-time subcarrier-level channel state; specifically: Before data transmission, the background noise power, interference power, and subcarrier attenuation of each subcarrier in the current optimal frequency band are obtained, and the signal-to-noise ratio (SNR) of each subcarrier is calculated. With a preset target bit error rate as a constraint, the Chow algorithm is used to assign a modulation order and power adjustment factor to each subcarrier, generating a modulation parameter table. The modulation mode index or predefined configuration mode number of the modulation parameter table is placed in the frame control header of the data frame to be transmitted. After successfully demodulating the data, the receiving node carries the latest subcarrier SNR and bit error rate back to the transmitting node via a feedback frame. The transmitting node re-executes the modulation parameter table generation process based on the feedback information and monitors the bit error rate to dynamically adjust the overall transmit power.

[0028] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0029] The preferred embodiments of the invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A power line carrier communication system based on extended frequency band, characterized in that, include: The concentrator periodically broadcasts channel probe frames to obtain analog signals from each communication node; The channel detection module is used to perform feature analysis based on the analog signal to obtain the characteristic parameters of the communication node and the communication link in each frequency band. The characteristic parameters include the background noise power and interference intensity of the communication node, as well as the attenuation value of the communication link in each frequency band. The frequency band detection module is used to calculate prior coefficients for each communication link based on the feature parameters. The prior coefficients are the maximum information transmission rates of the communication links on each frequency band, and the prior coefficients are updated periodically. The path planning module is used to select a target transmission path for each data transmission task based on the prior coefficients and the load parameters of the communication link in real time on each frequency band, and to allocate the optimal frequency band for each hop on the path. The dynamic loading unit, deployed inside each communication node, is used to dynamically adjust the modulation order and transmit power of each subcarrier within the optimal frequency band based on the real-time subcarrier and channel status.

2. The power line carrier communication system based on extended frequency band according to claim 1, characterized in that, The analysis process for background noise power and interference intensity of communication nodes includes: The analog signal is converted into a discrete time-domain sequence using a digital-to-analog converter, and then windowed and subjected to a Fast Fourier Transform to convert it to the frequency domain, obtaining the complex value X(f) for each frequency point, which corresponds to a subcarrier; the power spectral density P(f) = |X(f)| on each subcarrier is calculated. 2 / (R×Δf), where R is the receiver input impedance and Δf is the subcarrier spacing; the measurement is repeated at different times, and the power spectral density of each subcarrier is averaged over time to obtain the average background noise power spectral density; at the same time, the peak noise power on each subcarrier is recorded, and for each subcarrier, its long-term average power spectral density is taken as the background noise power of the subcarrier. The background noise power of all subcarriers in the frequency band is averaged to obtain the background noise power of the frequency band; For each subcarrier, the instantaneous power is compared with the background noise power. If the instantaneous power minus the background noise power is greater than the preset noise interference threshold, then the instantaneous power minus the background noise power is taken as the interference power of the affected subcarrier. Then, the interference power of all subcarriers in the frequency band is averaged to obtain the interference intensity of the frequency band.

3. The power line carrier communication system based on extended frequency band according to claim 2, characterized in that, The analysis process of communication link attenuation values ​​in each frequency band includes: Extract historical communication records, which include the sending and receiving nodes corresponding to the communication link in each communication record, the receiving time, the frequency band identifier used by the signal, the receiving power of each subcarrier of the receiving node in the frequency band, and the transmitting power used by the sending node when transmitting the signal; The interval time is calculated by subtracting the reception time of each record from the current system time. If the interval time is greater than a preset timeliness threshold, the record is discarded; only records with an interval time less than or equal to the preset timeliness threshold are retained. For each retained record, the set of subcarriers included in the frequency band is determined according to the frequency band used. If uniform power allocation is used, the transmission power of each subcarrier is the total transmission power divided by the number of subcarriers; if dynamic power allocation is used, the transmission power of each subcarrier is extracted from the frame header. For each subcarrier, the attenuation d of the signal on the subcarrier is calculated according to the following formula: d = 10 × log 10 (Transmit power) -10×log 10 (Received power); Take the arithmetic mean of the attenuation of all subcarriers in the frequency band to obtain the average attenuation in the frequency band; From this, the average attenuation of each record can be obtained. For the same link in the same frequency band, all average attenuations are sorted in descending order, and the median is selected as the attenuation value of the communication link in that frequency band. Thus, the attenuation value of each communication link in each frequency band can be obtained.

4. The power line carrier communication system based on extended frequency band according to claim 3, characterized in that, The prior coefficients for each communication link are calculated based on the aforementioned feature parameters, including: The noise floor is calculated by summing the background noise power and interference intensity at the receiving node in the communication link. The noise floor is then converted from decibels to watts. Next, the maximum transmit power of the transmitting node in the communication link is calculated, and the maximum receive power of the receiving node after frequency band attenuation is calculated using the formula: P B =P A，max ×10 -D / 10 Where A represents the sending node, B represents the receiving node, and P... A，max The maximum transmit power of the transmitting node is represented by D; the attenuation value of the communication link in the specified frequency band is represented by D; the signal-to-noise ratio (SNR) is obtained by dividing the maximum receive power of the receiving node B by the noise floor. b ; According to Shannon's formula, the maximum information transmission rate r achievable by receiving node B in a certain frequency band is calculated. b =W b ×log2(1+S) b ), where W b Let b be the width of frequency band b on the frequency axis, and b be the frequency band index; the maximum information transmission rate is used as the prior coefficient of the communication link on each frequency band.

5. The power line carrier communication system based on extended frequency band according to claim 4, characterized in that, The path planning module includes: The load parameters of the communication link on each frequency band are acquired in real time. The load parameters include the amount of data to be transmitted, the proportion of actual occupied time in the most recent fixed time period, and the retransmission rate. The congestion ratio is obtained by normalizing the amount of data to be transmitted, and the congestion ratio, the proportion of actual occupied time, and the retransmission rate are linearly weighted and fused to obtain a load index with a value range of [0,1]. The prior coefficients are reduced by the load index to obtain the posterior coefficients, and the frequency band with the largest posterior coefficient is selected as the optimal frequency band for the communication link. Based on the source node and target node of the data transmission task, a limited breadth-first search or Dijkstra's algorithm is used to generate candidate transmission paths that do not exceed the preset maximum number of hops. The posterior coefficients of each communication link on the candidate path in the optimal frequency band are aggregated to obtain the transmission index that quantifies the transmission capacity of the candidate path, and the target transmission path is selected according to the service type of the data transmission task.

6. The power line carrier communication system based on extended frequency band according to claim 5, characterized in that, The aggregation of posterior coefficients is performed using a minimum value model, whereby the transmission index is obtained by taking the minimum value of the posterior coefficients of each communication link in the candidate path at the optimal frequency band.

7. The power line carrier communication system based on extended frequency band according to claim 6, characterized in that, The step of selecting the target transmission path based on the service type of the data transmission task includes: When the data transmission task is a second-level or minute-level task, the candidate transmission path with the largest transmission index is selected as the target transmission path; when the data transmission task is an emergency reporting task, the ratio of the transmission index to the number of hops of each candidate path is calculated as the energy efficiency index, and the candidate transmission path with the largest energy efficiency index is selected as the target transmission path. After determining the optimal frequency band and target transmission path, transmission is performed sequentially according to the set priority.

8. The power line carrier communication system based on extended frequency band according to claim 7, characterized in that, The sequential transmission according to the set priority includes: Priority queues are set up on each communication link, with urgent reporting tasks having the highest transmission priority, followed by second-level tasks, and minute-level tasks having the lowest priority. When there is an urgent reporting task, it is directly transmitted at the top; otherwise, it is transmitted in batches according to fixed time periods. Within the same batch, it is transmitted in order of service priority, and within the same service type, it is transmitted in order of time.

9. The power line carrier communication system based on extended frequency band according to claim 8, characterized in that, The dynamic loading unit includes: Before data transmission, the background noise power, interference power, and subcarrier attenuation of each subcarrier in the current optimal frequency band are obtained, and the signal-to-noise ratio (SNR) of each subcarrier is calculated. With a preset target bit error rate as a constraint, the Chow algorithm is used to assign a modulation order and power adjustment factor to each subcarrier, generating a modulation parameter table. The modulation mode index or predefined configuration mode number in the modulation parameter table is placed in the frame control header of the data frame to be transmitted. After successfully demodulating the data, the receiving node carries the latest subcarrier SNR and bit error rate back to the transmitting node via a feedback frame. The transmitting node re-executes the modulation parameter table generation process based on the feedback information and monitors the bit error rate to dynamically adjust the overall transmit power.

10. A power line carrier communication method based on extended frequency band, characterized in that... The method applied to the power line carrier communication system based on any one of claims 1-9 includes the following steps: Step 1: Periodically broadcast channel probe frames to obtain analog signals from each communication node; Step 2: Perform feature analysis based on the analog signal to obtain the characteristic parameters of the communication node and communication link in each frequency band. The characteristic parameters include the background noise power and interference intensity of the communication node, as well as the attenuation value of the communication link in each frequency band. Step 3: Calculate prior coefficients for each communication link based on the feature parameters. The prior coefficients are the maximum information transmission rates of the communication links in each frequency band, and update the prior coefficients periodically. Step 4: Based on the prior coefficients and the real-time acquired load parameters of the communication link on each frequency band, select a target transmission path for each data transmission task and allocate the optimal frequency band for each hop on the path. Step 5: Within the optimal frequency band, dynamically adjust the modulation order and transmit power of each subcarrier according to the real-time subcarrier-level channel status.

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